What structure is built across gullies to prevent water erosion?

• A. Check Dams
• B. Dykes
• C. Terraces
• D. Shelter Belts

Answer: (A)

Water erosion on sloping land is tackled by structures that interrupt the flow of water and trap sediment. A check dam spans the mouth of a gully, slowing the moving water, increasing friction, and causing sediments to settle out. This reduces the velocity of runoff, lowers the rate of gully incision, and helps stabilize the land downstream. Over time, the gully may become a series of smaller, more stable steps as sediment builds up behind the dam.

Other options don’t fit this specific purpose. A dyke is an embankment built along rivers to hold back floodwaters, not across gullies. Terraces are flat, stepped ridges cut into slopes to reduce runoff and improve infiltration, but they are built along the slope rather than across a gully. Shelter belts are rows of trees designed to reduce wind erosion, not water erosion.