Abdullah A. Sabtan

Coupling of remote sensing data aided with field investigations for geological hazards assessment in Jazan area, Kingdom of Saudi Arabia

The city of Jazan is situated on the eastern flank of the Read Sea and considered as one of the fastest growing cities in the Kingdom of Saudi Arabia. This zone attracts a lot of investors for various development projects. Recently, many new projects have been implemented and constructed in this region including new urban areas, infrastructures, and industrial projects. However, historically this area has been challenged from different types of geological hazards. These geological hazards are catastrophic events that can cause human injury, loss of life, and economic devastation. The current study is aimed at evaluating the different types of geological hazards in Jazan city. This study is based on interpretation of satellite data such as LANDSAT and QuickBird images, existing geological maps, and physiographical characteristics with the help of field and laboratory analyses. The results of the analysis indicate that there exist various types of geological hazards in the study area mostly related to the natural factors which include (1) Sabkha soil; (2) Salt dome; (3) Loess soil; and (4) Sand dune/drift. Further, the findings of this study revealed that, most of these geological hazards have a severe impact on the ongoing development activities in Jazan area.

Assessment of the industrial utilization of scoria materials in central Harrat Rahat, Saudi Arabia

Although basaltic volcanic scoria deposits are widespread in and around the scoria cones present in the Harrats, very few occurrences have been evaluated and still fewer have been exploited. The scoria from a quarry in central Harrat Rahat was investigated and assessed for its industrial utilization. Cubes were prepared from several concrete mixes using scoria as lightweight coarse and fine aggregates in different percentages. The compressive strength values of the cubes were found to be acceptable and satisfy the ASTM (1995) requirement for structural concrete. The scoria was also assessed for its utilization as a cement additive. Pozzolanic activity was tested according to the Italian standards and found to be acceptable. The strength activity index with Portland cement and the effectiveness of scoria admixture in controlling alkali-silica reactions were tested according to ASTM (1995) standards. Mortar cubes were specially prepared for these studies using different mixes and different storage procedures. The results satisfied the ASTM (1995) requirements as cement additive. The utilization of scoria as a heat-insulating material was tested and the results were found to satisfy the ASTM (1995) requirements. This fact suggests it could be utilized in the manufacture of the building blocks. It is recommended to evaluate the other scoria deposits, exploit the economically feasible ones and utilize them for different industrial applications. The manufacturing of heat-insulating concrete or building blocks using scoria is of prime importance as an energy saver.

Moisture retention characteristics of coastal sabkhas

Abstract Water plays an important role in governing the properties and behaviour of engineering soils. The amount of water a soil can retain depends not only on the nature of soil, including its mineral composition, texture and structure, but also on the type and concentration of the salts dissolved in the water. In this experimental study, samples of a siliciclastic aeolian soil are mixed separately with different concentrations of salt water. The mixing waters used in these experiments are representative of the groundwaters encountered in different types of sabkhas occurring near the coastal town of Dahban in the Kingdom of Saudi Arabia. A number of graphs are prepared to display relationships between the salinity of the mixing water and the amount of water that is retained by the soil at different temperatures. In general, the higher the salinity of the groundwater, the greater is the amount of water retained by the sabkha. For the same drying temperature, the rate of moisture decrease diminishes with time. The maximum rate of moisture decrease is experienced by the soil mixed with the least concentrated salt solution.

Earth Fissures in Wadi Najran, Kingdom of Saudi Arabia

The formation of earth fissures due to groundwater depletion has been reported in many places in North America, Europe, and Asia. Najran Basin is in the southern part of the Kingdom of Saudi Arabia, and agricultural activities and other groundwater uses have caused significant groundwater depletion there. The basin recently experienced a sudden appearance of numerous earth fissures. An interdisciplinary study consisting of an evaluation of land-use changes, and hydrological, hydrogeological, and geophysical investigations was conducted to determine the reason for the formation of the earth fissures. The hydrological analysis strongly revealed that the groundwater level is decreasing with time. Groundwater depletion would lead to the accumulation of subsurface stress, causing soil hydro-consolidation which creates the ideal condition for the formation of earth fissures. Electrical resistivity, data indicated that there are anomalies in the profiles, which are most probably due to the presence of subsurface topography, another key factor for the formation of the earth fissures.

Geological and Engineering Studies for Solid Waste Site in Wadi Malakan, Makkah Al Mukaramah@@@دراسات جيولوجية وهندسة لرمى نفايات بلدية صلبة في وادي ملكان - مدينة مكة المكرمة

يتم في هذا البحث اختيار موقع جديد لمرمى النفايات البلدية الصلبة في مدينة مكة المكرمة يقع في وادي ملكان كبديل لمرمى المعيصم الحالي وذلك بالنظر لتمتعه بمقومات فنية واقتصادية واجتماعية إيجابية وتوفر الأراضي المتاحة اللازمة لأحجام الدفن المتوقعة لمدة لا تقل عن عشرة سنوات قادمة. وقد تمت دراسة الموقع بيئيا وجيولوجيا وجيوفيزيقيا ودعمت هذه الدراسات حقليا ومخبريا مع التركيز على الدراسات الهندسية تحديد مدى ملائمة الموقع كعازل طبيعي للملوثات وتقدير كميات السيول وتصاميم العزل السفلي والخلايا والتغطية الوسطية والنهائية مع اقتراح طرق التخلص من الغازات الخطرة المتولدة لمنع أو تقليل التلوث والأضرار البيئية وذلك للحفاظ على صحة وسلامة سكان مدينة مكة المكرمة.

Numerical techniques in reservoir capacity evaluation

Abstract Several methods exist for estimating reservoir capacity based on field surveys of reservoir bottom features and the sediment thickness. Recently, the grid method was proposed which reduces the cost by measuring only a few sediment cross sections on selected parts of the reservoir from which the water depths in the remainder can be estimated by interpolation. The objective of the research reported here is to enhance the performance of the grid method by utilizing three additional numerical techniques, namely the Newton and Lagrangian polynomials and the cubic spline. The proposed technique was verified by estimating the known volume of a model dam reservoir in the laboratory. The reservoir volume was successfully evaluated using these numerical methods. It was found that the maximum error using the Newton and Lagrangian methods was 10%, while the maximum error using the cubic spline was as high as 24% and so this method is clearly less applicable. Although the Newton and the Lagrangian methods yield similar results, the latter is preferred as it is easier to use.