Geo-spatial Approach for Estimation of Precipitation over the Upper Ganga River Basin (UGRB), Uttarakhand, India

Background: Estimation of precipitation over hilly terrain is challenging due to its complex topography and uncertain climatic conditions. In this paper an attempt has been made to understand the potential of Remote Sensing (RS) and Geographical Information System (GIS) in estimating the precipitation over a hilly river basin of India. Methods: Precipitation data is derived from TRMM (Tropical Rainfall Measuring Mission) in Upper Ganga river basin. It is further compared and validated with ground based gauge rainfall data using following 4 statistical keys: Average Percentage Error (Avg. % Error), Root Mean Square Error (RMSE), Correlation Coefficient (r) and Mean Square Error (MSE). GIS technique is utilized to relate the three-dimensional distribution of TRMM precipitation with observed monthly precipitation products (isohyets) for rainy season. Finding: The findings have shown that TRMM sensors provide reliable information on precipitation with good accuracy for Himalayan river basins. The Correlation Coefficient (CC) is found 0.99 for the 4 rain stations. A very good agreement in addition to strong relationship is seen between the TRMM monthly precipitation and observed precipitation products. There are several studies done to validate the performance of TRMM over plain areas but for hilly Himalayan river basins more such studies are required. Application: For hilly areas where rain gauge stations are sparse, the TRMM provides reliable information on precipitation with acceptable accuracy. Therefore, the TRMM derived precipitation information can be used for various studies and applications such as disaster management,weather forecasting, environmental monitoring, water resources management etc.