有咸水区深层淡水可持续利用研究

天津市东丽区第四系Ⅱ组深层淡水在长期较强开采状态下未发生水位持续下降及大面积深层淡水成化污染,十余年来地层沉降基本消失.该地多年来中更新统淡水及上更新统、全新统咸水水位具有同步不等幅的动态,证明它们之间联系密切,地层中渗透系数小于10-3m/d的历次海侵沉积层及压实的粘土层具有半透膜特性,咸水越流补给第Ⅱ承压含水组的是淡水.适量加大Ⅱ组淡水开采强度,使其产生越流系统,稳定后不会再加大地面沉降.最终使全新统地下水下入渗水位降低,夺取潜水蒸发的水量.在有咸水分布区,地表入渗水是尚没有引起足够重视的可持续利用地下淡水的补给来源.

Study on Sustainable Utilization of Deep freshwater in the Saline water region

Over a long period of exploitaiton, neither the expectant continuous drawdown of groundwater level of deep freshwater in the quaternary II aquifer nor large area of saline water pollution to be occurred in Dongli district of Tianjin, and the land subsidence has faded away for over 10 years. In this area, the dynamic groundwater level of Holocene series freshwater, Middle Pleistocene and Upper Pleistocene series saline water has the character of Synchronization and different in amplitude, indicating the close relationship of them. The depositional stratum caused by the previous ocean invasions and the constringent clay stratum with the permeability coefficient less than 10~(-3)m/d has the feature of semi-permeable film. The saline water over flow recharge to II confined aquifer is fresh water. So, proper increasing the exploit intensity of the fresh water of quaternary II aquifer will lead to cause overflow system, and when the system getting steady, the trend of increasing land subsidence will cease. At last, the adoption of the above-mentioned practice can decrease the level of the Pleistocene saline groundwater level, and capture the phreatic water evaporation. In the saline water region, infiltration of surface water is the important source of fresh groundwater that can be sustainable utilized, but no sufficient importance has been attached to it.