Notes

yield 1,050 cubic meters of soil. The soil removed during construction is a valuable asset in land development and in regreening hillsides. These hillsides are often deforested and stripped of vegetation during the road-building process. This damage can be remediated by replanting trees on hill slopes in combination with building eyebrow terraces and stone strips. This approach slows runoff while facilitating regreening.

Controlled Grazing Uncontrolled grazing can be a major cause of land degradation in medium- and high-altitude areas. Measures to reverse this trend and restore pastures include area enclosures, better pasture management, and, in some cases, reducing herd sizes.

Controlled grazing requires the establishment of well-defined grazing areas and regulation of their use, closure, and resting. “resting” is generally proposed to restore perennial grasslands, which may result in an initial burst of growth in vegetation that was being overgrazed and can now grow freely. Properly grazed grasslands act like sponges, storing humus and carbon. The roots of grasses perforate the soil and open it up, increasing porosity and infiltration capacity. The trampling of the sealed soil surface, or soil crust, by animals helps this process by breaking the surface. The increase in porosity and infiltration capacity allows water to soak in where it can be used by plants, or eventually trickle down to feed springs, rivers, and boreholes or wells, thus increasing the time rainfall remains resident in the catchment. Controlled grazing also decreases risks of floods and siltation downstream and the resulting damage to road infrastructure.

Grazing areas may be further enhanced by the spreading of floodwater or meltwater. When water is flowing in mountain streams, it can be diverted to grazing areas that are short of moisture, which will also reduce the risk of downstream floods because the water is spread over a large area. Care should be taken to avoid interference with existing downstream water uses.

Regreening In several mountain areas, the demand for fuel wood and timber has had a severe impact on stands of trees and shrubs. regreening will stabilize slopes, help retain water, and even change the microclimate by achieving shorter precipitation cycles. regreening involves a series of measures: land use planning and controlled grazing are often prerequisites for successful revegetation. regreening campaigns may provide incentives to mountain communities or forest enterprises to plant and safeguard new tree stands. alternative arrangements can be powerful too, such as farmer-managed natural revegetation (whereby natural tree sprouts are protected and nourished), farmer-owned timber or fuel wood plantings, and agroforestry farms or roadside tree plantings (see chapter 12).

NOTES

1. according to the nepal rural road Standard, the maximum cross slope differs for different road types: for an earthen road, 5 percent; for a gravel road, 4 percent; and for a bituminous seal coat road, 3 percent. 2. Based on dSCWM (2016) and desta et al. (2005).