Fundamental study on the making method of a groundwater pollution vulnerability map using GIS

点击翻译按钮获取中文摘要

The system of making a groundwater pollution vulnerability map which showed the possibility of groundwater deterioration caused by a unit volume of groundwater extraction in the Katsura River watershed was developed. First the mechanism of shallow groundwater deterioration near the Katsura River was studied with field investigations and numerical simulations. The results showed that the cause of the deterioration seemed to be the recharge of deteriorated river water induced by the large quantity of groundwater extraction. This meant that the quantity of the recharge from the Katsura River could be compared to the possibility of groundwater deterioration of this area. Therefore, we made the groundwater pollution vulnerability map by simulating the groundwater recharge from the Katsura River using various numerical map data on the open market. For making the map, the analytical region was automatically decided and divided into finite elements, the catchment area was automatically evaluated, and transmissivity and the quantity of groundwater extraction were estimated from the numerical map data. This procedure can be used for the other area in Japan where there is not enough quantity of groundwater data. The results of the application of the procedure to the Katsura River watershed showed that the simulation using only the numerical map data was qualitatively effective and such a vulnerability map as the one created in this study was thought to be useful for deciding a new plant location or environmental impact assessment.