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1
Tarawneh, Zeyad S. "Water supply in Jordan under drought conditions." Water Policy 13, no. 6 (May 26, 2011): 863–76. http://dx.doi.org/10.2166/wp.2011.094.
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This paper discusses the Mujib Dam reservoir's storage during the drought years of 2007–2009. It has been concluded that the policy of unplanned water release during the dry year 2007, when little attention was paid to the possibility of a continuation of the drought, contributed to the remarkable lack of surface water storage during 2008, another dry year. For better management and planning, this paper presents theoretical models to evaluate the occurrence probability and return period for extreme droughts, assuming that drought deficits are Beta distributed. Droughts of a short length (2–3 years) and deficits that exceed a threshold deficit (Do) are the most frequent droughts in the central Jordan region. Regardless of the drought deficit magnitude and the drought length, the return period of any drought condition is nearly 4 years. This paper recommends the application of large-scale sustainable solutions to reduce the gap between the demand on water and supply in Jordan during drought conditions. Furthermore, it is recommended that water losses from the clean water distribution systems be reduced below the existing loss rate, that large-scale rainwater capturing techniques are employed, and that large-scale desalination practices are applied to the readily available brackish and seawater in Jordan.
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Kapsambelis, Dorothée, David Moncoulon, and Jean Cordier. "An Innovative Damage Model for Crop Insurance, Combining Two Hazards into a Single Climatic Index." Climate 7, no. 11 (October 26, 2019): 125. http://dx.doi.org/10.3390/cli7110125.
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Extreme weather events have strong impacts on agriculture and crop insurance. In France, drought (2003, 2011, 2017, and 2018) and excess of water (2016) are considered the most significant events in terms of economic losses. The crop (re)insurance industry must estimate its financial exposure to climatic events in terms of the average annual losses and potential extreme damages. Therefore, the objective of this paper was to develop a model that links meteorological indices to crop yield losses with a specific focus on extreme climatic events. We designed a meteorological index (DOWKI: Drought and Overwhelmed Water Key Indicator) based on a water balance cumulative anomaly that can explain drought and excess of water at the department scale. We propose a crop damage model calibrated by combining historical yield records and the DOWKI values. To estimate the financial exposure of insured crops at a national level, stochastic simulations of the DOWKI were performed to produce one thousand years of yield losses. Our objective was to estimate the effect of climatic extremes affecting the global production. Simulated average annual losses and the possible maximum claim for three crops (soft winter wheat, winter barley, and sunflower) are presented in the results.
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Mátyás, Csaba, Imre Berki, András Bidló, György Csóka, Kornél Czimber, Ernő Führer, Borbála Gálos, et al. "Sustainability of Forest Cover under Climate Change on the Temperate-Continental Xeric Limits." Forests 9, no. 8 (August 10, 2018): 489. http://dx.doi.org/10.3390/f9080489.
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Climate change particularly threatens the xeric limits of temperate-continental forests. In Hungary, annual temperatures have increased by 1.2 °C–1.8 °C in the last 30 years and the frequency of extreme droughts has grown. With the aim to gain stand-level prospects of sustainability, we have used local forest site variables to identify and project effects of recent and expected changes of climate. We have used a climatic descriptor (FAI index) to compare trends estimated from forest datasets with climatological projections; this is likely for the first time such a comparison has been made. Four independent approaches confirmed the near-linear decline of growth and vitality with increasing hot droughts in summer, using sessile oak as model species. The correlation between droughts and the expansion of pest and disease damages was also found to be significant. Projections of expected changes of main site factors predict a dramatic rise of future drought frequency and, consequently, a substantial shift of forest climate classes, especially at low elevation. Excess water-dependent lowland forests may lose supply from groundwater, which may change vegetation cover and soil development processes. The overall change of site conditions not only causes economic losses, but also challenges long-term sustainability of forest cover at the xeric limits.
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Jemai, Sabrine, Manel Ellouze, Belgacem Agoubi, and Habib Abida. "Drought intensity and spatial variability in Gabes Watershed, south-eastern Tunisia." Journal of Water and Land Development 31, no. 1 (December 1, 2016): 63–72. http://dx.doi.org/10.1515/jwld-2016-0037.
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AbstractChronological series of monthly and annual precipitation data recorded in Gabes Watershed, south-eastern Tunisia, were analyzed. The study is based on the standardized precipitation index (SPI) values, computed for 10 rainfall stations over the period 1987–2012, which corresponds to an observatory period of 25 hydrologic years (from September to August). The results obtained show a great variability in SPI values. The historical evolution of the SPI made it possible to define the periods of excess and deficit, corresponding to wet and dry periods respectively. The wet years were found to be 1989–1990, 1995–1996 and 2006–2007 while the dry years were 1987–1988, 1996–1997, 2000–2001, 2001–2002, 2007–2008, 2008–2009 and 2009–2010. This clearly shows alternating wet and dry periods, but with drought episodes taking prevalence over rainy fronts throughout the study period. Indeed, a high tendency towards a drop in precipitation and important sequences of drought were observed. Spatial variability of drought throughout Gabes Watershed was examined by geostatistical analysis of SPI, as drought and rainfall distribution vary with latitude, longitude, topography and proximity to the Mediterranean Sea. The results obtained showed that, compared to coastal and southern areas, drought was observed to be more important in the West and the North of Gabes Watershed. The SPI showed that moderate droughts are generally more frequent than severe or extreme droughts in most of the Watershed.
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Minea, Gabriel, Georgiana Tudor, Florentina-Iuliana Stan, Gabriela Ioana-Toroimac, and Raluca Zamfir. "How can the grasslands under rainfall events modify water balance in drought conditions." Journal of Water and Land Development 38, no. 1 (September 1, 2018): 53–65. http://dx.doi.org/10.2478/jwld-2018-0042.
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AbstractTaking into account the well-established influence of hillslopes grasslands on runoff processes, the purpose of this study was to investigate how grasslands can affect the water flow pathways on hillslopes, in drought conditions. This study was performed in experimental grassland at plot-scale (e.g., Festuca pratensis), in temperate humid continental climatic conditions of Curvature Subcarpathians, Romania. The rainfall, evapotranspiration, and soil moisture daily data, respectively 208 rainfall and 16 rainfall-runoff events data measured in grassland hills during the growing season (1 April up to 30 September 2015 and 2016) were used. Our results suggest that a runoff event response in extreme drought conditions occurs on grasslands only if precipitation exceeds the threshold of 31 mm Hortonian overland flow (HOF), while this threshold drops to 17 mm during moderate droughts and up to 8 mm for wet conditions. The rainfall events up to 16 mm proved to be insufficient to completely saturate the soil. Therefore, HOF has only a minor contribution in drought conditions, on grassland and light on bare soil. A complementary and negative effect of grasslands in drought conditions is the water resources suppressing on hillslopes.
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Kane, Douglas L., Larry D. Hinzman, Robert E. Gieck, James P. McNamara, Emily K. Youcha, and Jeffrey A. Oatley. "Contrasting extreme runoff events in areas of continuous permafrost, Arctic Alaska." Hydrology Research 39, no. 4 (August 1, 2008): 287–98. http://dx.doi.org/10.2166/nh.2008.005.
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Spring snowmelt floods in the Arctic are common and can be expected every year, mainly because of the extensive snow cover that ablates relatively quickly. However, documentation of extreme flows (both low and high) in the Arctic is lacking in part because extreme flows are relatively rare and gauging sites are very sparse, with most of short duration. In the nested Kuparuk River research watersheds on the North Slope of Alaska, two large summer floods have been observed (July 1999 and August 2002) in the headwaters; these high flows are contrasted to the low flows (drought conditions) observed in the summers of 2005 and 2007. It is clear that the continuous permafrost and the limited near-surface storage in the shallow active layer are responsible for both the high and low flow responses. Or, stated another way, the active layer is a poor buffer to both floods and droughts. When contrasting summer floods with snowmelt floods, it is clear from flood frequency analyses that the smaller, high-gradient headwater basins will be dominated by summer floods while those watersheds draining the low gradient coastal plain will be dominated by snowmelt floods. The two summer floods in the headwaters had flows that were three to four times greater than the largest measured snowmelt flood, while on the coastal plain the 2002 summer storm for the whole of the Kuparuk River only produced the maximum summer runoff of record that was about 1/4 of the maximum snowmelt flood. So, on the coastal plain and even for the Greater Kuparuk River that drains across the coastal plain, snowmelt floods dominate. Drought conditions prevail in summers when the limited surface water storage in the active layer and surface water bodies is depleted because evapotranspiration exceeds precipitation.
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Martin, Justin T., Gregory T. Pederson, Connie A. Woodhouse, Edward R. Cook, Gregory J. McCabe, Kevin J. Anchukaitis, Erika K. Wise, et al. "Increased drought severity tracks warming in the United States’ largest river basin." Proceedings of the National Academy of Sciences 117, no. 21 (May 11, 2020): 11328–36. http://dx.doi.org/10.1073/pnas.1916208117.
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Across the Upper Missouri River Basin, the recent drought of 2000 to 2010, known as the “turn-of-the-century drought,” was likely more severe than any in the instrumental record including the Dust Bowl drought. However, until now, adequate proxy records needed to better understand this event with regard to long-term variability have been lacking. Here we examine 1,200 y of streamflow from a network of 17 new tree-ring–based reconstructions for gages across the upper Missouri basin and an independent reconstruction of warm-season regional temperature in order to place the recent drought in a long-term climate context. We find that temperature has increasingly influenced the severity of drought events by decreasing runoff efficiency in the basin since the late 20th century (1980s) onward. The occurrence of extreme heat, higher evapotranspiration, and associated low-flow conditions across the basin has increased substantially over the 20th and 21st centuries, and recent warming aligns with increasing drought severities that rival or exceed any estimated over the last 12 centuries. Future warming is anticipated to cause increasingly severe droughts by enhancing water deficits that could prove challenging for water management.
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Sharma, Kannan, Cook, Pokhrel, and McKenzie. "Analysis of the Effects of High Precipitation in Texas on Rainfed Sorghum Yields." Water 11, no. 9 (September 14, 2019): 1920. http://dx.doi.org/10.3390/w11091920.
