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
Saskatchewan River Delta Agassiz, and to a lesser extent the delta of the Mossy River at Cumberland Lake north of Cumberland House. As the SRD developed through time, the principal channels of the Saskatchewan River frequently changed courses (avulsed) as part of the normal process of delta evolution. In the upper delta alone, at least nine major avulsions have occurred in the past 5,400 years. Remnants of these avulsions can be observed today as partly or wholly abandoned channels scattered over the delta surface. The most recent avulsion, initiated in the 1870s, has had profound effects on the physiography and ecosystems in the