నైరూప్య

Influence mechanism of the xiaolangdi hydraulic engineering operation on the evolution of the yellow river estuary coastline

L.V. Cong, L.I.XinJu, QianQian YAO ,Yi Liu, Xinxin Kong

The Xiaolangdi Hydraulic Engineering Operation can affect the coastline evolution to some extent by changing the flow and sediment condition in the Yellow River. The results showed one-year lag in the response of the Yellow River estuary coastline to the flow and sediment condition. The flow and sediment in the Yellow River sharply declined (even exhausted) in the 1990s, showing a negatively increased status for the shortage of flow/sediment supply. The erosion rate of spit in the estuary was 0.45 [km/a] in 1995– 2003. The land area erosion rate was 14.9 [km2/a] in the late 1990s, and the bending and complexity degree of the coastline remained at a high level. The flow/sediment regulation of the Xiaolangdi Hydraulic Engineering optimized the flow/sediment allocation after 2002. The spit in the estuary considerably extended, resulting in a land-forming rate 1.24 times higher than that under the natural flow/sediment condition. In addition, the coastline tended to be straight and smooth. The Xiaolangdi Hydraulic Engineering should regulate the flow/sediment within 0.02 [t/m3] and the incoming sediment coefficient to about 0.01 [(kg·s)/m6] in the Lijin station, which is about 20 billion [m3] of flow and 300– 400 million [tons] of transported sediment, to drive the coastline development in the positive direction.