In recent days, the cases of using wetlands in treating waste water, storm events, mining leachate, and
agriculture effluents are increasing. But there is the lack of the data for wetlands because of the difficulty in long
term monitoring. Such an aspect makes the proper use of wetland impractical. In this study for the purpose of
generating a long term hydrologic data, the time series of storage amount for Upo, Mokpo, Sajipo, and Jjokjibeol in
Topyeong watershed is simulated using SWAT model. Based on the SWAT-Topyeong model involved in several
scenarios for constructing new washlands in Topyeong watershed, the temporal behavior of new washlands is
analyzed. It is also revealed that the constructed washland can affect the Upo in some degrees.