A HYDROLOGIC CLIMATE STUDY FOR AN ARID REGION
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Abstract
Water is the most precious natural resource in arid regions due to the limitation of
water resources, expanding population, and increasing volumes of industrial and
domestic waste. The purpose of this research was to evaluate methods to estimate water
quantity in an arid region. The research consisted of three separate studies.
In the first study, hydrologic models used to estimate water quantity were
evaluated for suitability of use in arid regions. Most hydrologic models that have been
used in arid regions were originally developed for humid regions. Rainfall events in arid
regions can be characterized as short-term, high intense rainstorms causing severe runoff
in arid regions. This study provides an assessment various rainfall-runoff models and a
comparison of methods and/or modifications used by researchers to adapt these models to
arid regions. Mike 11, Sacramento, Pitman, and the IHACRES models have been used in
arid regions with mixed results.
The second study evaluated the annual rainfall for the Tabuk region obtained from
observed datasets for the period 1978–2013. The objective of this study was to determine
Tabuk catchment climate characteristics in terms of precipitation. The Tabuk region has
common aridity characteristics in terms of the small precipitation amounts and high
temperature rate. There is a drop in the annual rainfall from (25-30) mm to (5-10) mm
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(1978-2004). The lowest annual rainfall (0-6.0 mm) occurred in the year 2004, which is
the driest year in 35-year period. The mean annual rainfall is less than 33.5 mm.
The third study analyzed flash floods caused by short-intense rainstorms. The
objective of this study was to determine flood risk related to identified precipitation
depths. The project quantized the runoff corresponding to different design storms and
used hydraulics and geospatial data to determine flood elevations. The study constructed
hydrologic and hydraulic models to quantify flood hazards in the adjacent area of Wadi
Abu Nashayfah. Peak discharges for the wadi were computed by using observed rainfall
data, and the output of this process was applied to compute water surface elevations
within the flow channel. The depth of precipitation at which the channel was overtopped
was determined in several locations. The predicted overtopping was compared to historic
events with good agreement.