大兴区位于北京市南端，为永定河冲积洪积平原的一部分。面积1030 km2，人口52．4万。过境和境内河道19条，除凉水河、新凤河有市区污水过境外，其余均为干河。区内社会各业用水全部依赖开采地下水。1999年各业用水总量达3．01亿m3，水资源可利用量2．06亿m3，其中地下水可开 Daxing District, located in the southern tip of Beijing, is part of the alluvial and alluvial plain of the Yongding River. Area of ​​1030 km2, population 524000. 19 transit and the territory of the river, in addition to Liangshui River, Xinfeng River urban sewage transiting, the rest are dry river. All sectors of society rely on the exploitation of groundwater. In 1999, the total water consumption of all industries reached 301 million m3, and the water resources available amount was 206 million m3, of which groundwater was open