Zoning of Critical Hubs of Climate Change (Flood-Drought) Using the Hydrologic Engineering Center-Hydrologic Modeling System and Copula Functions Case study: Khorramabad Basin

Abstract

Climate change is currently the major challenge facing mankind, and this crisis has been the topmost global issue due to the increasing role of human activities and the high sensitivity of human societies to the threats caused by these changes. The climate changes created for humans and nature have led to risks and threats that occur on different spatial and temporal scales. Therefore, adopting policies to deal with climate change will be a critical issue in risk management. Nonetheless, identifying critical hubs in the study area helps improve the risk management process in the ​​risk assessment of climate change consequences, such as floods and droughts. Accordingly, this study mainly aimed to identify such points in the study area according to this principle. As with other parts of the world, the Khorramabad Basin (Lorestan province, Iran) is prone to serious risks in terms of climate change. This area is located as a Class III sub-basin in the Class II Karkheh basin and the Class I basin of the Persian Gulf and the Sea of ​​Oman. In this study, the critical hubs of the desired watershed were identified using the HEC-HMS rainfall simulation model to prioritize the flood-prone sub-basins of the Khorramabad Basin. The sub-basins with a high drought risk were prioritized with the detailed function (copula) statistical method. An important point in this evaluation is the use of Global Precipitation Measurement (GPM) precipitation data as common data in the analyses made in the flood and drought sections. The return rate was also calculated in both methods. The model implementation and statistical analysis revealed that the highest probability of flood occurrence belonged to the flooded part of W990, W1140, and W710 sub-basins, with respective flow volumes and maximum flow rates of 5140.8364 mm and 1389.276 m3/s, 539.0018 mm and 383.838 m3/s, and 466.8089 mm and 1561.104 m3/s, based on the flow volume in all the estimated return periods. In the drought section, the sub-basins W1070, W730, and W610 would be the most critical hubs in terms of drought probability, with return periods of 1.1578, 1.1923, and 1.1976 years, respectively.