Satellite-Observed Evolution Dynamics of the Yellow River Delta in 1984–2018
Zhengjia Liu, Nan Xu, Jieyong Wang
Abstract
The Yellow River delta (YRD) is regarded as one of the most rapid sedimentation deltas in the worldwide and the youngest land in China. Existing studies more focused on evolutions of river mouth region, thus provided limited knowledge on the evolution of the entire YRD and its corresponding trajectories of shrinkage and expansion. Here, we used 1984-2018 Landsat images and the change detection analysis algorithm to track annual area change trajectories of present YRD with the help of Google Earth Engine cloud platform. Results showed that entire YRD area documented a significantly shrinking trend with slope of -18.5 km <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /decade (p <; 0.05) at the past 35 years. Particularly, this study found muddy coast in northern and southeastern YRD exhibited severely coast erosion with the slopes of -29.3 km <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /decade (p <; 0.01) and -13.1 km <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /decade (p <; 0.01). Their mean coast erosion distance ranged from 2 to 4 km in 1984-2018. Area changes in the two regions contributed more to shrinkage of entire YRD. Besides, the expanding rate of current river mouth region was gradually slowdown due to decreases of sediment discharges, although area of new river mouth was still seemingly expanding. The significantly shrinking phenomena of the present YRD should be paid more attention.