Projection of future climate change impacts on nonpoint source pollution loads for a forest dominant dam watershed by reflecting future vegetation canopy in a Soil and Water Assessment Tool model

摘要

This study is to assess the future impact of climate change on hydrological behavior consideringnfuture vegetation canopy prediction and its propagation to nonpoint source pollution (NPS) loads.nThe SWAT (Soil and Water Assessment Tool) model was used for the assessment. For a forestndominant ChungjuDam watershed of South Korea, the MIROC3.2hires climate data of SRES A1Bnand B1 scenarios were adopted and downscaled for the watershed. The future vegetationncanopy information was projected by the monthly relationship between Terra MODISn(MODerate resolution Imaging Spectroradiometer) LAI (Leaf Area Index) and temperature. Thenfuture predicted LAI increased up to 1.9 in 2080s April and October because of the temperaturenincrease 3.68C and 5.38C respectively. By reflecting the future LAI changes, the future estimatednpercent changes of maximum annual dam inflow, SS, T-N, and T-P were + 42.5% in 2080snA1B, 2 35.6% in 2020s A1B,+73.7% in 2080s A1B and 2 21.0% in 2080s B1 scenario respectively.nThe increase of T-N load was from the increase of subsurface lateral flows and the groundwaternrecharges by the future rainfall increase. The decrease of T-P load was by decrease of sedimentnload during wet days because the effect of LAI increase is greater than the increase of rainfall.