随着气候变化和人类活动对流域水沙的影响愈加剧烈，关注流域输沙变化趋势、合理调控水沙是保护生态系统、实现可持续发展面临的必要而现实的课题。我国外流河流域占国土面积的64%，流域输沙量变化剧烈。本研究在分析中国松花江、辽河、海河、黄河、淮河、长江、钱塘江、闽江和珠江九个典型流域1980-2015年输沙量与流域环境变化的基础上，识别影响不同空间尺度流域输沙量的关键环境因子，构建输沙量模型，分析流域输沙量对气候变化和人类活动的响应敏感度。并结合未来气候情景数据和人口数据模拟预测了2016-2030年流域输沙量的变化情况。主要结论如下：

（1）九大流域除了钱塘江流域和松花江流域外，其他七个流域输沙量均呈现减少趋势。输沙量突变的时间节点受到流域降水、径流等自然因素以及修建水库、实施退耕还林还草工程等人类活动因素的综合影响。输沙量对暴雨洪灾等因素响应敏感。地形因素对不同空间尺度流域输沙量起到了关键作用，相同空间尺度的大流域、中流域和小流域中，降水的增加会导致输沙量的增加，温度升高和人口密度增大会促使输沙量减少。人类活动和温度升高对输沙量的影响在大流域中更为显著，而中流域和小流域的输沙量对于降水的变化更为敏感。

（2）九个流域构建的综合输沙量模型主要体现了地形因素对不同空间尺度输沙量的关键控制作用，其贡献度约为63.5%。相同空间尺度的大流域、中流域和小流域构建的三种输沙量模型则更能体现输沙量的年际变化特点。气候变化和人类活动是输沙模型的变量。大、中、小流域的输沙量都受到降水量和人口密度的影响，温度因子对大流域的输沙量影响显著。模型通过验证，能够体现输沙量的变化趋势。为预测未来输沙量的变化提供了工具。

（3）在2016-2030年的输沙量趋势预测中，除了海河流域外，其他八个流域输沙量均表现出减少趋势。海河流域保持了2001年后输沙量小于0.01万吨的输沙状态。其中，大流域的输沙量变化最为剧烈，中流域和小流域的输沙量变化较为平稳。为了应对气候变化、保护水生生态系统，需要重视输沙量的管理，并结合水库调节作用和采砂活动的管控，来进行科学的水沙调控。

The impact of climate change and human activities on water and sediment in the river basin is becoming more and more obvious. It is necessary to pay attention to the trend of sediment transport in the river basins and regulate water and sediment rationally which is an important way to achieve sustainable development goals. Outflow river basins account for 64% of the China’s land area, mainly distributed in densely populated and economically active monsoon regions. This study analyzed the changes in sediment transport in nine important basins in China (the Songhua River, the Liao River, the Hai River, the Yellow River, the Huai River, the Yangtse River, the Qiantang River, the Min River and the Pearl River) from 1980 to 2015, and identified key environmental factors affecting sediment transport in different basins. A sediment transport model was constructed to analyze the response of the sediment transport to climate change and human activities. Base on the sediment transport model, we simulated the changes of sediment transport in the basins from 2016 to 2030 by using future climate scenario data and future population data. The main conclusions are as follows:

(1) Except for the Qiantang River and Songhua River, sediment transport in the other seven river basins decreased significantly. The years of the sudden change of sediment transport were affected by the natural factors such as precipitation and runoff in the basin, as well as human activities such as the construction of reservoirs, the Grain for Green Project. The amount of sediment transport was sensitive to the response to storms and floods. Topographic played a key role in the transportation of sediment in the basins, and its impact was far greater than climate change and human activities. The impacts of climate change and human activities on the transportation of sediment was highlighted after the classification of basins according to basin area. It was mainly reflected by the significant positive correlation between precipitation and sediment transport, the significant negative correlation between temperature and sediment transport, and the significant negative correlation between population density and sediment transport. In large basins, human activities had a greater impact on sediment transport than in middle and small basins. The amount of sediment transport in middle and small basins was more sensitive to changes in precipitation and runoff than in large basins. 

(2) The sediment transport model constructed in nine river basins mainly reflected the key control effects of topographic, and their contribution were about 63.5%. The sediment transport models of large basins, middle basins and small basins could reflect the factors that influence the interannual variation of sediment transport. Climate change and human activities were the main variables of the sediment transport model. The amounts of sediment transport in large, medium and small basins were affected by precipitation and population density. The temperature factor had a significant effect on the amount of sediment transport in large basins. The model had been verified and can reflect the trend of interdecadal sediment transport. It provided a tool for predicting the change of sediment transport in the future.

(3) By predicting the amount of sediment transport, it can be concluded that except for the Haihe River Basin, the other eight river basins show a decreasing trend from 2016 to 2030. The Haihe River Basin had maintained a state of transporting sediment near 0 million tons after 2001. The amount of sediment transport in large watersheds changes drastically, while the amount of sediment transport in medium and small basins changes smoothly.In response to climate change the study of sediment transport in river basins should be paid attention to. Human beings needed to combine the balance value of erosion and silting in the basin to control the water and sand scientifically.