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Journal articles on the topic 'Arid land resource sciences'
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Cabello, Violeta, Ansel Renner, and Mario Giampietro. "Relational analysis of the resource nexus in arid land crop production." Advances in Water Resources 130 (August 2019): 258–69. http://dx.doi.org/10.1016/j.advwatres.2019.06.014.
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Elhag, Mohamed, Hanaa K. Galal, and Haneen Alsubaie. "Understanding of morphometric features for adequate water resource management in arid environments." Geoscientific Instrumentation, Methods and Data Systems 6, no. 2 (August 10, 2017): 293–300. http://dx.doi.org/10.5194/gi-6-293-2017.
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Abstract. Hydrological characteristics such as topographic parameters, drainage attributes, and land use/land cover patterns are essential to evaluate the water resource management of a watershed area. In the current study, delineation of a watershed and calculation of morphometric characteristics were undertaken using the ASTER global digital elevation model (GDEM). The drainage density of the basin was estimated to be very high, which indicates that the watershed possesses highly permeable soils and low to medium relief. The stream order of the area ranges from first to sixth order, showing a semi-dendritic and radial drainage pattern that indicates heterogeneity in textural characteristics, and it is influenced by structural characteristics in the study area. The bifurcation ratio (Rb) of the basin ranges from 2.0 to 4.42, and the mean bifurcation ratio is 3.84 in the entire study area, which signifies that the drainage pattern of the entire basin is controlled much more by the lithological and geological structure. The elongation ratio is 0.14, which indicates that the shape of the basin has a narrow and elongated shape. A land use/land cover map was generated by using a Landsat-8 image acquired on 10 August 2015 and classified to distinguish mainly the alluvial deposit from the mountainous rock.
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Hu, Yuxian, Ke Zhang, Yuan Li, Yanan Sun, Hongyan Li, and Gaiqiang Yang. "Human Activities Increase the Nitrogen in Surface Water on the Eastern Loess Plateau." Geofluids 2021 (June 1, 2021): 1–9. http://dx.doi.org/10.1155/2021/9957731.
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Human activities have greatly accelerated the input of nitrogen into waters, resulting in water quality degradation. Facing the water crisis of nitrogen pollution, the state of surface water in arid areas needs close attention. Although numerous studies have indicated that waters’ nitrogen is often impacted by land use covers, the correlation between the two remains obscure. This paper explored the spatial relationship between anthropogenic activity and waters’ nitrogen on the eastern Loess Plateau, based on the Geographic Information System (GIS) spatial analysis using land use covers. There were 3 human land use types and 2 nitrogen indices used to assess the rivers’ state at the watershed scale. The results showed that rivers’ nitrogen was closely associated with human land use covers. Nitrogen pollution was most serious in urban areas. This study provided new evidence for the relationship between anthropogenic activities and river ecology. The findings may be helpful for policymakers to make strategic decisions of water resource management and land use planning in arid areas.
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Mubako, Stanley, Omar Belhaj, Josiah Heyman, William Hargrove, and Carlos Reyes. "Monitoring of Land Use/Land-Cover Changes in the Arid Transboundary Middle Rio Grande Basin Using Remote Sensing." Remote Sensing 10, no. 12 (December 11, 2018): 2005. http://dx.doi.org/10.3390/rs10122005.
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Expanding urbanization in highly fragile desert environments requires a thorough understanding of the current state and trends of land uses to achieve an optimal balance between development and the integrity of vital ecosystems. The objectives of this study are to quantify land use change over the 25-year period 1990–2015 and analyze temporal and spatial urbanization trends in the Middle Rio Grande Basin. We conclude by indicating how the results can inform on-going water resource research and public policy discussion in an arid region. Results show that the predominant upland mixed vegetation land cover category has been steadily declining, giving up land to urban and agricultural development. Urban development across the region of interest increased from just under three percent in 1990 to more than 11 percent in 2015, mainly around the major urban areas of El Paso, Ciudad Juárez, and Las Cruces. Public policy aspects related to results from this study include transfer of water rights from agriculture to land developers in cities, higher risk of flooding, loss of natural ecosystems, and increased water pollution from point and non-point sources. Various stakeholders can find the study useful for a better understanding of historical spatial and temporal aspects of urban development and environmental change in arid regions. Such insights can help municipal authorities, farmers, and other stakeholders to strike a balance between development needs and protecting vital ecosystems that support the much needed development, especially in regions that are endowed with transboundary natural resources that often are incompletely represented in single nation data.
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ALI, HUSSIEN, KATRIEN DESCHEEMAEKER, TAMMO S. STEENHUIS, and SURAJ PANDEY. "COMPARISON OF LANDUSE AND LANDCOVER CHANGES, DRIVERS AND IMPACTS FOR A MOISTURE-SUFFICIENT AND DROUGHT-PRONE REGION IN THE ETHIOPIAN HIGHLANDS." Experimental Agriculture 47, S1 (January 2011): 71–83. http://dx.doi.org/10.1017/s0014479710000840.
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SUMMARYLand use and land cover changes are driven by human actions and, in turn, drive changes that alter the availability of products and services for people and livestock. For proper planning, these cause-and-effect interrelations need to be understood. This is especially important for Ethiopia where the resource base is declining and should be improved in order to feed the growing population. To better understand these interrelations, we studied trends in the natural resource base over a 35-year period for two contrasting sites in the Ethiopian Highlands: semi-arid and water-short Lenche Dima, and sub-humid and moisture-sufficient Kuhar Michael. Information was obtained using time-series satellite images, geographical positioning system, a socio-economic survey and a document review. Results showed that for sub-arid Lenche Dima there were minimal changes in land use and land cover patterns, while in water-sufficient Kuhar Michael cropland greatly increased at the expense of the grazing land and bare soil. At the same time land holding size and cattle numbers decreased in Lenche Dima while they remained the same in Kuhar Michael, although overall land holdings remained larger in Lenche Dima than in Kuhar Michael. This study thus found large differences in development of agriculture since the 1970s: intensification of agriculture is possible in the water-sufficient sub-humid climate by displacing animal husbandry with high value crops that need irrigation during the dry monsoon season. This is not possible for the semi-arid area where water is the limiting factor in production even if a market is close by. Agriculture in the semi-arid areas also requires larger land holdings because of the risk of droughts and low yields during some years. This comparative analysis suggests that without sufficient water, the shift from subsistent to commercial market-driven agriculture cannot be easily accomplished.
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Cogle, AL, J. Littlemore, and DH Heiner. "Soil organic matter changes and crops responses to fertiliser under conservation cropping systems in the semi-arid tropics of North Queensland, Australia." Australian Journal of Experimental Agriculture 35, no. 2 (1995): 233. http://dx.doi.org/10.1071/ea9950233.
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Soil organic matter changes due to cropping in the semi-arid tropics were studied in an area with cropping potential. Soil organic carbon and total nitrogen (N) decreased after clearing and tillage, but decline was less where pasture-crop rotations were used. Crop N removal was high and exceeded the recommended fertiliser N rate. These results suggest that if cropping expansion occurs, careful management the is necessary for long-term productivity and land resource protection.
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Wu, Yage, Guang Yang, Lijun Tian, Xinchen Gu, Xiaolong Li, Xinlin He, Lianqing Xue, Pengfei Li, and Senyuan Xiao. "Spatiotemporal variation in groundwater level within the Manas River Basin, Northwest China: Relative impacts of natural and human factors." Open Geosciences 13, no. 1 (January 1, 2021): 626–38. http://dx.doi.org/10.1515/geo-2020-0258.
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Abstract The Manas River Basin (MRB), Northwest China, is an arid basin dependent on irrigation for agriculture, and human activities are believed to be the primary factor affecting the groundwater level fluctuations in this basin. Such fluctuations can have a significant adverse impact on the social economy, agricultural development, and natural environment of that region. This raises concerns regarding the sustainability of groundwater use. In this study, we used ArcGIS spatial interpolation and contrast coefficient variance analysis to analyse groundwater level, land-use change, and water resource consumption patterns from 2012 to 2019 in the plains of the MRB. The aim was to determine the main factors influencing the groundwater level and to provide a scientific basis for the rational development, utilisation, and management of water resources in this area. During the study period, the groundwater level decreased, increased, and then fluctuated with a gradually slowing downward trend; the decline ranged from −17.82 to −11.67 m during 2012–2019. Within a given year, groundwater levels declined from March/April to August/September, then rose from August/September to March/April, within a range of 0.29–19.05 m. Primary factors influencing the groundwater level included human activities (e.g., changes in land use, river regulation, irrigation, and groundwater exploitation) and natural causes (e.g., climate and weather anomalies). Human activities were the primary factors affecting groundwater level, especially land-use change and water resource consumption. These results provide a theoretical basis for the rational exploitation of groundwater and the optimisation of water resource management in this region.
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Rayburg, Scott, and Martin Thoms. "A coupled hydraulic–hydrologic modelling approach to deriving a water balance model for a complex floodplain wetland system." Hydrology Research 40, no. 4 (August 1, 2009): 364–79. http://dx.doi.org/10.2166/nh.2009.110.
