干旱区生态环境知识资源中心

Due to the continuous intensification of human activities, the global water demand has dramatically increased. As a result, great changes have taken place in water runoff and sediment load in rivers all over the world. This paper selected fourteen major rivers of the world as its study objects on the basis of the significance of the rivers and the degree of difficulty in getting water and sediment data. Evidence from long-term water runoff and sediment load records indicates that water runoff of rivers located in humid and semi-humid areas has changed little while it has decreased significantly in rivers located in arid and semi-arid areas. Sediment load of rivers located in humid and semi-humid areas has changed little, while it has decreased dramatically in rivers located in arid and semi-arid areas. Though both water runoff and sediment load of rivers located in arid and semi-arid areas have decreased, the decrease of sediment load is much more significant than water runoff.