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Статті в журналах з теми "Extreme droughts and excess of water"
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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.
Повний текст джерелаАнотація:
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.
Повний текст джерелаАнотація:
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.
Повний текст джерелаАнотація:
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.
Повний текст джерелаАнотація:
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.
Повний текст джерелаАнотація:
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.
Повний текст джерелаАнотація:
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.
Повний текст джерелаАнотація:
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.
Повний текст джерелаАнотація:
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.
Повний текст джерелаАнотація:
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.
Повний текст джерелаАнотація:
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.
Дисертації з теми "Extreme droughts and excess of water"
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Kapsambelis, Dorothée. "Modélisation d’événements climatiques extrêmes sur les productions agricoles à horizon 2050 : Application à la gestion économique du risque." Thesis, Rennes, Agrocampus Ouest, 2022. http://www.theses.fr/2022NSARE061.
Повний текст джерелаАнотація:
Les productions végétales sont très fortement exposées aux aléas climatiques. En France, depuis 2016, les pertes enregistrées par les agriculteurs ont atteint chaque année des niveaux qui n’étaient jusqu’à présent que rarement enregistrés. Est-ce que ces catastrophes en chaines sont directement liées au changement climatique ? Si tel est le cas, comment une agriculture déjà fragilisée par des coûts de production élevés et des marges toujours plus faibles peut y faire face ? Cette thèse vise à apporter des éléments tangibles sur cette problématique. La thèse se concentre sur les céréales à paille et les prairies. La méthodologie porte sur la conception d’un modèle d’impact des événements extrêmes de sécheresse et d’excès d’eau sur les pertes de récoltes, intégrant leur projection à horizon 2050. Il s’agit dans un premier temps de développer un nouvel indice climatique, le DOWKI, caractérisant ces événements climatiques extrêmes à une résolution de 8 x 8 km sur la France métropolitaine. La corrélation entre cet indice et les pertes de récoltes historiques issues d’AGRESTE a permis de construire un modèle de dommages. Enfin, le couplage des données climatiques prospectives issues d’ARPEGE-Climat pour le scénario RCP 8.5 du GIEC a été mis en place pour évaluer les conséquences de ces événements extrêmes, toutes choses égales par ailleurs, à horizon 2050. Les résultats de cette étude montrent l’impact très significatif de l’augmentation de la fréquence et de l’intensité des sécheresses extrêmes en 2050. Pour les excès d’eau, l’impact n’est pas significatif : ces événements n’évoluent pas dans le futur. L’évolution des sécheresses a un impact différent sur les céréales à paille et sur les prairies. Sur les premières, une sécheresse extrême est caractérisée par un grand nombre d’agriculteurs touchés pour des pertes de récolte modérées, on peut le caractériser de risque « horizontal ». Sur les prairies, a contrario, les agriculteurs touchés sont nombreux mais les pertes peuvent atteindre des niveaux beaucoup plus élevés. On peut considérer ces risques comme à la fois « horizontaux et verticaux ». Les systèmes de gestion des risques doivent être adaptés à ces différents profils de risques. Dans le système proposé par le député Descrozaille et adopté en 2022, le profil de risque « horizontal » sera surtout pris en charge par l’assurance. Les pertes extrêmes, dont la fréquence va augmenter, devront faire appel à une mutualisation internationale. Les pertes « horizontales et verticales », comme les prairies, vont clairement poser la question du provisionnement du Fond Public. L’ère des nouvelles technologies doit permettre un partage de l’information sur la nature du risque et ses conséquences à l’ensemble des acteurs de la gestion du risque de manière à mettre en place des stratégies adaptées au changement climatique. La gestion du risque doit prendre en compte l’adaptation au changement climatique à l’échelle individuelle de l’exploitation agricole pour permettre à l’agriculture française d’évoluer dans le bon sens, avec le défi du changement climatiqueAgricultural crops are highly exposed to climate hazards. Since 2016, agricultural losses in France have reached levels that, until then, had seldom been reported. Is this sequence of catastrophes directly linked to climate change? If so, how can the agricultural sector face these events while it is already being undermined by rising production costs and decreasing benefits? The present thesis aims to contribute to the reflection on this topic with tangible answers, using two examples (soft wheat and winter barley) for winter cereals on the one hand and grasslands on the other hand. A model for the impacts of extreme drought and excess water events on crop yield losses was designed, and yields losses were projected in 2050. The first step was the development of a new climate index, called DOWKI, which characterizes these extreme weather events on an 8 x 8 km grid on mainland France. The correlation between this index and past observed yield losses from the AGRESTE database enabled the design of a damage model. Finally, prospective climate data from the ARPEGE-Climat model for IPCC scenario RCP 8.5 was plugged into the model to assess the consequences, other things being equal, of these extreme events in 2050. The results show the highly significant impact of the increase in frequency and in intensity of droughts in 2050. As for excess water events, there is no notable impact: these events do not evolve in the future. The evolution of droughts affects winter cereals and grasslands in different manners. On winter cereals, extreme drought events cause moderate crop yield losses to a large number of farmers. As for grasslands, fewer farmers are affected, but their losses can reach much higher levels. These risks can be considered as being “horizontal and vertical” at the same time. Risk management systems must be adapted to these various risk profiles. In the system proposed by Deputy Descrozaille and adopted in 2022, the “horizontal” risk profile will mostly be borne by the insurance market. Extreme losses, the frequency of which will increase, will have to resort to international reinsurance in order to be mutualized. “Horizontal and vertical” losses, such as those affecting grasslands, will clearly challenge how the Public Fund provisions so that it can face significant losses. New technologies must enable the sharing of information about the nature of risks and their consequences between all the entities involved in risk management so that strategies adapted to climate change can be rolled out. Risk management must take into account the adaptation of single farms to climate change so that the French agriculture can evolve in the right direction, along with the challenges posed by climate change
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TimÃteo, SÃsthenis de Lima. "Guidelines struture of water safety Plan for extreme events : droughts and floods. Case study company of the situation room omplementation of Management Water Resources of CearÃ." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13686.