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Wetlands, particularly those in semi-arid or arid environments, are hotspots of biological diversity and productivity. Water resource managers are therefore increasing their efforts to conserve wetlands from environmental degradation. To do this, they require a thorough understanding of the wetting and drying regimes of these wetlands, and how potential land use, climate change and water resource development might affect inundation patterns. Hydrologic models can help to enhance this understanding, and to predict and assess future impacts. However, for semi-arid environments, data to assist in model construction is scarce. This paper presents a new method for developing a water balance model for a semi-arid wetland, the Narran Lakes ecosystem in eastern Australia. This method combines hydraulic (improving our understanding of water movement through a wetland) and hydrologic (improving our predictive capability for inundation levels) models and satellite imagery (acting as calibration and validation data) to produce a predictive model of wetland inundation. We show that this coupled hydraulic–hydrologic model yields inundation patterns commensurate with those that actually occurred over more than 30 years. The model results indicate that current inundation levels are at historical lows, which is most likely associated with a naturally occurring drought and increasing water resource development upstream.
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Cui, Yaokui, Shihao Ma, Zhaoyuan Yao, Xi Chen, Zengliang Luo, Wenjie Fan, and Yang Hong. "Developing a Gap-Filling Algorithm Using DNN for the Ts-VI Triangle Model to Obtain Temporally Continuous Daily Actual Evapotranspiration in an Arid Area of China." Remote Sensing 12, no. 7 (April 1, 2020): 1121. http://dx.doi.org/10.3390/rs12071121.
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Temporally continuous daily actual evapotranspiration (ET) data play a critical role in water resource management in arid areas. As a typical remotely sensed land surface temperature (LST)-based ET model, the surface temperature-vegetation index (Ts-VI) triangle model provides direct monitoring of ET, but these estimates are temporally discontinuous due to cloud contamination. In this work, we present a gap-filling algorithm (TSVI_DNN) using a deep neural network (DNN) with the Ts-VI triangle model to obtain temporally continuous daily actual ET at regional scale. The TSVI_DNN model is evaluated against in situ measurements in an arid area of China during 2009–2011 and shows good agreement with eddy covariance (EC) observations. The temporal coverage was improved from 16.1% with the original Ts-VI tringle model to 67.1% with the TSVI_DNN model. The correlation coefficient (R), root mean square error (RMSE), bias, and mean absolute difference (MAD) are 0.9, 0.86 mm d−1, −0.16 mm d−1, and 0.65 mm d−1, respectively. When compared with the National Aeronautics and Space Administration (NASA) official MOD16 version 6 ET product, estimates of ET using TSVI_DNN are improved by approximately 49.2%. The method presented here can potentially contribute to enhanced water resource management in arid areas, especially under climate change.
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Fowler, Keirnan J. A., Suwash Chandra Acharya, Nans Addor, Chihchung Chou, and Murray C. Peel. "CAMELS-AUS: hydrometeorological time series and landscape attributes for 222 catchments in Australia." Earth System Science Data 13, no. 8 (August 6, 2021): 3847–67. http://dx.doi.org/10.5194/essd-13-3847-2021.
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Abstract. This paper presents the Australian edition of the Catchment Attributes and Meteorology for Large-sample Studies (CAMELS) series of datasets. CAMELS-AUS (Australia) comprises data for 222 unregulated catchments, combining hydrometeorological time series (streamflow and 18 climatic variables) with 134 attributes related to geology, soil, topography, land cover, anthropogenic influence and hydroclimatology. The CAMELS-AUS catchments have been monitored for decades (more than 85 % have streamflow records longer than 40 years) and are relatively free of large-scale changes, such as significant changes in land use. Rating curve uncertainty estimates are provided for most (75 %) of the catchments, and multiple atmospheric datasets are included, offering insights into forcing uncertainty. This dataset allows users globally to freely access catchment data drawn from Australia's unique hydroclimatology, particularly notable for its large interannual variability. Combined with arid catchment data from the CAMELS datasets for the USA and Chile, CAMELS-AUS constitutes an unprecedented resource for the study of arid-zone hydrology. CAMELS-AUS is freely downloadable from https://doi.org/10.1594/PANGAEA.921850 (Fowler et al., 2020a).
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Taimeh, Awni Y., and Nabil Katkhuda. "Dryland farming systems in Jordan." American Journal of Alternative Agriculture 12, no. 3 (September 1997): 100–104. http://dx.doi.org/10.1017/s0889189300007359.
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AbstractResources available for dryland farming in Jordan are limited since 91% of the country has an arid climate. Moreover, the available resources are subject to a wide range of natural and human constraints. The farming systems consist of two main types: annual crops such as wheat and barley, and fruit trees such as olives, grapes, and stone fruits. Socioeconomic factors coupled with a fluctuating rainfall pattern cause some shifting in land use and variation in land under cultivation. Alternative land use strategies and preservation and more efficient use of resources are the means to achieve higher production. Substantial addition of land suitable for cultivation is unlikely since it would require additional water resources, which are diminishing in Jordan. Environmental degradation such as desertification is a major concern to land use planners. Several issues must be addressed if agricultural productivity is to be sustained: preservation of resources; overcoming various pressures imposed on agricultural lands; adoption of new practical and economical practices; introduction of modern technologies such as water harvesting, supplemental irrigation, use of treated waste water, and proper soil conservation measures; and adaptive research.
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LI, GANG, GAOMING JIANG, YONGGENG LI, MEIZHEN LIU, YU PENG, LINGHAO LI, and XINGGUO HAN. "A new approach to the fight against desertification in Inner Mongolia." Environmental Conservation 34, no. 2 (May 29, 2007): 95–97. http://dx.doi.org/10.1017/s0376892907003864.
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The world's arid and semi-arid regions are severely affected by desertification. In China, wind erosion, water erosion, soil salinization and the freezing and melting processes have contributed to 2.64 million km2 of desertified land, covering 27.5% of the country's land surface (State Forestry Administration, Peoples' Republic of China 2005). Although climate change could be a reason for desertification, anthropogenic factors such as overgrazing and overcultivation also contribute to degradation in grassland areas (Millennium Ecosystem Assessment 2005; Zheng et al. 2006). The Chinese government has adopted afforestation as the main measure to control desertification. Major projects, including the ‘Three North Shelterbelt Programme’ (also known as the ‘Green Great Wall’) and the ‘Sandstorm Source Control Project around Beijing and Tianjin’, are necessary to shield northern and eastern agricultural ecosystems against sand and dust (Zhou 2002). However, these countermeasures require substantial effort and investment, and, in the semi-arid and arid regions of Inner Mongolia, newly planted trees have often died of drought, while tree planting could also be responsible for exhausting the precious groundwater resources of these regions (Jackson et al. 2005). Alternative and more practical ways of combating desertification by using multi-disciplinary approaches observing both social and ecological principles are required. The Hunshandake Sandy Land restoration demonstration project conducted by the Chinese Academy of Sciences was an attempt to restore desertified grassland mainly through natural processes, and requiring limited investment.
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Gao, P., Z. J. Li, G. C. Zhang, and Z. X. Liu. "Rainwater efficient use of the cellar-greenhouse system on slope land in hilly semi-arid area of North China." Plant, Soil and Environment 55, No. 4 (May 5, 2009): 146–53. http://dx.doi.org/10.17221/1642-pse.
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Water resources in semi-arid and arid regions are the most strongly limiting factor of the growth for plants. Rainwater efficient use is one of the focuses of the water resources research. In this paper, an experiment was conducted at Ka Zuo Research Station of Ecological Agriculture, Institute of Applied Ecology, Chinese Academy of Sciences in the hilly semi-arid area of North China. It aimed at studying the efficient use of rainwater harvesting of the cellar-greenhouse system (CGS). Results showed that, on average, the rainwater harvesting efficiency and sediment yield of the CGS were 5.7–15.7% and 865.8–1794.0 kg/ha, respectively, and that the rainwater harvesting efficiency and sediment yield of the CGS on slopes of 6° and 7° were significantly higher than that of the CGS on slope of 4.5°. In the CGS, over 52.1% of the irrigation rainwater was saved; the irrigation efficiency was significantly improved, by 21.15 kg/m<sup>3</sup>/ha on average, for sub-surface irrigation. Moreover, compared with flood irrigation, sub-surface irrigation could increase vegetable yield by 8.1–22.3%, improve output value of rainwater by 116.8–164.6%, and furthermore, the environmental conditions of the greenhouse on slope land were improved obviously. The mean unit area value of the CGS was about 13.5 times higher than that of the traditional land use system. By using the CGS, three goals, which were reducing water and soil losses, getting high rainwater use efficiency and gaining corresponding benefits, were realized.
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Foster, Stephen, and Héctor Garduño. "Irrigated agriculture and groundwater resources – towards an integrated vision and sustainable relationship." Water Science and Technology 67, no. 6 (March 1, 2013): 1165–72. http://dx.doi.org/10.2166/wst.2013.654.
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Globally, irrigated agriculture is the largest abstractor, and predominant consumer, of groundwater resources, with large groundwater-dependent agro-economies now having widely evolved especially in Asia. Such use is also causing resource depletion and degradation in more arid and drought-prone regions. In addition crop cultivation practices on irrigated land exert a major influence on groundwater recharge. The interrelationship is such that cross-sector action is required to agree more sustainable land and water management policies, and this paper presents an integrated vision of the challenges in this regard. It is recognised that ‘institutional arrangements’ are critical to the local implementation of management policies, although the focus here is limited to the conceptual understanding needed for formulation of an integrated policy and some practical interventions required to promote more sustainable groundwater irrigation.
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Waudby, Helen P., Sophie Petit, and Guy Robinson. "Pastoralists’ knowledge of plant palatability and grazing indicators in an arid region of South Australia." Rangeland Journal 35, no. 4 (2013): 445. http://dx.doi.org/10.1071/rj13021.
