Coupling Remote Sensing and GIS with KINEROS2 Model for Spatially Distributed Runoff Modeling in a Himalayan Watershed

Abstract

Excessive runoff and high soil erosion rate are the critical problems in the Himalayan terrain, mainly due to rugged topography and high intensity rains. Accurate quantification of runoff and erosion is thus of paramount importance for taking appropriate measures to sustain the soil productivity in the Himalayan watersheds. Distributed, process-based hydrological and erosion models are ideal for this purpose. However, model parameterization in the rugged, inaccessible and thus generally a data scarce Himalayan watershed is a major challenge. The present study primarily investigates the applicability of kinematic runoff and erosion model (KINEROS2) model in a Himalayan watershed besides exploring the potential of satellite remote sensing and GIS in spatially distributed runoff modeling. The KINEROS2 model, is an event-based, distributed, water and erosion process model. It discretizes the watershed into a mosaic of planes and channels based on topography. The runoff is estimated for each plane which eventually flows to adjacent channel and is then routed to estimate the total runoff at the watershed outlet. Remote sensing is primarily used for model parameterization, i.e., characterizing the individual planes and channels. Optimized digital elevation model and fine-scale land-use/land-cover information are generated using high-resolution panchromatic and multi-spectral optical and microwave satellite imagery. The resulting data on near-surface soil moisture from radar imagery (ENVISAT ASAR) calibrated the initial soil moisture in the model, whose performance is evaluated using root mean square error and Nash–Sutcliffe that reveals that KINEROS2 model works quite well in a small Himalayan watershed. The sensitivity analysis indicates that saturated soil hydraulic conductivity is the most sensitive parameter influencing the runoff compared to Manning’s coefficient and initial soil moisture. The model output is also used for validating the remote sensing and geographical information system (GIS) based hydrologic response units delineated in a previous research study. The study highlights that the coupling of remote sensing and GIS with process models, such as KINEROS2, can provide valuable information in planning sustainable watershed management practices in the Himalayan watersheds.