A levee is a man-made or natural wall that blocks water from going where it is not wanted. Levees can be naturally occurring ridge structures that form next to the bank of a river or be an artificially constructed fill or wall that regulates water. They are typically placed in alluvial rivers perpendicular, or at an angle, to the bank of the channel or the revetment, and are used widely along coastlines. Levees are designed to contain, control, or divert the flow of water in order to provide protection to towns and/or agricultural land from flooding. They are built to hold back a certain amount of floodwater and are used to reduce the risk of flooding near areas with water. Levees can be made from stones laid in horizontal rows with a bed of thin turf between each of them, which is known as a spetchel. They are common in any river with a high suspended sediment fraction and thus are a natural consequence of the flooding of meandering rivers which carry high proportions of suspended sediment in the form of fine sands, silts, and muds.