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Indicator species have been used for several decades as measures of ecosystem health. In arid Australian rangelands, which are dominated by commercial grazing enterprises reliant on native pastures, the development of efficacious indicators is particularly important to monitor production and biodiversity values. The high temporal and spatial climatic variability of arid rangelands means that developing broad indicators is difficult and resource intensive. However, pastoralists, who observe their pastures and the species favoured by stock under a range of conditions, can provide information on local indicators. This paper examines pastoralists’ knowledge in terms of its value for natural resource management in rangelands, including their use of local indicators and understanding of palatability of selected plant species. A survey was mailed to all 51 occupants of pastoral properties in the Stony Plains region of South Australia. Pastoralists were asked what species they considered indicators of overgrazing, whether they would destock if they noted changes in these indicators, what they knew of the palatability of certain plant species, and the usefulness of cracking-clay areas (a key landscape feature in the region) for grazing. Views of respondents on indicator species and plant palatability mostly concurred with published reports on the preferences of livestock for these species. A wide range of indicators (all perennial plant species and no animal species) was listed by respondents, suggesting that indicators are highly location-specific, plant-focussed, and not viewed consistently among pastoralists. Respondents related specific information about cracking-clay areas on their leases, including the influence of the timing and amount of rainfall on pasture productivity, and the value of these areas for livestock. It can be difficult for natural resource management practitioners, who may not observe the landscape regularly, to evaluate land condition and prescribe appropriate land management strategies. It is argued that the participation of pastoralists in science and policy development is fundamental to achieving sustainable land management, providing opportunities for social learning within an adaptive management framework.
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Dai, Shanshan, Lanhai Li, and Honggang Xu. "Simulation of water scarcity in a leap-forward developing arid region: a system dynamics model of Xinjiang Uygur Autonomous Region." Water Policy 19, no. 4 (March 25, 2017): 741–57. http://dx.doi.org/10.2166/wp.2017.132.
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The leap-forward development policy emphasizes water resource scarcity. Given the importance of water resources to an economy, especially in arid areas, this paper explores various management strategies that could be used in the semi-arid region of Xinjiang to increase the effectiveness and efficiency of multifunctional water projects and support sustainable ‘leap-forward’ economic growth. Embedding the logistic growth function within a system dynamics framework, our model provides a universally implementable model for sustainable water planning. The dynamic current and projected water supply and demand and water use efficiency are captured. Potential water management strategies are simulated to test system performance. The results suggest that, as water scarcity becomes more acute, the current water supply will not be able to support the leap-forward development policy with current water usage efficiency. In the short term, implementing efficient industrial water consumption technology and promoting water-saving irrigation technology may postpone the cultivated land reduction process. In the long term, developing more water-saving industrial enterprises, and planning to use more drought-tolerant plants, will be effective ways to avoid a decrease in cultivated land area.
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Mwalyosi, Raphael B. B. "Land-use Changes and Resource Degradation in South–West Masailand, Tanzania." Environmental Conservation 19, no. 2 (1992): 145–52. http://dx.doi.org/10.1017/s0376892900030629.
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This study uses sequential aerial photography to identify environmental changes. The interpreted aerial photos constitute a data-bank of past and present land cover/uses.* Substantial changes have been observed in the areas of cultivation, woody cover, and bare ground.An increased 449.9% of the surveyed area has been cleared for cultivation during the last 30 years, while 77.2% of the former woodland has been destroyed during the same period, contributing to a 15.6% increase in grassland. Bare ground increased by 33.1%. Increased cultivation is caused by increase in the population of subsistence farmers and mechanization. Expansion of cultivation and overexploitation of woody resources (fuel-wood and building materials) are the causes of decline in the woody vegetation. As consumption of woody resources exceeds natural regeneration, woody cover is gradually replaced by grasslands.Diminution of the woody vegetation results in shortage of fuel-wood and building materials and consequent misery to the local people. Expansion of cultivation reduces grazing-land, leading to overstocking and overgrazing. Extensive cultivation, based on soil ‘mining’, subjects more and more land to physical and chemical soil degradation, leading in turn to decline in soil fertility and crop yields. Both overgrazing and extensive cultivation accelerate soil erosion in the area, reducing available cropland, while siltation and flooding cause serious damage to property and infrastructure.Lack of effective land-use planning, uncontrolled population growth, and introduction of the Tanzanian village agricultural production system in a semi-arid area, have contributed to the present deplorable state of affairs. In general, the area shows increasing environmental degradation and resource depletion, while very little conservation effort is being made to reverse the trend. These results indicate that a sustainable resource management plan is urgently needed for the area.
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Whitney, James E., Keith B. Gido, and David L. Propst. "Factors associated with the success of native and nonnative species in an unfragmented arid-land riverscape." Canadian Journal of Fisheries and Aquatic Sciences 71, no. 8 (August 2014): 1134–45. http://dx.doi.org/10.1139/cjfas-2014-0153.
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Native fish persistence is threatened by the establishment and spread of nonnatives. Identifying environmental and biotic factors associated with the success of co-occurring native fishes and nonnative taxa is central to identifying mechanisms responsible for native declines and nonnative expansion. We related physicochemical variables, food resources, and community composition to the success (secondary production) of native and nonnative fishes, tadpoles, and crayfish across six sites in three reaches (tributary, canyon, and valley) during 2008–2011 in the Gila River, New Mexico. Native fish success was greater than nonnative success across a range of physicochemical conditions, basal resource supply rates, and nonnative communities, although nonnative fish, tadpole, and crayfish success could approach or exceed that of native fishes in canyon habitats, a warm-water tributary, or in downstream valley sites, respectively. Native fish success was lowest in canyon reaches, when flathead catfish (Pylodictis olivaris) and common carp (Cyprinus carpio) were highly productive. These results demonstrate the potential for native fish persistence in the presence of nonnatives in physically unmodified streams, highlighting the importance of habitat preservation for native conservation.
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Arabameri, Alireza, Saro Lee, John P. Tiefenbacher, and Phuong Thao Thi Ngo. "Novel Ensemble of MCDM-Artificial Intelligence Techniques for Groundwater-Potential Mapping in Arid and Semi-Arid Regions (Iran)." Remote Sensing 12, no. 3 (February 4, 2020): 490. http://dx.doi.org/10.3390/rs12030490.
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The aim of this research is to introduce a novel ensemble approach using Vise Kriterijumska Optimizacija I Kompromisno Resenje (VIKOR), frequency ratio (FR), and random forest (RF) models for groundwater-potential mapping (GWPM) in Bastam watershed, Iran. This region suffers from freshwater shortages and the identification of new groundwater sites is a critical need. Remote sensing and geographic information system (GIS) were used to reduce time and financial costs of rapid assessment of groundwater resources. Seventeen physiographical, hydrological, and geological groundwater conditioning factors (GWCFs) were derived from a spatial geo-database. Groundwater data were gathered in field surveys and well-yield data were acquired from the Iranian Department of Water Resources Management for 89 locations with high yield potential values ≥ 11 m3 h−1. These data were mapped in a GIS. From these locations, 62 (70%) were randomly selected to be used for model training, and the remaining 27 (30%) were used for validation of the model. The relative weights of the GWCFs were determined with an RF model. For GWPM, 220 randomly selected points in the study area and their final weights were determined with the VIKOR model. A groundwater potential map was created by interpolating the values at these points using Kriging in GIS. Finally, the area under receiver operating characteristic (AUROC) curve was plotted for the groundwater potential map. The success rate curve (SRC) was computed for the training dataset, and the prediction rate curve (PRC) was calculated for the validation dataset. Results of RF analysis show that land use and land cover, lithology, and elevation are the most significant determinants of groundwater occurrence. The validation results show that the ensemble model had excellent prediction performance (PRC = 0.934) and goodness-of-fit (SRC = 0.925) and reasonably high classification accuracy. The results of this study could aid management of groundwater resources and assist planners and decision makers in groundwater-investment planning to achieve sustainability.
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El Kenawy, Ahmed M., Mohamed E. Hereher, and Sayed M. Robaa. "An Assessment of the Accuracy of MODIS Land Surface Temperature over Egypt Using Ground-Based Measurements." Remote Sensing 11, no. 20 (October 12, 2019): 2369. http://dx.doi.org/10.3390/rs11202369.
