Chrome Publishing Journal of Water Resources and Environment Engineering 2015, Volume 1, Issue 1, pp. 31-38 Assessment of Surface Runoff in a Barinallah Watershed using Distributed Parameter Model (SWAT Model) 1 Department of Water Resources Development and Management, Indian Institute of Technology, Roorkee, Uttarakhand, India 2 Department of HP Irrigation cum Public Health, Himachal Pradesh, India 3 Department of Civil Engineering, Graphic Era University, Dehradun, Uttarakhand, India Publication Date: 1 May 2015 Abstract A study was undertaken to simulate runoff of a small hilly watershed which is located on the western hills in Chamba district, Himachal Pradesh, using Soil and Water Assessment Tool (SWAT) model. The model was calibrated using field-measured discharge data of watershed for two years (2002 to 2003) and validation was performed for the year 2004. The monthly simulated runoff of Barinallah watershed for the calibration and validation periods were found to match with their measured discharge value of coefficient with correlation (R 2 ) in both the cases 0.9385 and 0.9361 respectively. The model simulated daily runoff is corroborated by reasonably high Nash–Sutcliffe simulation coefficients of 0.8958 and 0.8229, high index of agreement (d) of 0.9755 and 0.9600 and low root mean square errors of 0.1477 and 0.2589, respectively for calibration and validation periods. The results of this study indicate efficiency of the model for simulating the runoff is good. 1. Introduction The SWAT (Soil and Water Assessment Tool) is one of the most recent models developed jointly by the United States Department of Agriculture (USDA), Agricultural Service and Agricultural Experiment Station in Temple, Texas. It is a physically based, continuous time, long-term simulation, lumped parameter, deterministic, and originated from agricultural models. The computational components of SWAT can be placed into eight major divisions: hydrology, weather, sedimentation, soil temperature, crop growth, nutrients, pesticides, and agricultural management. The application of ArcSWAT in the present study provides the capabilities to stream line GIS processes tailored towards hydrologic modeling and to automate data entry communication and editing environment between GIS and the hydrologic model. Human activities have a profound impact on the environment. Alteration of the land surface for a variety of uses has changed water pathways and induced changes to natural processes (Starrett and Yunsheng, 2003). The models help in evaluating and selecting the alternative land use and management practices. Implementation of these practices can help to reduce the damaging effects of storm water runoff and the landscape. Developing reliable watershed simulation models and calibrating/validating them for watersheds with measured and simulated data is a challenging issue (Borah et. al., 2002). The increasing rate of water resources development activities have focused attention on development and application of physically based hydrological models to deal with constantly changing hydrological environment. Considering hydrological behavior of the study watershed and applicability of the existing models, the current study was undertaken with the application of SWAT in integration with GIS and remote sensing to estimate the surface runoff for Barinallah watershed located in District Chamba, Himachal Pradesh. The specific objective of the present study is to calibrate and validate the ArcSWAT model for runoff estimation in Barinallah watershed. Authors: 1 Deepak Khare, 2 Rajinder Singh, 3 Nitin Mishra, 1 Rituraj Shukla Correspondence: Nitin Mishra, nitinuag@gmail.com Keywords: SWAT Model; Hilly Watershed; Surface Runoff; Sensitivity Analysis; Model Calibration Research Article