Повний текст джерелаАнотація:
A Water Safety Plan for Extreme Events - PSAEE, has the purpose of description the procedures in potentially critical situations due to the occurrence of extreme weather
events (droughts and floods). Provides the developing of preventive actions and contingency plan as a way to mitigate the effects of these phenomena. Will be developed in different and complementary steps, aiming anticipation, recognition and risk assessment, identification and monitoring of vulnerable regions and the implementation of a warning network against Floods and Droughts. The present document describes guidelines for structuring a Water Safety Plan for Extreme Events, Floods and Droughts, structured in five (05) steps; 1. Preliminary Steps, 2 Diagnostic System; 3 Operational Monitoring; 4. Management Plans and 5.Validation and Verification. As a case study, the document analyzed the process of implementing the Situation Room of the Water Resources Management Company of Cearà - COGERH , also presenting some suggestion of a Work Plan for the Situation Room, which will serve as a Management Center of Extreme Hydrological Events for the State of CearÃ, Brazil.Um Plano de SeguranÃa de Ãgua para Eventos Extremos â PSAEE, tem como objetivo a descriÃÃo de procedimentos em situaÃÃes potencialmente criticas devido a ocorrÃncia de eventos climÃticos extremos (Secas e Cheias). Prevà o desenvolvendo de aÃÃes preventivas e plano de contingÃncia como forma de mitigar os efeitos destes fenÃmenos. Serà desenvolvido em etapas distintas e complementares, visando a antecipaÃÃo, reconhecimento e avaliaÃÃo de riscos, a identificaÃÃo e monitoramento de regiÃes vulnerÃveis, a implementaÃÃo de rede de alerta contra Cheias e Secas. O presente trabalho descreve diretrizes para estruturaÃÃo de um Plano de SeguranÃa de Ãgua para Eventos Extremos, Cheias e Secas, estruturado em 05 (cinco) etapas; 1. Etapas Preliminares, 2. DiagnÃstico do Sistema; 3. Monitoramento Operacional; 4. Planos de GestÃo e 5. ValidaÃÃo e VerificaÃÃo. Como estudo de caso, o trabalho analisou o processo de implantaÃÃo da Sala de SituaÃÃo da Companhia de GestÃo dos Recursos HÃdricos do Cearà â COGERH, apresentando, tambÃm, sugestÃo de um Plano de Trabalho para a Sala de SituaÃÃo, a qual servirà de Centro de GestÃo de Eventos Extremos HidrolÃgicos para o Estado do CearÃ, Brasil.
Книги з теми "Extreme droughts and excess of water"
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Fletcher, Roland, Brendan M. Buckley, Christophe Pottier, and Shi-Yu Simon Wang. Fourteenth to Sixteenth Centuries AD. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199329199.003.0010.
Повний текст джерелаАнотація:
Angkor, the capital of the Khmer Empire in Southeast Asia, was the most extensive low-density agrarian-based urban complex in the world. The demise of this great city between the late 13th and the start of the 17th centuries AD has been a topic of ongoing debate, with explanations that range from the burden of excessive construction work to disease, geo-political change, and the development of new trade routes. In the 1970s Bernard-Phillipe Groslier argued for the adverse effects of land clearance and deteriorating rice yields. What can now be added to this ensemble of explanations is the role of the massive inertia of Angkor’s immense water management system, political dependence on a meticulously organized risk management system for ensuring rice production, and the impact of extreme climate anomalies from the 14th to the 16th centuries that brought intense, high-magnitude monsoons interspersed with decades-long drought. Evidence of this severe climatic instability is found in a seven-and-a-half century tree-ring record from tropical southern Vietnam. The climatic instability at the time of Angkor’s demise coincides with the abrupt transition from wetter, La Niña-like conditions over Indochina during the Medieval Warm Period to the more drought-dominated climate of the Little Ice Age, when El Niño appears to have dominated and the ITCZ migrated nearly five degrees southward. As this transition neared, Angkor was hit by the double impact of high-magnitude rains and crippling droughts, the former causing damage to water management infrastructure and the latter decreasing agricultural productivity. The Khmer state at Angkor was built on a human-engineered, artificial wetland fed by small rivers. The management of water was a massive undertaking, and the state potentially possessed the capacity to ride out drought, as it had done for the first half of the 13th century. Indeed, Angkor demonstrated just how powerful a water management system would be required and, conversely, how formidable a threat drought can be. The irony, then, is that extreme flooding destroyed Angkor’s water management capacity and removed a system that was designed to protect its population from climate anomalies.
