Evaluation of Supplying Instream Flow by Operation Rule Curve for Heightening Irrigation Reservoir

Abstract

Baekgog reservoir is located in Jincheon county, Chungbuk province, of which full water levels will be heightened from EL. 100.1 m to EL. 102.1 m, and total storages from 21.75 Mm 3 to 26.67 Mm 3 . The simulation for reservoir inflow was conducted by DAWAST model. The annual average irrigation water was estimated to 33.19 Mm 3 supplied to 2,975 ha and the instream flows could be allocated with 0.14 mm/d from October to April w ith annual average of 2.52 Mm 3 . The operation rule curve was drawn using inflow, irrigation, and instream flow requirements data. The reservoir water storage was simulated on a daily basis in case of both normal and withdrawal limit operation. In case of normal operation, the annual average irrigation water supply increased from 31.95 Mm 3 to 33.32 Mm 3 , the instream water supply from 2.40 Mm 3 to 2.44 Mm 3 , the water storages from 15.74 Mm 3 to 19.88 Mm 3 , and the water supply reliability from 77.3 % to 81.6 %. In case of operation with withdrawal limit, the amount of instream water supply was 2.52 Mm 3 from reservoir regardless of the condition while the water storage increased from 16.77 Mm 3 to 20.65 Mm 3 . The irrigation water supply capacity was appropriate for the case of normal operation with 2 m heightened condition. The present instream water supply capacity was 35,000 m 3 /d (6.86 Mm 3 /y) while 42,000 m 3 /d (8.36 Mm 3 /y) in 2 m heightened condition in case of withdrawal limit operation.