Hydro-Meteorological Study of Dudhkoshi Basin with Frequency Analysis and Flood Forecasting using HEC-HMS Model
Date
2015
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Department of Hydrology and Meteorology
Abstract
Many rivers in Nepal are either ungauged or poorly gauged due to complex terrains, extreme
monsoon climate and lack of technical and financial capabilities. In this context, the role of
hydrological models are extremely useful. A model, once calibrated and verified on catchments,
provides a multi-purpose tool for further analysis. Hydrological simulation methods are relatively
simple and reasonably accurate in practical applications.
The study was carried out in DudhKoshi River basin, Nepal. Long term hydrology, Flood
frequency analysis using statistical approach and Regional Climate Model (RCM) were used to
determine the characteristics of high flow events in the basin. High flow events are a key
component in river engineering, for the design and risk assessment of various projects. In case of
ungauged basin where no historical data are available, regional flood frequency analysis is
considered as a viable means to approximate at-site flood characteristics by exploiting the
information available at neighboring sites.
This research investigates the potential changes on discharge and flood events in future in
DudhKoshi Basin. For this study, a lumped hydrological model developed in HEC-HMS 4.0 is
implemented over the study area (3849 km
2
), calibrated and validated at a daily time step, fed by
ground observations and using the future decadal climate data obtained from the RCM named
Providing Regional Climates for Impact Studies (PRECIS). The result shows that HEC-HMS has
the best fit among the methods used. The simulation depicts a univocal increasing trend of
discharge for middle centuries (2030-2060) indicating the possibility of increased frequency and
intensity of floods.
It is suggested that the calibrated model then can be used as a decision support tool in the operation
and management of DudhKoshi Dam Reservoir. Hence, Hydrological modeling is a powerful
technique in the planning and development of integrated approach for management of water
resources.
Description
Keywords
Frequency analysis, HEC-HMS, Flood forecast