Частини книг з теми "Extreme droughts and excess of water"
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Gál, Norbert, and Andrea Farsang. "Weather Extremities and Soil Processes: Impact of Excess Water on Soil Structure in the Southern Great Hungarian Plain." In Geomorphological impacts of extreme weather, 313–25. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6301-2_20.
Повний текст джерела
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Nzengya, Daniel M., and Francis Rutere. "Primary Versus High School Students’ Environmental Attitudes and Pro-environmental Behavior: The Case of Embu County, Kenya." In African Handbook of Climate Change Adaptation, 2653–74. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-45106-6_134.
Повний текст джерелаАнотація:
AbstractDegradation of natural resources exacerbates a country’s vulnerability to the effects of climate change. IPCC projections suggest that countries within the horn of Africa, which include Kenya, will suffer most from extreme climate change events, particularly more frequent and prolonged droughts. Women and children suffer disproportionately from the consequences of environmental degradation. Public participation is one of the strategies governments pursue to combat environmental degradation; however, there has been limited research to better understand students’ environmental attitudes and pro-environmental behavior to better inform student-led participatory designs. Students comprise a significant proportion of the population in Kenya. This research conducted in 2018 at Nginda Ward, Embu County, comprised a survey of 121 students: 58 high school and 63 primary school students. The research investigated students’ environmental knowledge, environmental attitudes, and pro-environmental behavior. Qualitative data were analyzed thematically. Multivariate statistics (MANOVA) were used to examine the relationship between the dependent variables and the participant’s gender and level of schooling. From the results obtained, the top five most frequently mentioned local environmental problems by the students sampled included water pollution, deforestation, air pollution, scarcity of safe sources for water for domestic use, and soil erosion. Inferential statistical results revealed that there is a significant relationship between students’ level of schooling and environmental attitudes, F = 11.79, (1, 120), p < 0.01. In addition, there is a significant relationship between students’ level of schooling and environmental knowledge, that is, perceived severity of environmental problems, F = 5.33, (1, 120), p < 0.05. Research findings further revealed a significant relationship between gender and environmental knowledge, F = 9.62, (1, 120), p < 0.01. However, gender differences in pro-environmental behavior were not statistically significant. Also, differences between primary and high school students’ pro-environmental behavior were insignificant.
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Zaman, M., K. Kleineidam, L. Bakken, J. Berendt, C. Bracken, K. Butterbach-Bahl, Z. Cai, et al. "Greenhouse Gases from Agriculture." In Measuring Emission of Agricultural Greenhouse Gases and Developing Mitigation Options using Nuclear and Related Techniques, 1–10. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-55396-8_1.
Повний текст джерелаАнотація:
AbstractThe rapidly changing global climate due to increased emission of anthropogenic greenhouse gases (GHGs) is leading to an increased occurrence of extreme weather events such as droughts, floods, and heatwaves. The three major GHGs are carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). The major natural sources of CO2 include ocean–atmosphere exchange, respiration of animals, soils (microbial respiration) and plants, and volcanic eruption; while the anthropogenic sources include burning of fossil fuel (coal, natural gas, and oil), deforestation, and the cultivation of land that increases the decomposition of soil organic matter and crop and animal residues. Natural sources of CH4 emission include wetlands, termite activities, and oceans. Paddy fields used for rice production, livestock production systems (enteric emission from ruminants), landfills, and the production and use of fossil fuels are the main anthropogenic sources of CH4. Nitrous oxide, in addition to being a major GHG, is also an ozone-depleting gas. N2O is emitted by natural processes from oceans and terrestrial ecosystems. Anthropogenic N2O emissions occur mostly through agricultural and other land-use activities and are associated with the intensification of agricultural and other human activities such as increased use of synthetic fertiliser (119.4 million tonnes of N worldwide in 2019), inefficient use of irrigation water, deposition of animal excreta (urine and dung) from grazing animals, excessive and inefficient application of farm effluents and animal manure to croplands and pastures, and management practices that enhance soil organic N mineralisation and C decomposition. Agriculture could act as a source and a sink of GHGs. Besides direct sources, GHGs also come from various indirect sources, including upstream and downstream emissions in agricultural systems and ammonia (NH3) deposition from fertiliser and animal manure.
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Ashton, Peter. "Water and Development: A Southern African Perspective." In Managing Water Resources, Past and Present. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780199267644.003.0015.
