A Check Dam is an obstruction built across a water course. Normally, a check dam blocks small streams in watershed or steeply sloping areas. Check dams reduce the velocity of water flow and collect silt, preventing it from flowing downstream. In all, they are effective soil and water conservation instruments.
His Majesty classified check dams into two categories, one which provides and maintains moisture, and the other which prevents sand from flowing into the main reservoirs. In other words, the first type is a watershed dam, or moisture-retaining dam, while the second type is a silt-collecting dam.