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Most of the recent studies on the consequences of extreme weather events on crop yields are focused on droughts and warming climate. The knowledge of the consequences of excess precipitation on the crop yield is lacking. We attempted to fill this gap by estimating reductions in rainfed grain sorghum yields for excess precipitation. The historical grain sorghum yield and corresponding historical precipitation data are collected by county. These data are sorted based on length of the record and missing values and arranged for the period 1973–2003. Grain sorghum growing periods in the different parts of Texas is estimated based on the east-west precipitation gradient, north-south temperature gradient, and typical planting and harvesting dates in Texas. We estimated the growing season total precipitation and maximum 4-day total precipitation for each county growing rainfed grain sorghum. These two parameters were used as independent variables, and crop yields of sorghum was used as the dependent variable. We tried to find the relationships between excess precipitation and decreases in crop yields using both graphical and mathematical relationships. The result were analyzed in four different levels; 1. Storm by storm consequences on the crop yield; 2. Growing season total precipitation and crop yield; 3. Maximum 4-day precipitation and crop yield; and 4. Multiple linear regression of independent variables with and without a principal component analysis (to remove the correlations between independent variables) and the dependent variable. The graphical and mathematical results show decreases in rainfed sorghum yields in Texas for excess precipitation could be between 18% and 38%.
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Kajári, Balázs, Csaba Bozán, and Boudewijn Van Leeuwen. "Monitoring of Inland Excess Water Inundations Using Machine Learning Algorithms." Land 12, no. 1 (December 22, 2022): 36. http://dx.doi.org/10.3390/land12010036.
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Nowadays, climate change not only leads to riverine floods and flash floods but also to inland excess water (IEW) inundations and drought due to extreme hydrological processes. The Carpathian Basin is extremely affected by fast-changing weather conditions during the year. IEW (sometimes referred to as water logging) is formed when, due to limited runoff, infiltration, and evaporation, surplus water remains on the surface or in places where groundwater flowing to lower areas appears on the surface by leaking through porous soil. In this study, eight different machine learning approaches were applied to derive IEW inundations on three different dates in 2021 (23 February, 7 March, 20 March). Index-based approaches are simple and provide relatively good results, but they need to be adapted to specific circumstances for each area and date. With an overall accuracy of 0.98, a Kappa of 0.65, and a QADI score of 0.020, the deep learning method Convolutional Neural Network (CNN) gave the best results, compared to the more traditional machine learning approaches Maximum Likelihood (ML), Random Forest (RF), Support Vector Machine (SVM) and artificial neural network (ANN) that were evaluated. The CNN-based IEW maps can be used in operational inland excess water control by water management authorities.
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Lin, Chen, and Margret Sauter. "Control of root system architecture by phytohormones and environmental signals in rice." Israel Journal of Plant Sciences 67, no. 1-2 (February 25, 2020): 98–109. http://dx.doi.org/10.1163/22238980-20191108.
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Drought and flooding are environmental extremes and major threats to crop production. Water uptake is achieved by plant roots which have to explore new soil spaces to alleviate water deficit during drought or to cope with water excess during flooding. Adaptation of the root system architecture helps plants cope with such extreme conditions and is crucial for plant health and survival. While for dicot plants the well studied model plant Arabidopsis thaliana has provided insight into the genetic and molecular regulation of the root system, less information is available for monocot species, which include the agronomically important cereal crops. Rice (Oryza sativa L.) is a semi-aquatic monocot plant that develops strong tolerance to flooding. Flooding tolerance of rice is closely linked to its adaptive root system. The functional root system of rice is mainly composed of crown roots and is shifted to nodal adventitious roots during flooding which allows rice to maintain oxygen supply to the roots and to survive longer periods of partial submergence as compared with other crops. Likewise, a number of drought-tolerance traits of rice are the result of an altered root system architecture. Hence, the structure of the root system adapts to, both, flooding and drought. Understanding the regulatory mechanisms that control root system adaptation to extreme environments is a key task for scientists to accelerate the breeding efforts for stress-tolerant crops. This review summarizes recently identified genes and molecular mechanisms that regulate root system architecture in rice in response to drought and flooding.
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Melgarejo, Ana E., Paulina Ordoñez, Raquel Nieto, Cristina Peña-Ortiz, Ricardo García-Herrera, and Luis Gimeno. "Mechanisms for Severe Drought Occurrence in the Balsas River Basin (Mexico)." Atmosphere 12, no. 3 (March 11, 2021): 368. http://dx.doi.org/10.3390/atmos12030368.
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This work provides an assessment of the two most intense seasonal droughts that occurred over the Balsas River Basin (BRB) in the period 1980–2017. The detection of the drought events was performed using the 6 month scale standardized precipitation–evapotranspiration index (SPEI-6) and the 6 month standardized precipitation index (SPI-6) in October. Both indices were quite similar during the studied period, highlighting the larger contribution of precipitation deficits vs. temperature excess to the drought occurrence in the basin. The origin of the atmospheric water arriving to the BRB (1 May 1980–31 October 2017) was investigated by using a Lagrangian diagnosis method. The BRB receives moisture from the Caribbean Sea and the rest of the tropical Atlantic, the Gulf of Mexico, the eastern north Pacific and from three terrestrial evaporative sources: the region north of BRB, the south of BRB and the BRB itself. The terrestrial evaporative source of the BRB itself is by far the main moisture source. The two most intense drought events that occurred in the studied period were selected for further analysis. During the severe drought of 2005, the summertime sea surface temperature (SST) soared over the Caribbean Sea, extending eastward into a large swathe of tropical North Atlantic, which was accompanied by the record to date of hurricane activity. This heating generated a Rossby wave response with westward propagating anticyclonic/cyclonic gyres in the upper/lower troposphere. A cyclonic low-level circulation developed over the Gulf of Mexico and prevented the moisture from arriving to the BRB, with a consequent deficit in precipitation. Additionally, subsidence also prevented convection in most of the months of this drought period. During the extreme drought event of 1982, the Inter Tropical Convergence Zone (ITCZ) remained southern and stronger than the climatological mean over the eastern tropical Pacific, producing an intense regional Hadley circulation. The descent branch of this cell inhibited the development of convection over the BRB, although the moisture sources increased their contributions; however, these were bounded to the lower levels by a strong trade wind inversion.
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Faski, G. I. S. L., Ig L. S. Purnama, and S. Suprayogi. "Application of hydrometeorological data to analyze water balance conditions in Bengkulu watershed." IOP Conference Series: Earth and Environmental Science 893, no. 1 (November 1, 2021): 012078. http://dx.doi.org/10.1088/1755-1315/893/1/012078.
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Abstrak Water balance serves to determine hydrological conditions in a watershed, one of which is by analyzing the surplus (excess water) and deficit (water shortage) that occurs. Extreme surpluses or deficits can cause hydrometeorological disasters, such as floods or droughts. This study aims to calculate the monthly water balance using the Thornthwaite-Mather method to determine variations in the incidence of surplus and deficit months in all three sub-watersheds in Bengkulu Watershed, namely Rindu Hati, Susup, and Bengkulu Hilir sub-watershed. The data used are monthly hydrometeorological data for 2009-2018 (10 years) were divided into two periods of water balance based on land use data. Water balance period 1 (2009-2013) uses 2009 land use data, while period 2 (2014-2018) uses 2014 land use data. The results show that the surplus, deficit, runoff, and discharge in the three sub-watersheds in the Bengkulu watershed are affected by rainfall. In general, the deficit incidents in all three sub-watersheds occur almost every three years. The Rindu Hati and Susup sub-watersheds have the same variations of surplus and deficit month incidents, while the Bengkulu Hilir sub-watershed is different, both in periods 1 and 2. It is not only the rainfall that affects the variation in the events of surplus and deficit in all three sub-watersheds of the Bengkulu watershed, but also the amount of water holding capacity (WHC). Therefore, the application of hydrometeorological data to analyze the water balance conditions in the Bengkulu watershed provides information on climate impact on water resources and environmental impact on flows in the watershed.
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Marchina, Chiara, Claudio Natali, and Gianluca Bianchini. "The Po River Water Isotopes during the Drought Condition of the Year 2017." Water 11, no. 1 (January 16, 2019): 150. http://dx.doi.org/10.3390/w11010150.
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The year 2017 was anomalously warm and dry across the whole Italian Peninsula, and the paucity of precipitation was emphasized during the extreme summer drought of the main Italian river, i.e., the Po river, which was characterized by a discharge persistently below 600 m3/s (in spite of the average discharge of 1500 m3/s). During these extreme conditions, the Po river oxygen and hydrogen stable isotopes (δD, δ18O) displayed a relation (δD = 6.1*δ18O − 6.6) significantly different from that recorded in the previous investigation of the years 2012–2014 (δD = 7.5*δ18O + 6.5). The lowering of the slope and the negative intercept clearly reflect the transition toward arid conditions that characterized the investigated period. The difference is expressed by the derivative parameter Line-Conditioned excess (LC-exc), which better describes the compositional difference of Po river water in the year 2017 with respect to that of the period 2012–2014, when the system was less affected by warm or dry conditions and the river discharge was more similar to the historical trends. The isotopic anomaly observed in 2017 throughout the river is even greater in the terminal part of the river, where in the meanders of the deltaic branches, the river flow progressively slows down, suffering significant evaporation. The isotopic signature of the water appears, therefore, an appropriate tool to monitor the watershed response to evolving environmental conditions. These sensitive isotopic parameters could be interpreted as “essential climate variables” (ECV) that are physical, chemical, or biological geo-referenced parameters that critically contribute to the characterization of Earth’s climate. Future research needs to find relationships between ECV (including the water stable isotopes) and the evolution of ecosystems, which especially in the Mediterranean area, appear to be fragile and severely affected by natural and anthropogenic processes.
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Mohy, Hala Mohammad, and Basim Sh Abed. "Design of Expert System for Managing the System of AthTharthar Lake." Journal of Engineering 26, no. 1 (December 25, 2019): 142–59. http://dx.doi.org/10.31026/j.eng.2020.01.11.
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The operation and management of water resources projects have direct and significant effects on the optimum use of water. Artificial intelligence techniques are a new tool used to help in making optimized decisions, based on knowledge bases in the planning, implementation, operation and management of projects as well as controlling flowing water quantities to prevent flooding and storage of excess water and use it during drought.
In this research, an Expert System was designed for operating and managing the system of AthTharthar Lake (ESSTAR). It was applied for all expected conditions of flow, including the cases of drought, normal flow, and during floods. Moreover, the cases of hypothetical operating of flow under extreme conditions were considered. The results showed a good capability of the designed expert system to operate the potential cases for those discharges and with high efficiency. Also the results showed the inability of AthTharthar Lake System to pass the discharge up to 12600 m3/s during floods. It was recommended to accomplish Tigris River training and increasing the level of levees, reshaping the cross-sections and longitudinal section of the river. It was suggested to expanded AthTharthar Head Regulator and the intake canal to accommodate more flood discharges.