Повний текст джерелаАнотація:
Water is acknowledged as the most indispensable of all natural resources, and neither biological diversity nor social and economic development can be sustained in its absence (Hudson 1996; Ashton 2002). Every country faces a similar challenge, namely, providing sufficient water to meet the escalating needs of expanding populations while continuing to ensure that the available resources are used equitably and efficiently (Biswas 1993; Gleick 1998; Ashton and Haasbroek 2002). Increasing rates of industrialization, urbanization, and mechanization aggravate the pressures imposed by population growth, while increasing rates of utilization and pollution place further demands on dwindling resources (Falkenmark 1994,1999; Rosegrant 1997; Gleick 1998; Ashton 2002). This situation is especially serious in arid regions where water scarcity hinders social and economic development and is linked closely to the prevalence of poverty, hunger, and disease (Falkenmark 1989; Gleick 2000; Ashton 2002). In southern Africa, water resources are unevenly distributed in both geographical extent and time, and large areas of the region regularly experience prolonged and extreme droughts. Ironically, these droughts are often ‘relieved’ by equally extreme flood events (Christie and Hanlon 2001). Whilst the availability of water resources is naturally variable and often unpredictable, there is also compelling, though as yet unverified, evidence that projected trends in global climate change could worsen this situation (Ashton 2002). Falkenmark (1989) noted that several African countries had approached or would soon pass the point indicating severe water stress or water deficit, and that this could hinder further development in these countries. Recent estimates suggest that more African countries will exceed the limits of their economically usable, land-based water resources before the year 2025 (Ashton 2002). These disturbing statistics emphasize the urgent need to find sustainable solutions to the problem of ensuring secure and adequate water supplies for all countries in the region. The consequences of social and political dispensations imposed by previous colonial and apartheid administrations in southern Africa are reflected in the disparate levels of social, economic, and political development attained by these countries. These unequal levels of development have been accompanied by differing levels of need for water, further complicating the search for equitable and sustainable solutions to water supply problems (Ashton 2000, 2002).
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Brunini, Orivaldo, and Alice M. Grimm. "Agricultural Drought Phenomenon in Latin America with Focus on Brazil." In Monitoring and Predicting Agricultural Drought. Oxford University Press, 2005. http://dx.doi.org/10.1093/oso/9780195162349.003.0020.
Повний текст джерелаАнотація:
Latin America encompasses a vast territory between 12°30'N and 55°30'S latitude and between 29°W and 82°W longitude. This subcontinent has 13 countries with complex climatic conditions. Extremely humid weather is typical closer to the equator, while semiarid, arid, and desertic conditions prevail in the Bolivian and Chilean high plains. The wide variation in climatic conditions leads to distinct agricultural conditions across Latin America. For example, forests, equatorial fruits, and perennial vegetation exist throughout the Amazonian region. Farther from the equator, toward the Andes and at higher latitudes, there is a noticeable change in agricultural systems. There is a greater emphasis on growing cereal/grain crops in Argentina and Brazil. The countries that compose the Amazon River basin experience a higher amount of annual precipitation, and drought is not a characteristic phenomenon there, except during high-intensity El Niño years (Marengo et al., 2001). In contrast, drought is a regular event commonly observed in parts of Peru, Chile, Paraguay, Argentina (Scian and Donnari, 1996), Uruguay, and Brazil. The Atacama Desert in Chile is one of the most arid regions on the earth, where the average annual precipitation is as low as 0.8 mm in Arika or even 0.5 mm in other regions of this desert. Figure 12.2 provides a more detailed description on climatic conditions of Brazil. Although the average annual precipitation in the northeastern region is less than 300 mm, it exceeds 2500 mm in some other regions of Brazil (Grimm, 2003). Agricultural operations take place during the rainy season (March–October). The northeast region is drought prone, but the central, west, and southeast regions are traditionally grain-producing regions. In the northeast and central-west regions, water deficiency is higher, which seriously affects food production. Table 12.1 shows production losses in Brazil due to climate anomalies including droughts that occurred during 1978–1986 (Mota, 1979) and 1991–1994 (Rossetti, 2001). About 33% (about 50% in the northeast region) of these losses were attributed to droughts. Maize production also significantly declined due to drought that occurred during 1990–91, 1993–94, 1996–97, and 1997–98.
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Horne, James, Cecilia Tortajada, and Larry Harrington. "Achieving the Sustainable Development Goals: improving water services in cities affected by extreme weather events." In Urban Resilience to Droughts and Floods, 3–17. Routledge, 2020. http://dx.doi.org/10.4324/9780429400728-2.
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Wambua, Raphael Muli. "Drought Estimation-and-Projection Using Standardized Supply-Demand-Water Index and Artificial Neural Networks for Upper Tana River Basin in Kenya." In Research Anthology on Artificial Neural Network Applications, 1098–117. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-2408-7.ch051.
Повний текст джерелаАнотація:
Drought occurrence, frequency and severity in the Upper Tana River basin (UTaRB) have critically affected water resource systems. To minimize the undesirable effects of drought, there is a need to quantify and project the drought trend. In this research, the drought was estimated and projected using Standardized Supply-Demand-Water Index (SSDI) and an Artificial Neural Network (ANN). Field meteorological data was used in which interpolated was conducted using kriging interpolation technique within ArcGIS environment. The results indicate those moderate, severe and extreme droughts at varying magnitudes as detected by the SSDI during 1972-2010 at different meteorological stations, with SSDI values equal or less than -2.0. In a spatial domain, the areas in south-eastern parts of the UTaRB exhibit the highest drought severity. Time-series forecasts and projection show that the best networks for SSDI exhibit respective ANNs architecture. The projected extreme droughts (values less than -2.00) and abundant water availability (SSDI values ³ 2.00) were estimated using Recursive Multi-Step Neural Networks (RMSNN). The findings can be integrated into planning the drought-mitigation-adaptation and early-warning systems in the UTaRB.
