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 the delta has been impeded due to the construction of dams along the river. The reduction of freshwater due to the dams also increases salinity, making the waters of the delta unsuitable for the freshwater species. In case of the Indus dolphin, the damming of the river has isolated the delta dolphin population from those dolphins upstream. The 2010 Pakistan floods were considered "good news" for the ecosystem of the river delta as they brought an excess of much needed fresh water. The Sindh government announced that 8,000 hectares of mangrove forests had been planted, and more plantation was considered