Flood Inundation Mapping of Kankai River Basin, Nepal
Date
2020
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Department of Hydrology and Meteorology
Abstract
Flood is growing as major water related hazard in the world. The degree of impairment that
it causes to each and every component goes on increasing with the time. The main objective
of this research is to analyze the flood frequency, prepare inundation map of Kankai river
basin corresponding to different return period, and to identify the hazardous region along the
Kankai river basin. Kankai river basin of 1284 kmĀ² area is selected for the study. Frequency
analysis is done with Gumbel calculation method and HEC-HMS. Flood hazard mapping is
the one of the procedure to find the inundation level. Flood hazard map was prepared by
using the HEC-RAS 5.0.7 with integration of ArcGIS 10.1 and its extension HEC-GeoRAS.
ASTER DEM of 20*20 spatial resolution was used for the research. The discharge data we
have used is validated with the discharge data we have measured in the study area. The
discharge value was seen to be simultaneously increasing with the return period of 2, 10, 50,
100, 200, 500, 1000 years. The magnitude of flood depth increased with the increasing return
period. The number of household inundated corresponding to the return period is also
calculated. The maximum depth of inundation we obtained was 6.46m, which was of 1000
year return period and along the chure range where the cross-section is shorter and depth is
greater and going downward the depth of inundation decreases. The depth is categorized as
high risk, medium risk and low risk based on DHM reference for Kankai river. Inundation
of area of settelements indicates that in future human lives are more prone to flood disaster.
Thus, the study may help in future planning and management for future probable disaster.
Description
Keywords
Flood Inundation, hazard,, HEC-RAS, HEC-GeoRAS