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Space-based data have provided important advances in understanding climate systems and processes in arid and semi-arid regions, which are hot-spot regions in terms of climate change and variability. This study assessed the performance of land surface temperatures (LSTs), retrieved from the Moderate-Resolution Imaging Spectroradiometer (MODIS) Aqua platform, over Egypt. Eight-day composites of daytime and nighttime LST data were aggregated and validated against near-surface seasonal and annual observational maximum and minimum air temperatures using data from 34 meteorological stations spanning the period from July 2002 to June 2015. A variety of accuracy metrics were employed to evaluate the performance of LST, including the bias, normalized root-mean-square error (nRMSE), Yule–Kendall (YK) skewness measure, and Spearman’s rho coefficient. The ability of LST to reproduce the seasonal cycle, anomalies, temporal variability, and the distribution of warm and cold tails of observational temperatures was also evaluated. Overall, the results indicate better performance of the nighttime LSTs compared to the daytime LSTs. Specifically, while nighttime LST tended to underestimate the minimum air temperature during winter, spring, and autumn on the order of −1.3, −1.2, and −1.4 °C, respectively, daytime LST markedly overestimated the maximum air temperature in all seasons, with values mostly above 5 °C. Importantly, the results indicate that the performance of LST over Egypt varies considerably as a function of season, lithology, and land use. LST performs better during transitional seasons (i.e., spring and autumn) compared to solstices (i.e., winter and summer). The varying interactions and feedbacks between the land surface and the atmosphere, especially the differences between sensible and latent heat fluxes, contribute largely to these seasonal variations. Spatially, LST performs better in areas with sandstone formations and quaternary sediments and, conversely, shows lower accuracy in regions with limestone, igneous, and metamorphic rocks. This behavior can be expected in hybrid arid and semi-arid regions like Egypt, where bare rocks contribute to the majority of the Egyptian territory, with a lack of vegetation cover. The low surface albedo of igneous and limestone rocks may explain the remarkable overestimation of daytime temperature in these regions, compared to the bright formations of higher surface albedo (i.e., sandy deserts and quaternary rocks). Overall, recalling the limited coverage of meteorological stations in Egypt, this study demonstrates that LST obtained from the MODIS product can be trustworthily employed as a surrogate for or a supplementary source to near-surface measurements, particularly for minimum air temperature. On the other hand, some bias correction techniques should be applied to daytime LSTs. In general, the fine space-based climatic information provided by MODIS LST can be used for a detailed spatial assessment of climate variability in Egypt, with important applications in several disciplines such as water resource management, hydrological modeling, agricultural management and planning, urban climate, biodiversity, and energy consumption, amongst others. Also, this study can contribute to a better understanding of the applications of remote sensing technology in assessing climatic feedbacks and interactions in arid and semi-arid regions, opening new avenues for developing innovative algorithms and applications specifically addressing issues related to these regions.
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Cogle, AL, RJ Bateman, and DH Heiner. "Conservation cropping systems for the semi-arid tropics of North Queensland, Australia." Australian Journal of Experimental Agriculture 31, no. 4 (1991): 515. http://dx.doi.org/10.1071/ea9910515.
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A farming systems project was commenced in the semi-arid tropics of north-eastern Australia to assess the cropping potential and reliability of a newly developing region. Emphasis was placed on evaluation of conservation cropping systems, since it was expected that these would be the most successful and protective uses of the land. This paper discusses the agronomy of peanuts, maize and sorghum grown under different conservative cropping practices (reduced tillage, no tillage, ley) on the soil (red earth) most likely to be developed for large-scale cropping in the region. Crop yields with all practices were limited by establishment difficulties including high soil temperatures, poor weed control and climatic variability. Reduced tillage was more successful than no tillage due to higher yields in dry years; however, in wet years no tillage produced similar yields. The ley cropping system may have some advantages in this environment for integrated production and resource protection.
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Acharya, Bibek, Vivek Sharma, James Heitholt, Daniel Tekiela, and Fabian Nippgen. "Quantification and Mapping of Satellite Driven Surface Energy Balance Fluxes in Semi-Arid to Arid Inter-Mountain Region." Remote Sensing 12, no. 24 (December 8, 2020): 4019. http://dx.doi.org/10.3390/rs12244019.
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Crop evapotranspiration (ETc) estimates, on a regional scale, hold enormous potential in managing surface and groundwater resources. This is particularly important for the headwater state of Wyoming, which provides water to found major river basins of the US. In this study, METRIC (Mapping evapotranspiration at high resolution with internalized calibration), a satellite-based image processing model, was used to map and quantify daily, monthly, and seasonal ETc and other energy balance fluxes, i.e., net radiation (Rn), sensible heat (H), and soil heat flux (G) dynamics for different land-use classes. Monthly and seasonal ETc estimated were further used to approximate regional water consumption patterns for different land-use types for nine irrigation districts in semi-arid to arid intermountain region of Big Horn Basin (BHB), Wyoming. The validation of METRIC retrievals against Bowen ratio energy balance system (BREBS) fluxes measured over three vegetative surfaces, viz. sugar beet in 2017, dry bean in 2018, and barley in 2019, indicated high accuracy. The pooled correlation observed between estimated (pooled) and measured instantaneous fluxes had R2 values of 0.91 (RMSE = 0.08 mm h−1, NSE = 0.91), 0.81 (RMSE = 49.6 Wm−2, NSE = 0.67), 0.53 (RMSE = 27.1 Wm−2, NSE = 0.53), and 0.86 (RMSE = 59.2 Wm−2, NSE = 0.84) for ETc, Rn, G, and H, respectively. The biggest discrepancy between measured and estimated monthly ETc values was observed during times when BREBS flux tower footprint was devoid of any crops or the crops at footprint were not actively transpiring. Validation results improved when comparisons were made on monthly scales with METRIC underestimating growing season ETc in the range between 3.2% to 6.0%. Seasonal ETc by land-use type showed significant variation over the study area where crop ETc was 52% higher than natural vegetation ETc. Furthermore, it was found that, in the arid to semi-arid intermountain region of Wyoming, the contribution of irrigation to total seasonal ETc varied in the range of 73–81% in nine irrigation districts that fall within the study area. The high relative contribution of irrigation highlights the importance of identifying and quantifying ETc for improved management in irrigation system design and water allocation.
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PEASE, ALLISON A., J. JUSTINE DAVIS, MELANIE S. EDWARDS, and THOMAS F. TURNER. "Habitat and resource use by larval and juvenile fishes in an arid-land river (Rio Grande, New Mexico)." Freshwater Biology 51, no. 3 (March 2006): 475–86. http://dx.doi.org/10.1111/j.1365-2427.2005.01506.x.
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Lebrini, Youssef, Abdelghani Boudhar, Ahmed Laamrani, Abdelaziz Htitiou, Hayat Lionboui, Adil Salhi, Abdelghani Chehbouni, and Tarik Benabdelouahab. "Mapping and Characterization of Phenological Changes over Various Farming Systems in an Arid and Semi-Arid Region Using Multitemporal Moderate Spatial Resolution Data." Remote Sensing 13, no. 4 (February 6, 2021): 578. http://dx.doi.org/10.3390/rs13040578.
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Changing land use patterns is of great importance in environmental studies and critical for land use management decision making over farming systems in arid and semi-arid regions. Unfortunately, ground data scarcity or inadequacy in many regions can cause large uncertainties in the characterization of phenological changes in arid and semi-arid regions, which can hamper tailored decision making towards best agricultural management practices. Alternatively, state-of-the-art methods for phenological metrics’ extraction and long time-series analysis techniques of multispectral remote sensing imagery provide a viable solution. In this context, this study aims to characterize the changes over farming systems through trend analysis. To this end, four farming systems (fallow, rainfed, irrigated annual, and irrigated perennial) in arid areas of Morocco were studied based on four phenological metrics (PhM) (i.e., great integral, start, end, and length of the season). These were derived from large Moderate resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) time-series using both a machine learning algorithm and a pixel-based change analysis method. Results showed that during the last twenty-year period (i.e., 2000–2019), a significant dynamism of the plant cover was linked to the behavior of farmers who tend to cultivate intensively and to invest in high-income crops. More specifically, a relevant variability in fallow and rainfed areas, closely linked to the weather conditions, was found. In addition, significant lag trends of the start (−6 days) and end (+3 days) were found, which indicate that the length of the season was related to the spatiotemporal variability of rainfall. This study has also highlighted the potential of multitemporal moderate spatial resolution data to accurately monitor agriculture and better manage land resources. In the meantime, for operationally implementing the use of such work in the field, we believe that it is essential consider the perceptions, opinions, and mutual benefits of farmers and stakeholders to improve strategies and synergies whilst ensuring food, welfare, and sustainability.
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Yang, Ze-Yuan, Kai Wang, Yue Yuan, Jinting Huang, Zhi-Jun Chen, and Chen Li. "Non-Negligible Lag of Groundwater Infiltration Recharge: A Case in Mu Us Sandy Land, China." Water 11, no. 3 (March 18, 2019): 561. http://dx.doi.org/10.3390/w11030561.
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Groundwater is often the main source of available water, and precipitation is one of the main recharge sources of groundwater in arid and semi-arid regions. This paper studies a fixed dune in Mu Us Sandy Land in China, establishes a numerical model, acquires hydraulic parameters and heat parameters of the vadose zone, and calculates the recharge coefficient based on field observation data and numerical modelling. These measurement results show that the response depths of storm rain are more than 90 cm, while those of small rain events are less than 10 cm. The numerical results show that infiltration depths are 10 cm for small rain and more than 90 cm for middle rain respectively. The lag time of the water content at 90 cm below the surface was 25 h following a middle rain, 18–19 h following a heavy rain, and 16–18 h following a storm rainfall. Groundwater recharge lag times (matrix flow) varied from 11 h to 48 h. Excluded precipitation for groundwater recharge was 11.25–11.75 mm in 1 h when groundwater depth was 120 cm and 15–15.5 mm when 140 cm, showing significant influence in groundwater resource evaluation.
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Westing, Arthur H. "Population, Desertification, and Migration." Environmental Conservation 21, no. 2 (1994): 110–14. http://dx.doi.org/10.1017/s0376892900024528.
