 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.The construction of river dams for flood control and hydropower reduces sediment supply to many coastlines due to the trapping of sediment and the decrease in flood peaks and flood intensity.In places such as Southern California of the United States, in particular the San Luis Rey River, dams are built to control flooding of properties along the river.