Flood damage assessment using HEC-FDA software in shoor watershed, Esfahan, Iran

Abstract

Flood damage assessment is essential for the economic analysis of flood risk management in municipal and agricultural areas. In order to develop effective flood risk management plans, it is essential to have reliable flood damage models. This study aims to assess the economic losses caused by flood in the Shoor watershed, Esfahan, Iran, in April 2019. A digital elevation model (DEM) with a resolution of 1:1000 has been used to generate the river geometric cross-sections in HEC-GeoRAS software, and the inundation maps and vulnerable areas were specified by HEC-RAS software. Based on the results of this step, the HEC-FDA software has been employed to assess agricultural and municipal financial damage. The Monte-Carlo method was utilized to estimate Expected Annual Damage (EAD) based on vulnerability curves. Although HEC-FDA is primarily developed for estimating municipal damage, it was used to assess damage to agriculture indirectly by incorporating agricultural characteristics into the software. Results indicate that in the Shoor watershed, total losses were estimated about $517.800 in April 2019, mainly in agricultural classes. In this regard, the Damage-Reach No. 7 (D.R.7) experienced the highest economic losses with approximately about $317.000, while D.R.6 had the lowest amount of economic losses, with only about $16.900. These results show 84% compliance and correctness of our study results with the amount of damage caused by this flood in April 2019, which was about $440,000. Also, the results showed that discharge estimation with different return periods by HEC-FDA has high accuracy and is within the range of 5 to 95% confidence interval. Therefore, this watershed is relatively affected by floods and has noticeable economic losses. This study also could be beneficial for decision-makers in making decisions in flood management and reducing flood economic losses.