城市硬化背景下潜水含水层的海绵效应和净化作用

Sponge Effect and Purification Function of Phreatic Aquifer Under Background of Urban Hardening

不同于地表水和深部地下水,潜水含水层既是降水补给的直接承载体,又具有较强的吸水能力和给水能力,是典型的地下"海绵体"。为了充分阐明和论证潜水含水层的海绵效应,从矿物组成、补给条件、蒸发条件、给水条件、排泄条件和区域地质条件等因素着手,对潜水含水层的海绵效应、净化作用和制约条件等特性展开专题研究。结果表明,潜水的海绵效应受含水层厚度、下渗率、排泄条件、地表植被覆盖率、人工开采、侧向补给、与深部地下水的连通状况等因素制约,导致城市地面过度硬化使潜水的海绵效应无法有效发挥;此外,"海绵城市"建设应避开高污染地区和地下水脆弱地区。

Unlike surface water and deep groundwater, phreatic aquifer is not only the direct cartier of precipitation recharge, but also has a strong water absorption capacity and water yield capacity, it is a typical under-ground ＂Sponge＂. This paper carries out special study on phreatic aquifer＇s sponge effect, purification function, and restricting factors from aspects of mineral composition, water yield conditions, evaporation condi- tions, recharge conditions, discharge conditions and regional geological conditions, etc. The results show that the sponge effect of phreatic aquifer is restricted by such factors as thickness of the aquifer, infiltration rate, discharge conditions, vegetation cover, artificial exploitation, lateral recharge , and deep groundwater connectiv- ity etc, which leads to the excess hardening of the urban ground and the sponge effect of phreatic aquifer can- not be exerted effectively. In addition,the ＂Sponge City＂ should avoid the highly polluted areas and groundw- ater vulnerable areas.