Controlling Sand Movement Through Mechanical Measures: China’s Experience - Combating Desertification in Asia, Africa and the Middle East - page 32

Fig. 2.9 The patterns of some sand barriers

Fig. 2.10 The section of linear-shaped sand barrier

of wind is single, linear-shaped or parallel linear-shaped sand barriers are usually
adopted, but in an area where side winds are strong, the check-shaped sand barriers
are often used (Fig. 2.9 ).
Linear-shaped sand barriers are generally established in an area where the threat
of sand-driving wind is serious. Its function is to hold back the shifting sand. This
kind of sand barrier is called “stopping up the wind gaps” by local people. The
linear-shaped sand barriers are often used as high standing sand barriers or hedges.
When the dropped sand buries a sand barrier, the barrier should be raised or rebuilt.
The height of the sand mound on the leeward side of sand barrier will gradually
increase and the dropped sand will form a great sand dune - a great sand-blocking
dam-in the end (Fig. 2.10 ).
Parallel linear-shaped and check-shaped sand barriers are used not only to
stabilize the original sand dune on the spot, but also to hold back the passing sand
carried by the sand-driving wind. These two kinds of sand barriers are usually
adopted to guarantee the survival rate and growth of seedling of sand plants that
are planted on the sand dunes.
All of the above patterns of sand barriers are only suitable for areas where the
sandy land is gentle and the landforms are simple. For an area where the landforms
are varied, other patterns of sand barriers should be set up in the light of the type,
run and slopes of the sand dunes.
When sand barriers are set up on crescent (barchans or semi-lunar) dunes, the top
of the windward slope of the dune should be left open so as to let the part which is