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Janardhanan, Rajan. "Water Management." In Handbook of Research on Future Opportunities for Technology Management Education, 387–400. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-8327-2.ch023.
Повний текст джерелаАнотація:
The world faces an unprecedented crisis in water resources management, with profound implications for global food security, protection of human health, and maintenance of all ecosystems on Earth. Large uncertainties still plague quantitative assessments of climate change impacts and water resource management, but what is known for certain is that the climate is changing and that it will have an effect on water resources. Therefore, increased efforts will be needed to plan and manage water supplies in the future through increased monitoring and understanding of the interrelationships between population size, climate change, and water availability. The focus of water management is gradually shifting from developing new water sources to using existing water sources more effectively and efficiently. The world needs policy change in water management. Respect for water resources and their value is the starting point of deliberations. Governments have the essential water management function: to protect and allocate water resources to allow both individual and collective interests to benefit from water. Societies must also lead in understanding, provisioning for mitigating the impact of disasters, ranging from extreme droughts to unprecedented floods, caused by climate change and poor management of water and land. Public funds will likely remain the main source of water sectoral funding. It is up to governments to invest wisely to enhance the crucial role that water has for social and economic development in a country. Integrated water resource management strategy is accepted as a global model for achieving the objective of a sustainable water management system.
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El Baz, Soraia, and Kholoud Kahime. "Waterborne Diseases Arising From Climate Change." In Research Anthology on Environmental and Societal Impacts of Climate Change, 64–87. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-3686-8.ch004.
Повний текст джерелаАнотація:
As a result of increased frequency and intensity of heat waves, increased floods and droughts, change in climate will affect biological, physical, and chemical components of water through different paths thus enhancing the risk of waterborne diseases. Identifying the role of weather in waterborne infection is a priority public health research issue as climate change is predicted to increase the frequency of extreme precipitation and temperature events. This chapter provides evidence that precipitation and temperature can affect directly or indirectly water quality and consequently affect the health human. This chapter also highlights the complex relationship between precipitation or temperature and transmission of waterborne disease such as diarrheal disease, gastroenteritis, cryptosporidiosis, giardiasis, and cholera.
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El Baz, Soraia, and Kholoud Kahime. "Waterborne Diseases Arising From Climate Change." In Advances in Environmental Engineering and Green Technologies, 408–31. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7775-1.ch021.
Повний текст джерелаАнотація:
As a result of increased frequency and intensity of heat waves, increased floods and droughts, change in climate will affect biological, physical, and chemical components of water through different paths thus enhancing the risk of waterborne diseases. Identifying the role of weather in waterborne infection is a priority public health research issue as climate change is predicted to increase the frequency of extreme precipitation and temperature events. This chapter provides evidence that precipitation and temperature can affect directly or indirectly water quality and consequently affect the health human. This chapter also highlights the complex relationship between precipitation or temperature and transmission of waterborne disease such as diarrheal disease, gastroenteritis, cryptosporidiosis, giardiasis, and cholera.
Тези доповідей конференцій з теми "Extreme droughts and excess of water"
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KHOLIAVCHUK, Dariia, and Marta CEBULSKA. "Precipitation Shortage in the High Ukrainian and Polish Carpathians." In Air and Water – Components of the Environment 2021 Conference Proceedings. Casa Cărţii de Ştiinţă, 2021. http://dx.doi.org/10.24193/awc2021_04.
Повний текст джерелаАнотація:
In the recent decades, droughts and dry episodes throughout a year have become common for both arid and humid regions. The Carpathian Mountains referred to as natural water towers are also the case. Accordingly, the study aims and distinguishing monthly and daily patterns and peculiarities of precipitation shortage in the high-mountain areas (above 1000 m) of the Polish and the Ukrainian Carpathians using monthly and daily data series (1984-2015) of weather stations Kasprowy Wierch (1991 m a.s.l), Dolina Pięciu Stawów (1670 m a.s.l) and Morskie Oko (1408 m a.s.l) in the Polish Carpathians, Play (1343 m a.s.l) and Pogegevskaya (1429 m a.s.l) in the Ukrainian Carpathians. Here, in all the months throughout a year, dry episodes have been detected. In the Polish Carpathians, represented by three measuring stations, the driest episodes in the years took place from August to October and January, and slightly less – about 11-16% in the remaining months. In the monthly context, the highest frequency of dry months, exceeding 20%, is detected in June both in Pogegevskaya, as well and in April and July in Play. In March, April, as well as November extreme atmospheric drought took place in the entire area of the Polish Tatra Mountains, the highest mountain range of the Polish Carpathians. In all the measuring stations of the area in November 2011, the precipitation amount did not exceed 11 mm. They accounted for less than 10% of the average multiannual precipitation sum. Alongside, the positive trend in the years from 1984 to 2015 with significance levels of 0.1 and 0.2 was only established in the lowest monthly precipitation sums at Pogegevskaya. The longest episodes without precipitation, periods that begin and end with a day without precipitation, are detected in most parts of the study area in October and November 2011, especially in the western and southern parts of the Polish Carpathians.
