Page 153 - Arabian Studies (I)

Man and Environment in Eastern Saudi Arabia 137

supporting a population of about 200,000, while QatTf oasis covers
4,000 hectares. Both have substantially decreased in size as the result
of both man’s activities and the adverse physical environment.
Al-Hasa, in particular, provides a good example of the problems oasis
society has encountered in its struggle for existence in a harsh
environment.
Al-Hasa, according to Hava’s dictionary, means ‘swampy ground
covered with sand’ (Vidal, 1955) and it has probably been settled
since late Neolithic times. A number of artesian springs were
originally responsible for this swampy ground, but subsequent
cultivation of date palms and over-irrigation has increased the area of
marsh. Dowson (1949) comments on the cultivation of dates that, with
‘roots in water, fronds in sand, given good drainage it is hardly possible
to over-water a date palm’. However, the salinity of the water in the
eastern part of the oasis increases to over 6mmhos/cm. at 25°Cand
the combination of over-irrigation with this saline water and the
presence of an impermeable horizon of Neogene limestone at shallow
depth caused extensive areas to go out of cultivation. Additional
areas were only capable of a very low level of date cultivation. Birkat
al-Asfar (Fig. I) formed a natural drainage channel eastwards but
with the vast amounts of drainage water, the water table rose and
salinity increased and this area too became a large swamp. A
particular effect of these extensive swampy areas was the high
incidence of malaria that occurred, as described by Daggy (1959).
‘The intensity of malarial attack in the population is directly
proportional to its nearness to irrigated agricultural areas.’
Apart from the man-induced hazards, the area of al-Hasa oasis was
also being steadily reduced by aeolian sand. Northerly winds
predominate over much of the year and these have caused sand dunes
to encroach on, and overwhelm, parts of the eastern portion of the
oasis which juts out into the Jafura sand sea. These dunes rise to a
height of at least 25 metres above the saline flats and their movement
is estimated to cause the direct loss of at least 2 hectares of
cultivated land each year. In addition, the wind-blown sand blocks
irrigation and drainage canals, causing water shortages and enhancing
the salinity problems of the oasis, as well as causing direct damage to
crops when high winds blow.
Problems like these are typical of the oases in the eastern Arabian
Peninsula, though the deterioration of the environment has not yet
reached the point where change is irreversible. It is only those areas
which have been completely overwhelmed by aeolian sand that are
completely lost, though such areas are extensive. At al-Hasa, Vidal
(1955) states that ‘perhaps even during the Middle Ages, the
cultivation area reached much further to the north along the eastern

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