GIS-based groundwater vulnerability assessment using a modified DRASTIC model: a case study at Cangzhou City, China

摘要

Groundwater protection has become increasingly important for social-economic sustainable development. In north China, groundwater is the main source of water supply. Cangzhou City, was selected as a representative of cities in north China for groundwater vulnerability assessment. By considering the specific hydrogeological conditions in the study area, the DRASTIC model was modified. In the new model the factors include: depth to water table, net recharge, aquifer media, soil media, impact of the vadose zone and aquifer thickness. Data from 78 boreholes were collected to provide information about static water levels and lithology. In addition, net recharge and other geological data were also collected. The vulnerability map was finally constructed based on these point-source data using the spatial analysis procedure of GIS. Comparing the vulnerability map with the shallow groundwater pollution degree distribution map at Cangzhou indicates that most of highly polluted regions coincide with high groundwater vulnerability sub-area, and most unpolluted regions have low vulnerability. The method of vulnerability assessment is, in general, applicable in other areas hydrogeologically similar to Cangzhou.