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. |