Flood Inundation Mapping Using HAND (A Case Study of Kashkan River, Western Iran)

Floods pose significant risks as natural disasters on a global scale.In addition to climate change, anthropogenic activities have exacerbated the damaging effects of flooding over the past decade.Findings indicate that over 91 billion hectares of land in Iran are susceptible to flooding.Extensive hydrologic records reveal a total of 467 flooding events in the country up until 2002, contributing to a loss of 630 lives between 1982 and 1992.These alarming statistics underscore the necessity of studying and analyzing floods, as well as mapping inundation areas, in order to mitigate potential damage associated with future flooding events.One particular region in western Iran that has been heavily affected by recurring floods is the Kashkan River.This river traverses numerous urban and rural areas that are prone to annual flooding.Although various methodologies exist to investigate floods and identify areas susceptible to inundation, many of these approaches require data that may not be readily accessible.Consequently, this study employs the Height Above the Nearest Drainage (HAND) model to examine the flood-prone sections along the Kashkan River.Unlike other methods, the HAND model solely relies on a Digital Elevation Model (DEM), making it a promising and accurate technique for mapping inundation areas.By utilizing the HAND model, this research aims to identify specific sections of the Kashkan River that are prone to flooding.The findings of this study will contribute to a better understanding of flood dynamics in the region, enabling the development of effective strategies to minimize potential damage. -MethodologyIn order to examine the areas that are prone to flooding, we employed the Height Above Nearest Drainage (HAND) model.This model was originally introduced by Rennó et al. ( 2008) and operates by utilizing a Digital Elevation Model (DEM) to compute the distance between a grid-cell within the topography data and the nearest cell along the stream it drains into.By considering cells with HAND values below a specific threshold as inundated, we can identify areas that are susceptible to flooding.Notably, the HAND model offers the advantage of being raster-based, eliminating the need for the construction of cross-sections, which is a requirement for alternative techniques like HEC-RAS.For our investigation, we employed the Shuttle Radar Topography Mission (SRTM) DEM, which possesses a resolution of 30 meters.To validate the findings obtained from the HAND model, we employed flood maps generated from Sentinel-1 Synthetic Aperture Radar (SAR) data from March 2019.These flood maps were created using the Sentinel Application Platform (SNAP) software and the