River delta slope offshore, waves will make river deltas smoother. Waves can also be responsible for carrying sediments away from the river delta, causing the delta to retreat. For deltas that form further upriver in an estuary, there are complex yet quantifiable linkages between winds, tides, river discharge, and delta water levels. Erosion is also an important control in tide-dominated deltas, such as the Ganges Delta, which may be mainly submarine, with prominent sandbars and ridges. This tends to produce a "dendritic" structure. Tidal deltas behave differently from a river- and wave-dominated deltas, which tend to have a few main distributaries. Once
Yangtze River Delta Yangtze River Delta The Yangtze River Delta or YRD is a triangle-shaped metropolitan region generally comprising the Wu Chinese-speaking areas of Shanghai, southern Jiangsu province and northern Zhejiang province. The area lies in the heart of the Jiangnan region (literally, "south of the River"), where Yangtze River drains into the East China Sea. The urban build-up in the area has given rise to what may be the largest concentration of adjacent metropolitan areas in the world. It covers an area of and is home to over 115 million people as of 2013, of which an estimated 83 million is urban.