Comparing Water Quantity between Korean and Japanese River

Abstract

To compare water quantity and quality on the Korean and Japanese rivers, two watersheds with similar watershed area were selected. The one from Korea is called the Yongdam dam watershed in the Geum river basin with watershed area of 930 km2, the other from Japan is called the Nakama watershed in the Onga river basin with watershed area of 925 km2. The 3 discharge, 2 water quality stations from Korea and 14 discharge, 2 water quality stations from Japan were selected and analyzed to determine flow durations. Korean data were collected during 2000 to 2013 from water management information system. Japanese rainfall and discharge data were collected during 1980 to 2013 from water information system. Numbers of station–year were 38 on Korea and 436 on Japan. Annual rainfalls were averaged to 1418.1 mm ranged from 778.2 mm to 2061.9 mm on Korea and 1972.5 mm ranged from 845.0 mm to 3623.0 mm on Japan, from which Japanese showed more 1.39 times than Korean. Streamflow data were generated daily by the ONE (One parametric New Exponential) hydrological model. Simulated annual streamflows were averaged to 854.2 mm ranged from 273.6 mm to 1571.4 mm on Korea and 1481.6 mm ranged from 360.6 mm to 3177.4 mm on Japan, from which Japanese showed 1.73 times more than Korean. The flow durations with 10 year frequency were compared, in which the 1st flows were 18.77 mm in Korea and 88.27 mm in Japan, the 95th flows of 0.43 and 3.97, the 185th of 0.13 and 1.92, the 275th of 0.06 and 0.93, and the 355th of 0.05 and 0.30, respectively. Japanese flows were 4 to 15 times more than Korean. On the other hand, mean flow durations showed the 1st flows of 67.11 mm and 88.27, the 95th of 1.58 and 3.97, the 185th of 0.51 and 1.92, the 275th of 0.21 and 0.93, and the 355th of 0.08 and 0.30, respectively. Japanese flows also showed 1.3 to 4.4 times more than Korean. Mean annual runoff ratios were 58.2% ranged from 35.2% to 76.2% on Korean river, and 73.7% from 42.6% to 90.0% on Japanese river. Japanese runoff ratio also showed 1.27 times more than Korean. This result shows some more necessities and difficulties on low flow management in Korean river than in Japanese river