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 of wave energy, coupled with lack of silt flowing in from the Indus river (as mentioned above), has resulted in the formation of sand beaches. The Indus river started to form some 50 million years ago. 25 million years ago, the Indus Plain was lifted. Mangrove forests are one of the most abundant ecological communities of the delta, but they have declined over the years. According to Haq "et al.", they covered an area of until the 1980s and could be found along the entire 240 km coastline, in 40% of the tidal zone, and in 10% of the delta