Estuaries
Water of all streams and rivers eventually drain into the sea. Estuaries is the place where this freshwater joins the salt water. As such estuaries are the transitional zones between the sea and rivers and are the sites of unique ecological properties. They are semienclosed coastal bodies of water that have a free connection with the open and within which seawater is measurably diluted with freshwater from river. However, all the rivers are not open into estuaries. Some rivers simply discharge their runoff into the ocean. Estuaries are not alike. Instead they differ in size, shape and volume of water flow, they are influenced by the geology of the region in which they occur. As the river reaches the encroaching sea, the stream carried sediments are dropped in the quiet water. These accumulate to form deltas in the upper reaches of the mouth and shorten the estuary.