Iso-severity flood hazard patterns in diverse relief and climatic regions to support flood management

Abstract

Floods are one of the most devastating natural events that threaten social and economic conditions more than any other natural disaster. Therefore, the aim of this study was to map the Iso-severity flood patterns and determining the seasonality of flood events over different return periods in in Ardabil province, Iran with diverse relief and climatic regions. Thus, the data of 32 River Gauge Stations (RGS) were used in the spatiotemporal analysis in a 40-year recorded period. EasyFit software was used to determine the most appropriate statistical distribution for the discharge data at 2-, 5-, 10-, 25-, 50- and 100-year return periods. Then, the frequency of monthly and seasonal flood events was quantified in each RGS. Then, the significant trend of flood frequency in each RGS was tested, and the seasonality of flood events was explored. According to the results, it can be said that in the studied RGS, about 63.63% of the floods are occurred in April. On the other hand, the seasonality of flood events showed that the maximum number and percentage of flood events are assigned to spring season over different return periods. As in some stations such as Yamchi, Nouran, Naneh-Karan, Mashiran, Amouqin, Doroud and Pole- Almas, almost 100% of the floods are related to spring and this shows that the floods in Ardabil province are spring floods. Iso-severity flood mapping in different return periods showed that the frequency of floods was higher than the central and northern regions in the southern and highlands of the study area. It is necessary for the southern and Iso-severity flood areas of the province, while conducting the necessary studies, proper planning should be considered with the focus on Integrated Watershed Management (IWM) in order to reduce the flood occurrence in the future and minimize its human and economic losses.