A HYDROLOGIC CLIMATE STUDY FOR AN ARID REGION

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 xviii (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.