城市“土壤水库”库容的萎缩及其环境效应

"土壤水库"具有容纳和调节水分的功能,不仅能供给植物生长所需的水分,而且具有防洪减灾的作用。城市土壤的水分储蓄和调节功能对于城市生态环境具有非常重要的作用。城市化造成了大量的封闭地表,使得土壤的功能几乎完全丧失。本文以南京市为例,选择不同压实程度的土壤,根据其饱和含水量、田间持水量和萎蔫点含水量计算土壤的总库容、有效库容、滞洪库容和死库容。结果表明,随着城市土壤压实程度的增加,土壤水库的总库容、有效库容和滞洪库容萎缩也越严重,而死库容却明显增加。城市土壤普遍存在压实现象,使城市土壤疏导和容纳水分的能力减弱,城市里出现瞬时洪涝的几率增加,强度加大。因此,良好的城市环境需要有更多的绿地和良好的土壤条件。

Loss of Soil Water Capacity in Urban Areas and It's Impacts on Environment

Urban soil water "reservoir" can not only supply water to plants, but also minimize flooding risk by holding and adjusting soil water balance. Surface sealing during urbanization can weaken soil environmental buffering function which is very important to urban eco-environment. This study estimated the total soil water storage capacity, available water storage capacity, short time water storage capacity and invalid water storage capacity based on the saturation moisture content, field water moisture capacity and wilting point moisture content of different compacted soils in Nanjing. The results showed that with the increase of urban soil compaction, the total soil water storage capacity, available water storage capacity and short time water storage capacity reduced gradually, but the invalid water storage capacity increased gradually. As urban soil compaction is ubiquitous, its ability in discharging and holding water reduces, which often causes rapid urban flooding. In general, more open space with suitable soil condition is needed for an ecologically-sound urban environment.