Floods have various impacts, including loss of life and damage to property. Flood- management reservoirs can help mitigate floods, but their operation can also worsen flood impacts. This paper presents a novel forensic engineering approach to assess the role of reservoir operation on flood control. Fourteen criteria are employed for assessing forecast-based prereleases of water from reservoir storage to reduce the impact of flooding. The proposed approach is applied for forensic assessment of the system performance of reservoirs during the large flood of 2019 in southwestern Iran (the Great Karun Basin). The two main study areas are in the sub-basins of Karun and Dez. Results concerning two key performance criteria (the peak discharge reduction (PDR) and flood volume reduction (FVR)) show the PDR criterion in the Karun sub-basin multi-reservoir system reached about 79% (where 100% is the theoretically best performance) under historic operations (actual operating conditions in 2019), and improved from 8 to 19% if various prerelease operations were made. The FVR achieved about 33% in the historical situation and improved from 20 to 59% under prerelease operations scenarios, respectively. The PDR criterion achieved 26% under the historical scenario, but with better operation could exceed 55% in the Dez sub-basin multi-reservoir system, whereas FVR was as low as 11% in 2019 but could be raised to between 15 and 25% under prerelease operations. This forensic work’s assessments establish that improved reservoir operation could be achieved by applying specialized operation approaches.

洪水有各种影响，包括生命损失和财产损失。防洪水库可以帮助减轻洪灾，但其运营也会加剧洪灾影响。本文提出了一种新颖的法医工程方法，以评估水库运行在防洪中的作用。使用十四个标准来评估基于预测的水库蓄水的预释放量，以减少洪水的影响。拟议的方法适用于在伊朗西南部（大卡伦盆地）2019年大洪水期间对水库系统性能进行法医评估。两个主要研究领域位于Karun和Dez的子流域。有关两个关键性能指标（峰值流量减少量（PDR）和洪水流量减少量（FVR））的结果表明，卡伦次流域多水库系统中的PDR标准达到了约79％（其中100％是理论上的最佳性能）在历史操作（2019年的实际操作条件）下，如果进行了各种预发行操作，则从8％提高到19％。在历史情况下，FVR达到了约33％，在预发行操作方案下从20％提高到59％。在历史情景下，PDR标准达到了26％，但在Dez子盆地多水库系统中，更好的运行可能超过55％，而FVR在2019年低至11％，但可能提高到15％至25％在预发行操作下。