Effects of Agricultural Large‐And Medium‐Sized Reservoirs on Hydrologic Processes in the Arid Shiyang River Basin, Northwest China. Issue 2 (10th February 2023)

• Record Type: Journal Article
• Authors: Sang, Liyuan; Zhu, Guofeng; Xu, Yuanxiao; Sun, Zhigang; Zhang, Zhuanxia; Tong, Huali
• Is Part Of: Water resources research. Volume 59:Issue 2(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-02-10
• Subjects: agricultural reservoirs -- arid regions -- stable isotopes -- hydrology -- water evaporation losses; Hydrology -- Periodicals; 333.91
• DOI: 10.1029/2022WR033519
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: Agricultural large and medium‐sized reservoirs in arid regions increase the water stresses within local hydrologic systems, adding to pressures on aquatic ecosystems and also threatening the sustainability of water resources. Yet, there is limited research concerning how agricultural reservoirs affect the hydrology of inland river basins, which has hampered a comprehensive assessment of sustainable water use in these systems. We explore the use of stable isotopes of water to evaluate the effects of agricultural reservoirs on hydrology and the sustainable use of water in the arid Shiyang River basin. Results show that agricultural large‐ and medium‐sized reservoirs in this arid region alter local isotopic hydrologic patterns increasing water‐body evaporation and enriching the isotopic composition of water near the reservoir. As a result, evaporation losses of reservoir water can be as high as 30.7% in downstream desert reservoirs. Reservoir water also exchanges with surrounding groundwater and contributes 22% to local precipitation due to reservoir evaporation. Detailed studies of individual reservoirs show that the isotopic composition is most enriched at the surface of the reservoir and then gradually depletes toward the bottom. The cumulative effect of multiple large and medium sized reservoirs profoundly alters hydrologic processes in inland river basins, leading to an evaporation‐led water loss in these systems. Plain Language Summary: Water‐scarce drylands have tended to rely on the construction of agricultural reservoirs to maintain the sustainability of their water resources. However, such agricultural reservoirs have resulted in greater water losses. In view of the weak observational basis of the hydrologic processes in the arid zone, we selected the Shiyang River Basin, a typical inland river basin in the arid zone of China, to establish a comprehensive ecological observation system and to investigate the impact of agricultural large‐and medium‐sized reservoirs on hydrology. The results show that reservoirs interrupt the natural flow patterns of inland rivers and have a greater evaporation effect than the natural river. Reservoirs alter the natural processes of the local precipitation and groundwater cycle through their own strong evaporation and frequent infiltration. The cumulative effect of multiple agricultural reservoirs increases water losses and significantly alters hydrologic processes in inland river basins. We believe that this study will not only attract wide interest from readers in terms of results, but also provide a process reference for research on monitoring hydrological systems in arid zones. Key Points: Agricultural large‐and medium‐sized reservoirs alter the natural hydrologic processes in inland river basins Agricultural reservoirs increase the water losses of reservoir through strong evaporation and frequent infiltration The loss of water resources is exacerbated by combined influence of multiple agricultural reservoirs