Dilemma of a small dam with large basin area under climate change condition

초록

Problems of under-sized dams (small dams with large basin area) could get worse under the global warming condition. This study evaluates the possible change of these problems with the Namgang Dam an under-sized dam in Korea. For this purpose first this study simulates the dam inflow data using a rainfall-runoff model which are then used as input for the reservoir operation. As a result daily dam storage dam release and dam water supply are derived and compared for both past observed period (1973~2022) and future simulated period (2006~2099) based on the global warming scenarios. Summarizing the results are as follows. First the inflow rate in the future is expected to be increased significantly. The maximum inflow could be twice of that observed in the past. As a result it is also expected that the frequency of the water level reaching the high level is increasing. Also the amount and frequency of dam release are to be increased in the future period. More seriously this increase is expected to be concentrated on rather extreme cases with large dam release volume. Simply the condition for flood protection in the downstream of the Namgang Dam is becoming worse and worse. Ironically the severity of water shortage problem is also expected to become much worse. As the most extreme case the frequency of no water supply was zero in the observed period but in the future period it becomes once every five years. Both the maximum consecutive shortage days and the total shortage volume are expected to become more than twice in the future period. To prevent or mitigate this coming problem of an under-sized dam the only countermeasure at this moment seems to be its redevelopment. Simply a bigger dam with larger dam reservoir can handle this adverse effect more easily. © 2024 Techno-Press. All rights reserved.

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