Assessment of Future Climate Change Impact on Agricultural Water Supply Capacity in Geum River Basin Using SWAT and MODSIM-DSS

Sehoon Kim,Jinuk Kim,Chunggil Jung,Seongjoon Kim,Jiwan Lee

doi:10.9798/kosham.2020.20.6.55

Abstract

This study is to evaluate future agricultural water supply capacity in Geum river basin (9,865 km2) using SWAT and MODSIM-DSS. The MODSIM-DSS was established by dividing the basin into 14 subbasins, and the irrigation facilities of agricultural reservoirs, pumping stations, diversions, culverts and groundwater wells were grouped within each subbasin, and networked between subbasins including municipal and industrial water supplies. The SWAT was calibrated and validated using 11 years (2005-2015) daily streamflow data of two dams (DCD and YDD) and 4 years (August 2012 to December 2015) data of three weirs (SJW, GJW, and BJW) considering water withdrawals and return flows from agricultural, municipal, and industrial water uses. The Nash−Sutcliffe efficiency (NSE) of two dam and three weirs inflows were 0.55∼0.70 and 0.57∼0.77 respectively. Through MODSIM-DSS run for 34 years from 1982 to 2015, the agricultural water shortage had occurred during the drought years of 1982, 1988, 1994, 2001 and 2015. The agricultural water shortage could be calculated as 197.8 × 106 m3, 181.9 × 106 m3, 211.5 × 106 m3, 189.2 × 106 m3 and 182.0 × 106 m3 respectively. The big shortages of agricultural water were shown in water resources unit map number of 3004 (Yeongdongcheon) and 3012 (Geumgang Gongju) areas exceeding 25.1 × 106 m3 and 47.4 × 106 m3. From the estimation of future agricultural water requirement using RCP 8.5 INM-CM4 scenario, the 3004 and 3012 areas showed significant water shortages of 26.1 × 106 m3 (104.1%) and 50.9 × 106 m3 (107.4%) in 2080s (2070∼2099) compared to the present shortages. The water shortages decreased to 23.6 × 106 m3 (94.0%) and 43.3 × 106 m3 (91.4%) below of the present shortages by developing irrigation facilities.

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