Controlling Sand Movement Through Mechanical Measures: China’s Experience - Combating Desertification in Asia, Africa and the Middle East - page 25

Fig. 2.4 Covering sand dunes with straw or branches

3.2 Covering the Sand Dunes with Straw or Branches

This method involves covering the sand dunes densely with straw or branches. It is
usually used in areas where straws or branches are abundant. For this method, there
are two types of covering sand dunes: (1) complete covering and (2) belt covering
(Fig. 2.4 ).

3.2.1 Complete Covering

The sand dunes are completely covered with straws or branches and then sand is
placed on the straws and branches, or they are held down with some big branches
across them. The advantage of this type of sand barrier is that it can stabilize the
sand dunes completely. Its shortcomings are that it will consume a lot of materials
(approximately 370 kg of straws per hectare) and it is inimical to the growth of sand
plants because the moisture conditions of dunes protected by this kind of barrier are
unfavorable.

3.2.2 Belt (Strip) Covering

Here the dunes are covered with strips or belt of straws or other plant matter. The
widths of the belt are varied. In general, the width is the same as the length of the
straws or branches used in the barrier, that is, 50-100 cm. The row spacing is about
3 m. The run of the belt should be at right angles to the direction of the prevailing
wind. In order to prevent the belt barrier from being blown away by the wind, the
barrier should be covered with sand along the central line of the belt.

3.3 Covering Sand Dunes with Other Materials

In areas where clay is in short supply but cobblestone, baijang soil (clay pan or
plano soil) and gypsum are abundant and available, this kind of sand barrier is often
adopted.