Flood Risk Analysis: The Case of Tigris River (Tikrit /Iraq)

Abstract

The study of flood risks has a fundamental role in ensuring the safety of cities near rivers and drawing up plans to protect them during future floods. This study aims to manage potential flood risks, and Tikrit city was used as a case study. The daily discharge of the Tigris River in the study area was provided by the Iraqi Ministry of Water Resources from 2019 to 2022. The HEC-RAS software was utilized to build a 2-D flood model to simulate potential flood scenarios. First, the model was calibrated by adjusting the value of Manning's coefficient (n), and it was found that n = 0.031 reflects the nature of the region because the Nash-Sutcliff Error (NSE) was 0.93. Then, the efficiency of the 2-D flood model was verified by comparing the model’s results with the study area’s satellite images, and the results showed a great match. Following that, the 2-D model was used under different flooding scenarios. The results showed that the size of areas exposed to flooding increased with the discharges passing through the Tigris River. For instance, increasing the discharge to 800m3/s increased the flooded areas by 13.7%, while increasing the discharge to 1500 m3/s increased the flooded areas by 90.7 % compared to the river’s normal flow. Also, the results showed that the eastern regions of the riverbanks are more vulnerable to flooding than the western side because the ground levels are low on the eastern side compared to the western part of the riverbanks.