Assessment of the Spatiotemporal Effects of Land Use Changes on Runoff and Nitrate Loads in the Talar River.

This research surveyed the effects of land use changes on flow nitrate pollution in the Talar River (northern Iran), using Landsat images of 1991 and 2013 and the Soil and Water Assessment Tool (SWAT). The results indicated that forest areas decreased by 14.9% and irrigated crops, dry land farming areas, range lands and residential areas increased by 46.8%, 31.1%, 4.7% and 17.5%, respectively. To calibrate and validate the studied period, the Nash Sutcliffe model efficiency (NSE) and coefficient of determination (<italic>R</italic>²) were applied, ranging from 0.57 to 0.75 and from 0.62 to 0.76 for flow simulation and 0.84 and 0.63 and 0.75 and 0.83 for nitrate simulation, respectively. The results of land use scenarios indicated that respective water flow and nitrate loads increased by 34.4% and 42.2% in 1991–2013 and may even increase by 42.3% and 55.9% in the simulated period of 2013–2050 in all sub-basins. It is likely that the main reason for these results was due to the increase in agricultural activities and the decrease in forestry areas. Our findings showed the useful combination of modelling techniques (land cover changes and SWAT) to develop valuable maps able to design correct land management plans and nature-based solutions for water quality of runoff water harvesting systems in the future. [ABSTRACT FROM AUTHOR]