| dc.description.abstract | Due to climate change impact, the uncertainty of water resources system is getting worse, which enhance the importance of water resources planning and management on regional and global scale. In Taoyuan, a system dynamic model was used to simulate a unique agricultural irrigation method called pond irrigation system. This irrigation method was not only to assist the irrigation water supply, but also used for water storage during rainfall events. In this study, two observation stations, upstream and downstream of the irrigation area, were compared and used as examples to discuss the rise in groundwater level caused by rainfall, and the decrease in long-term non-rainfall period. Then simulation is performed for the pond irrigation system with a system dynamic model by utilized the measurement of water intake and rainfall. The changes of field water depth and the groundwater level were compared during the irrigation operation for two different crop period in 2015 and 2017.
According to the simulation results, the groundwater level in the upstream area rose rapidly during rainfall events, and fell sharply when rainfall ceased. On the other hand, the groundwater level in the downstream area experienced little impact of irrigation water due to that irrigation maintained stable field water supply. In the agricultural field, groundwater level is affected by rainfall kept in the field, which continues to supply groundwater recharge. Based on the theory of the recharge of the groundwater level in the agricultural field, a regression equation is introduced by utilized the data collected in 2014 to 2017, which relating the groundwater level rose with the cumulative residual water in the site. As a result, when the rainfall is small, the next day groundwater level would be approximate to the current observation, due to minor changes in the groundwater level. However, in the heavy rainfall event, although there may be some estimation overrated, the simulation results effectively predict the changes in the groundwater level. | en_US |