Quantification and mapping of hydrological services of a Himalayan watershed using geo-spatial approach

Abstract:

Himalayan ecosystem provides a vast array of goods and services to more than half of the world’s population. Along with provisioning and cultural services, the Himalayan watersheds deliver colossal amount of regulating services. Quantification of services can help to recognize their value which facilitates conservation planning and sustainable use of natural resources. As the services are result of complex interaction of ecosystem processes, their proxy- or indicator based assessments are preferred. The present study is an approach to quantify and map different indicators of hydrological services (HS) viz. soil water content, surface runoff, actual evapotranspiration, and soil loss, ground water content and environmental loss of Bausan watershed part of upper Yamuna basin of Indian Himalayan region. It was performed by calculating water balance equation from Soil and water assessment tool (SWAT) under geospatial environment. Model calibration and validation was performed with 22 hydrological parameters using semi-automated Sequential Uncertainty Fitting Algorithm (SUFI-2) of SWAT calibration and Uncertainty program (SWATCUP). The overall model simulation was performed for the year 2005 to 2015. The model was calibrated against station observed stream flow discharge for year 2005 to 2011 and validated from 2012 to 2015 at two hydrological station site viz. Naugaon and Bausan. Model performance was evaluated using multiple statistical parameters. For calibration at Naugaon site, satisfactory p-factor and r-factor of 0.52 and 0.81 was obtained whereas they were 0.72 and 0.61 for Bausan site. The value of R²=0.79 and 0.68, and the Nash Sutcliff Efficiency (NSE) of 0.61 and 0.50 for calibration and validation period at Naugaon site. However, a slightly improved model performance with R2=0.85 and 0.82 and, NSE=0.81 and 0.78 for calibration and validation period was observed at Bausan respectively. Calibrated SWAT model was then used to map the indicators of HS for the watershed studied.