Driving forces of changes in the water and sediment relationship in the Yellow River.

The world is composed of various river basins. Within a specific river basin, water and sediment dynamics, and the relationship between them, can be assessed to reflect the basin's functions and services. Due to its changing nature, understanding and balancing the relationship between water and sediment is a global concern and is crucial for the sustainable management of river basins, especially for the Yellow River (YR), which is one of the most sediment-laden rivers in the world. Here, we used the past 60years of runoff and sediment load observations to investigate the middle reach of the YR, i.e., the Loess Plateau (LP), the source of nearly 90% of the sediment load of the river. We found that a sharp (58%) reduction of sediment after 1979 was mainly (59%) caused by a water yield decrease. Engineering and vegetation measures have induced land surface modifications, which are responsible for 76% of the water reduction. These measures have been implemented as part of a coordinated set of soil and water conservation, and sediment control polices. We propose the cessation of such construction and the maintenance of a sustainable (i.e., minimal water consumption) vegetated ecosystem on the LP for soil conservation, and the establishment of an integrated basin-wide ecosystem and land use management regime for sustainable water use and sediment regulation.