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Szwed, M., G. Karg, I. Pińskwar, M. Radziejewski, D. Graczyk, A. Kędziora, and Z. W. Kundzewicz. "Climate change and its effect on agriculture, water resources and human health sectors in Poland." Natural Hazards and Earth System Sciences 10, no. 8 (August 19, 2010): 1725–37. http://dx.doi.org/10.5194/nhess-10-1725-2010.
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Abstract. Multi-model ensemble climate projections in the ENSEMBLES Project of the EU allowed the authors to quantify selected extreme-weather indices for Poland, of importance to climate impacts on systems and sectors. Among indices were: number of days in a year with high value of the heat index; with high maximum and minimum temperatures; length of vegetation period; and number of consecutive dry days. Agricultural, hydrological, and human health indices were applied to evaluate the changing risk of weather extremes in Poland in three sectors. To achieve this, model-based simulations were compared for two time horizons, a century apart, i.e., 1961–1990 and 2061–2090. Climate changes, and in particular increases in temperature and changes in rainfall, have strong impacts on agriculture via weather extremes – droughts and heat waves. The crop yield depends particularly on water availability in the plant development phase. To estimate the changes in present and future yield of two crops important for Polish agriculture i.e., potatoes and wheat, some simple empirical models were used. For these crops, decrease of yield is projected for most of the country, with national means of yield change being: –2.175 t/ha for potatoes and –0.539 t/ha for wheat. Already now, in most of Poland, evapotranspiration exceeds precipitation during summer, hence the water storage (in surface water bodies, soil and ground) decreases. Summer precipitation deficit is projected to increase considerably in the future. The additional water supplies (above precipitation) needed to use the agro-potential of the environment would increase by half. Analysis of water balance components (now and in the projected future) can corroborate such conclusions. As regards climate and health, a composite index, proposed in this paper, is a product of the number of senior discomfort days and the number of seniors (aged 65+). The value of this index is projected to increase over 8-fold during 100 years. This is an effect of both increase in the number of seniors (over twofold) and the number of senior-discomfort days (nearly fourfold).
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Das, N. N., K. Andreadis, and A. Ines. "MONITORING AND FORECASTING OF SEASONAL RICE CROP PRODUCTIVITY FOR PADDY DOMINATED REGIONS OF INDIA." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W6 (July 26, 2019): 201–9. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w6-201-2019.
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<p><strong>Abstract.</strong> The relevance of this study is immense for India. The Indian economy largely depends on agriculture, which is impacted by weather extremes and variability in monsoon. India is more vulnerable to disruption from drought than countries like the United States. While agriculture accounts for just 16 percent of India’s economy, half of its 1.3 billion people work on farms, thus, making agriculture the backbone of the Indian economy. However, in agriculture, rice is India’s most important food crop with nearly 1 billion Indian people reliant on it as their major food source. Most important constraint to rice production is water stress which affects nearly ~40 million ha of rainfed system from the total ~45 million ha area under rice cultivation. Future climate change effects on rainfall timing and amount, and projected increases in temperature are expected to exacerbate existing water stresses and will have a direct impact on agriculture in India, especially rice cultivation. We have developed an integrated system that is successfully implemented in many countries. The integrated system RHEAS (Regional Hydrological Extreme and Assessment System) coupled with M-DSSAT (modified DSSAT crop model) ingests various NASA Earth science data to produce a set of relevant hydrologic products (e.g., drought indices, water excess/stress information) and rice yields nowcasts (current conditions), forecasts, and seasonal projections, and then feed them into the operational agency. The overarching goal of this study is to provide this integrated system to stakeholder to improve decision-making process and mitigate the plights of rice farmers and prepare the country to deal with ground realities based on the forecast of rice production.</p>
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Da Silva, Djane Fonseca, Maria José DA SILVA LIMA, PEDRO FERNANDES DE SOUZA NETO, Heliofábio Barros Gomes, Fabrício Daniel Dos Santos Silva, Henrique ravi Rocha de carvalho Almeida, Rafaela Lisboa Costa, and Marcos Paulo Santos Pereira. "Caracterização de eventos extremos e de suas causas climáticas com base no Índice Padronizado de Precipitação Para o Leste do Nordeste." Revista Brasileira de Geografia Física 13, no. 2 (April 7, 2020): 449. http://dx.doi.org/10.26848/rbgf.v13.2.p449-464.
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Os eventos climáticos extremos demonstram um papel significativo das sociedades, seja por sua intensidade, pela frequência de ocorrência ou pela vulnerabilidade socioambiental. Objetiva-se classificar e quantificar as precipitações na porção leste da região Nordeste (NE) do Brasil através do índice SPI, como também detectar maiores déficits e/ou excesso de precipitação. O Standardized Precipitation Index (SPI) foi utilizado para quantificar déficits de precipitação e identificar eventos secos e chuvosos em diferentes escalas temporais, auxiliando no monitoramento da sua dinâmica temporal. No cálculo do SPI foi utilizado a distribuição gama, e estimados os limites de precipitação que representam a cada categoria do índice. Foram utilizados dados pluviométricos das capitais dos estados que compõem no leste do Nordeste do Brasil, no período de 1961 a 2014 provenientes da Agência Nacional das Águas (ANA). A análise de Ondeletas foi utilizada com objetivo de identificar ciclos de extremos pluviométricos e de suas causas através das escalas temporais detectadas em séries de precipitação para as capitais do leste do Nordeste do Brasil. Os resultados mostraram que as ocorrências de secas foram as maiores em todas as cidades, todavia na categoria extrema os eventos chuvosos revelaram-se mais frequentes. Os anos normais foram os mais persistentes em todas cidades analisadas. Recife apresentou máximas ocorrências de eventos chuvosos. Os eventos com intensidade extrema, seja chuvoso ou seco, ocorreram em boa parte da série em anos de ENOS. O SPI revelou-se uma excelente ferramenta na detecção e no monitoramento de seca/chuvas na região analisada. A presença de escalas temporais relacionadas com eventos ENOS, Dipolo do Atlântico, ciclo de manchas solares e Oscilação Decadal do Pacífico foram identificadas em todas as capitais do leste do NEB. Characterization of Drought Events Based on the Standardized of Precipitation Index for the East NortheastA B S T R A C TExtreme weather events demonstrate a significant role for societies, whether by their intensity, frequency of occurrence or socio-environmental vulnerability. Objective-classify and quantify as precipitation in the eastern portion of the Northeast (NE) of Brazil through the SPI index, as well as detect larger deficits and / or excess occurrence. The Standardized Precipitation Index (SPI) was used to quantify use deficits and to identify dry and rainy events in different temporal variations, helping to monitor their temporal utilization. No SPI calculations were used for gamma distribution, and estimated capture limits representing each category of the index. Rainfall data were used from the capitals of the states that make up the eastern Northeast of Brazil, with no period from 1961 to 2014, Registration of the National Water Agency (ANA). A wave analysis was used to identify extreme rainfall cycles and their causes caused by temporary variations detected in monitoring series for the eastern capitals of Brazil. The results shown as drought occurrences were the highest in all cities, however in the extreme category of rain events most frequently revealed. The normal years were the most persistent in all cities analyzed. Recife presents maximum occurrences of rain events. Extreme intensity events, whether rainy or dry, occur in much of the series in ENSO years. The SPI revealed an excellent tool for detection and monitoring of drought / gloves in the analyzed region. The presence of temporary variations related to ENOS, Atlantic Dipole, sunspot cycle and Pacific Oscillation events are identified in all eastern NEB capitals.Keywords: SPI; extreme rainfall; drought; Wavelet analysis.
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Novaes da Silva, Gabriel Italo, Pedro José Hermínio, Antonio Gebson Pinheiro, Alexandre Maniçoba Da Rosa Ferraz Jardim, Renan Matheus Cordeiro Leite, Thieres George Freire da Silva, and Luciana Sandra Bastos de Souza. "Entendendo as Características Associadas à Precipitação Para uma Região do Nordeste Paraense: Uma Análise do Comportamento, Tendência, Eventos Extremos e Tempo de Retorno para o período de 1973-2010." Revista Brasileira de Geografia Física 14, no. 6 (December 31, 2021): 3173. http://dx.doi.org/10.26848/rbgf.v14.6.p3173-3192.
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Este trabalho utilizou uma série de dados de precipitação referente ao período de 1973 à 2010 para o município de Castanhal-PA com a finalidade de investigar: 1) os padrões de precipitação; 2) as mudanças de tendência; 3) a ocorrência dos eventos de déficit e excesso de água pelo uso do Índice Padronizado de Precipitação (SPI) e suas relações com fenômenos atmosféricos como El Niño e La Niña; 4) a associação entre a probabilidade de ocorrência das chuvas e o tempo de retorno (TR). Para tanto, utilizaram-se dados de chuva obtidos em uma estação pluviométrica da Agência Nacional de Águas e Saneamento Básico (ANA). Os dados foram analisados por períodos, tendo sido considerados os intervalos: mensais, trimestrais, anuais ou decadais realizando estatística descritiva, para entendimento da variação sazonal, valores médios, análise da tendência por meio do teste não paramétrico de Mann-Kendall e da ocorrência de valores extremos associados à probabilidade de ocorrência e tempo de retorno. Nossos resultados demonstraram que: a média anual de precipitação para o período estudado foi de 2573,15mm; o intervalo de 2003-2010 foi aquele de menor variação nos valores de precipitação anual. Não foram observadas tendências nos valores de precipitação durante o período analisado. O SPI-1 mostrou boa adequabilidade a ocorrência dos valores extremos de precipitação no local em alguns casos associado aos fenômenos El Niño e La Niña. O maior (4.709,4 mm) e menor (1.379,6 mm) volume de chuva foram observados nos anos de 1994 e 1981, respectivamente, com probabilidade de ocorrência de 3% e TR = 39 anos. Understanding the Characteristics Associated with Precipitation for a Northeastern Region of Pará: An Analysis of Behavior, Tendency, Extreme Events and Time of Return for the 1973-2010 period A B S T R A C TThis work used a series of precipitation data for the period 1973 to 2010 for the municipality of Castanhal-PA in order to investigate: 1) precipitation patterns; 2) changes in trend; 3) the occurrence of deficit and excess water events using the Standardized Precipitation Index (SPI) and its relationship with atmospheric phenomena such as El Niño and La Niña; 4) the association between the probability of rain occurrence and the return time (TR). For this purpose, rainfall data obtained from a rainfall station of the National Water and Basic Sanitation Agency (ANA) were used. Data were analyzed by periods, considering the intervals: monthly, quarterly, annual or decadal performing descriptive statistics, to understand seasonal variation, mean values, trend analysis using the nonparametric Mann-Kendall test and the occurrence of extreme values associated with the probability of occurrence and turnaround time. Our results showed that: the mean annual rainfall for the period studied was 2573.15mm; the 2003-2010 interval was the one with the smallest variation in annual precipitation values. There were no trends in precipitation values during the analyzed period. SPI-1 showed good suitability for the occurrence of extreme precipitation values at the site in some cases associated with the El Niño and La Niña phenomena. The highest (4,709.4 mm) and lowest (1,379.6 mm) volume of rainfall were observed in 1994 and 1981, respectively, with a probability of occurrence of 3% and TR = 39 years.Keywords: Rainfall; Droughts; Floods; Atmospheric phenomena.
