English abstract
ABSTRACT
Countries in the arid climates of the world are all suffering increasingly from water
shortages. In oil producing countries, governments often invest in large desalination plants
to overcome water shortages. Desalinated water, nevertheless, is expensive, and people are
encouraged to conserve water in their everyday use. This study aims to demonstrate that
soil water that has previously been considered irretrievable can be collected, by harnessing
the power of the sun to retrieve water from wet soil using a rugged metal collector sunk
into the ground. Specifically the experimental goals of this study were to determine the
effects of environmental factors on the amount of soil water collected as a condensate in
the specially designed solar powered apparatus. These factors included, soil type, air
temperature, and soil water content. In addition, properties of the soil water collector were
adjusted in order to maximize the amount of condensate. The amount of water collected
depended largely on the air temperature and soil water content. In winter 465 ml m2 day!
were collected compared to 1163 ml m2 day in summer. However, the initial soil water
content was equally important; dry soil tended to yield less condensate than wet soil. Saturated soils yielded 814 ml m2 day in winter compared to 1395 ml m2 day in
summer. The type of soil also affected the release of water from the surface, as a result of
differences in soil water release characteristics. The air space between the soil surface and
the condensate collecting surface also had an effect on condensate collection within
experimental limits, the greater this distance, the more the condensate that was collected.
However, the amount decreased over time. The configuration of the condensate collecting
surface also had an effect on the amount of condensate obtained, the shallower the angle of
the surface, the more condensate was collected. Collection of soil water condensate was
feasible under the conditions investigated. The amounts of collected condensate can be of
agricultural significance especially in coastal areas when mixed with sea water to support
some salt and drought tolerant crop. The designed collector was most effective in the
summer, with wet poorly-drained silt soils, on cloudless days.
