Page 154 - Arabian Studies (I)

138 Arabian Studies I

border of Al-Buraiga and at least as far as the locality called
Jawatha', this area now being completely covered by sand dunes
(Fig. 1).
Reclamation of the salt-affected marsh lands and preventive
measures to reduce the effect of aeolian sand have had to await
technological advance and the availability of capital to finance the
work. A major irrigation and drainage scheme was opened at al-Hasa
in 1971 and this will provide an additional 12,000 hectares of
cultivated land. By draining the marshy areas, former cultivated lands
are being brought back into cultivation and new areas added. A more
economical use of water is also obtained by the construction of
concrete irrigation channels, thus minimising transmission losses,
while the saline sources of water in the eastern part of the oasis need
no longer be utilised. The breeding ground for the malarial
mosquitoes has also been eradicated, and malaria is now virtually
unknown in the oasis area.
A sand stabilisation scheme was started in 1962, to prevent
encroachment on the cultivated area by sand dunes. Brushwood
fences were first constructed for 25 km. along the northern edge of
the oasis to give protection from surface movement of sand grains.
Behind the fences the dunes were levelled by bulldozers and topsoil
from the saline flats spread evenly over the levelled dunes. Tamarisk
species, notably Tamarix aphylla, are planted, being irrigated every
seven days in summer and 15 days in winter, as the annual total
potential evapotranspiration amounts to 2450 mm. (Wakuti, 1970).
The use of tamarisk for this woodland has a number of
advantages - it is quick growing, capable of withstanding the saline
topsoil that is applied to the dunes and, once established, requires
virtually no irrigation. So far, over 500 hectares of woodland have
been planted, forming a belt lA—Vi km. wide between the brushwood
fences and the cultivated land. The woodland is an additional
amenity to the area for not only will it provide for a small timber
industry but it is also extensively used for recreation.
Technological advance has led to major changes in the type of
agriculture being carried out in the oases and these have been
analysed (Stevens 1972). However, the introduction of new
techniques or methods of cropping can be affected by the
environment or even alter part of the environment. Two instances
may be cited. Lucerne has now became a major crop in the oases of
eastern Saudi Arabia and while good yields are obtained, nodulation
is rare, even with innoculated strains, unless the crop is cultivated
under the protection of a tree crop. It would appear that the bacteria
required to stimulate nodulation appear unable to survive the high

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