The researchers used a model called SWAT to estimate surface runoff in a watershed in the Punpun basin near Patna, India. They used remote sensing and GIS data to run the model and validate it with observed runoff from 2005 to 2010. The model showed that surface runoff was highest in 2007 at 710 mm and lowest in 2005 at 185 mm. The model estimates were close to the observed values, differing by about 10 to 11%.