Groundwater recharge and exploitative potential zone mapping using GIS and GOD techniques

Two-thirds of the total area of Taiwan is mountainous terrain, which is the main groundwater recharge source of the plains region. This study assesses groundwater recharge and exploitative potential zone in the central division of the mountain areas of Taiwan (the middle reaches of the Jhuoshuei River Basin). Basic information from remote sensing and a satellite phantom is collected to set up the basic data maps using elevation, Formosa-II images, the Normalized Difference Vegetation Index, drainage distribution, slope, aspect ratio, lineament distribution, and land cover. A geographical information system is used to integrate five contributing factors, namely lithology, land cover/land use, drainage, slope, and lineaments. The criteria for the recharge potential assessment are established to demarcate the potential groundwater recharge zone. Finally, the GOD rating system is adopted to evaluate the potential exploitation zone. Three main parameters are considered: the groundwater occurrence, the lithology of the overlying layers, and the depth to groundwater. The results show that the middle reaches of the Chenyuland River have large potential exploitation zones due to its high rainfall recharge capacity. Regions west of the Jhuoshuei River and the downstream regions of the Chingshui River are medium potential exploitation zones because of their high infiltration rates and shallow groundwater levels.