Abstract
Changes in non‐point source pollutant loads in the Mankyeong River Basin for the 30‐year future period (2011–2040) were assessed with consideration of the uncertainties in the climate change scenario data. The downscaled weather variables from eleven Climate Models for the Representative Concentration Pathways (RCP) 8.5 scenario were used as input to the calibrated and validated Soil and Water Assessment Tool (SWAT) model for simulating the changes of future NPS pollutant loads. The bias‐corrected data appropriately reproduced the spatial and temporal patterns of the NPS pollutant load, which was derived by using observed weather data. The rates of change in sediment, total nitrogen (TN) and total phosphorus (TP) loads within each sub‐basin under the RCP8.5 future scenario showed an average increase of 13.1 to 143%, −13.4 to 49.5%, and 0.40 to 128%, respectively. It can be concluded that sediment and TP loads are sensitive to changes in the characteristics of climate variables by showing an increase trend in most of the sub‐basins. Looking at the temporal distribution, the uncertainty ranges for both sediment and TP were higher during the wet season from June to September. Copyright © 2016 John Wiley & Sons, Ltd.