采用修正通用土壤流失方程(revised universal soil loss equation,RUSLE)对三江源区1997-2012年的土壤侵蚀模数和土壤侵蚀量进行定量模拟,并对其生态工程实施前、后时空变化特征进行对比分析,采用空间叠加法分析降雨侵蚀力及植被覆盖度对土壤侵蚀状况的影响,利用模型参数控制法对气候变化和生态工程对土壤侵蚀变化的贡献率进行分析。结果表明:1)生态工程实施后,三江源区土壤侵蚀增加的趋势尚未得到遏制,多年平均年土壤侵蚀模数和侵蚀量较工程实施前增加6.5%,但局部地区土壤侵蚀状况有所好转,约占总面积的45%;2)长江流域在工程实施后的土壤侵蚀量与工程实施前基本持衡;黄河流域土壤侵蚀量增加明显,增幅超过45%;澜沧江流域土壤侵蚀量有所下降,降幅为9.8%;3)降水增强导致土壤侵蚀加剧的贡献率达到180%,植被恢复对土壤侵蚀变化的贡献率为-80%。全面遏制三江源区土壤侵蚀增加趋势,仍需持续努力。
英文摘要:
In this study,the annual soil erosion modulus and amount of soil loss during 1997to 2012in the Three-River Headwaters region were calculated using the revised universal soil loss equation(RUSLE),and the spatial and temporal dynamics of soil erosion after the first stage of ecological conservation and restoration project were compared and analyzed.The impacts of rainfall erosivity and fractional vegetation coverage on soil erosion were analyzed using the spatial overlay tool in ArcGIS,and contribution rates of ecological projects and climate change were measured using the model variable control method.The results showed that:1)The conservation and restoration projects did not curb the trend of increased soil erosion.During 1997to 2012,total soil erosion increased by 6.5%,although soil erosion decreased in nearly 45%of the total area.2)Among the three main watersheds,the Yangtze River watershed showed the smallest change in soil erosion.Soil erosion increased by 45%in the Yellow River watershed,and decreased by 9.8%in the Lancang River watershed.3) The continuous increase in precipitation was the main reason for the increase in soil erosion(contribution rate, 180%),while the increase in fractional vegetation coverage reduced soil erosion by 80%.Persistent efforts are required to curb the trend of increasing soil erosion in the Three-River Headwaters Region.