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
Indus River Delta water quality, causes eutrophication, reducing the amount of habitat. Indus delta has shrunk by 92% since 1833. In light of the threats, Indus Delta was designated a Ramsar site on November 5, 2002. The WWF is working on conservation methods to alleviate the Indus delta's shortage of freshwater. The population of the delta was estimated at 900,000 in 2003 (the total population of Indus River Delta-Arabian Sea mangroves was 1.2 million). Within the river delta, about 140,000 (16% of the population) depended on the mangrove forests for their livelihood, and 60% depended on the forests for fuels. At least 75%