Groundwater recharge and exploitative potential zone mapping using RS and GIS in the central division of mountain (Jhuoshuei River Basin), Taiwan

Two-thirds of the total area of Taiwan is mountainous terrain, which is the main groundwater recharge source of the plain region. This study assesses groundwater recharge and exploitative potential zone in the central division of the mountain area (the middle reaches of the Jhuoshuei River Basin). Basic information from remote sensing (RS) and a satellite phantom is collected to set up the basic data maps using elevation, Formosa-II images, Normalized Difference Vegetation Index (NDVI), drainage distribution, slope, aspect ratio, lineament distribution, and land cover. A geographical information system (GIS) is used to integrate five contributing factors, namely lithology, land cover/land use, drainage, slope, and lineaments. The criteria for recharge potential assessment are established to demarcate the groundwater recharge potential zone. The resultant map of the groundwater potential zone demonstrates that the highest recharge potential areas are located towards the downstream regions of the Chingshui River, between the Chi-Chi Weir and the Changyun Bridge, and the eastern mountain of the Chenyuland River. The spatial distribution map of groundwater recharge indicates that recharge is controlled by precipitation. The main recharge zones are located in the eastern and southern mountains of the study region. The Jhuoshuei River is a medium recharge zone, and the Chingshui River and Tungpuna River are low recharge zones. Finally, the GOD rating system is adopted to evaluate the exploitative potential 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 exploitative potential zones due to plentiful rainfall. West of the Jhuoshuei River and downstream regions of the Chingshui River are medium exploitative potential zones because of their high infiltration rates and shallow groundwater levels.