Impact of Land use Land cover change on Storm Runoff Generation: A case study of suburban catchments of Pune, Maharashtra, India

Urbanization has evolved as one of the key factors responsible for the environmental health not only for the urban centres, but also for the suburban regions. In the recent years, most of the suburban regions in India are experiencing flash floods during the high intensity low duration rainfall condition. Such situations of flash floods in the urban and suburban areas are referred to as storm runoff. This paper deals with the computation of storm runoff in the suburban catchments of the Pune City. Five catchments, known for flash floods in the recent years, are identified for the present work. Storm runoff estimations in these catchments have been done using LandsatTM data of 1989 and 2011. Population-calibrated impervious surfaces (IS) were extracted for these catchments, and runoff has been calculated using the Soil Conservation Service-Curve Number method. Major changes in the land use land cover pattern in these 22 years have been detected, with a net growth in built-up area of almost 10 times from 1989 to 2011, leading to the increase in IS in the catchment. The impact of increase in built-up area and IS has augmented storm runoff in the catchment. Estimated runoff values increased from 461.8 m3 to 1068.52 m3 (Baner), 2026.4 m3 to 3638.73 m3 (Kharadi), 2947.5 m3 to 4736.46 m3 (Kondhwa Ghorpadi ), 1021.1 m3 to 2039.57 m3 (Wadgaon Sheri) and 1176.89 m3 to 3691.18 m3 (Wadgaon Budruk) from 1989 to 2011. Thus, it is quite evident that the growth in built-up area and impervious surfaces has enhanced the capacity of suburban basins to generate more runoff.