TheImprovement ofTropical and Subtropical Rangelands

THE BEMA SYSTEM IN THE ARABIAN PENINSULA 329
soon collects in the wadi beds, then disappears into the sea, into
salty depressions, or nearby sand dunes. The scarcity of plant cover
and destruction ofwater conservation works have thus become major
factors inhibiting percolation ofrainwater. The decreased percolation
in most areas has in turn reduced the flow of spring water. A survey
showed that the old dams constructed in pre-Islamic times are now
useless. Samalagee Dam, 400 m wide, and situated below Bema.
Thumula, can store no water because the spillway was destroyed by
floods. The construction of this gigantic dam proves that ancient
peoples had a keen interest in water conservation works. Five more
dams, or ,a.d, close to Bema. Nageeb, have met a similar fate, and
about 10 surrounding villages have been adversely affected. Wells
have almost dried up, and villages are constantly asking for help.
Altogether, there are 20 ruined dams (,a.d) in the area and about 40
smaller ,a.d known as ,tORy oka.d.
Sad Saisad is an example of another neglected dam. It was probably
constructed by Moawia, the fifth Islamic caliph, who succeeded
Muhammad the Prophet 13 centuries ago. The Ministry of Agriculture
of Saudi Arabia has lately authorized the development of a soil,
water, and vegetation plan in the Sad Saisad area to include a part of
the adjacent abandoned Bema. Saisad, thus reviving its protection.
The only two springs (gheil) that kept flowing after a long period
of drought have their main rainfall catchment areas along two wellprotected
a.hmia.: Bema. al Nomoor (the largest hema. in the At Ta'if
area) and Bema. al-Machada.
Recharging of the groundwater table by reconstruction of the
ancient dams and waterworks and revegetation of the a.hmia. would
greatly increase water supplies for the deficient area at At Ta'if.
BEMA IN THE RANGE IMPROVEMENT AND
CONSERVATION
PROGRAMS IN THE NEAR EAST
The hema. system was once common in parts of the Arabian
Peninsula and is still used in parts of Saudi Arabia, Yemen, Oman,
and Syria. It originated in the Near East and is suitable as a means for
controlled grazing in selected areas in arid, semiarid, and mountain
ranges where nomadic grazing is the only system practiced. Carefully
protected a.hmia. would fumish fodder reserves essential for stability
of nomadic growing. They would also change the attitude of the