气候变迁情境下土壤冲蚀可能变化

降雨是导致土壤冲蚀的主要原因,而通用土壤流失公式(USLE)为目前世界上应用最广泛的土壤流失模式,式中之降雨冲蚀指数直接反映了降雨对土壤侵蚀的程度,为评估土壤侵蚀状况的重要因子之一.研究以基隆、新竹、嘉义、高雄、宜兰、花莲、台东等雨量测站资料之历年雨量记录建立各月之降雨冲蚀指数,所采用之记录为1975-2000年之降雨资料,并建立月降雨冲蚀指数及月降雨量关系式.由于气候变迁导致的降雨变化将影响土壤冲蚀之估算,而不同时间之雨量资料所推估的降雨冲蚀指数精度不同,又必须配合气候变迁模拟之时间尺度,故本研究以月雨量及月降雨冲蚀指数为基础探讨之.采用IPCC公告之B2情境下的大气环流模型(GCMs)模拟基隆、新竹、嘉义、高雄、宜兰、花莲、台东等测站未来降尺度月雨量变化.推估基隆、新竹、嘉义、高雄、宜兰、花莲、台东等测站未来短期、中期、长期之月降雨冲蚀指数,以供推估土壤流失量,可以发现各模型之平均值未来土壤冲蚀量在B2情境约-80%～+60%.

Soil Erosion Variation Under Climate Change Scenarios

Rainfall is the main factor resulting in soil erosion. USLE is the most commonly used formula to estimate soil erosion in the world. The rainfall erosion index is one of the most important factors which directly reacts the degree of soil erosion. The rainfall records (from 1975 to 2000) of Keelung, Hsinchu,Chiayi, Kaohsiung, Ilan, Hualien and Taitung released by Central Weather Bureau were used in this study to establish the relationship between the monthly rainfall erosion index and monthly rainfall amount. Because the precision of rainfall erosion index estimated by the rainfall data from different timescales is different, and moreover the timescale of GCMs has to be considered. In this study, we use GCMs of the downscaling monthly rainfall data simulated by GCMs under B2 scenario issued by IPCC to estimate the shortterm, medium-term and long-term monthly rainfall erosion index in the future of Keelung, Hsinchu,Chiayi, Kaohsiung, Ilan, Hualien and Taitung released by Central Weather Bureau, and to estimate soil loss variation. The results show that the soil erosion ranges of average variation from different models are -80%～+60% in B2 scenario.