Integrated Hydrologic and Hydraulic Flood Modelling for a Scarcely Gauged Inter-Montane Basin: a Case Study of Jhelum Basin in Kashmir Valley

The present study was undertaken to simulate floods in the complex terrain of inter-montane Jhelum Basin in Kashmir Valley using an integrated hydrological and hydrodynamic modelling approach. A conceptual hydrological model MIKE 11 NAM was calibrated and validated for rainfall-runoff simulations. MIKE 11-HD was used for the simulation of the unsteady flow of river Jhelum and its tributaries. MIKE 11 NAM model was calibrated using daily precipitation, evaporation, temperature and discharge data from 1985 to 2005. The model was then validated by calculating the daily discharge values for the next nine years. Model performance was judged based on the coefficient of determination (R2) and Nash–Sutcliffe Efficiency (NSE). The results exhibited that the integrated model can simulate the rainfall-runoff processes in the basin and route the discharge through the main river channel and its tributaries (Calibration: R2 = 0.78, NSE = 0.76 and Validation: R2 = 0.81, NSE = 0.80) at daily time-scales. The model also performed suitably well in simulating peak and low flows at a daily time scale. Sensitivity analysis showed that the Coefficient of Overland flow (CQOF) was the most sensitive parameter affecting model efficiency and peak and low flows. The developed model can be used to design hydraulic structures, prepare floodplain inundation maps, and develop a flood forecasting system.