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Túri, Norbert, János Rakonczai, and Csaba Bozán. "Condition Assessment of Subsurface Drained Areas and Investigation of their Operational Efficiency by Field Inspection and Remote Sensing Methods." Journal of Environmental Geography 14, no. 3-4 (November 1, 2021): 14–25. http://dx.doi.org/10.2478/jengeo-2021-0008.
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Abstract The extreme weather events highlight the need to develop action concepts to maintain agricultural production security in the future. Hydrological extremes can occur within a year in the form of surplus water (i.e. inland excess water), water scarcity or even drought. These adverse effects are influenced, inhibited and also facilitated by human activity. Previously, complex amelioration interventions, including subsurface drainage, aimed to improve the productivity of agricultural areas with unfavourable water management properties. The current efficiency of the subsurface drain networks in the regulation of groundwater level or soil moisture content can be questioned from several aspects. After the end of the socialist era (after 1990s), lack of maintenance and operation tasks have become typical, and are still a problem today in Hungary. Unfortunately, there is no exact national cadastre on the tile drained areas, and data is only available to a limited extent in the original amelioration plan documentations. In the present study, we aimed to reveal the possibilities of delineating the subsurface drained areas, and to develop a new method of condition assessment. Three tile drained study sites were selected on the Great Hungarian Plain in Central Europe. Our field investigations revealed the typical problems of the drained areas: (1) excessive vegetation of the receiving channels; (2) inadequate condition of the receiving main channel bed; (3) soil compaction in multiple layers above the drainage network; and (4) poor condition of outlets of the drain pipes. The developed methodology enabled us to evaluate the soil and the surface/subsurface water of the tile drained areas, and the technical condition of the drains. The necessary action plans or treatments were also outlined to replace the unused drain networks into use. Based on the scientific literature, we also sketched the target conditions and technological solutions that are required for the installation of new drains. The organization of the derived data into a GIS database could serve as a basis for the development of a cadastre of the tile drained areas based on a regional approach.
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Hrachowitz, M., R. Bohte, M. L. Mul, T. A. Bogaard, H. H. G. Savenije, and S. Uhlenbrook. "On the value of combined event runoff and tracer analysis to improve understanding of catchment functioning in a data-scarce semi-arid area." Hydrology and Earth System Sciences 15, no. 6 (June 27, 2011): 2007–24. http://dx.doi.org/10.5194/hess-15-2007-2011.
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Abstract. Hydrological processes in small catchments are not quite understood yet, which is true in particular for catchments in data scarce, semi-arid regions. This is in contrast with the need for a better understanding of water fluxes and the interactions between surface- and groundwater in order to facilitate sustainable water resources management in such environments, where both floods and droughts can result in severe crop loss. In this study, event runoff coefficient analysis and limited tracer data of four small, nested sub-catchments (0.4–25.3 km2) in a data scarce, semi-arid region of Tanzania helped to characterize the distinct response of the study catchments and to gain insights into the dominant runoff processes. The estimated event runoff coefficients were very low and did not exceed 0.09. They were found to be significantly related to the 5-day antecedent precipitation totals as well as to base flow, indicating a close relation to changes in soil moisture and thus potential switches in runoff generation processes. The time scales of the "direct flow" reservoirs, used to compute the event runoff coefficients, were up to one order of magnitude reduced for extreme events, compared to "average" events, suggesting the activation of at least a third flow component, besides base- and direct flow, assumed to be infiltration overland flow. Analysis of multiple tracers highlighted the importance of pre-event water to total runoff, even during intense and high yield precipitation events. It further illustrated the distinct nature of the catchments, in particular with respect to the available water storage, which was suggested by different degrees of tracer damping in the individual streams. The use of multiple tracers subsequently allowed estimating uncertainties in hydrograph separations arising from the use of different tracers. The results highlight the presence of considerable uncertainties, emphasizing the need for multiple tracers in order to avoid misleading results. This study shows the value of hydrological data collection over one whole wet season using multi-tracers to improve the understanding of hydrological functioning and thus for water resources management in data scarce, semi-arid environments.
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Tamás, János, Attila Nagy, and Tamás Németh. "Risks of agricultural water management and opportunities to reduce them in V4 countries." Scientia et Securitas 2, no. 4 (March 26, 2022): 459–67. http://dx.doi.org/10.1556/112.2021.00064.
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Summary. The food security with good and excellent nutrition quality and food safety with food quantity in the V4 countries is a strategic issue, where society is less tolerant of the risk that can be caused by a short-term disruption of supply chain. Climate change is leading to more extreme weather anomalies, with increasing frequency and intensive amplitudes of drought, floods and excess waters and serious agricultural damages. Agricultural water management problems overlap more national borders, so an agricultural geopolitical risk assessment is justified that would allow for a more coherent cross-border integrated territorial water management decision-making process. In this study, the authors review climatic, hydrological, and crop production risks based on the major river basins in the V4 countries. Összefoglalás. A V4-ek országaiban a megfelelő mennyiségű és minőségű élelmiszer folyamatos biztosítása stratégiai kérdés, amelynek rövid idejű zavara is jelentős kockázatokat és társadalmi feszültségeket okozhat. A klímaváltozás egyre szélsőségesebb időjárási anomáliák előfordulásával jár, aminek következtében nő az aszály, árvíz és a belvizek mezőgazdasági kártétele. A mezőgazdasági termelés az egyik legnagyobb vízfelhasználó gazdasági tevékenység a világon, így annak térben és időben történő optimalizálása a klímaadaptáció kulcsterülete. A mezőgazdasági vízgazdálkodási problémák túlnyúlnak az országok határain, így indokolt egy olyan mezőgazdasági geopolitikai értékelése a kockázatoknak, amely lehetővé tenné egy egységesebb határokon átnyúló integrált területi vízgazdálkodási döntéshozatal megalapozottságát. A publikációban a szerzők áttekintik a V4 országainak főbb vízgyűjtői alapján a klimatikus, hidrológiai és termesztéstechnológiai kockázatokat. Az öntözési lehetőség és a tényleges öntözés kulcsszerepet játszik a termés mennyiségének és minőségének stabilitásában. A fokozott vízigényű időszakban fellépő aszály rontja a terméshozamot, mind mennyiségi, mind minőségi szempontból. A termésbiztonság érdekében feltételesen öntözhető északi területeken 4-5 évente (Lengyelország), a V4 országok dél-magyarországi területein 2-3 évente szükséges öntözni. Ennek hiányában akár 50-70%-os terméskieséssel is számolhatunk. Mivel a V4-ek messze elmaradnak Nyugat-Európa és a mediterrán térség öntözési kapacitásától, így ha a jövőben az öntözési lehetőség nem bővül a V4 országokban, a társadalomnak egyre inkább az öntözés nélküli termesztés veszélyével kell szembenéznie. Ugyanakkor különösen a gyümölcs- és zöldségtermesztés megköveteli az öntözhetőséget. A legelőterületek és a tömegtakarmányok lehetséges csökkenő mennyisége és minősége súlyosan befolyásolni fogja az állati termékek árát, különösen a vízigényes marha- és sertéshús, valamint a tejtermékek esetében. Az emelkedő fogyasztói árak azonban egyre kevésbé megfizethetőek a társadalom szegényebb része számára. A felszíni víztározásban és a vízgazdálkodásban nagy lehetőségek rejlenek, amelyeknek a rendelkezésre álló pénzügyi források szabnak határt. A felszíni víztestek minősége gyakran nem felel meg az öntözővíz minőségi követelményének, így egyre nagyobb a nyomás a felszín alatti vízbázisokra, ami veszélyezteti az ivóvíz minőségét. A közeljövőben ezért fokozni kell a kapacitásépítést és a rendelkezésre álló jó gyakorlatok megosztását a határokon átnyúló fenntartható területi vízgazdálkodás szereplői között.
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Zhang, Xiaodan, Guoyu Ren, Yuda Yang, He Bing, Zhixin Hao, and Panfeng Zhang. "Extreme historical droughts and floods in the Hanjiang River Basin, China, since 1426." Climate of the Past 18, no. 8 (August 3, 2022): 1775–96. http://dx.doi.org/10.5194/cp-18-1775-2022.
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Abstract. The major droughts and floods in the Hanjiang River Basin, central China, have a significant impact on flood prevention and control in the middle reaches of the Yangtze River and water resources management in the areas of the South–North Water Diversion Middle Line Project. However, there is a lack of understanding of the multi-decadal to centennial-scale patterns of extreme droughts and floods in the area. Applying the yearly drought and flood records from historical documents and precipitation data in the period of instrumental measurements, this study constructs a time series of extreme droughts and floods in the Hanjiang River Basin from 1426–2017 and analyzes the temporal and spatial characteristics of the extreme drought and flood event variations. The results show that there were a total of 45 extreme droughts and 52 extreme floods in the basin over the past 592 years. Extreme droughts and floods were highly variable on a multi-decadal to centennial scale, and the frequencies were higher in the first and last 100 years or so of the study period and lower in between. Spatially, the frequencies of extreme droughts and floods were generally higher in the middle and lower reaches than in the upper reaches. It was also found that there is a good correlation of drought and flood frequencies between the upper Hanjiang River Basin and North China. These results are informative for the study of mechanisms and predictability of multi-decadal to centennial-scale variability of extreme hydroclimatic events in the river basin.
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Getirana, Augusto. "Extreme Water Deficit in Brazil Detected from Space." Journal of Hydrometeorology 17, no. 2 (January 27, 2016): 591–99. http://dx.doi.org/10.1175/jhm-d-15-0096.1.
