Abstract
This study assesses the future effects of land use and climate (rainfall) changes on river flow regime and subsequent impacts on the water quality in Gin river, Sri Lanka. Future land use in the Gin catchment was predicted using a GIS based statistical regression approach. HadRM3P Regional Climate Modelling system generated the future rainfall for the SRES A2 and SRES A1B emission scenarios. Yamanashi distributed hydrological model (YHyM/BTOPMC) was used to simulate the future hydrological conditions in the basin. Year 2020 total iron load was modeled using a rating curve constructed with the observed relationship between total iron concentration and stream flow. Results indicate that future total iron load would be peaked in June following more pronounced peak flows under SRES A2 scenario compared to the current peak load in October. Due to the future extreme rainfall events, peak total iron load occurrence in Gin river could be increased by about 40%.