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Kiang, Julie E., and Erik R. Hagen. "Preparing for Extreme Droughts: Moving Beyond the Historical Planning Event in the Potomac Basin." In World Water and Environmental Resources Congress 2004. Reston, VA: American Society of Civil Engineers, 2004. http://dx.doi.org/10.1061/40737(2004)313.
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Deylami, Behavar. "Improving Social Capital, A Solution to Manage Water Conflicts." In 8th Peace and Conflict Resolution Conference [PCRC2021]. Tomorrow People Organization, 2021. http://dx.doi.org/10.52987/pcrc.2021.007.
Повний текст джерелаАнотація:
Abstract Water systems are categorized as coupled human-natural systems. It is argued that extreme events are primarily associated with the natural component of the system, while conflicts are considered as part of the human component of the water systems. Since the system is coupled, both human and natural components interact with each other. For instance, extreme events such as droughts can trigger conflict among societies. What needs to be noted here is that such disturbances in both systems are, to some extent, inevitable. However, by using the proper mechanisms and leverages, they can be alleviated. Enhancing social capital among stakeholders is one of those leverages to reduce the conflicts' likelihood or at least intensity. Social capital reflects people’s collective level of awareness on the issues, their reciprocal relationships, and public participation. In other words, social capital captures three concepts of “Public Justice,” “Public Cohesion,” and “Public Participation.” This paper aims to descriptively analyze the effect of social capital in social conflicts in the context of water systems. The results of this study indicated that social capital is effective in alleviating water conflicts, but requires large and long-term investments. Therefore, it can be used to alleviate conflicts to reduce vulnerability, and achieve development. Keywords: Social capital, Water systems, Conflict, Vulnerability
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Sheldon, Seth, and Anamarija Frankic´. "A Model for Relating Environmental Variation to Water Permit Violations at Thermoelectric Facilities in the Taunton River Watershed." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-63785.
Повний текст джерелаАнотація:
An original model is presented that relates the rate of National Pollutant Discharge Elimination System (NPDES) water use permit violations and reduced capacity events (dial-back) at once-through cooled thermoelectric power plants to electricity demand and ambient environmental conditions using historical data. 31 percent of U.S. generation capacity is composed of thermoelectric facilities that use once-through (open loop) cooling [1]. Open loop systems have substantial water demands, which put energy facilities and downstream ecosystems at risk during extreme climate events (e.g. heat waves, droughts) [2]. During such events, power plant managers must decide to either dial back electricity generation or violate their water permits by using too much water or by discharging it at too high a temperature. Withdrawal rate and effluent temperature violations can be costly for energy utilities and are detrimental to the biota of receiving waters [3].
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Gutiérrez, Juan David. "Comparing the Identification of Sites With High Risk of Landslides Using Isohyets of Precipitation vs Alterations of Rainfall by La Niña in Santander Colombia." In ASME 2015 International Pipeline Geotechnical Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipg2015-8502.
Повний текст джерелаАнотація:
Extreme meteorological events associated with climate change are a real issue and have important impact over the economy of infrastructure sector, including highways, hydrocarbon transport by pipelines, mines, etc., because saturation of soils by water can produce landslides and it could produce the fracture of pipelines or other kind of tangible assets. For example, an assessment of historical geotechnical failures in Ecopetrol (Colombian Oil Company) vs. extreme meteorological events shows that during La Niña (extreme rainfall period) geotechnical failures are three times greater. This work shows a method to identify places of risk by extreme meteorological events, mainly La Niña phenomenon, with focus in most probably alteration of rainfall. Our results illustrate the hot spots where there is a high probability of slight excess (120–160% of average rainfall) and high excess (>160%) of average rainfall. The results were intersected in a GIS with pipelines and mass movement risk maps to identify the places of high risk along Santander region.
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Dahal, Swaechchha, Thomas Øyvang, Gunne John Hegglid, Shailendra Kumar Jha, and Bhupendra Bimal Chhetri. "Himalayan Run-Off River Power Generation Modelling for Power Security in Evolving Weather Conditions." In 63rd International Conference of Scandinavian Simulation Society, SIMS 2022, Trondheim, Norway, September 20-21, 2022. Linköping University Electronic Press, 2022. http://dx.doi.org/10.3384/ecp192022.
