Contour trenches
Contour trenches are made
by excavating the soil to form an artificial depression/ pit on the steep land
surfaces to reduce soil erosion and to absorb rainwater in the soil. This type
of engineering structure is advocated for the land with a slope higher than 15%.
Most commonly, trenches are of 0.30 m x 0.30 m
dimension at 1 to 2 m vertical interval. However, the continuous trenches may be as long as 100 to 200 m long across the
slope depending on the land width. Trench protects the
soil from erosion and reduces the run-off by absorbing the velocity of
rainwater. The vegetation like broom
grass can be planted on either side of the trenches to prevent erosion. It improves moisture status in soil, water yield, and increases crop production.