Staggered Contour Trenches under MGNREGA Conserve Water

Cheemaldari village under Mominpet mandal of Vikarabad District executed staggered contour trenches work under MGNREGA in 2015-16 on 30 acres of hill area land. Staggered contour trench technique is useful in slowing surface water run-off and soil erosion from sloping land, and in re-vegetating degraded land. This is especially useful in areas with high rainfall, steep slopes, and thin soils which should use slightly graded bunds/terraces/trenches to allow some drainage.

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IMPLEMENTATION

33The work was planned at an estimated cost of Rs 11.4 lakh. Contour trenches are useful in areas with slope above 8%. Staggered contour trenches are trenches dug in a trapezoid shape with a top width of 1.0 meters, and a bottom width of 1.0 meters, and a depth of 0.6 meters. The soil removed is used to create a berm just downhill from the trench. The trenches should be dug perpendicular to the slope (along the contours). They can either be continuous or staggered, such that they are 3 meters long, with 1-meter gap between every section, and 3 meters between every row. The actual expenditure incurred was Rs 6 lakhs.

IMPACT

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The work generated a total number of 3853 person-days. In hilly areas, staggered contour trenches have shown a decreased surface water run-off by 80%. Thus rain water is conserved and does not immediately run off the hill and the water does not evaporate uselessly. This increases the overall water balance and the crops grown on the trenches do not suffer later from water shortage.

The soil erosion checked by the staggered contour trenches restores the fertile soil particles that are not lost by water and wind force. Further, when the sun shines on the water, light and heat are reflected onto plants on the northern shore of the trench, this affects the increased humidity create micro climate in the area. These micro climates can support plants from different hardiness zones.

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