The purpose of this research is the performance evaluation of groundwater recharge of storage pond in Taoyuan area. A field experiment using a seepage meter was conducted to measure the infiltration rate to calibration the numerical simulation. Series laboratory of the field soil sample, such as soil-water characteristic curves, specific gravity, particle size distribution, porosity and saturated hydraulic conductivity. The groundwater flow of the storage pond was simulated by a numerical model, FEMWATER. FEMWATER is a two-dimensional finite element model which suit for simulation of water flow through Saturated-Unsaturated Porous Media. A series of simulation as conducted to determine the infiltration rate in the different water depth of the storage pond. The simulation results show that the lowest hydraulic conductivity soil layer is bottle - neck of the infiltration rate from the storage pond through the soil to the groundwater. In this project, a soil infiltration theory (in MODFLOW) was applied to investigate the quantities of groundwater recharge by seepage released from water storage ponds. The infiltration rates of water storage ponds #l-12 were found to be approximately 4x10-3 m/day (i.e. 4 mm/day) based on the experimental results from infiltration tests measured with a seepage meter. This finding indicates the efficacy of groundwater recharge attributable to the infiltration from these water storage ponds is not quite high. On the other hand, it indicates the efficacy of water storage of these ponds is good since the infiltration rate is small. The effects of water level variation on the infiltration rate have been evaluated by combining the results from infiltration tests and MODFLOW simulation. The infiltration rate was increased to approximately 7.5x10-3 m/day {i.e. 7.5 mm/day}, which is smaller than the minimum requirement on the recharge rate listed in the standards for groundwater recharge ponds when the water level was increased to 5 meter. This finding indicates that these ponds can only be used as water storage ponds rather than groundwater recharge ponds under the specific geophysical conditions.
