Geoscience Reference
In-Depth Information
sand hazard along the roads. So-called “stocking” is to erect artificial sand barriers
at some distance from the road on the windward side of road to stock shifting
sands; “fixing” is to adopt engineering measure in combination with plantation of
sand binder on the sand dunes close to road along sides of road to stabilize the
surfaces of dunes; “transporting” is to build a streamline section for highway, sand
guiding bank, sand transportation bank or shallow trough to promote wind velocity
and prevent or lessen sand accumulation. These measures are applied according to
different natural conditions and types of sand (Squires and Warsame
1998
).
There has been experience in managing sand dunes along both sides of transport
corridors including railways and highways so as to protect railroad beds from wind
erosion and sand accumulation. This action will guarantee the safe operation of
transportation (see Chap.
2
for the mechanical methods used).
The biological approaches are widely used for stabilizing shifting sands along
railways/highways in the sandy deserts and other affected regions of Northern
China. Revegetation along railways/highways for controlling sand encroachment
and sand accumulation, and the plantation of trees or shrubs along railways and
highways to decrease wind velocity and increase roughness of surface to prevent the
traffic lines from sand disasters are possible even without irrigation. Such examples
are available at Shapotou Station, Zhongwei Country, Ningxia Hui Autonomous
Region and Cross-Taklimakan Desert Expressway, Xinjiang.
The initial step to fix shifting sands, measures for planting vertical mechanical
barriers were adopted to prevent dune surface from sand transport and dune
movement in given cases (see Chap.
2
for detail).
After the mobile sand dune surface were stabilized some selected species were
transplanted from nurseries. The transplants are wrapped with dried plant branches
to deter grazing and protect against wind. These newly planted biological complexes
are fenced for years to avoid animal trampling, to increase the silt crust on vegetated
dune surface and slow down the wind velocity.
6.1
Control of Sand Harms Along Railway in Semi-Desert
Region
For railway lines running through the border zone of semi-desert where shifting sand
dunes stretch and undulate, there are protective belts built and forming a protective
system in combination of “sand-fixing, sand-stocking and sand-transporting” on
both sides of the road in proportion to the yearly advance rates of sand dunes. The
Zhongwei-Gantang section of Baotou-Lanzhou Railway on the southeastern fringe
of the Tengger Desert is such a case. There they built a 500 m wide belt on the side
of the main wind direction and a 200 m wide belt in the secondary wind direction
which widespread straw checkerboard sand barriers (1 m
1 m) with planting sand-
fixing plants in grids (Fig.
3.10
). Besides providing gravel protection on the slopes
of the road and gravel platforms on both sides of the road for transporting sand
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