Calculation of the Spatial Flooding Intensity with Unit Flood Response Method in the Tangrah Watershed, Iran

Abstract

Increased flooding in recent years indicates that most parts of the country are subjected to periodic and destructive flood attacks. Therefore, the identification of high-risk areas with potential runoff production within a watershed area is one of the most important measures in flood control and reduction of the damage caused by it. In this study, the quasi-distributional ModClark method was employed to simulate the hydrograph of flooding, and the unit flood response method was applied to determine the intensity of flooding of different areas of the Tangrah watershed, Iran. For this purpose, the ModClark model was first calibrated and verified. Thereafter, the design of rainfall with 50 and 100-year return periods (T r ) was extracted at the Tangrah station and the design flood was calculated with the above-mentioned return periods. By combining the curve number layers, slope, precipitation, and flow distance, homogeneous units were obtained in terms of the flood. The effect of each homogeneous unit on the total watershed output was obtained by the removal of each unit and implementation of the rainfall-runoff model. According to the 100-year return runoff production potential, homogeneous units of 116 with a fi (0.54 m 3 / s. km 2 ) were identified as the most effective cell in the Tangrah watershed area, which could be explained by the soil type, vegetation, and other physical factors of these units.

Intercomparison of Rainfall Estimates of Three Distributions for Computation of PFD using Rational Formula and SUH Approach

“…Kumari and Goel (2015) adopted the SUH approach for flood estimation for rivers of Saurashtra Region contributing into Gulf of Khambhat. Gharib et al (2017) made an attempt to simulate the flood hydrograph of Tangrah catchment, a tributary of Madarsoo basin in Golestan province in northeastern Iran through semi-distributed version of the modified Clark method. Kim and Mun-Ju Shin (2018) developed the relationship between the parameters such as runoff coefficient, intensity of rainfall and curve number, and then utilized the relationship to calculate the peak flow using the rational formula for ungauged catchments.…”

River Flood Modelling For Flooding Risk Mitigation in Iraq

“…Although Iraq is a developing country, where statistics and data are rarely available, there are some convenient flood models which can solve these constraints [18]. For instance, Gharib et al (2017) [15] and Patel & Joshi (2017) [17] showed in their studies that the lack of availability of data can be avoided by adopting computer software for flooding simulation. For examples, GIS, Global Mapper, Artificial Neural Network (ANN), and rainfall-runoff modelling that can be used in specifically in developing countries, due to its simplicity and efficiency.…”