Abstract:
This paper is the result of hydrogeological survey engineering.
Objectives The Yellow River irrigation area of Ningxia is one of the important grain production bases in China. Since the implementation of water-saving irrigation, projects such as canal lining and field water-saving have affected the regional water balance. It is of great significance to study the influence mechanism and ecological effect of water-saving irrigation on water balance for the optimal management of regional water resources.
Methods By constructing the water-soil-gas-generation diversified database of the Yellow River irrigation area of Ningxia, adopting rank correlation analysis and Spearman correlation analysis methods, the evolution trend of water balance elements, water balance evolution mechanism and ecological effect of the Yellow River irrigation area of Ningxia from 2000 to 2020 were studied.
Results The economic development of the Yellow River irrigation area of Ningxia mainly depends on the Yellow River water. Since the implementation of water-saving irrigation, the water circulation flux decreased significantly. From 2000 to 2020, the amount of agricultural water intake, water diversion and water discharge decreased by 21.38×108 m3, 19.52×108 m3 and 19.11×108 m3, respectively. Water-saving irrigation is the main driving factor of water balance evolution, and the decrease of agricultural water intake directly leads to the decrease of the amount of water diversion and groundwater recharged by surface water (P < 0.01). After the implementation of water-saving irrigation, the amount of groundwater recharged by surface water decreased by 8.68×108 m3, and the amount of groundwater resources decreased by 8.89×108 m3. The groundwater table decreased, and the degree of salinization reduced. In addition, the decline of the groundwater table changed hydraulic connection between lakes and groundwater, resulting in an increase in ecological water demand.
Conclusions After the implementation of water-saving irrigation, the utilization efficiency of agricultural water has been improved, water circulation flux has been significantly reduced, and the decline of groundwater table has affected the ecological environment. It is suggested to further optimize the water-saving scheme based on ecological security. Relevant research results provide support for regional natural resource management and ecological protection and restoration.
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