• Journal of Wetlands Research
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• v.25 no.1
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• pp.14-25
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• 2023

Floodplain in a reservoir is defined as the area naturally formed between the design flood level and the normal pool level. Located around the dam reservoir, floodplain has been damaged in many different ways including cultivation. As it is impossible to restore all the damaged floodplain at once, it is necessary to determine their order of priority. This process considers various factors, among which the flooding frequency is an important hydrologic characteristic, Different from the floodplains in a river, all the floodplains around the given dam reservoir have the same flooding frequency. To overcome this problem, this study proposes to use the cumulative flooding area curve, which represents the cumulative flooding area corresponding to the reservoir water level. Especially, this study evaluates the flooding frequency of those water levels corresponding to the cumulative flooding area of 30%, 50% and 70%. As application examples, this study considers the five restoration candidates each selected in the Andong Dam, Imha Dam, Youngju Dam and Nam river Dam of the Nakdong River Basin. As a result, the cumulative flooding area curve was found to well represent the overall shape of the floodplain (i.e., steep-to-mild slope or mild-to-steep slope). Also, the flooding frequency of those water levels corresponding to the cumulative flooding area of 30%, 50% and 70% was found to be so effective to quantify the hydrologic characteristics of a floodplain.