A semi-circular bund (also known as a demi-lune or half-moon) is a rainwater harvesting technique consisting in digging semilunar holes in the ground with the opening perpendicular to the flow of water. [1] [2]
These holes are oriented against the slope of the ground, generating a small dike in the curved area with the soil from the hole itself, so they capture the rainwater running downhills. [3]
These structures allow water to seep into the soil, retaining in the subsoil a greater amount of moisture. But also, it prevents the loss of fertile soil. [4]
Semi-circular bunds are used to reforest arid zones with irregular rain patterns, allowing the growth of plants and trees, such as in the Sahel. [5]