Geoscience Reference
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Fig. 2.19
The installer's method of soft spread sand barriers
will rise up; (3) close the two separate sides of the straws into one and tramp the
base of the sand barriers on both sides with feet. The advantages of this method
are that it is fast and saving of manpower.
4.4.3
Installation of Concealed Sand Barriers
The materials for concealed sand barriers are usually wheat straw, reeds or other
grasses. The installing method is as follows: (1) cut the straws or grasses into 20-
25 cm lengths and then bundle up the cut straws or grasses to a diameter of 5 cm;
(2) dig the furrows on the sandy land to a depth which is the same as the length
of the bundle; (3) stand the bundles into the furrow and then fill the furrow with
sand and tramp it firm. The tips of the bundles of straws or grasses are at ground
level. Such sand barriers cannot break the sand-driving wind above the ground. But
they can control the moving of the sand ripples on the surface of sand dunes. When
the concealed sand barriers are set up, the existing landforms can be kept although
the sand is still moving. This phenomenon is advantageous to afforestation on the
moving dunes. The patterns of this kind of sand barrier are usually parallel linear-
shaped with row spacing of around 2 m, or check-shaped with a size of 2
3m.
For this kind of sand barrier, there is another installing method; this is digging a
furrow to a depth of 15-20 cm and laying the straws or grasses into the furrow and
then filling the furrow with sand (Fig. 2.20 ). This method can save man-hours, but
its efficacy at sand-control is not very satisfactory. This method is usually adopted
when the materials are broken straws or grasses.
4.4.4
Installation of Clay Sand Barrier
The clay sand barrier belongs to the low standing type of sand barrier with
windproof structure. In many sandy areas, the clay sand barrier is set up first
before the sand-adapted species, such as Haloxylon ammodendron ,areplanted
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