Повний текст джерелаАнотація:
Extreme black-swan occurrences like earthquakes, glacial lake outbursts, flash floods, landslides, etc. are important concerns in Himalayan countries like Nepal, which are highly susceptible, geologically active, and exquisitely fragile. Nepal generates 97 percent of its electricity from hydropower, where 56.08 percent of it is coming from seasonal run-off-river (RoR) hydro plants. Landslides and mudflows are common in the monsoon, and low discharge is common in the winter season. These RoR plants must be able to withstand high-impact events like earthquakes and lengthy droughts in order for the Nepalese grid to remain secure. This study gives a presentation and overview of previously occured natural hazards in Nepal related to hydropower plants. In particular, the 2014 Sunkoshi landslide and the 2021 Melamchi flood are evaluated as extreme events and their impacts on hydropower plant has been studied. In addition, an in-depth investigation on a ROR plant is carried out. Moreover, the water discharge and extreme rainfall peaks in time series data is evaluated using an ARIMA-based model. This paper shows the feasibility of predicting the energy produced by a run-off river hydropower plant. The purpose is to forecast discharge and hence the ROR power generation with the aim to facilitate the hydropower operators for their availability declaration which will again help in the overall energy planning. The results are discussed together with performance metrics, and indicates that the implemented technique is promising.These predictions can be further used for planning and estimating the power generation on a more complex level.
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Mohr, Henning, Scott Draper, and David White. "Free Field Sediment Mobility on Australia’s North West Shelf." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11490.
Повний текст джерелаАнотація:
Under cyclonic conditions, sediment on the North West Shelf (NWS) of Australia may become mobile in shallow water due to classical sediment transport or local liquefaction, and this can affect, for example, the on-bottom stability of subsea pipelines. In this paper, three calcareous sediments sampled from the NWS are analysed, together with realistic metocean data, to illustrate this potential for sediment mobility on the NWS. Specifically, experiments are performed in a recirculating flume (known as an O-Tube) to measure the erosional behaviour and an additional series of experiments are performed using a shaking table, on which each of the sediments have been liquefied and excess pore pressure measurements recorded to back calculate the consolidation coefficient. Soil characterisation data, threshold velocity measurements and shaking table results have then combined to illustrate the potential for sediment mobility for each of the NWS sediments. Best practice models are used to calculate wave and current combined shear stress at the seabed and excess pore pressure accumulation. We find that for these sediments, freshly deposited in laboratory samples, mobility due to sediment transport or liquefaction is very likely in cyclonic conditions on the NWS. Liquefaction is most likely for loosely packed silt, whilst sediment transport is most likely for sand. However, we also show that in more extreme cyclonic conditions there are a subset of sediments that can become mobile due to both sediment transport and liquefaction.
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Garza, Zacharias, Kevin Pan, Anthony Izaguirre, Saul Loza, Jonathan Serrano, Oscar Lopez, Jim Kuo, and Jonathan Sauder. "Design of a Horizontal Axis Wind Turbine for a Venusian Environment." In ASME 2021 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/imece2021-73558.
Повний текст джерелаАнотація:
Abstract The atmosphere of Venus is 96% carbon dioxide and contains clouds of sulfur dioxide and sulfuric acid, with surface temperatures in excess of 470°C and pressures 92 times that of Earth. These extreme environmental conditions make planetary exploration difficult, as modern electronics cannot survive for prolonged periods of time. Photovoltaics, a conventional power generation method for Mars rovers, are inefficient on the planet’s surface due to the dense cloud cover and harsh environment. The NASA – JPL Hybrid Automaton Rover Venus proposes using a mechanical wind energy harvester to further explore the Venusian surface. At the proposed landing site, the surface wind speeds range from 0.3 to 1.3 m/s with an average wind speed of 0.6 m/s. These wind speeds, combined with the high density of Venusian air, results in promising potential for power generation. The power goal for the proposed wind harvester is 9W at the average wind speed of 0.6 m/s. A horizontal axis wind turbine (HAWT) is used to avoid dynamic stall experienced by vertical axis wind turbines at low wind speeds. In the HAWT, existing airfoil profiles were evaluated and chosen using an iterative design process. The blade designs were analyzed using blade element momentum theory (BEM) to predict and improve turbine performance. Testing was performed in water, as the greater fluid density allowed for testing at a lower speed than in air to better simulate Venus surface conditions. The preliminary water testing was carried out to characterize turbine performance. In this process, a 3D printed PLA 1:4 scale turbine was placed in an open-channel pool with flow supplied through a pump. The turbine was a fixed 2.3 m distance away from the inlet of the flow. The flow speed, turbine rotational speed, and torque produced were recorded. The results yielded turbine efficiencies between 7.7% and 46.1%. These results exceeded design expectations at the designed TSR, where an efficiency of 40% was to be expected. Based on the preliminary results, modifications are being made to the water testbed to improve the testing process as well as more accurately simulate conditions on the surface of Venus. The collected data and the aforementioned design tools are used to improve the current turbine design.
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Teixeira, Fernando J. R., Anderson T. Oshiro, and Eduardo A. Tannuri. "Drifting Time of a Standard Drillship." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-24338.
