Evaluating the groundwater resources in the Liwu and Hualien watersheds

This study collected and combined the investigation results from the projects of Central Geological Survey, MOEA, Taiwan in the Liwu and Hualien watersheds. The groundwater level data from the Water Resources Agency, MOEA, Taiwan were also adopted. Base on the collected information and data, two groundwater numerical models for Liwu and Hualien watersheds were developed by using MODFLOW in the software of Groundwater Modeling System (GMS). The quantity of groundwater safe yield and the exploitable quantity of groundwater resources in these two watersheds were evaluated by using the developed models. The safe yield of groundwater is defined as the excess groundwater quantity flows out of the study area. The results show that the safe yields in the Liwu and Hualien watersheds are about 170.12 × 10⁶~189.54 × 106 ton/year and 191.31 × 10⁶~199.23 × 10⁶ ton/year, respectively. The exploitable quantity of groundwater is defined as the pumping quantity per unit drawdown of groundwater level and per unit area in the high exploitive potential zone. There are two potential zones in the Hualien watershed naming zone A and zone B. The results show that the exploitable quantities of groundwater in Liwu watershed and Hualien watershed zones A and B are 4.7 × 10⁶, 6.4 × 10⁶, and 5.3 × 10⁶ ton/year‒km², respectively. The quantities are larger than those in the reference due to the estimated area in this study is focused on the high exploitive potential zone. The study results provide the information for groundwater plan, exploitation, and management in the study areas.