Abstract
Understanding the changes on future water resources resulting from climate variations will assist in developing effective management strategies for a river basin. Our area of interest is the Osan watershed in South Korea, where the summer monsoon contributes approximately 60–70% of the annual runoff and precipitation for the country. We determined the effects that future climatic changes have on this area. To accomplish this, we made use of global climate models (GCMs). A total of 10 GCMs were downscaled with the help of climate information production tools. Coupled with the GCMs and the Soil and Water Assessment (SWAT) model, three periods were used to assess these climate impacts. The baseline, mid-century (MC), and end-century (EC) periods include 1993–2018, 2046–2065, and 2081–2099, respectively. The entire process was performed using two scenarios (4.5 and 8.5) from the representative concentration pathways (RCPs). Some of the statistical metrics used for model calibration and validation were p-factor, r-factor, percent bias, root-mean-square error (RMSE), and Nash–Sutcliffe model efficiency. Their respective values were 0.88, 0.88, 8.3, 0.91, and 0.91 for calibration, and 1.16, 0.85, 7.9, 0.88, and 0.87 for validation. For the MC and EC periods under both scenarios, we projected an increase in temperature and precipitation of approximately 2–5 °C and 15–30%, respectively. A predicted rise in precipitation, surface flow, lateral flow, and water yield were noted for the month of June. Subsequently, a decline in July followed during the summer monsoon season. Summer monsoon rains will fluctuate more sharply, with heavy rainfall in June, lower rainfall in July, and more rain in the late summer, leading to the possibility of both flooding and drought within a given period. Annual precipitation, surface flow, lateral flow, and water yield will increase whereas evapotranspiration would decrease in both periods under both scenarios during the summer monsoon period, which will lead to wetter conditions in the future.
Highlights
Recurring changes in the climate have been predicted to detrimentally affect water resources on a global scale [1]
These results would be of use in projecting future increase under representative concentration pathways (RCPs) 4.5 was in June, with 0.6 mm (43%) for the MC period and 0.89 mm (63.5%) in water availability within the Osan watershed
Under RCP 4.5, the surface flow increased by 13.4% and 22.0% and, under RCP 8.5, it increased by 22.9% and 49.0% in the MC and EC periods, respectively
Summary
Recurring changes in the climate have been predicted to detrimentally affect water resources on a global scale [1]. In South Korea, the SWAT model has been used as a tool for water management [16], drought assessment [17], water quality assessment [18], hydrologic partitioning [19], water balance analysis [20], and prediction of the effects of changes on future water resources [21,22,23,24,25,26]. Previous studies of climate change in South Korea have generally been based on a single water balance component (either surface flow, ET, or groundwater recharge) and a single GCM, while others have focused only on precipitation and temperature in terms of hydrology.
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