To Study Hydrological Variabilities by Using Surface and Groundwater Coupled Model - A Case Study of PingTung Plain, Taiwan

The main objective of this research is to study the hydrological variabilities by using surface and groundwater coupled model. On that Taiwan is labeled as mountainous watershed with accompanying heavy rains occurred frequently, it is important to understand better the water flow conditions after extreme event occurred. The particular geology and highly concentrated river system could provide more infiltration and percolation of rainwater from surface or streams through permeable soils into water-holding rocks. It may provide useful water supply to undergrounds. In order to study the possible water storage underground in PingTung Plain, we used WASH123D watershed model to study this issue. The WASH123D numerical model is a physical based computational model with dealing surface flow and groundwater interactions competently. We firstly used field wells data to construct modeling environment, and then applied observation data to calibrate simulated parameters. Modelling environment including rivers, overland and groundwater are constructed in our model. Three examples with including extreme typhoon events insides are studied. We designed the period at last one month to calibrate our model parameters. It is because the flow condition after extreme rainfall occurred is one of the major phenomena that we are interested. The reactions of pressure head on different layers after extreme event occurred have focused. And we examined this mode to evaluate the efficiency of an ongoing groundwater supply plan in this region.