ASSESSMENT OF CLIMATE CHANGE IMPACT ON THE INFLOW AND OUTFLOW OF TWO AGRICULTURAL RESERVOIRS IN KOREA

This study assessed the impact of potential future climate change on the inflow to all agricultural reservoir and its downstream streamflow front reservoir operation for paddy irrigation using SLURP (semi-distributed land use-based runoff process), a physically based hydrological model. For a 366.5 km(2) watershed that includes two agricultural reservoirs located in the tipper middle part of South Korea, the SLURP model was calibrated using six years (1998-2003) of daily streamflow records and validated using three years (2004-2006) of streamflow data, before the future analysis. The CCCma CGCM2 data of the SRES (special report on emissions scenarios) A2 and B2 scenarios of the IPCC (Intergovernmental Panel oil Climate Change) was adopted for the future climate condition, and then the change factor method was used to downscale the future weather data through bias-correction. In addition, the future land covers were predicted with a modified CA (cellular automata)-Markov technique using a time series of Landsat land cover data, and the future vegetation information was predicted by linear regression between the monthly NDVI (normalized difference vegetation index) front NOAA AVHRR (advanced very high resolution radiometer) images and the monthly mean temperature data. The results for the future impact oil reservoir storage showed that it would not have recovered to 100% by the end of the year (December) because of a decrease in precipitation and all increase in evaporation from July to September Therefore, this reduced reservoir storage could bring a spring drought that causes all insufficient guarantee of water for rice paddy transplanting at the end of May The future impact on the monthly streamflow of the watershed showed that the future streamflow for the three months of April, May, and June would increase because of a future increase in precipitation, and that the future streamflow for the next three months (July, August, and September) would decrease because of a future decrease in precipitation and increase in temperature. Considering the future decrease in the summer and autumn streamflows, the reservoir operation has to be more conservative when supplying water for paddy irrigation during this period and in the decision making process for reservoir releases during storm events.