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Abstract Extreme droughts have caused significant socioeconomic and environmental damage worldwide. In Brazil, ineffective energy development and water management policies have magnified the impacts of recent severe droughts, which include massive agricultural losses, water supply restrictions, and energy rationing. Spaceborne remote sensing data advance our understanding of the spatiotemporal variability of large-scale droughts and enhance the detection and monitoring of extreme water-related events. In this study, data derived from the Gravity Recovery and Climate Experiment (GRACE) mission are used to detect and quantify an extended major drought over eastern Brazil and provide estimates of impacted areas and region-specific water deficits. Two structural breakpoint detection methods were applied to time series of GRACE-based terrestrial water storage anomalies (TWSA), determining when two abrupt changes occurred. One, in particular, defines the beginning of the current drought. Using TWSA, a water loss rate of −6.1 cm yr−1 over southeastern Brazil was detected from 2012 to 2015. Based on analysis of Global Land Data Assimilation System (GLDAS) outputs, the extreme drought is mostly related to lower-than-usual precipitation rates, resulting in high soil moisture depletion and lower-than-usual rates of evapotranspiration. A reduction of 20%–23% of precipitation over an extended period of 3 years is enough to raise serious water scarcity conditions in the country. Correlations between monthly time series of both grid-based TWSA and ground-based water storage measurements at 16 reservoirs located within southeastern Brazil varied from 0.42 to 0.82. Differences are mainly explained by reservoir sizes and proximity to the drought nucleus.
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Kapsambelis, Dorothée, David Moncoulon, Martine Veysseire, Jean-Michel Soubeyroux, and Jean Cordier. "Modeling the Impact of Extreme Droughts on Agriculture under Current and Future Climate Conditions Using a Spatialized Climatic Index." Applied Sciences 12, no. 5 (February 27, 2022): 2481. http://dx.doi.org/10.3390/app12052481.
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Extreme droughts have a strong impact on agricultural production. In France, the 2003 drought generated records of yield losses at a national scale for grassland (more than 30%) and for cereals (more than 10% for soft winter wheat and winter barley). These extreme events raise the question of farm resilience in the future. Studying them makes it possible to adapt risk management policy to climate change. Therefore, the objective of this paper was to analyze the frequency and the intensity of extreme drought in 2050 and their impact on crop yield losses (grassland and cereals) in France. We used the DOWKI (Drought and Overwhelmed Water Key Indicator) meteorological index based on a cumulative water anomaly, which can explain droughts and their consequences on agricultural yield losses at a departmental scale. Then, using the ARPEGE-Climat Model developed by Meteo-France, DOWKI was projected in 2050 and grassland, soft winter wheat, and winter barley yield losses were simulated. The results compare the frequency and intensity of extreme droughts between the climate in 2000 and 2050. Our results show that the frequency of extreme droughts (at least as intense as in 2003) doubled in 2050. In addition, the yield losses due to 10-year droughts increased by 35% for grassland and by more than 70% for cereals.
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Lai, Peiyu, Miao Zhang, Zhongxi Ge, Binfei Hao, Zengjing Song, Jing Huang, Mingguo Ma, Hong Yang, and Xujun Han. "Responses of Seasonal Indicators to Extreme Droughts in Southwest China." Remote Sensing 12, no. 5 (March 3, 2020): 818. http://dx.doi.org/10.3390/rs12050818.
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Significant impact of extreme droughts on human society and ecosystem has occurred in many places of the world, for example, Southwest China (SWC). Considerable research concentrated on analyzing causes and effects of droughts in SWC, but few studies have examined seasonal indicators, such as variations of surface water and vegetation phenology. With the ongoing satellite missions, more and more earth observation data become available to environmental studies. Exploring the responses of seasonal indicators from satellite data to drought is helpful for the future drought forecast and management. This study analyzed the seasonal responses of surface water and vegetation phenology to drought in SWC using the multi-source data including Seasonal Water Area (SWA), Permanent Water Area (PWA), Start of Season (SOS), End of Season (EOS), Length of Season (LOS), precipitation, temperature, solar radiation, evapotranspiration, the Palmer Drought Severity Index (PDSI), the Normalized Difference Vegetation Index (NDVI), the Enhanced Vegetation Index (EVI), Gross Primary Productivity (GPP) and data from water conservancy construction. The results showed that SWA and LOS effectively revealed the development and recovery of droughts. There were two obvious drought periods from 2000 to 2017. In the first period (from August 2003 to June 2007), SWA decreased by 11.81% and LOS shortened by 5 days. They reduced by 21.04% and 9 days respectively in the second period (from September 2009 to June 2014), which indicated that there are more severe droughts in the second period. The SOS during two drought periods delayed by 3~6 days in spring, while the EOS advanced 1~3 days in autumn. All of PDSI, SWA and LOS could reflect the period of droughts in SWC, but the LOS and PDSI were very sensitive to the meteorological events, such as precipitation and temperature, while the SWA performed a more stable reaction to drought and could be a good indicator for the drought periodicity. This made it possible for using SWA in drought forecast because of the strong correlation between SWA and drought. Our results improved the understanding of seasonal responses to extreme droughts in SWC, which will be helpful to the drought monitoring and mitigation for different seasons in this ecologically fragile region.
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Lee, Chan Wook, Moo Jong Park, and Do Guen Yoo. "Quantitative Determination Procedures for Regional Extreme Drought Conditions: Application to Historical Drought Events in South Korea." Atmosphere 11, no. 6 (June 2, 2020): 581. http://dx.doi.org/10.3390/atmos11060581.
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Recently, the signs of extreme droughts, which were thought of as exceptional and unlikely, are being detected worldwide. It is necessary to prepare countermeasures against extreme droughts; however, current definitions of extreme drought are just used as only one or two indicators to represent the status or severity of a drought. More representative drought factors, which can show the status and severity that are relevant to extreme drought, need to be considered depending on the characteristics of the drought and comprehensive evaluation of various indices. Therefore, this study attempted to quantitatively define regional extreme droughts using more acceptable factors. The methodology comprises five factors that are indicative of extreme drought. The five factors are (1) duration (days), (2) number of consecutive years (years), (3) water availability, (4) return period, and (5) regional experience. The results were analyzed by applying the procedure to droughts that took place in 2014–2015 in South Korea. The results showed that the applied historical event did not enter the status of extreme drought, which is proposed in this study; however, the proposed methodology is applicable because it uses acceptable and reasonable factors to judge extreme drought, but it can also take into account the past regional experience of extreme drought.
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He, Qiu-Lan, Jun-Lan Xiao, and Wei-Yu Shi. "Responses of Terrestrial Evapotranspiration to Extreme Drought: A Review." Water 14, no. 23 (November 26, 2022): 3847. http://dx.doi.org/10.3390/w14233847.
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Terrestrial evapotranspiration (ET) is crucial to the exchange of global carbon, water, and energy cycles and links the hydrological and ecological processes. The frequency and intensity of extreme droughts are expected to increase due to ongoing climate change, strongly impacting terrestrial ET with implications for ecosystems, societies, and climate systems. However, the response of terrestrial ET to extreme drought and the underlying mechanism of terrestrial ET change during droughts are still unclear. Here, we review previous studies on terrestrial ET’s responses to extreme drought and investigate the control factors of ET change in response to extreme drought under different situations. The response of terrestrial ET to extreme drought is affected by various factors including the duration and intensity of the drought, the original climate conditions, as well as the plant species. Terrestrial ET change during droughts is controlled by complex biological and physical processes that can be divided into four parts including supply, energy, demand, and vegetation activities. The response of terrestrial ET to elevate CO2 may offset the effects of drought because CO2 fertilization tends to increase water use efficiency through stomatal regulation. We found that large uncertainties remain in the terrestrial ET response to drought due to the discrepancies among different ET products and simulations. This work highlights the requirement for accurate estimates of ET changes in ET products and models. This review provides a systematic investigation of the terrestrial ET response to extreme drought and the underlying mechanism of terrestrial ET changes during droughts and will significantly improve the development of water management strategies under climate change.
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Katipoğlu, Okan Mert, Reşat Acar, and Serkan Şenocak. "Spatio-temporal analysis of meteorological and hydrological droughts in the Euphrates Basin, Turkey." Water Supply 21, no. 4 (January 21, 2021): 1657–73. http://dx.doi.org/10.2166/ws.2021.019.
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Abstract In this study, the aim was to measure changes in the spatio-temporal distribution of a potential drought hazard area and determine the risk status of various meteorological and hydrological droughts by using the kriging, radial basis function (RBF), and inverse distance weighting (IDW) interpolation methods. With that goal, in monthly, three-month, and 12-month time periods drought indices were calculated. Spatio-temporal distributions of the droughts were determined with each drought index for the years in which the most severe droughts were experienced. According to the results, the basin is under risk of meteorological drought due to the occurrence of severe and extreme droughts in most of the area, and especially in the north, during the monthly and three-month time periods. During the 12-month period, it was found that most of the basin is under risk of hydrological drought due to the occurrence of severe and extreme droughts, especially in the southern parts. The most effective interpolation method for the prediction of meteorological and hydrological droughts was determined as kriging according to the results of the cross-validation test. It was concluded that a drought management plan should be made, and early warnings and precautions should be applied in the study area.
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Asefi-Najafabady, Salvi, and Sassan Saatchi. "Response of African humid tropical forests to recent rainfall anomalies." Philosophical Transactions of the Royal Society B: Biological Sciences 368, no. 1625 (September 5, 2013): 20120306. http://dx.doi.org/10.1098/rstb.2012.0306.
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During the last decade, strong negative rainfall anomalies resulting from increased sea surface temperature in the tropical Atlantic have caused extensive droughts in rainforests of western Amazonia, exerting persistent effects on the forest canopy. In contrast, there have been no significant impacts on rainforests of West and Central Africa during the same period, despite large-scale droughts and rainfall anomalies during the same period. Using a combination of rainfall observations from meteorological stations from the Climate Research Unit (CRU; 1950–2009) and satellite observations of the Tropical Rainfall Measuring Mission (TRMM; 1998–2010), we show that West and Central Africa experienced strong negative water deficit (WD) anomalies over the last decade, particularly in 2005, 2006 and 2007. These anomalies were a continuation of an increasing drying trend in the region that started in the 1970s. We monitored the response of forests to extreme rainfall anomalies of the past decade by analysing the microwave scatterometer data from QuickSCAT (1999–2009) sensitive to variations in canopy water content and structure. Unlike in Amazonia, we found no significant impacts of extreme WD events on forests of Central Africa, suggesting potential adaptability of these forests to short-term severe droughts. Only forests near the savanna boundary in West Africa and in fragmented landscapes of the northern Congo Basin responded to extreme droughts with widespread canopy disturbance that lasted only during the period of WD. Time-series analyses of CRU and TRMM data show most regions in Central and West Africa experience seasonal or decadal extreme WDs (less than −600 mm). We hypothesize that the long-term historical extreme WDs with gradual drying trends in the 1970s have increased the adaptability of humid tropical forests in Africa to droughts.
