Successful Biological Methods for Combating Desertification at Degraded Areas of China - Combating Desertification in Asia, Africa and the Middle East - page 68

protecting natural vegetation and establishing artificial vegetation to form the
measure of “blocking shifting sand in front and cutting off the sand source from
behind” so as to stop the encroachment of blown sand to the Lake.

6.5.3 Planting Sand-Fixing Forests

Sand-fixing forests were planted on the area where the original natural vegetation
and terrain were not disturbed, in the light of the principle of “planting suitable
trees in accordance with local natural conditions”, after two and a half years the
vegetation coverage reached 45 %. Sand-fixing forests were planted on the sand
land formed by leveling off the sand mounds covered by Nitraria tangutorum. By
contrast , the undisturbed native vegetation coverage only reached 27.5 % during the
same period. The dune-leveling system was more effective.

6.5.4 Watering Shifting Sand Dunes Through Sprinkler in Winter

The surface of sand dunes was frozen after irrigation by sprinkler; as a result the
wind erosion and movement of sand dunes were avoided. In addition, the water
content in the sand dunes was ideal for afforestation next spring. The comprehensive
protective measures have been carried out in Jilantai Salt Lake since 1984. The
average annual amount of sand (1984-1986) entering the Lake had decreased
by 908,000 m 3

(from 1,275,000 to 367,000 m 3 ), compared with that 3 years

before 1984.

6.6 Control of Sand Hazard to Reservoirs

The control of sand hazard to Jiefang Village Reservoir in Jingtai County of Gansu
Province is taken as an example. The Jiefang Village Reservoir adjoins Baishuiquan
Desert on the west, northwest and north. The northwest is the main wind direction.
The Baishuiquan Desert encroaches upon the Reservoir and constantly spills the
sand into the Reservoir. The annual amount of sand entering into the Reservoir
reaches 300,000 m 3 . The shelter system around the Reservoir is necessary to be
established. Three rows of standing sand barrier with an interval of 3-6 m between
the neighboring barriers on the part of windward slope (2/3 up the windward slope)
of fourth barchan chain (from the Reservoir) 1,300 m away from the Reservoir
were set up. The windward slope became steeper after the wind season (usually late
winter-early spring each year). The bare sand surface on the windward slope (down
2/3 the windward slope) was paved with gravels from swales between the dunes
to form a permanent artificial sand-accumulating bank, by which shifting sand was
piled up and the sand source was cut off.