Shuiwen dizhi gongcheng dizhi (Sep 2022)
Discussion on ecological water level threshold of groundwater in Baoding Plain area
Abstract
Groundwater is of important ecological value. The changes in groundwater level, water quality, water content and salt content in the unsaturated zone in groundwater ecosystems drive the evolution of supergene ecological pattern. So far, the research on the ecological threshold of each variable is still at the starting stage, and the theoretical and methodological system is not perfect. In this study the Baoding Plain is taken as an example, and the driving force and ecological effect of groundwater level changes are analyzed from the perspective of time and space by using the historical regression method, GIS method and difference grid calculation method of groundwater levels and groundwater ecological environments. On this basis, the ecological water level thresholds of different hydrogeological units are determined. The results show that: (1) In the 1950s-60s, the ecological pattern of the study area depending on groundwater basically maintained a natural state; from 1959 to 2000, the groundwater levels continued to decline, and the groundwater depression cones appeared in some areas. From 2000 to 2008, the groundwater levels dropped sharply, the groundwater depression cones expanded rapidly, and the recharge and discharge relationship between groundwater and surface water changed. Since 2008, groundwater levels have gradually increased in some regions. (2) The depth of groundwater ecological water level in the piedmont zone of the study area is 10–15 m deep, the Juma River alluvial fan group and Cao River-Pu River alluvial fan group are 5–10 m, the Tang-Dasha River alluvial fan group is 3–5 m, the Dingzhou-Wangdu area in the alluvial plain is 3–5 m, the city of Baoding is about 10–15 m, and the rest are 5–10 m. The area around the alluvial lacustrine plain is less than 3 m. (3) Taking the determined ecological groundwater level as the standard, it is preliminarily estimated that the water demand for restoring the current groundwater level to the ecological water level in the study area is 57.14×108 m3. The research results are of important significance for restoring the local groundwater ecological environment pattern and for determining the ecological groundwater level in the North China Plain.
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