台西至麥寮地區地層下陷與地下水補注之研究─台西至麥寮地區地層下陷與地下水補注之研究-子計畫：台西至麥寮地區地下水天然補注量之研究(V)

The purpose of the study is to quantity the amount of annual recharge in the area from Tai-shi to Mai-lau. The result will be useflul to the government for planning and management of groundwater resources. The study has established the relationship between the lateral and vertical percolation in paddy field, assessed the potential methods of increasing the ground water recharge from the paddy field. The data of soil characteristics and hydraulic parameters obtained from Ten-Chung flooded paddy field are used for the simulation model. The l-D SAWAH and 3-D model FEMWATER are adopted to simulate infiltration and groundwater recharge in paddy field.
According to the simulation results, the paddy field remains the higrest infiltration rate than the other landuse patterns, its infiltration capacity is restricted by the hardpan. Though the irrigationlinfiltration is just taken place from March to May in a year , the annual amount of irrigation water infiltrating through hardpan is 1,558,000 cubic meters in Tai-Shi and 4,549,000 cubic meters in Mai-Lau. Simulation results also show that the movement of infiltration water is mainly vertically downward in most area for regional flooded paddy field, the lateral movement is obviously occur on the wet to dry boundary. The ratio of lateral seepage depend on the length of wet to dry boundary, the area of flooded paddy field, and the different initial water content in floodedldry farm soils. The cracks developed when paddy field in drainage condition will obviously increase the infiltration rate because of the breakage of hard pan. It suggests that the usage of these paddy field farms and its irrigationlconduit system is a feasible way in increasing the amount of recharge and flood control on summer times.