Controlling Sand Movement Through Mechanical Measures: China’s Experience - Combating Desertification in Asia, Africa and the Middle East - page 26

3.3.1 Covering Sand Dunes with Cobblestones

The principle and the method of covering sand dunes with cobblestone or gravel are
the same as for covering dunes with earth, but the depth of the covering using these
materials is around 3 cm, not 6-16 cm.

3.3.2 Covering Sand Dunes with Baijang Soil

Covering sand dunes with baijang soil is usually used in those areas which are near
a lake basin because baijang soil is commonly located in lake basin. The techniques
are as follows:

• Mix the baijang soil with water

• Spread the baijang soil mixture onto the surface of the dunes. A very firm crust

will be formed after the baijang soil is dry because baijang soil will cement the
surface sand together.

3.3.3 Covering Sand Dunes with Gypsum

Covering sand dunes with gypsum is usually used in areas where gypsum is
abundant. The establishing method is as follows:

• make plaster of paris into slabs

• crush the plaster of paris into powder

• mix the plaster of paris and sand, the ratio of plaster to sand is 7:3

• Spread the mixture into the surface of the sand dunes evenly

• Spray water on the mixture. A crust with depth of 2-3 cm will form on the surface

of the sand dunes after the mixture is dry.

Among the above three kinds of barriers, the erosion resistance of the cobble-
stone or gravel surface is the best, and the service of the cobblestone or gravel
sand barrier is the strongest. The other two kinds of sand barriers are liable to be
destroyed by livestock, people or rain.

3.3.4 Covering Sand Dunes with Man-Made Materials

and Chemical Stabilizers

This measure involves laying or spraying chemicals on the surface of moving
sand to form a surface crust or permeate the chemical substance into the sand,
then a cohesion layer will come into being, which can stop sand from drifting or
moving. Sand-fixation of this kind has been trialled, especially the use of pitch
emulsion, compounded chemical emulsion of wild plants, and animal's glue. Some
achievements have been gained and the results showed that the method of using