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20201
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Subject: Irrigation and Drainage Engineering × Author: KAU × End date: 2021 × Start date: 2020 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Flood frequency analysis and modelling of flood using HEC-HMS for a river basin: a case study
    (Department of Irrigation and Drainage Engineering, Kelappaji Collge of Agricultural Engineering and Technology, Tavanur, 2020) Riyola, George; KAU; Asha, Joseph
    Meenachil river basin, located in southern part of Kerala, is an area frequently liable to flood. The area is predominant with agricultural land and falls under the tropical humid zone, where water resources planning and management is necessary for irrigation scheduling, flood control and design of various engineering structures. In view of the importance of water resources management especially in this humid region, it is necessary to understand the rainfall-runoff relationship along with its land characteristics. HEC-HMS model which is widely used rainfall-runoff modelling was chosen for the simulation of watershed responses and generation of flood hydrographs of Meenachil sub basin. The simulated runoff is useful for well-planned programmes in water resource management and future prediction of runoff for flood mitigation strategies in the catchment. Hence, an attempt was made to conduct flood frequency analysis for predicting the magnitude of flood for different return periods and to calibrate and validate the HEC-HMS model for simulating the flood hydrographs of Meenachil sub basin. Flood frequency analysis was carried out using annual maximum discharge data for 34 years (1985-2018) using HEC-SSP software. The HEC-HMS model for the sub basin was developed using SCS-UH, SCS-CN and Muskingum methods to find out the loss rate, runoff transformation and routing of flood respectively. Flood frequency analysis clearly indicated the good capability of the Gumbel and Log-Pearson Type III distribution function to predict flood magnitudes of the river flow in the sub basin of Meenachil River. Test statistic values of Chi-Square and Kolmogorov-Smirnov test showed the best fit of both the distributions for the basin. HEC-HMS model of the sub basin was developed with good accuracy. The performance indices of the model NSE and R² were obtained above 0.7. The Error in Peak Flow and Error in Volume were figured below 20% where as RSR was found 0.5 and below. All these values indicated satisfactory performance of HEC-HMS model simulation both in calibration and validation. The close agreement of simulated stream flow and observed stream flow indicated that the model was able to simulate flood hydrograph and present credible results for the sub basin.