Abstract
Highly concentrated precipitation during the rainy season poses challenges to the South Korean water resources management in efficiently storing and redistributing water resources. Under the new climate regime, water resources management is likely to become more challenging with regards to water-related disaster risk and deterioration of water quality. To alleviate such issues by adjusting management plans, this study examined the impact of climate change on the streamflow in the Bocheongcheon basin of the Geumgang river. A globally accepted hydrologic model, the HEC-HMS model, was chosen for the simulation. By the calibration and the validation processes, the model performance was evaluated to range between “satisfactory” and “very good”. The calibrated model was then used to simulate the future streamflow over six decades from 2041 to 2100 under RCP4.5 and RCP8.5. The results indicated significant increase in the future streamflow of the study site in all months and seasons over the simulation period. Intensification of seasonal differences and fluctuations was projected under RCP 8.5, implying a challenge for water resources managers to secure stable sources of clean water and to prevent water-related disasters. The analysis of the simulation results was applied to suggest possible local adaptive water resources management policy.
Highlights
South Korea demonstrates a strong seasonality: 55.3% of its average annual rainfall (723.2 mm of 1307.7 mm) in the 30 year period between 1981 and 2010 was concentrated in the summer season, from June to August [1,2]
Projections of the near and the far future streamflow in the Bocheongcheon basin in this study shed a light on the site-specific trend, distinct from other previous studies conducted over South Korea
As the pattern of streamflow varies by regions, we suggest that future streamflow be simulated at a basin level if the purpose of hydrologic modeling is to serve as evidence for local adaptive measures
Summary
South Korea demonstrates a strong seasonality: 55.3% of its average annual rainfall (723.2 mm of 1307.7 mm) in the 30 year period between 1981 and 2010 was concentrated in the summer season, from June to August [1,2]. If precipitation increases compared to the average or if the rainy season is prolonged, serious flooding may occur in the downstream regions Such difficulties in domestic water resource management resulting from the seasonality are projected to be exacerbated under the changing climate [4,5,6,7,8,9,10]. According to the Korea Meteorological Administration, the summer rainy season in 2020 started on June 24 and ended on August 16, which was the longest rainy season on record since 1973 [11] During this period, multiple extreme events of torrential rains (87 and 79 mm per hour in Busan and Daejeon metropolitan cities, respectively) were observed under the influence of the typhoon “rose”. The mitigation of damage against such water-related natural disasters is the main target of national disaster reduction policies [12]
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