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Paynter, Shayne, and Mahmood Nachabe. "Use of generalized extreme value covariates to improve estimation of trends and return frequencies for lake levels." Journal of Hydroinformatics 13, no. 1 (March 31, 2010): 13–24. http://dx.doi.org/10.2166/hydro.2010.077.
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One of the most important tools in water management is the accurate forecast of long-term and short-term extreme values for flood and drought conditions. Traditional methods of trend detection are not suited for hydrologic systems while traditional methods of predicting extreme frequencies may be highly inaccurate in lakes. Traditional frequency estimates assume independence from trend or initial stage. However, due to autocorrelation of lake levels, initial stage can greatly influence the severity of an event. This research utilizes the generalized extreme value (GEV) distribution with time and starting stage covariates to more accurately identify trend direction and magnitude and provide improved predictions of flood and drought stages. Traditional methods of predicting flood or drought stages significantly overpredict or underpredict stages depending on the initial stage. Prediction differences can exceed one meter, a substantial amount in regions with flat topography; these differences could result in significant alterations in evacuation plans or other management decisions such as how much lake water to release in preparation for an approaching hurricane, appropriate lake levels to maintain, minimum structure floor elevations and more accurate forecasting of future water supply or impacts to tourism. The methods utilized in this research can be applied globally.
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Silva, A. C. S., C. O. Galvão, and G. N. S. Silva. "Droughts and governance impacts on water scarcity: an~analysis in the Brazilian semi-arid." Proceedings of the International Association of Hydrological Sciences 369 (June 11, 2015): 129–34. http://dx.doi.org/10.5194/piahs-369-129-2015.
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Abstract. Extreme events are part of climate variability. Dealing with variability is still a challenge that might be increased due to climate change. However, impacts of extreme events are not only dependent on their variability, but also on management and governance. In Brazil, its semi-arid region is vulnerable to extreme events, especially droughts, for centuries. Actually, other Brazilian regions that have been mostly concerned with floods are currently also experiencing droughts. This article evaluates how a combination between climate variability and water governance might affect water scarcity and increase the impacts of extreme events on some regions. For this evaluation, Ostrom's framework for analyzing social-ecological systems (SES) was applied. Ostrom's framework is useful for understanding interactions between resource systems, governance systems and resource users. This study focuses on social-ecological systems located in a drought-prone region of Brazil. Two extreme events were selected, one in 1997–2000, when Brazil's new water policy was very young, and the other one in 2012–2015. The analysis of SES considering Ostrom's principle "Clearly defined boundaries" showed that deficiencies in water management cause the intensification of drought's impacts for the water users. The reasons are more related to water management and governance problems than to drought event magnitude or climate change. This is a problem that holdup advances in dealing with extreme events.
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Tuong, Vo, Thanh-Van Hoang, Tien-Yin Chou, Yao-Min Fang, Chun-Tse Wang, Thanh-Danh Tran, and Dung Duc Tran. "Extreme Droughts Change in the Mekong River Basin: A Multidisciplinary Analysis Based on Satellite Data." Water 13, no. 19 (September 28, 2021): 2682. http://dx.doi.org/10.3390/w13192682.
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This study evaluates droughts in the Mekong River Basin (MKB) based on a multidisciplinary method, mainly using the Standardized Precipitation Index (SPI) and Mann–Kendall (MK) test. Precipitation data corresponding to the seasonality of the regional climate were retrieved from Integrated Multi-satellitE Retrievals for Global Precipitation Measurement from 2001 to 2020, at a monthly temporal scale and 0.1 degree spatial resolution. Drought events and their average interval, duration, and severity were determined based on Run theory. Our results revealed the most extreme drought period was in January 2014, at the time the lowest precipitation occurred. Spatial extreme drought results indicated that Zone 2 in the upstream MKB has the highest frequency of drought, with 44 events observed during 19 years, and experiences the most severe droughts, whereas Zone 24 in the downstream MKB has the most prolonged drought duration of seven months. The periods and locations of extreme drought were identified using the SPI, corresponding to historic droughts of the MKB. Furthermore, the MK test shows an increasing trend of droughts in the lower MKB and the cluster analysis identified six clusters of times series. Overall, our study provides essential findings for international and national water resource stakeholders in identifying trends of extreme drought in the MKB.
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Gao, Qing-Gang, Vonevilay Sombutmounvong, Lihua Xiong, Joo-Heon Lee, and Jong-Suk Kim. "Analysis of Drought-Sensitive Areas and Evolution Patterns through Statistical Simulations of the Indian Ocean Dipole Mode." Water 11, no. 6 (June 23, 2019): 1302. http://dx.doi.org/10.3390/w11061302.
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In this study, we investigated extreme droughts in the Indochina peninsula and their relationship with the Indian Ocean Dipole (IOD) mode. Areas most vulnerable to drought were analyzed via statistical simulations of the IOD based on historical observations. Results of the long-term trend analysis indicate that areas with increasing spring (March–May) rainfall are mainly distributed along the eastern coast (Vietnam) and the northwestern portions of the Indochina Peninsula (ICP), while Central and Northern Laos and Northern Cambodia have witnessed a reduction in spring rainfall over the past few decades. This trend is similar to that of extreme drought. During positive IOD years, the frequency of extreme droughts was reduced throughout Vietnam and in the southwestern parts of China, while increased drought was observed in Cambodia, Central Laos, and along the coastline adjacent to the Myanmar Sea. Results for negative IOD years were similar to changes observed for positive IOD years; however, the eastern and northern parts of the ICP experienced reduced droughts. In addition, the results of the statistical simulations proposed in this study successfully simulate drought-sensitive areas and evolution patterns of various IOD changes. The results of this study can help improve diagnostic techniques for extreme droughts in the ICP.
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Kim, Hyeok, Dong-Hyeok Park, Jae-Hyun Ahn, and Tae-Woong Kim. "Development of a Multiple-Drought Index for Comprehensive Drought Risk Assessment Using a Dynamic Naive Bayesian Classifier." Water 14, no. 9 (May 9, 2022): 1516. http://dx.doi.org/10.3390/w14091516.
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Korea has made various efforts to reduce drought damage; however, socio-economic damage has increased in recent years due to climate change, which has led to increasing frequency and intensity of drought. In South Korea, because precipitation is concentrated in the summer, drought damage will be significant in the event of failure of water resources management. Seasonal and regional imbalances in precipitation have contributed to recent extreme droughts in South Korea. In addition, population growth and urbanization have led to increased water use and contributed to water shortage. Drought risk analysis must address multiple contributing factors and comprehensively assess the effects or occurrence of future droughts, which are essential for planning drought mitigation to cope with actual droughts. Drought mitigation depends on the water supply capacity during dry spells. In this study, a dynamic naive Bayesian classifier-based multiple drought index (DNBC-MDI) was developed by combining the strengths of conventional drought indices and water supply capacity. The DNBC-MDI was applied to a bivariate drought frequency analysis to evaluate hydrologic risk of extreme droughts. In addition, future changes of the risk were investigated according to climate change scenarios. As a result, the drought risk had a decreasing trend from the historic period of 1974–2016 to the future period of 2017–2070, then had an increasing trend in the period of 2071–2099.
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Lahnsteiner, J., and G. Lempert. "Water management in Windhoek, Namibia." Water Science and Technology 55, no. 1-2 (January 1, 2007): 441–48. http://dx.doi.org/10.2166/wst.2007.022.
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For decades, the city of Windhoek in Namibia succeeded in stretching their limited potable water resources through strict water management, latterly including wastewater reclamation and direct potable reuse. An integrated approach was followed and proper policies were put in place. This was followed up with appropriate legislation, education, policing and technical and financial measures with the result that extreme water shortages were overcome even in times of severe droughts.
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Markus, Momcilo, Ximing Cai, and Ryan Sriver. "Extreme Floods and Droughts under Future Climate Scenarios." Water 11, no. 8 (August 19, 2019): 1720. http://dx.doi.org/10.3390/w11081720.
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Climate projections indicate that in many regions of the world the risk of increased flooding or more severe droughts will be higher in the future. To account for these trends, hydrologists search for the best planning and management measures in an increasingly complex and uncertain environment. The collection of manuscripts in this Special Issue quantifies the changes in projected hydroclimatic extremes and their impacts using a suite of innovative approaches applied to regions in North America, Asia, and Europe. To reduce the uncertainty and warrant the applicability of the research on projections of future floods and droughts, their continued development and testing using newly acquired observational data are critical.
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Cunha, Ana Paula M. A., Marcelo Zeri, Karinne Deusdará Leal, Lidiane Costa, Luz Adriana Cuartas, José Antônio Marengo, Javier Tomasella, et al. "Extreme Drought Events over Brazil from 2011 to 2019." Atmosphere 10, no. 11 (October 24, 2019): 642. http://dx.doi.org/10.3390/atmos10110642.
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Drought-related disasters are among the natural disasters that are able to cause large economic and social losses. In recent years, droughts have affected different regions of Brazil, impacting water, food, and energy security. In this study, we used the Integrated Drought Index (IDI), which combines a meteorological-based drought index and remote sensing-based index, to assess the drought events from 2011 to 2019 over Brazil. During this period, drought events were observed throughout the country, being most severe and widespread between the years 2011 and 2017. In most of the country, the 2014/15 hydrological year stands out due to the higher occurrence of severe and moderate droughts. However, drought intensity and observed impacts were different for each region, which is shown by the different case studies, assessing different types of impacts caused by drought in Brazil. Thus, it is fundamental to evaluate the impacts of droughts in a continental country such as Brazil, where a variety of vegetation, soil, land use, and especially different climate regimes predominate.
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Hatchett, Benjamin J., and Daniel J. McEvoy. "Exploring the Origins of Snow Drought in the Northern Sierra Nevada, California." Earth Interactions 22, no. 2 (February 1, 2018): 1–13. http://dx.doi.org/10.1175/ei-d-17-0027.1.
