Lesotho: Desertification Control Program - Combating Desertification in Asia, Africa and the Middle East - page 154

Fig. 8.9 Watersheds have
boundaries and an outlet
(mouth). They represent a
useful management unit

Watershed Boundary

Headwaters

1

1

2

2

3

1

Confluence

Stream
Order

Outlet
(mouth)

3.2 Erosion Control Measures in Lesotho

Erosion control measures can be divided into two types, The Mechanical measures
and the biological measures. The mechanical are used to stabilize the condition but
are temporary and the biological are permanent (see also Chaps. 2 and 3).

3.2.1 Structural Options

Various structural measures can be used depending on the particular requirements of
an area. Material like loose stones, bricks, bamboo piles, bamboo mats, stone filled
gabions, and sand filled bags are all used. With appropriate support the community
can do the bulk of the work including collecting stones, filling the gabions, and
earthworks etc. Dykes run along the side of river rather than protruding into the
river. They protect the river bank from erosion but do not redirect the river.

3.2.2 Mechanical Measures

1. Stone-lines
Constructed along the contour line on the slope to trap silt and reduce the runoff
speed
2. Pasture furrows
Constructed without outlet to improve moisture content of the area