Повний текст джерелаАнотація:
This paper presents a methodology in order to perform a drift off calculation for drillships according to given parameters such as: environmental conditions and water depth. Drift off occurs when there is insufficient thruster force so that the vessel is drifted away from the target position by the environmental forces. For a safe operational drillship it is expected that the drifting off will be resumed in due time when blackout recovery system starts running and, therefore, enough thrust takes place. Water depth plays an important role when considering the default maximum release of Lower Flex Joint (LFJ) angle for physically disconnecting, which is 10 degrees in the majority of suppliers. This methodology is intended to be applied to drillship design, by comparing the time to stop drifting and the distance from the reference point after a total blackout occurs. Electrical generators sets installed in drillships are designed to work with extreme environmental conditions. Since there is an excess of installed power for the majority of the operational time, drillships often operate with all high voltage busbars connected to each other improving engine efficiency, decreasing levels of pollution emissions and reducing maintenance. The use of this electrical power configuration is possible because there is no need to turn on all generators at the same time, but only the ones that are needed on that particular moment. However, when a single failure such as a short circuit occurs and the system is not prepared to disable and segregate the failure, all electrical system will crash, causing a total blackout and the drillship will start to drift off. The drifting off time was obtained by numerical simulations conducted by modeling a standard drillship using time domain software. The model took into consideration the vessel hydrodynamics under environmental conditions (wind, current and wave), the drag force in marine drilling riser, and the thrusters in Dynamic Positioning (DP) operation. The simulation is divided into three steps: First, the behavior of the DP system in full operation is simulated until system is stable. After that, all thrusters are turned off to simulate a total blackout. Finally, since the ship will not stop immediately because of its inertia, a time range for the ship’s inertia was also considered and this time is added to the pre-established blackout duration. The conclusion of the study shows how parameters as water depth, environmental conditions, and blackout recovery time affect the necessary time to stop drifting off, so as to foresee that after a total blackout the standard drillship will remain in safe limits.
Звіти організацій з теми "Extreme droughts and excess of water"
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Heitman, Joshua L., Alon Ben-Gal, Thomas J. Sauer, Nurit Agam, and John Havlin. Separating Components of Evapotranspiration to Improve Efficiency in Vineyard Water Management. United States Department of Agriculture, March 2014. http://dx.doi.org/10.32747/2014.7594386.bard.
Повний текст джерелаАнотація:
Vineyards are found on six of seven continents, producing a crop of high economic value with much historic and cultural significance. Because of the wide range of conditions under which grapes are grown, management approaches are highly varied and must be adapted to local climatic constraints. Research has been conducted in the traditionally prominent grape growing regions of Europe, Australia, and the western USA, but far less information is available to guide production under more extreme growing conditions. The overarching goal of this project was to improve understanding of vineyard water management related to the critical inter-row zone. Experiments were conducted in moist temperate (North Carolina, USA) and arid (Negev, Israel) regions in order to address inter-row water use under high and low water availability conditions. Specific objectives were to: i) calibrate and verify a modeling technique to identify components of evapotranspiration (ET) in temperate and semiarid vineyard systems, ii) evaluate and refine strategies for excess water removal in vineyards for moist temperate regions of the Southeastern USA, and iii) evaluate and refine strategies for water conservation in vineyards for semi-arid regions of Israel. Several new measurement and modeling techniques were adapted and assessed in order to partition ET between favorable transpiration by the grapes and potentially detrimental water use within the vineyard inter-row. A micro Bowen ratio measurement system was developed to quantify ET from inter-rows. The approach was successful at the NC site, providing strong correlation with standard measurement approaches and adding capability for continuous, non-destructive measurement within a relatively small footprint. The environmental conditions in the Negev site were found to limit the applicability of the technique. Technical issues are yet to be solved to make this technique sufficiently robust. The HYDRUS 2D/3D modeling package was also adapted using data obtained in a series of intense field campaigns at the Negev site. The adapted model was able to account for spatial variation in surface boundary conditions, created by diurnal canopy shading, in order to accurately calculate the contribution of interrow evaporation (E) as a component of system ET. Experiments evaluated common practices in the southeastern USA: inter-row cover crops purported to reduce water availability and thereby favorably reduce grapevine vegetative growth; and southern Israel: drip irrigation applied to produce a high value crop with maximum water use efficiency. Results from the NC site indicated that water use by the cover crop contributed a significant portion of vineyard ET (up to 93% in May), but that with ample rainfall typical to the region, cover crop water use did little to limit water availability for the grape vines. A potential consequence, however, was elevated below canopy humidity owing to the increased inter-row evapotranspiration associated with the cover crops. This creates increased potential for fungal disease occurrence, which is a common problem in the region. Analysis from the Negev site reveals that, on average, E accounts for about10% of the total vineyard ET in an isolated dripirrigated vineyard. The proportion of ET contributed by E increased from May until just before harvest in July, which could be explained primarily by changes in weather conditions. While non-productive water loss as E is relatively small, experiments indicate that further improvements in irrigation efficiency may be possible by considering diurnal shading effects on below canopy potential ET. Overall, research provided both scientific and practical outcomes including new measurement and modeling techniques, and new insights for humid and arid vineyard systems. Research techniques developed through the project will be useful for other agricultural systems, and the successful synergistic cooperation amongst the research team offers opportunity for future collaboration.