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Abstract The concept of snow drought is gaining widespread interest as the climate of snow-dominated mountain watersheds continues to change. Warm snow drought is defined as above- or near-average accumulated precipitation coinciding with below-average snow water equivalent at a point in time. Dry snow drought is defined as below-average accumulated precipitation and snow water equivalent at a point in time. This study contends that such point-in-time definitions might miss important components of how snow droughts originate, persist, and terminate. Using these simple definitions and a variety of observations at monthly, daily, and hourly time scales, the authors explore the hydrometeorological origins of potential snow droughts in the northern Sierra Nevada from water years 1951 to 2017. This study finds that snow droughts can result from extreme early season precipitation, frequent rain-on-snow events, and low precipitation years. Late-season snow droughts can follow persistent warm and dry periods with effects that depend upon elevation. Many snow droughts were characterized by lower snow fractions and midwinter peak runoff events. These findings can guide improved evaluations of historical and potential future snow droughts, particularly with regards to how impacts on water resources and mountain ecosystems may vary depending on how snow droughts originate and evolve in time.
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Koster, R. D., S. D. Schubert, H. Wang, S. P. Mahanama, and Anthony M. DeAngelis. "Flash Drought as Captured by Reanalysis Data: Disentangling the Contributions of Precipitation Deficit and Excess Evapotranspiration." Journal of Hydrometeorology 20, no. 6 (June 1, 2019): 1241–58. http://dx.doi.org/10.1175/jhm-d-18-0242.1.
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Abstract Flash droughts—uncharacteristically rapid dryings of the land system—are naturally associated with extreme precipitation deficits. Such precipitation deficits, however, do not tell the whole story, for land surface drying can be exacerbated by anomalously high evapotranspiration (ET) rates driven by anomalously high temperatures (e.g., during heat waves), anomalously high incoming radiation (e.g., from reduced cloudiness), and other meteorological anomalies. In this study, the relative contributions of precipitation and ET anomalies to flash drought generation in the Northern Hemisphere are quantified through the analysis of diagnostic fields contained within the MERRA-2 reanalysis product. Unique to the approach is the explicit treatment of soil moisture impacts on ET through relationships diagnosed from the reanalysis data; under this treatment, an ET anomaly that is negative relative to the local long-term climatological mean is still considered positive in terms of its contribution to a flash drought if it is high for the concurrent value of soil moisture. Maps produced in the analysis show the fraction of flash drought production stemming specifically from ET anomalies and illustrate how ET anomalies for some droughts are related to temperature and radiation anomalies. While ET is found to have an important impact on flash drought production in the central United States and in parts of Russia known from past studies to be prone to heat wave–related drought, and while this impact does appear stronger during the onset (first several days) of flash droughts, overall the contribution of ET to these droughts is small relative to the contribution of precipitation deficit.
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Olsen, Conner, Alexander Kowalewski, Micah Gould, and John Lambrinos. "EVALUATING TWO RAINWATER HARVESTING SYSTEMS IN AN URBAN SETTING IN OREGON'S WILLAMETTE VALLEY." Journal of Green Building 12, no. 1 (January 2017): 1–10. http://dx.doi.org/10.3992/1552-6100.12.1.1.
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INTRODUCTION The recent trend toward more extreme periods of drought has been a shock to the residents of the Pacific Northwest – many of whom have relied upon heavy wateruse in the summer months in order to make a living (i.e. producers of grass seed and sod, berries, or nursery crops), or to maintain their landscapes at high levels (i.e. certain homeowners, recreational facilities, or commercial properties). Furthermore, population growth has reached the point where even an average year of precipitation has proven insufficient for urbanities that had not previously experienced issues with water scarcity (McDonald et al., 2011). This modern climate scenario has forced people of the Pacific Northwest, and people from all around the world, to rethink their water-use strategies, as the global trend has shifted toward greater sustainability (Tilman, 2001; McDonald et al., 2011). One potential mitigation strategy for cool-humid regions, such as Oregon's Willamette Valley, is to utilize rainwater-harvesting systems to alleviate freshwater demand (Kinkade-Levario, 2007). Rainwater harvesting is a logical choice for this climate zone because the average annual precipitation (42.7-in for Corvallis, OR) is sufficient for the majority of its crop production, however, this precipitation occurs almost exclusively in a nine-month period spanning from fall to spring (US Climate Data, 1981–2010). Although annual precipitation is adequate, irrigation is still required for at least three months of every year. This study considered rainwater harvesting to be ideally suited for the cool-humid Willamette Valley; the excess rainfall in the wet season that could be stored for use in the summer months, thus decreasing demand for municipal water by an equivalent amount. It should be stated that rainwater harvesting is not a novel idea; there have been studies dating back to the 1980's and earlier that have shown significant watersavings when retrofitting homes with new features like rainwater-harvesting systems (Boers et al., 1982, Karpisack et al., 1990). Even before that, golf courses, sporting complexes, and industrial sites alike were making use of this strategy. However, their methods typically consisted of catching rainwater via surface runoff and storing it in retention ponds (Ferguson, 1998), which is a strategy that is less applicable to the small-acreage homeowner who wants to irrigate their property without having to turn half of their backyard into a pond. Fortunately, there are alternative methods of rainwater harvesting that make a lot more sense in a residential setting, where irrigated land is small in relation to the roof-area for which rain can be easily harvested. This study documents the construction of two distinct rainwater-harvesting systems (an aboveground cistern and a belowground AQUABLOX™ matrix storage system), and gives insight into their advantages and disadvantages.
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Beevers, Lindsay, Christopher J. White, and Maria Pregnolato. "Editorial to the Special Issue: Impacts of Compound Hydrological Hazards or Extremes." Geosciences 10, no. 12 (December 9, 2020): 496. http://dx.doi.org/10.3390/geosciences10120496.
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Liu, Yinge, Yanjun Wen, Yaqian Zhao, and Haonan Hu. "Analysis of Drought and Flood Variations on a 200-Year Scale Based on Historical Environmental Information in Western China." International Journal of Environmental Research and Public Health 19, no. 5 (February 27, 2022): 2771. http://dx.doi.org/10.3390/ijerph19052771.
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Historical environmental evidence has been characterized by time accuracy, high spatial resolution and rich information, which may be widely used in the reconstruction of historical data series. Taking the upper reaches of the Weihe River as an example in Western China, the grades and index sequences of the drought and flood disasters from 1800 to 2016 were reconstructed based on various historical environmental information and standardized precipitation indicator (SPI). Moreover, the characteristics of droughts and floods were analyzed using statistical diagnostic methods, and the mechanisms affecting centennial-scale droughts and floods were discussed. The validity of reconstruction sequence of droughts/floods was verified, which showed that the reconstruction sequence may reasonably indicate the status of drought and flood. The reconstruction indicated the following periods of drought/flood: a period of extreme and big droughts in 1835s–1893s, 1924s–1943s and 1984s–2008s, a period of extreme and big floods in 1903s–1923s, and a period of extreme and big droughts/floods in 1944s–1983s. Moreover, the droughts were more serious in the western part of this region and the floods were relatively severe in the east of this region, while the droughts and floods have long-term period of about 100 years and mutation. The influence mechanism of external environmental forcing factors driving floods/droughts were revealed. The results showed that the cycle of El Niño Southern Oscillation (ENSO) and sunspot activities were closely related to the variations of drought/flood, meanwhile, ENSO has a significant lag time scale cumulative influence on droughts and floods, especially the 15-year sliding effect was the most obvious. In the peak year of sunspots, the probability of heavy drought/extreme floods was large, and the 102-year sunspot cycle has a more significant effect on drought and flood disasters. The mutation of droughts and floods occurred in the context of the drastic changes in the ground environment, and transformation of precipitation and land use structure. These results will enhance the understandings of historical environmental climate characteristics and mechanisms over the hundred years, and be useful for the future regional water resources and assessment, and ecological environment management.
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TEMBATA, KAORI, and KENJI TAKEUCHI. "THE IMPACT OF CLIMATE VARIABILITY ON DROUGHT MANAGEMENT: EVIDENCE FROM JAPANESE RIVER BASINS." Climate Change Economics 09, no. 04 (November 2018): 1850010. http://dx.doi.org/10.1142/s2010007818500100.
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This study examines the effect of climate variability on water resource management during droughts. We use data from local droughts in Japan over three decades to investigate how variability in precipitation and temperature affects water restrictions implemented by drought coordination councils. We find that climate variability is significantly related to water restrictions in terms of both intensity and duration. The regression results show that a 100-mm decrease in annual precipitation is associated with a 0.2% increase in the water withdrawal restriction rate and an increase of one day in the restriction period. Our findings suggest that climate variability might induce more stringent water restrictions, implying negative consequences for water availability. This study thus shows the importance of strategically building adaptive capacity to climate change due to the risks of extreme weather events, such as prolonged droughts and extended summer seasons.
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Candogan Yossef, N., L. P. H. van Beek, J. C. J. Kwadijk, and M. F. P. Bierkens. "Assessment of the potential forecasting skill of a global hydrological model in reproducing the occurrence of monthly flow extremes." Hydrology and Earth System Sciences 16, no. 11 (November 15, 2012): 4233–46. http://dx.doi.org/10.5194/hess-16-4233-2012.
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Abstract. As an initial step in assessing the prospect of using global hydrological models (GHMs) for hydrological forecasting, this study investigates the skill of the GHM PCR-GLOBWB in reproducing the occurrence of past extremes in monthly discharge on a global scale. Global terrestrial hydrology from 1958 until 2001 is simulated by forcing PCR-GLOBWB with daily meteorological data obtained by downscaling the CRU dataset to daily fields using the ERA-40 reanalysis. Simulated discharge values are compared with observed monthly streamflow records for a selection of 20 large river basins that represent all continents and a wide range of climatic zones. We assess model skill in three ways all of which contribute different information on the potential forecasting skill of a GHM. First, the general skill of the model in reproducing hydrographs is evaluated. Second, model skill in reproducing significantly higher and lower flows than the monthly normals is assessed in terms of skill scores used for forecasts of categorical events. Third, model skill in reproducing flood and drought events is assessed by constructing binary contingency tables for floods and droughts for each basin. The skill is then compared to that of a simple estimation of discharge from the water balance (P−E). The results show that the model has skill in all three types of assessments. After bias correction the model skill in simulating hydrographs is improved considerably. For most basins it is higher than that of the climatology. The skill is highest in reproducing monthly anomalies. The model also has skill in reproducing floods and droughts, with a markedly higher skill in floods. The model skill far exceeds that of the water balance estimate. We conclude that the prospect for using PCR-GLOBWB for monthly and seasonal forecasting of the occurrence of hydrological extremes is positive. We argue that this conclusion applies equally to other similar GHMs and LSMs, which may show sufficient skill to forecast the occurrence of monthly flow extremes.