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It is noted that the number of more or less permanently displaced persons throughout the world (now of the order of 1% of the total human population) continues to increase at a rate of approximately 3 millions per year; the situation in Africa is especially grave, with the number of displaced persons there (now of the order of 3% of the African population), continuing to increase at a rate of approximately 1.5 million per year. Human displacement — which can be seen to originate largely in rural areas — results primarily from one or more of three factors, namely escape from persecution, escape from military activities, or escape from inadequate means of subsistence. A number of examples from Africa are provided of the social and political consequences of human displacement, with emphasis on conflict situations at the sites of relocation.It is further noted that the numbers of displaced persons continue to grow relentlessly despite there being no discernible rise in persecution or military activities, and despite the long-sustained ameliorative efforts and financial assistance by intergovernmental agencies and others.It is accordingly suggested that the major cause of the continuing increase in the numbers of displaced persons is an ever-growing imbalance between population numbers and the human carrying capacity of the land. Population increases lead to smaller per caput natural resource bases, a predicament exacerbated by over-use — and thus degradation — of the land and its natural resources. In the arid and semi-arid regions of Africa, over-use of the land most often takes the form of overgrazing, leading to land degradation that is severe enough to be referred to as desertification. It is concluded that to achieve sustainable utilization of the land and its natural resources will necessitate the integrated attainment of environmental security and societal security — the latter inter alia requiring participatory governance, non-violent means of conflict resolution, and especially population controls.
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Liu, Xingran, and Yanjun Shen. "Quantification of the impacts of climate change and human agricultural activities on oasis water requirements in an arid region: a case study of the Heihe River basin, China." Earth System Dynamics 9, no. 1 (March 5, 2018): 211–25. http://dx.doi.org/10.5194/esd-9-211-2018.
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Abstract. Ecological deterioration in arid regions caused by agricultural development has become a global issue. Understanding water requirements of the oasis ecosystems and the influences of human agricultural activities and climate change is important for the sustainable development of oasis ecosystems and water resource management in arid regions. In this study, water requirements of the main oasis in Heihe River basin during 1986–2013 were analyzed and the amount showed a sharp increase from 10.8 × 108 m3 in 1986 to 19.0 × 108 m3 in 2013. Both human agricultural activities and climate change could lead to the increase in water requirement. To quantify the contributions of agricultural activities and climate change to the increase in water requirements, partial derivative and slope method were used. Results showed that climate change and human agricultural activities, such as oasis expansion and changes in land cropping structure, has contributed to the increase in water requirement at rates of 6.9, 58.1, and 25.3 %, respectively. Overall, human agricultural activities were the dominant forces driving the increase in water requirement. In addition, the contribution of oasis expanding to the increased water requirement was significantly greater than that of other concerned variables. This reveals that controlling the oasis scale is extremely important and effective for balancing water for agriculture and ecosystems and to achieving a sustainable oasis development in arid regions.
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He, Tianming, Chunxia Wang, Zonglan Wang, Xinlin He, Hongguang Liu, and Jia Zhang. "Assessing the Agricultural Water Savings–Economy–Ecological Environment System in an Arid Area of Northwest China Using a Water Rights Transaction Model." Water 13, no. 9 (April 29, 2021): 1233. http://dx.doi.org/10.3390/w13091233.
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As water trading has become increasingly used to optimize the allocation of water resources, it has become necessary to transfer agricultural water allocations for economic development and ecological environmental uses by way of water rights trading. In this paper, we constructed an example water rights trading model in the arid oasis area of Shihezi Irrigation District (located in Northwest China), using the field investigation method and governmental water management decisions based on the systems theory of the agricultural water savings–economy–ecological environment. Furthermore, focusing on the added industrial value produced by trading water, the value of the ecological services provided by fresh water, the negative value of the reduction in greenhouse gas emissions, and the negative ecological value of reduced fertilizer application, a quantitative analysis was carried out using the Shihezi Irrigation District as an example. The results showed that under the most stringent water resource management plan and with the objective of returning land and reducing water, the irrigation area can save 52,504,500 m3 of surplus water from the agricultural sector, of which 49,879,300 m3 can be reallocated to the industrial sector and 2,625,200 m3 can be reallocated to the ecological sector. Using the water rights transaction method, this regional agricultural water saving could generate an industrial benefit equal to 35,024,300 yuan, an ecosystem service equal to 19,482,200 yuan, and an overall benefit equal to 54,420,500 yuan. The water rights trading model proposed in this paper for an arid oasis areas can provide a reference for other arid areas, helping to achieve the sustainable economic development of the economic and ecological environments in arid oasis areas through water rights trading.
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Abdelkareem, Mohamed, Fathy Abdalla, Samar Y. Mohamed, and Farouk El-Baz. "Mapping Paleohydrologic Features in the Arid Areas of Saudi Arabia Using Remote-Sensing Data." Water 12, no. 2 (February 4, 2020): 417. http://dx.doi.org/10.3390/w12020417.
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At present, the Arabian Peninsula is one of the driest regions on Earth; however, this area experienced heavy rainfall in the past thousand years. During this period, catchments received substantial amounts of surface water and sustained vast networks of streams and paleolakes, which are currently inactive. The Advanced Land Observing Satellite (ALOS) Phased Array Type L-band Synthetic Aperture Radar (PALSAR) data reveal paleohydrologic features buried under shallow aeolian deposits in many areas of the ad-Dawasir, Sahba, Rimah/Batin, and as-Sirhan wadis. Optical remote-sensing data support that the middle of the trans-peninsula Wadi Rimah/Batin, which extends for ~1200 km from the Arabian Shield to Kuwait and covers ~200,000 km2, is dammed by linear sand dunes formed by changes in climate conditions. Integrating Landsat 8 Operational Land Imager (OLI), Geo-Eye, Shuttle Radar Topography Mission (SRTM) digital elevation model, and ALOS/PALSAR data allowed for the characterization of paleodrainage reversals and diversions shaped by structural and volcanic activity. Evidence of streams abruptly shifting from one catchment to another is preserved in Wadi ad-Dawasir along the fault trace. Volcanic activity in the past few thousand years in northern Saudi Arabia has also changed the slope of the land and reversed drainage systems. Relics of earlier drainage directions are well maintained as paleoslopes and wide upstream patterns. This study found that paleohydrologic activity in Saudi Arabia is impacted by changes in climate and by structural and volcanic activity, resulting in changes to stream direction and activity. Overall, the integration of radar and optical remote-sensing data is significant for deciphering past hydrologic activity and for predicting potential water resource areas.
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Bajjali, William, and Khair Al-Hadidi. "Recharge origin, overexploitation, and sustainability of water resources in an arid area from Azraq basin, Jordan: case study." Hydrology Research 37, no. 3 (June 1, 2006): 277–92. http://dx.doi.org/10.2166/nh.2006.013.
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The Azraq groundwater basin, found in Jordan, is an important resource for available water to the public. Its magnitude and value has been decreasing for the last two decades. The groundwater level has been declining on a yearly basis since the 1980s, and over-pumping, which has tripled since 1983, has led to the drying up of major springs in the 1990s. Overexploitation is considered as the adverse effect on groundwater mass balance, where the abstraction increases yearly and beyond the safe yield. Over-pumping and irrigation activities cause groundwater to become more saline. The isotopic composition of groundwater is divided into two groups. The first group is associated with EMWL, and the second with GMWL. The recharge origin of the first group, which includes the upper and middle aquifers, originate from outside the Azraq basin with a land elevation higher than 1150 m asl. The groundwater of the second group is considered palaeowater. No major recharge component is identified in the basin. Accurate and reliable scientific approaches are indispensable to better understand, plan and manage the groundwater resources.
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Li, K. Y., M. T. Coe, and N. Ramankutty. "Investigation of Hydrological Variability in West Africa Using Land Surface Models." Journal of Climate 18, no. 16 (August 15, 2005): 3173–88. http://dx.doi.org/10.1175/jcli3452.1.
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Abstract The availability of freshwater is a particularly important issue in Africa where large portions of the continent are arid or semiarid and climate is highly variable. Sustainable water resource management requires the assessment of hydrological variability in response to nature climate fluctuation. In this study, a land surface model, the Integrated Biosphere Simulator (IBIS), and a hydrological routing model, the Hydrological Routing Algorithm (HYDRA), are used to investigate the hydrological variability in two large basins, the Lake Chad basin (LCB) and the Niger River basin (NRB), located in West Africa, over the period from 1950 to 1995. The IBIS land surface hydrological module was calibrated and validated for arid and semiarid Africa, and major enhancements were made to the module, including the development of a dynamic root water–extraction formulation, the incorporation of a Green–Ampt infiltration parameterization, and modification to the prescribed root distribution, the runoff module, and weather generator. The results show that the hydrology in this area is highly variable over time and space. The coefficient of variance (CV) of annual rainfall ranges from 10%–15% in the southern portions of the basins to 30%–40% in the northern portions. The annual evapotranspiration (ET) varies with a slightly lower CV compared to the rainfall, but the runoff is extremely sensitive to the rainfall fluctuation, particularly in the central portions of the basins (8°–13°N in LCB and 12°–16°N in NRB) where the CVs in runoff are as high as 100%–200%. The annual river discharge varies largely in concert with the rainfall fluctuation, with the CV being 37% in LCB and 23%–63% in NRB. In terms of the whole basin, the relative hydrologic variability (rainfall, evapotranspiration, runoff, and river discharge) is significantly higher in the dry period than in the wet period, and the interannual variability in runoff is more than twice as high as compared to rainfall or ET.
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Hussainzada, Wahidullah, and Han Soo Lee. "Hydrological Modelling for Water Resource Management in a Semi-Arid Mountainous Region Using the Soil and Water Assessment Tool: A Case Study in Northern Afghanistan." Hydrology 8, no. 1 (January 22, 2021): 16. http://dx.doi.org/10.3390/hydrology8010016.
