节水灌溉对黄河流域宁夏引黄灌区水平衡的影响机制及其生态效应

Influence mechanism and ecological effect of water saving irrigation on water balance in the Yellow River irrigation area of Ningxia

【研究目的】宁夏引黄灌区是中国重要的粮食生产基地之一,自实施节水灌溉以来,渠系衬砌、田间节水等节水工程影响了区域水平衡状况,研究节水灌溉对水平衡的影响机制及其生态效应对于区域水资源优化管理具有重要意义。【研究方法】通过构建宁夏引黄灌区“水-土-气-生”多元化数据库,运用秩相关分析和Spearman相关分析方法,研究了2000—2020年宁夏引黄灌区的水平衡要素演变趋势、水平衡演化机制及其生态效应。【研究结果】宁夏引黄灌区社会经济发展主要依赖过境黄河水,节水灌溉后水循环通量显著减少,2000—2020年农业用水量减少21.38×10^(8)m^(3),引黄水量减少19.52×10^(8)m^(3),排水量减少19.11×10^(8)m^(3);节水灌溉是水平衡演化的主要驱动因子,农业用水量减少直接导致引黄水量与地表水体补给地下水资源量减少(P<0.01);节水灌溉后地表水体补给地下水量减少8.68×10^(8)m^(3),地下水资源量减少8.89×10^(8)m^(3),地下水位普遍下降,盐渍化程度有所减轻,但改变了湖泊和地下水的水力联系,导致生态需水量增加。【结论】节水灌溉后农业用水效率得到提高,水循环通量显著减少,地下水位下降对生态环境造成一定影响,建议以生态安全为底线进一步优化节水方案,相关研究成果为区域自然资源管理及生态保护修复提供支撑。

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 21.38×10^(8)m^(3), 19.52×10^(8)m^(3)and 19.11×10^(8)m^(3), 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 8.68×10^(8)m^(3), and the amount of groundwater resources decreased by 8.89×10^(8)m^(3). 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.