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Janský, Bohumír, and Jan Kocum. "Peat bogs influence on runoff process: Case study of the Vydra and Křemelná River basins in the Šumava Mountains, southwestern Czechia." Geografie 113, no. 4 (2008): 383–99. http://dx.doi.org/10.37040/geografie2008113040383.
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Specific part of wide complex of preventive measures against floods and extreme droughts could be procedures realized in river headstream areas. In order to increase a water retention in headwaters the detailed analysis of peat bogs hydrological function needs to be carried out. Suitable conditions for the research realization at present is related to an existence of several automatic water level gauges and utilization of modern equipment and methods in experimental catchments of the Otava River headstream area (Šumava Mts., southwestern Czechia), representing the core zone of a number of extreme floods in Central Europe. Thorough analyses of extreme runoff phases show more distinct discharge variability of streams draining peat land localities. For the retention potential assessment the detailed measurement of potential accumulation reservoirs, bathymetric mapping of bog pools and the detailed analysis of snow conditions as an important component of a rainfall-runoff process in headwaters is being pursued. The final part of the paper is consisted of suggestions of several unforceable measures implementation that could contribute to reduction of peak flows and to increase of water resources during extreme droughts in future.
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Masih, I., S. Maskey, F. E. F. Mussá, and P. Trambauer. "A review of droughts on the African continent: a geospatial and long-term perspective." Hydrology and Earth System Sciences 18, no. 9 (September 17, 2014): 3635–49. http://dx.doi.org/10.5194/hess-18-3635-2014.
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Abstract. This paper presents a comprehensive review and analysis of the available literature and information on droughts to build a continental, regional and country level perspective on geospatial and temporal variation of droughts in Africa. The study is based on the review and analysis of droughts occurred during 1900–2013, as well as evidence available from past centuries based on studies on the lake sediment analysis, tree-ring chronologies and written and oral histories and future predictions from the global climate change models. Most of the studies based on instrumental records indicate that droughts have become more frequent, intense and widespread during the last 50 years. The extreme droughts of 1972–1973, 1983–1984 and 1991–1992 were continental in nature and stand unique in the available records. Additionally, many severe and prolonged droughts were recorded in the recent past such as the 1999–2002 drought in northwest Africa, 1970s and 1980s droughts in western Africa (Sahel), 2010–2011 drought in eastern Africa (Horn of Africa) and 2001–2003 drought in southern and southeastern Africa, to name a few. The available (though limited) evidence before the 20th century confirms the occurrence of several extreme and multi-year droughts during each century, with the most prolonged and intense droughts that occurred in Sahel and equatorial eastern Africa. The complex and highly variant nature of many physical mechanisms such as El Niño–Southern Oscillation (ENSO), sea surface temperature (SST) and land–atmosphere feedback adds to the daunting challenge of drought monitoring and forecasting. The future predictions of droughts based on global climate models indicate increased droughts and aridity at the continental scale but large differences exist due to model limitations and complexity of the processes especially for Sahel and northern Africa. However, the available evidence from the past clearly shows that the African continent is likely to face extreme and widespread droughts in future. This evident challenge is likely to aggravate due to slow progress in drought risk management, increased population and demand for water and degradation of land and environment. Thus, there is a clear need for increased and integrated efforts in drought mitigation to reduce the negative impacts of droughts anticipated in the future.
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Masih, I., S. Maskey, F. E. F. Mussá, and P. Trambauer. "A review of droughts in the African continent: a geospatial and long-term perspective." Hydrology and Earth System Sciences Discussions 11, no. 3 (March 6, 2014): 2679–718. http://dx.doi.org/10.5194/hessd-11-2679-2014.
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Abstract. This paper presents a comprehensive review and analysis of the available literature and information on droughts to build a continental, regional and country level perspective on geospatial and temporal variation of droughts in Africa. The study is based on the review and analysis of droughts occurred during 1900–2013 as well as evidence available from past centuries based on studies on the lake sediment analysis, tree-ring chronologies and written and oral histories and future predictions from the global climate change models. Most of the studies based on instrumental records indicate that droughts have become more frequent, intense and widespread during the last 50 yr. The extreme droughts of 1972–1973, 1983–1984 and 1991–1992 were continental in nature and stand unique in the available records. Additionally, many severe and prolonged droughts were recorded in the recent past such as the 1999–2002 drought in Northwest Africa, 1970s and 1980s droughts in West Africa (Sahel), 2010–2011 drought in East Africa (Horn of Africa) and 2001–2003 drought in Southern and Southeast Africa, to name a few. The available (though limited) evidence before the 20th century confirms the occurrence of several extreme and multi-year droughts during each century, with the most prolonged and intense droughts that occurred in Sahel and Equatorial East Africa regions. Complex and highly variant nature of many physical mechanisms such as El Niño-Southern Oscillation (ENSO), Sea Surface Temperature (SST) and land–atmosphere feedback adds to the daunting challenge of drought monitoring and forecasting. The future predictions of droughts based on global climate models indicate increased droughts and aridity at the continental scale but large differences exist due to model limitations and complexity of the processes especially for Sahel and North Africa regions. However, the available evidence from the past clearly shows that the African continent is likely to face extreme and widespread droughts in future. This evident challenge is likely to aggravate due to slow progress in drought risk management, increased population and demand for water and degradation of land and environment. Thus, there is a clear need for increased and integrated efforts in drought mitigation to reduce the negative impacts of droughts anticipated in future.
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Todmal, Rahul S. "Droughts and Agriculture in the Semi-Arid Region of Maharashtra, Western India." Weather, Climate, and Society 11, no. 4 (August 20, 2019): 741–54. http://dx.doi.org/10.1175/wcas-d-18-0131.1.
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Abstract In the prevailing climate change scenario, to cope with drought, it is necessary to understand the characteristics of meteorological droughts in water-scarce regions to formulate judicial plans for the utilization of water resources. The present investigation, therefore, endeavored to assess the intensity and frequency of droughts over the five semiarid river basins in Maharashtra during the past (1980–2013) and future (2015–50). The study was carried out with the application of standardized precipitation index (SPI) methodology. The agricultural and satellite [normalized difference vegetation index (NDVI)] data were analyzed to understand the effects of meteorological droughts. Although the study area experienced three severe rainfall droughts in 1985/86, 2002/03, and 2011/12, higher frequency of low-intensity droughts is observed, particularly after 2000. The estimation suggests occurrence of moderate, severe, and extreme droughts once in 6, 28, and 50 years, respectively. Among the selected basins, the Agrani, the Karha, and the Man are expected to experience intense droughts and hence require special attention in drought management. The study also highlights that El Niño events considerably retard the monsoon rainfall. However, the occurrence of the positive phase of the Indian Ocean dipole in the El Niño years reduces the intensity of droughts. As agricultural productivity and cropped areas heavily depend on the monsoon rainfall, the meteorological droughts result in agricultural droughts. Moreover, the future warming (by 1.02°C) over the study area is very likely to exacerbate the meteorological droughts (estimated to occur in the 2030s) and increase the agricultural water demand, further adding to an already difficult water management challenge in the study basins.
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Baran-Gurgul, Katarzyna. "The Risk of Extreme Streamflow Drought in the Polish Carpathians—A Two-Dimensional Approach." International Journal of Environmental Research and Public Health 19, no. 21 (October 28, 2022): 14095. http://dx.doi.org/10.3390/ijerph192114095.
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Poland has relatively small water resources compared to other European countries. Droughts are a characteristic feature of the Polish climate; however, recent years have been particularly warm, causing longer and more severe droughts, including streamflow droughts. The most unfavourable streamflow droughts, considering the economic or social (including health-related) consequences, are the longest and/or the ones with the largest volumes. Such prolonged and severe droughts may constitute a natural disaster threatening public health. The main aim of this article was to define the spatial variability of the annual maximum streamflow drought in the Polish Carpathians and the risk of the maximum streamflow drought of a duration and volume exceeding the given value occurring in this region. This was conducted based on a 30-year time series of daily flows in selected gauging cross sections on rivers in the Polish Carpathians. One- and-two-dimensional probability distributions (utilising a copula function) of the two most important maximum streamflow drought characteristics were identified, specifically duration and volume, which, in consequence, led to identifying the maximum streamflow droughts of a given return period (a given risk level). Maps of maximum streamflow drought hazard were developed and understood as spatial distributions of the maximum streamflow drought frequency of duration and volume exceeding the annual given values. Analysis of the maps allowed for the selection of areas/basins being more or less at risk of extreme annual streamflow drought of a duration and/or volume exceeding the given value.
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Heidari, Hadi, Mazdak Arabi, Mahshid Ghanbari, and Travis Warziniack. "A Probabilistic Approach for Characterization of Sub-Annual Socioeconomic Drought Intensity-Duration-Frequency (IDF) Relationships in a Changing Environment." Water 12, no. 6 (May 27, 2020): 1522. http://dx.doi.org/10.3390/w12061522.
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Changes in climate, land use, and population can increase annual and interannual variability of socioeconomic droughts in water-scarce regions. This study develops a probabilistic approach to improve characterization of sub-annual socioeconomic drought intensity-duration-frequency (IDF) relationships under shifts in water supply and demand conditions. A mixture Gamma-Generalized Pareto (Gamma-GPD) model is proposed to enhance characterization of both the non-extreme and extreme socioeconomic droughts. Subsequently, the mixture model is used to determine sub-annual socioeconomic drought intensity-duration-frequency (IDF) relationships, return period, amplification factor, and drought risk. The application of the framework is demonstrated for the City of Fort Collins (Colorado, USA) water supply system. The water demand and supply time series for the 1985–2065 are estimated using the Integrated Urban water Model (IUWM) and the Soil and Water Assessment Tool (SWAT), respectively, with climate forcing from statistically downscaled CMIP5 projections. The results from the case study indicate that the mixture model leads to enhanced estimation of sub-annual socioeconomic drought frequencies, particularly for extreme events. The probabilistic approach presented in this study provides a procedure to update sub-annual socioeconomic drought IDF curves while taking into account changes in water supply and demand conditions.