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. Sediment delivery to the shoreline can be very intermittent mostly occurring during floods with the increase in flow typically creating an increase in sediment supplied to the coast. Some rivers are referred to as ‘large’ because they produce high amounts of sediment for which to nourish the coastal environment. For example, the Waimakariri River on the coast of Canterbury, New Zealand produces 77% of sediment supplied to the Pegasus Bay coastline. This is not always the case with some rivers referred to as ‘small’ because they struggle to supply enough sediment to keep their coastlines from eroding, for example, the Rakaia River South of Banks Peninsula in Canterbury, New Zealand.