兰州市城市化对地下水系统的影响研究

以地下水污染调查数据为基础,结合历史观测资料,揭示兰州市城市化过程中地下水水位、水质的变化特征及其影响因素。城市污水排放、蓄水设备修建及农业灌溉等因素使垂直渗入补给量增加,引起地下水上升,其中西固区地下水位上升剧烈,受地下水开采的影响,水源地地区形成大面积的地下水降落漏斗,水位下降显著;兰州市区地下水水质影响因素较多,土地利用类型的改变带来污染源强的增加、城市垃圾处理方式以及水位下降等是直接或间接地造成地下水质恶化的重要因素,老城区和工业区地下水总硬度、NO-3、氟离子、有机组分等指标呈逐年上升趋势,污染形势严峻。

Effect of urbanization on groundwater system in Lanzhou

Based on data of groundwater pollution survey and historical observation, this paper revealed the variation characteristics and its influencing factors of groundwater levels and quality in Lanzhou. Urban sewage discharge, water storage construction, agricultural irrigation and other factors increase the vertical infiltration recharge of groundwater which caused groundwater level to rise especially in Xigu district. Affected by groundwater exploitation, the water source regions formed a large area of groundwater drawdown funnel, the water level dropped significantly. There are many factors affecting groundwater quality in Lanzhou city.The change of land use type caused the increase of pollution sources, the disposal method of urban waste and the groundwater drawdown are important factors which caused deterioration of groundwater quality directly or indirectly.The indexes of groundwater such as TH, NO^-₃, F^- and organic compounds show an increasing trend in old city and industrial zone.The situation of pollution is grim.