华北平原地下水降落漏斗演变及主导因素分析

Analysis on Evolution of Groundwater Depression Cones and Its Leading Factors in North China Plain

通过对大量的野外资料分析,发现华北平原浅层地下水位最大埋深已达65m,埋深大于10m的区域面积占全区总面积的44.4%,浅层地下水降落漏斗串珠状分布于太行山和燕山山前平原的工业城市;深层地下水位最大埋深达110m,埋深大于40m分布区面积占总面积的43.1%,形成了华北平原复合漏斗,面积占52.6%。通过对20世纪50年代至今降水量减少、河道渗漏量减少和地下水开采量增加的变化分析,发现地下水位下降和漏斗的形成与人类开采地下水和降水量持续减少密切相关,通过采用关联度计算分析,认为人类开采地下水是区域地下水位下降的主导因子。

According to field investigation of 13.96×10^4km/ and dates from 4850 monitoring points from 2001 to 2007 in North China Plan, we carried out integrated analysis of the obtained change maps of groundwater flow field in deep and shallow aquifer layer of both high and low flow period in different years, and summarized the following points： 1 ） Areas of groundwater depression cones have enlarged and central buried depth has decreased continuously; 2） The maximum buried depth of shallow groundwater aquifer reached 65m and the area with buried depth above 10m has reached 44.4% of the whole region. The depression cone of shallow aquifer is mainly located in industrial cities in piedmont of Taihang Mountain and Yan Mountain like a moniliform, and the total area surrounded by equal water level line of cones has reached 9 657.9 km^2 ; 3） The maximum buried depth of deep groundwater aquifer has reached 110m and the areas with buried depth above 40m have reached 43.1% of the whole region, while the area with pressure bearing water head lower than sea level has reached 87 934.14 km^2, which is 52.6 % of the whole, and combined groundwater depression cones have been formed. The phenomenon of groundwater overflow, which was widely distributed in this region during 50-60＇s in the 20th century, has disappeared. We have reached several conclusions： the precipitation has reduced by 4%-9% in recent 30 years compared with the average earlier; the exploitation modulus of groundwater has increased from 11.13 ×10^4 m^3/（km^2· a）in the 70s to 15 ×10^4m^3/（km^2· a）at present, by a percentage of 32.8; due to the block store up projects in upper reaches, the main river is dry more than 300 days since 1980, which leads to the leakage reduction in supply. Being calculated by adopting analytic hierarchy process, the respective correlation coefficients of exploitation and precipitation with the declination of groundwater level were 0.711 and 0.601. It is agreed that both natural and human factors led to the formation of groundwater depression cones, but the human ones are in a leading position.