Development of a diffusive wave flood routing model for an ungauged basin: a case study in Kulsi River Basin, India

Flood is the most devastating and frequent disaster in North-East India, resulting in loss of human life and damage of properties. Its deleterious effects can be minimized by appropriate modeling, analysis, and management methods. Such modeling and analyzing techniques are hindered in flood prediction in an ungauged basin due to the lack of hydro-meteorological data. The main objective of this work is to develop a numerical approach for flood routing in an ungauged basin using the rainfall-runoff model and the diffusive wave flood routing model (DWFRM). GIS approach is used to extract the geographical information of the study area. The SCS-CN rainfall-runoff model is employed to obtain the inflow, and lateral inflow hydrographs of the ungauged sub-basins and DWFRM is employed to anticipate the flood hydrograph at the outlet of the ungauged basin. A new form of diffusive wave momentum equation of the Saint-Venant equation is derived for cross-section having a parabolic and rectangular channel. The modeling approach is employed to the Kulsi River Basin, India hypothetically considered ungauged basin, and the results obtained are compared with the observed data at the outlet of the basin. The performance of the model is validated by considering four parameters RMSE, peak flow error, peak time error, and total volume error. The results reveal that the proposed model diffusive wave flood routing model (DWFRM) is efficient to predict the flood hydrograph at the outlet of an ungauged basin.