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To address the issues of water shortages and the loss of agricultural products at harvest in northern Afghanistan, the Soil and Water Assessment Tool (SWAT) was applied for agricultural water resource management by simulating surface runoff in the Balkhab River basin (BRB) on a monthly basis from 2013 to 2018. Elevation, slope, land cover data, soil maps, and climate data such as temperature, precipitation, relative humidity, wind speed, and solar radiation were used as inputs in the SWAT modelling. During the dry season from July to September, the water resources downstream were basically attributed to baseflow from groundwater. In the calibration, the groundwater baseflow was estimated by analyzing station-recorded discharges for 190 springs. With the estimated baseflow, the SWAT results were markedly improved, with R2 values of 0.70, 0.86, 0.67, and 0.80, Nash-Sutcliff efficiency (NSE) values of 0.52, 0.83, 0.40, and 0.57, and percent bias (PBIAS) values of 23.4, −8.5, 23.4, and 17.5 in the four different subbasins. In the validation, the statistics also indicated satisfactory results. The output of this study can be used in agricultural water resource management with irrigation practices and further in the assessment of climate change effects on the water resources in the BRB.
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Acharya, Bibek, and Vivek Sharma. "Comparison of Satellite Driven Surface Energy Balance Models in Estimating Crop Evapotranspiration in Semi-Arid to Arid Inter-Mountain Region." Remote Sensing 13, no. 9 (May 7, 2021): 1822. http://dx.doi.org/10.3390/rs13091822.
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The regional-scale estimation of crop evapotranspiration (ETc) over a heterogeneous surface is an important tool for the decision-makers in managing and allocating water resources. This is especially critical in the arid to semi-arid regions that require supplemental water due to insufficient precipitation, soil moisture, or groundwater. Over the years, various remote sensing-based surface energy balance (SEB) models have been developed to accurately estimate ETc over a regional scale. However, it is important to carry out the SEB model assessment for a particular geographical setting to ensure the suitability of a model. Thus, in this study, four commonly used and contrasting remote sensing models viz. METRIC (mapping evapotranspiration at high resolution with internalized calibration), SEBAL (surface energy balance algorithm for land), S-SEBI (simplified surface energy balance index), and SEBS (surface energy balance system) were compared and used to quantify and map the spatio-temporal variation of ETc in the semi-arid to arid inter-mountain region of Big Horn Basin, Wyoming (Landsat Path/Row: 37/29). Model estimates from 19 cloud-free Landsat 7 and 8 images were compared with the Bowen ratio energy balance system (BREBS) flux stationed in a center pivot irrigated field during 2017 (sugar beet), 2018 (dry bean), and 2019 (barley) growing seasons. The results indicated that all SEB models are effective in capturing the variation of ETc with R2 ranging in between 0.06 to 0.95 and RMSD between 0.07 to 0.15 mm h−1. Pooled data over three vegetative surfaces for three years under irrigated conditions revealed that METRIC (NSE = 0.9) performed better across all land cover types, followed by SEBS (NSE = 0.76), S-SEBI (NSE = 0.73), and SEBAL (NSE = 0.65). In general, all SEB models substantially overestimated ETc and underestimated sensible heat (H) fluxes under dry conditions when only crop residue was available at the surface. A mid-season density plot and absolute difference maps at image scale between the models showed that models involving METRIC, SEBAL, and S-SEBI are close in their estimates of daily crop evapotranspiration (ET24) with pixel-wise RMSD ranged from 0.54 to 0.76 mm d−1 and an average absolute difference across the study area ranged from 0.47 to 0.56 mm d−1. Likewise, all the SEB models underestimated the seasonal ETc, except SEBS.
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Chung, Y. Anny, and Jennifer A. Rudgers. "Plant–soil feedbacks promote negative frequency dependence in the coexistence of two aridland grasses." Proceedings of the Royal Society B: Biological Sciences 283, no. 1835 (July 27, 2016): 20160608. http://dx.doi.org/10.1098/rspb.2016.0608.
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Understanding the mechanisms of species coexistence is key to predicting patterns of species diversity. Historically, the ecological paradigm has been that species coexist by partitioning resources: as a species increases in abundance, self-limitation kicks in, because species-specific resources decline. However, determining coexistence mechanisms has been a particular puzzle for sedentary organisms with high overlap in their resource requirements, such as plants. Recent evidence suggests that plant-associated microbes could generate the stabilizing self-limitation (negative frequency dependence) that is required for species coexistence. Here, we test the key assumption that plant–microbe feedbacks cause such self-limitation. We used competition experiments and modelling to evaluate how two common groups of soil microbes (rhizospheric microbes and biological soil crusts) influenced the self-limitation of two competing desert grass species. Negative feedbacks between the dominant plant competitor and its rhizospheric microbes magnified self-limitation, whereas beneficial interactions between both plant species and biological soil crusts partly counteracted this stabilizing effect. Plant–microbe interactions have received relatively little attention as drivers of vegetation dynamics in dry land ecosystems. Our results suggest that microbial mechanisms can contribute to patterns of plant coexistence in arid grasslands.
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Balasubramani, Karuppusamy. "Physical resources assessment in a semi-arid watershed: An integrated methodology for sustainable land use planning." ISPRS Journal of Photogrammetry and Remote Sensing 142 (August 2018): 358–79. http://dx.doi.org/10.1016/j.isprsjprs.2018.03.008.
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Miguelena, Javier G., and Paul B. Baker. "Effects of Urbanization on the Diversity, Abundance, and Composition of Ant Assemblages in an Arid City." Environmental Entomology 48, no. 4 (June 15, 2019): 836–46. http://dx.doi.org/10.1093/ee/nvz069.
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AbstractCities within arid regions make up a significant but understudied subset of the urban ecosystems of the world. To assess the effects of urbanization, fragmentation, and land-use change in an arid city, we sampled the ant assemblages in three habitat types in Tucson, Arizona: irrigated neighborhood parks, urban desert remnants, and preserved desert. We analyzed the abundance, species richness, evenness, as well as the species and functional group composition of ant assemblages. We found no significant differences in species richness or evenness. However, irrigated parks had significantly greater ant abundances. Although some exotic species were present in the urban habitats, they did not have significant effects on ant diversity. Ant assemblages from all three habitat types were distinct from each other in their composition. Irrigated parks included a significantly higher proportion of species typically found in cooler and wetter climates. The differences in abundance and species composition between irrigated parks and the other habitats are likely the effect of irrigation removing water as a limiting factor for colony growth and increasing resource availability, as well as producing a localized cooling effect. Our results show that arid urban ecosystems may include considerable biodiversity, in part thanks to increased landscape heterogeneity resulting from the irrigation of green areas.
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Hong, S. H., J. M. H. Hendrickx, J. Kleissl, R. G. Allen, W. G. M. Bastiaanssen, R. L. Scott, and A. L. Steinwand. "Evaluation of an extreme-condition-inverse calibration remote sensing model for mapping energy balance fluxes in arid riparian areas." Hydrology and Earth System Sciences Discussions 11, no. 12 (December 10, 2014): 13479–539. http://dx.doi.org/10.5194/hessd-11-13479-2014.
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Abstract. Accurate information on the distribution of the surface energy balance components in arid riparian areas is needed for sustainable management of water resources as well as for a better understanding of water and heat exchange processes between the land surface and the atmosphere. Since the spatial and temporal distributions of these fluxes over large areas are difficult to determine from ground measurements alone, their prediction from remote sensing data is very attractive as it enables large area coverage and a high repetition rate. In this study the Surface Energy Balance Algorithm for Land (SEBAL) was used to estimate all the energy balance components in the arid riparian areas of the Middle Rio Grande Basin (New Mexico), San Pedro Basin (Arizona), and Owens Valley (California). We compare instantaneous and daily SEBAL fluxes derived from Landsat TM images to surface-based measurements with eddy covariance flux towers. This study presents evidence that SEBAL yields reliable estimates for actual evapotranspiration rates in riparian areas of the southwestern United States. The great strength of the SEBAL method is its internal calibration procedure that eliminates most of the bias in latent heat flux at the expense of increased bias in sensible heat flux.
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Wang, L., P. D'Odorico, J. P. Evans, D. Eldridge, M. F. McCabe, K. K. Caylor, and E. G. King. "Dryland ecohydrology and climate change: critical issues and technical advances." Hydrology and Earth System Sciences Discussions 9, no. 4 (April 16, 2012): 4777–825. http://dx.doi.org/10.5194/hessd-9-4777-2012.
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Abstract. Drylands cover about 40% of the terrestrial land surface and account for approximately 40% of global net primary productivity. Water is fundamental to the biophysical processes that sustain ecosystem function and food production, particularly in drylands, where a tight coupling exists between water resource availability and ecosystem productivity, surface energy balance, and biogeochemical cycles. Currently, drylands support at least 2 billion people and comprise both natural and managed ecosystems. In this synthesis, we identify some current critical issues in the understanding of dryland systems and discuss how arid and semiarid environments are responding to the changes in climate and land use. Specifically, we focus on dryland agriculture and food security, dryland population growth, desertification, shrub encroachment and dryland development issues as factors of change requiring increased understanding and management. We also review recent technical advances in the quantitative assessment of human versus climate change related drivers of desertification, evapotranspiration partitioning using field deployable stable water isotope systems and the remote sensing of key ecohydrological processes. These technological advances provide new tools that assist in addressing major critical issues in dryland ecohydrology under climate change
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Jin, Jiaqi, Chicheng Yan, Yixuan Tang, and Yilong Yin. "Mine Geological Environment Monitoring and Risk Assessment in Arid and Semiarid Areas." Complexity 2021 (June 3, 2021): 1–10. http://dx.doi.org/10.1155/2021/3896130.
