Application of HEC-RAS (2D) for Flood Hazard Maps Generation for Yesil (Ishim) River in Kazakhstan

Nurlan Ongdas,Farida Akiyanova,Yergali Karakulov,Altynay Muratbayeva,Nurlybek Zinabdin

doi:10.3390/w12102672

Abstract

The use of hydraulic models for carrying out flood simulations is a common practice globally. The current study used HEC-RAS (2D) in order to simulate different flood scenarios on the River Yesil (Ishim). Comparison of different mesh sizes (25, 50 and 75 m) indicated no significant difference in model performance. However, a significant difference was observed in simulation time. In addition, the inclusion of breaklines showed that there was a slight improvement in model performance and a shortening of the simulation time. Sensitivity analysis and the consequent manual calibration of sensitive parameters resulted in a slight improvement (an increase in the model accuracy from 58.4% for uncalibrated to 59.7% for calibrated). Following the simulations inundation maps for 10-, 20- and 100-year flood events were obtained. Hazard classification of the flood extents generated indicated that the settlements of Zhibek Zholy and Arnasay were flooded in all the simulated events. Volgodonovka village experienced flooding when a 100-year flood event was simulated. On the other hand, settlement No. 42 did not experience any flooding in any of the scenarios. The model results also demonstrate that the Counter-Regulator was not overtopped in the event of the 100-year hydrograph.

Highlights

Flooding is a common natural disaster with a devastating and widespread effect responsible for economic losses and mortality [1,2]
There was no significant difference in inundation extent for high hazard class
If 10 and 20 year events resulted in larger area under medium hazard class than the 100 year flood event, in terms of medium hazard class an opposite trend was observed. 10 and 20 year events resulted in similar flood inundation areas for all the classes, except catastrophic class

Summary

Introduction

Flooding is a common natural disaster with a devastating and widespread effect responsible for economic losses and mortality [1,2]. This natural hazard is reported to comprise a significant proportion of the total number of reported natural disasters around the globe [1]. It is a problem for developing countries, and for developed countries.

Methods

Results

Discussion

Conclusion