Influence of Spatial Urbanization on Hydrological Components of the Upper Ganga River Basin, India

Abstract

The waterscape of the Upper Ganga river basin has reconfigured over the last few decades due to rapid population growth, urbanization, and industrialization. It has resulted in altered regional hydrology and water quality of the river basin. In this study, the Soil and Water Assessment Tool (SWAT) hydrological model was used to investigate the effects of spatial urbanization on key hydrological components of the study region. Time series of Land Use and Land Cover (LULC) maps of 1980, 2001, and 2012 were prepared using the object-based image analysis (OBIA) approach. To understand the existing interrelationships between urbanization and key hydrological variables, multivariate analysis of variance (MANOVA) and correlation statistical analyses were carried out between urbanization indicators [spatial urbanization level (Us) and population urbanization level (Up)] and hydrological parameters. Results revealed that from 1980 to 2012, an increase in the water yield was observed from 433.6 to 572.7 mm [standard deviation (σ) = 69.8; sum of squares (SS) = 9,740.6], and the annual average surface runoff increased from 80.7 to 149 mm [σ = 34.8; SS = 2,425.4], however, evapotranspiration (ET) decreased from 790.9 to 675 mm [σ = 63.2; SS = 7,986.6] in the river basin, corresponding to an increase in Us from 0.36 to 2.07. An increase in urbanization had a high influence on these hydrological parameters.