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Along with the accelerated shift of coal mining to the ecologically fragile west, the contradiction between coal resource development and ecological protection in the western arid and semiarid coal mining areas is rapidly intensifying. Based on the above background, this thesis takes the coal mining area in the arid and semiarid regions as an example; applies the theories of ecology, coal mining subsidence, geodesy, and ecological restoration; uses remote sensing in synthetic aperture radar (SAR), geographic information system (GIS), and mathematical modelling to reveal the ecological evolution law of the mining area; measures the ecological damage of the mining area; and then proposes a reasonable ecological restoration strategy. The surface deformation monitoring study in the study area shows that on the whole, some areas in the study area have different degrees of surface subsidence disasters, and the maximum surface subsidence value exceeds 800 mm. From the distribution of surface subsidence in the study area, surface subsidence disasters mainly occur in the eastern and central mountainous areas rich in coal resources, as well as in the mining areas west of the Yellow River, and the subsidence basins are distributed in a series of irregular concentric ovals. In terms of the scale of surface subsidence in the study area, a total of 230.03 km2 of land in the study area showed surface subsidence hazards during the monitoring period, accounting for 13.78% of the total area of the study area, of which the area of severe subsidence was 44.98 km2 (2.69%). The area of more serious subsidence area is 101.33 km2 (6.07%), and the area affected by subsidence is 83.72 km2 (5.01%).
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Xiang, Kunlun, Minna Ma, Wei Liu, Jie Dong, Xiufang Zhu, and Wenping Yuan. "Mapping Irrigated Areas of Northeast China in Comparison to Natural Vegetation." Remote Sensing 11, no. 7 (April 5, 2019): 825. http://dx.doi.org/10.3390/rs11070825.
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Accurate information about the location and extent of irrigation is fundamental to many aspects of food security and water resource management. This study develops a new method for identifying irrigation in northeastern China by comparing canopy moisture between the cropland and adjacent natural ecosystems (i.e., forests). This method is based on two basic assumptions, which we validated using field survey data. First, the canopy moisture of irrigated cropland, indicated by a satellite-based land surface water index (LSWI), is higher than that of the adjacent forest. Second, the difference in LSWI between irrigation cropland and forest is larger in arid regions than in humid regions. Based on the field survey and statistical dataset, our method performed well in indicating spatial variations of irrigated areas. Results from this study suggest that our method is a promising tool for mapping irrigated areas, as it is a general and repeatable method that does not rely on training samples and can be applied to other regions.
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Newby, John E., and John F. Grettenberger. "The Human Dimension in Natural Resource Conservation: A Sahelian Example from Niger." Environmental Conservation 13, no. 3 (1986): 249–56. http://dx.doi.org/10.1017/s0376892900036304.
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The Republic of Niger is establishing a vast national nature reserve in the Aïr Massif and Ténéré Desert. With its 77,360 km2, the reserve will cover a wide variety of arid-land habitats. Both rainfall and vegetation are sparse, but the area harbours a varied fauna that includes a number of threatened species. The Twareg inhabitants of the reserve subsist by raising livestock, by irrigating small gardens, and by caravanning. Their day-to-day existence relies heavily on natural resources, and their continued existence will depend on the conservation of those resources. Drought, desertification, and abusive use, are all responsible for the deterioration of those resources.Although highly necessary, the rational management of the area's natural resources will conflict with current landuse practices. Examples of where this happens are presented, and some proposals are put forward for their solution. Ideally, a flexible management system needs to be elaborated that will satisfy both the aspirations of the zone's managers and the immediate needs of its residents. The Authors hope that work in Niger will find its application elsewhere in the Sahel, and meanwhile emphasize the need to reconcile conservation with development.
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Tomaz, Alexandra, Patrícia Palma, Sofia Fialho, Ana Lima, Paula Alvarenga, Miguel Potes, Maria João Costa, and Rui Salgado. "Risk Assessment of Irrigation-Related Soil Salinization and Sodification in Mediterranean Areas." Water 12, no. 12 (December 19, 2020): 3569. http://dx.doi.org/10.3390/w12123569.
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Salinization and sodification are important processes of soil degradation affecting irrigated lands. A large proportion of the global irrigated area is affected by some degree of soil salinity or sodicity caused by the intensification of irrigation. The increase of the frequency of adverse climatic conditions, like high temperatures and variations in precipitation patterns caused by climate change, will potentially amplify these processes in arid, semi-arid, and Mediterranean areas. The use of integrated approaches for the spatial and temporal prediction of the risk of salinization and sodification in irrigated areas is of great value, helping in the decision-making regarding land uses and choice of more suitable agricultural practices. In this study, based on key criteria for the assessment of irrigation-related salinization processes (e.g., climate, topography, soil drainage, water quality for irrigation, and crop irrigation method), we developed a methodology for the prediction of soil salinity and sodicity risk in irrigated lands, using two composite indices, the Salinization Risk (RSA) index and the Sodification Risk (RSO) index. The application of these indices to a real scenario (a Mediterranean area in Southern Portugal) showed that 67% of the potentially irrigated area presented a low risk of salinity development, 68% had a moderate risk of sodification, and 16% was of high risk of sodicity development. Areas under moderate risk of salinization (26%) were mostly characterized by low slopes and fine-textured soils, like Luvisols and Vertisols, with limited drainage conditions. Areas with high risk of soil sodification presented a large incidence of low slope terrain, moderate-to-restricted soil drainage, in high clay content Luvisols, Vertisols and Cambisols, and land use dominated by annual crops irrigated with surface or sprinkler systems. These risk prediction tools have the potential to be used for resource use planning by policymakers and on-farm management decision by farmers, contributing to the sustainability of irrigated agriculture in Mediterranean regions.
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Deus, D., R. Gloaguen, and P. Krause. "Water balance modelling in a semi-arid environment with limited in-situ data: remote sensing coupled with satellite gravimetry, Lake Manyara, East African Rift, Tanzania." Hydrology and Earth System Sciences Discussions 8, no. 5 (September 26, 2011): 8737–92. http://dx.doi.org/10.5194/hessd-8-8737-2011.
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Abstract. Accurate and up to date information on the status and trends of water balance is needed to develop strategies for conservation and the sustainable management of water resources. The purpose of this research is to estimate water balance in a semi-arid environment with limited in-situ data by using a remote sensing approach. We focus on the Lake Manyara catchment, located within the East African Rift of northern Tanzania. We use remote sensing and a semi-distributed hydrological model to study the spatial and temporal variability of water balance parameters within Manyara catchment. Satellite gravimetry GRACE data is used to verify the trend of the water balance result. The results show high spatial and temporal variations and characteristics of a semi-arid climate with high evaporation and low rainfall. We observe that the Lake Manyara water balance and GRACE equivalent water depth show comparable trends a decrease after 2002 followed by a sharp increase in 2006–2007. Despite the small size of Lake Manyara, GRACE data are useful and show great potential for hydrological research on smaller un-gauged lakes and catchments in semi-arid environments. Our modelling confirms the importance of the 2006–2007 Indian Ocean Dipole fluctuation in replenishing the groundwater reservoirs of East Africa. The water balance information can be used for further analysis of lake variations in relation to soil erosion, climate and land cover/land use change as well as different lake management and conservation scenarios. We demonstrate that water balance modelling can be performed accurately using remote sensing data even in complex climatic settings.
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Marco-Dos Santos, Gema, Ignacio Melendez-Pastor, Jose Navarro-Pedreño, and Magaly Koch. "Assessing Water Availability in Mediterranean Regions Affected by Water Conflicts through MODIS Data Time Series Analysis." Remote Sensing 11, no. 11 (June 5, 2019): 1355. http://dx.doi.org/10.3390/rs11111355.
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Water scarcity is a widespread problem in arid and semi-arid regions such as the western Mediterranean coastal areas. The irregularity of the precipitation generates frequent droughts that exacerbate the conflicts among agriculture, water supply and water demands for ecosystems maintenance. Besides, global climate models predict that climate change will cause Mediterranean arid and semi-arid regions to shift towards lower rainfall scenarios that may exacerbate water conflicts. The purpose of this study is to find a feasible methodology to assess current and monitor future water demands in order to better allocate limited water resources. The interdependency between a vegetation index (NDVI), land surface temperature (LST), precipitation (current and future), and surface water resources availability in two watersheds in southeastern Spain with serious difficulties in meeting water demands was investigated. MODIS (Moderate Resolution Imaging Spectroradiometer) NDVI and LST products (as proxy of drought), precipitation maps (generated from climate station records) and reservoir storage gauging information were used to compute times series anomalies from 2001 to 2014 and generate regression images and spatial regression models. The temporal relationship between reservoir storage and time series of satellite images allowed the detection of different and contrasting water management practices in the two watersheds. In addition, a comparison of current precipitation rates and future precipitation conditions obtained from global climate models suggests high precipitation reductions, especially in areas that have the potential to contribute significantly to groundwater storage and surface runoff, and are thus critical to reservoir storage. Finally, spatial regression models minimized spatial autocorrelation effects, and their results suggested the great potential of our methodology combining NDVI and LST time series to predict future scenarios of water scarcity.
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Lin, Yingzhi, Anping Liu, Enjun Ma, and Fan Zhang. "Impacts of Future Climate Changes on Shifting Patterns of the Agro-Ecological Zones in China." Advances in Meteorology 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/163248.
