北京城市副中心海绵城市建设对地下水影响分析

Impact of sponge city construction on groundwater in Beijing

海绵城市通过透水铺装、下沉绿地和湿地花园等措施,增加了雨水入渗和地下水补给,减少了地表径流,影响了区域地表水-地下水交换作用过程,势必带来潜在的地下水污染风险。以北京市通州城市副中心为例,基于Hydrus-1D和MODFLOW建立包气带-饱和带耦合模型,实现地下水的水量与水质全过程模拟,并预测了城市化前、城市化现状、海绵城市建设条件对地下水的影响程度。研究结果显示:海绵城市建设后经过20年时间,建设区水位整体上升1~2 m;硝酸盐氮的运移距离是1535 m,污染晕面积是1.688 km^(2),超过硝酸氮三类标准的面积为0.333 km^(2),较城市化现状均有不同程度降低。

Through permeable pavement,sunken green space,wetland garden and other measures,sponge city increases rainwater infiltration and groundwater recharge,reduces surface runoff,affects the regional surface water groundwater exchange process,which bring potential environmental risk to the groundwater.In order to carry out pollution prevention and control of groundwater in sponge cities,the aeration and saturated zone coupling model based on Hydrus-1D and MODFLOW is established to predict the effect of sponge city development on groundwater before urbanization and at present during urbanization.TakingTongzhou,the sub-center of Beijing as an example,the results show that the sponge city development has a great impact on the quality and level of groundwater.After 20 years of sponge city construction,the groundwater level has increased from 1 m to 2 m.The transport distance of nitrate nitrogen is 1535 m,the area of pollution halo is 1.688 km^(2),and the area exceeding the three standards of nitrate nitrogen is 0.333 km^(2),which is lower than the current situation of urbanization.