 It is important to identify which processes operate on a particular littoral cell and also important to identify sediment sources and sinks, as by measuring the sediment gained or lost by these sources and sinks, a sediment budget can be determined.Rivers are major point sources of sediment contribution to the coastal sedimentary budget, this being particularly true of coasts with a steep gradient, where rivers directly dump their sediments at the coast.Coasts with a low gradient may lose river sediment to estuaries.