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An agroecological zone (AEZ) is a land resource mapping unit, defined in terms of climate, landform, and soils, and has a specific range of potentials and constraints for cropping (FAO, 1996). The shifting patterns of AEZs in China driven by future climatic changes were assessed by applying the agroecological zoning methodology proposed by International Institute for Applied Systems Analysis (IIASA) and Food and Agriculture Organization of the United Nations (FAO) in this study. A data processing scheme was proposed in this study to reduce systematic errors in projected climate data using observed data from meteorological stations. AEZs in China of each of the four periods: 2011–2020, 2021–2030, 2031–2040, and 2041–2050 were drawn. It is found that the future climate change will lead to significant local changes of AEZs in China and the overall pattern of AEZs in China is stable. The shifting patterns of AEZs will be characterized by northward expansion of humid AEZs to subhumid AEZs in south China, eastward expansion of arid AEZs to dry and moist semiarid AEZs in north China, and southward expansion of dry semiarid AEZs to arid AEZs in southwest China.
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Cha, Mingxing, Mengmeng Li, and Xiaoqin Wang. "Estimation of Seasonal Evapotranspiration for Crops in Arid Regions Using Multisource Remote Sensing Images." Remote Sensing 12, no. 15 (July 26, 2020): 2398. http://dx.doi.org/10.3390/rs12152398.
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An accurate estimation of evapotranspiration (ET) from crops is crucial in irrigation management, crop yield assessment, and optimal allocation of water resources, particularly in arid regions. This study explores the estimation of seasonal evapotranspiration for crops using multisource remote sensing images. The proposed estimation framework starts with estimating daily evapotranspiration (ETd) values, which are then used to calculate ET estimates during the crop growing season (ETs). We incorporated Landsat images into the surface energy balance algorithm over land (SEBAL) model, and we used the trapezoidal and sinusoidal methods to estimate the seasonal ET. The trapezoidal method used multitemporal ETd images, while the sinusoidal method employs time-series Moderate Resolution Imaging Spectroradiometer (MODIS) images and multitemporal ETd images. Experiments were implemented in the agricultural lands of the Kai-Kong River Basin, Xinjiang, China. The experimental results show that the obtained ETd estimates using the SEBAL model are comparable with those from the Penman–Monteith method. The ETs obtained using the trapezoidal and sinusoidal methods both have a relatively high spatial resolution of 30 m. The sinusoidal method performs better than the trapezoidal method when using low temporal resolution Landsat images. We observed that the omission of Landsat images during the middle stage of crop growth has the greatest impact on the estimation results of ETs using the sinusoidal method. Based on the results of the study, we conclude that the proposed sinusoidal method, with integrated multisource remote sensing images, offers a useful tool in estimating seasonal evapotranspiration for crops in arid regions.
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Takeuchi, Kazuhiko, and Edwin Akonno Gyasi. "Special Issue on Enhancing Resilience to Climate and Ecosystem Changes in Semi-Arid Africa." Journal of Disaster Research 9, no. 4 (August 1, 2014): 411. http://dx.doi.org/10.20965/jdr.2014.p0411.
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In 2011, a collaborative project focused on climate and ecosystem change adaptation and resilience studies in Africa (CECAR-Africa) with Ghana as the focal country, was initiated. The goal was to combine climate change and ecosystem change research, and to use that combination as a basis for building an integrated resilience enhancement strategy as a potential model for semi-arid regions across Sub-Saharan Africa. The Project is being financially supported by the Science and Technology Research Partnership for Sustainable Development (SATREPS), a collaborative programme of the Japan Science and Technology Agency (JST) and the Japan International Cooperation Agency (JICA). CECAR-Africa involves the following leading climate and ecosystems research organizations in Ghana and Japan: The University of Tokyo; Kyoto University; United Nations University Institute for the Advanced Study of Sustainability (UNU-IAS); University of Ghana; Ghana Meteorological Agency; University for Development Studies; and United Nations University Institute for Natural Resources in Africa (UNUINRA). CECAR-Africa has been operating fully since 2012, with a focus on three thematic areas, namely: Forecast and assessment of climate change impact on agro-ecosystems (Agro-ecosystem resilience); Risk assessment of extreme weather hazards and development of adaptive resource management methods (Engineering resilience); and Implementing capacity development programs for local communities and professionals (social institutions-technical capacity development) using the assessment results derived from work on the first two themes. This special issue presents major outcomes of the Project so far. The articles featured used various techniques and methods such as field surveys, questionnaires, focal group discussions, land use and cover change analysis, and climate downscaled modelling to investigate the impacts of climate and ecosystem changes on river flows and agriculture, and to assess the local capacity for coping with floods, droughts and disasters, and for enhancing the resilience of farming communities. We are happy to be able to publish this special issue just in time for an international conference on CECAR-Africa in Tamale, Ghana, on 6-7 August, 2014. It is hoped that the shared research outcomes will facilitate discussions on the project research themes and interactions and exchange of ideas among academics, professionals, and government officials on the way forward for the CECARAfrica Project. We find it only appropriate to conclude by thanking the authors and reviewers of the articles, and by acknowledging, with gratitude, the local knowledge and other bits and pieces of information contributed by the many anonymous farmers and other people of northern Ghana.
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Luo, Biao, Fan Zhang, Xiao Liu, Qi Pan, and Ping Guo. "Managing Agricultural Water Considering Water Allocation Priority Based on Remote Sensing Data." Remote Sensing 13, no. 8 (April 15, 2021): 1536. http://dx.doi.org/10.3390/rs13081536.
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To fairly distribute limited irrigation water resources in arid regions, a water allocation priority evaluation method based on remote sensing data was proposed and integrated with an optimization model. First, the water supply response unit was divided according to canal system conditions. Then, a spatialization method was used for generating spatial agricultural output value (income from planting industry) and grain yield (yield of food crops) with the help of NDVI and the potential yield of farmland. Third, the AHP-TOPSIS method was employed to calculate the water allocation priority based on the above information. Finally, the evaluation results were integrated with a nonlinear multiobjective model to optimally allocate agricultural land and water resources, considering the combined objective of minimum envy and proportional fairness. The method was applied to Hetao irrigation area, an arid agriculture-dominant region in Northwest China. After solving the model, optimization alternatives were obtained, which indicate that: (1) the spatial method of agricultural output value can improve the accuracy by around 16% compared with the traditional method, and the spatial method of grain yield also have good accuracy (MAPE = 14.66%); (2) the rank of water allocation priority can reflect more spatial information, and provide practical decision support for the distribution of water resources; (3) the envy index can better improve the efficiency of an allocation system compared to the Gini coefficient method.
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Gossweiler, Benjamin, Ingrid Wesström, Ingmar Messing, Mauricio Villazón, and Abraham Joel. "Impact of Land Use Change on Non-Point Source Pollution in a Semi-Arid Catchment under Rapid Urbanisation in Bolivia." Water 13, no. 4 (February 4, 2021): 410. http://dx.doi.org/10.3390/w13040410.
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Changes in pollution pressure exerted on the Rocha River in Bolivia from diffuse sources were assessed using potential non-point pollution indexes (PNPI) for 1997 and 2017. PNPI is a simple, low-effort, time- and resource-saving method suitable for data-scarce regions, as it works at catchment level with commonly available geographical data. Land use type (obtained by Landsat imagery classification), runoff (determined by runoff coefficient characterisation) and distance to river network (calculated at perpendicular distance) were each transformed into corresponding indicators to determine their relative importance in generating pollution. Weighted sum, a multi-criteria analysis tool in the GIS environment, was used to combine indicators with weighting values. Different weighting values were assigned to each of the indicators resulting in a set of six equations. The results showed that higher PNPI values corresponded to human settlements with high population density, higher runoff values and shorter distance to river network, while lower PNPI values corresponded to semi-natural land use type, lower runoff coefficient and longer distances to river. PNPI values were positively correlated with measured nitrate and phosphate concentrations at six sub-catchment outlets. The correlation was statistical significant for phosphate in 2017. Maps were produced to identify priority source areas that are more likely to generate pollution, which is important information for future management.
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Kang, Le, Xingguo Han, Zhibin Zhang, and Osbert Jianxin Sun. "Grassland ecosystems in China: review of current knowledge and research advancement." Philosophical Transactions of the Royal Society B: Biological Sciences 362, no. 1482 (February 22, 2007): 997–1008. http://dx.doi.org/10.1098/rstb.2007.2029.
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Grasslands are the dominant landscape in China, accounting for 40% of the national land area. Research concerning China's grassland ecosystems can be chronologically summarized into four periods: (i) pre-1950s, preliminary research and survey of grassland vegetation and plant species by Russians, Japanese and Western Europeans, (ii) 1950–1975, exploration and survey of vegetation, soils and topography as part of natural resource inventory programmes by regional and national institutions mainly led by the Chinese Academy of Sciences, (iii) 1976–1995, establishment of field stations for long-term ecological monitoring and studies of ecosystem processes, (iv) 1996–present, comprehensive studies of community dynamics and ecosystem function integrating multi-scale and multidisciplinary approaches and experimental manipulations. Major findings of scientific significance in China's grassland ecosystem research include: (i) improved knowledge on succession and biogeochemistry of the semi-arid and temperate grassland ecosystems, (ii) elucidation of life-history strategies and diapause characteristics of the native grasshopper species as one of the key grassland pests, and (iii) development of effective management strategies for controlling rodent pests in grassland ecosystems. Opportunities exist for using the natural grasslands in northern China as a model system to test ecosystem theories that so far have proven a challenge to ecologists worldwide.