HYDROGEOLOGICAL SURVEY AND COMPILATION OF HYDRO-GEOLOGICAL MAP IN CENTRAL FLOW BASIN, TAIWAN

The status of groundwater resource and in-situ hydro-geological information are lacking in mountainous regions of Taiwan. The Central Geology Survey (CGS) of MOEA leads an integrated project on groundwater resource investigations in central mountainous area started from 2010 to 2013. The major in-situ tasks include hydro-geological survey and installation of groundwater observation wells, executed and cooperated by three different teams named ITRI, Sinotech and Cheng-Kung University. The purpose of this integrated project is trying to understand the distribution of groundwater flow field, deploy the superfluous water resource and its quality, grasp totally the interaction between surface water and groundwater, and to conserve mountainous groundwater resource, as well as to raise the efficacy of water resource management and sustainable operation. The preliminary hydro-geological conceptual model of Taiwan central mountainous area has been drawn and can be classified into four types. First of all, the groundwater is mainly stored in both of the regolith formed as porous media and fractured bedrock. Secondary, groundwater recharge into the alluvium through the fractures in the bedrock, and down-flow in to the alluvial plain area. Thirdly, the basin in the mountainous area usually has thick aquifers which might be a good reservoir to store groundwater. Fourthly, water can recharge into the plain area through surface runoff , recharging from the top of alluvial fans, or deep circulation recharge.