Hydrological controls on the evolution of the Yellow River Delta: An evaluation of the relationship since the Xiaolangdi Reservoir became fully operational

Abstract

AbstractThe Xiaolangdi Reservoir, which was constructed in the trunk of the Yellow River, has controlled the flow process into the mouth of the Yellow River to a significant degree since it began fully operating in late 2002. To evaluate the relationship between the new hydrological process and the evolution of the Yellow River estuary, this study presents a detailed investigation of the morphodynamic adjustment in the river mouth using remote sensing satellite images. It was shown that the mouth channel rapidly extended in length from 2002 to 2004, although it was shrinking during 1999–2001, and then it expanded very slowly with considerable shifts at the place where the river flow mixes with seawater. In late 2007, an avulsion occurred on the northern bank of the mouth channel, far upstream from where the river water mixes with seawater. During 2008–2012, the new mouth channel extended its length into the sea at a slow pace, whereas since late 2013, it has divided into two branches that alternately discharge the main flow into the sea. Although both the water and the sediment input in the new hydrological process are much smaller in quantity than before, the geomorphic adjustments still manifest an excessive input of both. Moreover, after the avulsion, the seasonal pattern of land accretion in the river mouth has been characterized, with erosion occurring mostly in the wet seasons and accretion mostly occurring in the dry seasons.