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[摘要]
为探讨怀柔应急水源地及其周边地区地下水流场的演化情况,统计分析了1978年-2010年区域和水源地中心区的地下水水位变化。研究区地下水流场大致经历了4个发展阶段:1980年之前的天然流场阶段、1980年-1985年局部地下水位缓慢下降阶段、1986年-1998年地下水位动态平衡阶段和1999年-2010年地下水位强烈下降阶段。进一步研究发现,降水量锐减、河道弃水量的减少是造成本区地下水补给量锐减的自然因素,而人类活动的影响主要表现在下垫面入渗条件的改变和人工持续开采两个方面。:在近30年的时间里,研究区城市和农村聚落的建设增加了约120km2,水浇地和旱地面积减少了近102km2,下垫面条件的改变造成降雨入渗量的大幅减少。而地下水开采造成区域地下水位持续下降41m左右,地下水位降落漏斗经历了从无到有,从局部到区域的发展过程,面积达200km2,已经形成了区域地下水超采状态。目前,水源地单井出水量和总的开采量已经减少,地下水位持续下降,漏斗有进一步扩展的趋势,因此应当尽快停采涵养水源,恢复水源地应急备用功能,以保障供水安全。
[Key word]
[Abstract]
In order to investigate the evolution of groundwater flow field in Huairou emergency well field, the variations of regional groundwater level and water level in the well field were analyzed from 1978 to 2010. The evolution of the flow field in the study area underwent four periods: natural flow field period before 1980, locally slow water level decline period from 1980 to 1985, dynamic balance period from 1986 to 1998, and significant water level decline period from 1999 to 2010. Further studies suggested that the natural factors, such as decreasing in precipitation and abandoned water, and human activities, such as change in the infiltration of underlying surface conditions and continuous groundwater pumping, have caused the reduction in groundwater recharge. In the past 30 years, the construction area of urban and rural settlements increased by approximately 120 km2, and the area of irrigated land and dry land decreased by nearly 102 km2, which resulted in the change in underlying surface conditions and thus significant reduction in precipitation infiltration. Continuous groundwater pumping caused 41-m drawdown of groundwater level in this area. The cone of depression expanded from locally to regionally with a depression area of 200 km2, indicating groundwater overexploitation status in the area. The capacity of single well and the total production of well field have decreased with continuous groundwater level decline and expansion of cone of depression. Therefore, water conservation engineering should be performed in the area, and the function of emergency and standby of water source site needs to be reinstated to ensure the safety of water supply. .
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