Water Cycle Assessment of Seoul National University Applying Atmos-41 and SWMM

Urbanization has led to a significant water cycle distortion in South Korea. Seoul National University, located in Mt. Gwanak, is also harming the quantity and quality of the downstream as the increase in floating population and excessive construction. However, there are few related data or evaluations on the water cycle of Seoul National University. Therefore, this study aims to construct data related to the water cycle and evaluate the degree of distortion for the Seoul National University. The installation of the Atmos-41 enabled the collection of weather data as well as the calculation of potential evapotranspiration. When the factors (temperature, relative humidity precipitation, wind speed) were compared to the corresponding values of the Korea Meteorological Administration to determine the validity of calculating the potential evapotranspiration, the RRMSE was accurate from 0.001 to 0.03. Then, the SWMM model was applied to assess the elements of Seoul National University's water cycle. The SWMM model simulated surface runoff, infiltration, evaporation, and potential evapotranspiration. As a result of verifying the surface runoff and infiltration using the previous study results of the same target watershed, the RRMSE was 0.06 to 0.1. In the case of simulating the potential evapotranspiration, the SWMM results estimated by the Hargreaves method were compared and validated with the results of Atmos-41 calculated by the Penman-Monteith method. Changes in the water balance before and after the urbanization of Seoul National University for surface runoff, infiltration, and evaporation are 15.7% increase, 14.2% decrease, and 3.7% decrease, respectively. The water cycle distortion at the study basin has progressed so much that the increase rate in surface rate, and the decrease rate of infiltration are over 10%. This study suggests that Seoul National University maintains the current water balance ratio to move toward a sustainable campus.