Abdulaziz M. Al-Bassam

Climate change impact and runoff harvesting in arid regions

The most significant large-scale environmental challenge that many countries, especially in the arid and semi-arid regions of the world, will face in the middle and long-term are water scarcity problems, which are attributed to climate change impacts such as temperature increase, abundance of high solar radiation, and aridity in addition to population pressure. In many countries, current water resources use already exceeds sustainable and renewable supply. Various methodologies are suggested to increase the sources of water supply, among which one of the alternatives is rainwater and runoff harvesting (ROH). Water scarcity and additional stress are among the most specific problems in arid and semi-arid regions, where vegetation cover is very weak under extensive solar irradiation effects with high evaporation rates. Present global warming, climate change impacts, and their future patterns are expected to cause increase in the evapotranspiration rates and hence reduction in the groundwater recharges. Under such circumstances, any simple but effective water storage augmentation facility as the artificial groundwater recharge gains vital importance for sustainability of water supply and survivals in desert ecosystems. Although intensive and frequent rainfall events are rare they generate significant surface water flow during occasional floods and especially flash floods with huge amounts of surface water. It is, therefore, necessary to enhance artificial groundwater recharge from consequent frequent runoffs through suitable hydraulic structures. This paper aims at assessing the importance of ROH systems for domestic supply in arid regions with specific reference to the Kingdom of Saudi Arabia. For this purpose, it presents ROH from the surface flows in depressions of Quaternary wadi deposits in arid and semi-arid regions.

Assessing the hydrogeochemical processes affecting groundwater pollution in arid areas using an integration of geochemical equilibrium and multivariate statistical techniques

Rapid economic expansion poses serious problems for groundwater resources in arid areas, which typically have high rates of groundwater depletion. In this study, integration of hydrochemical investigations involving chemical and statistical analyses are conducted to assess the factors controlling hydrochemistry and potential pollution in an arid region. Fifty-four groundwater samples were collected from the Dhurma aquifer in Saudi Arabia, and twenty-one physicochemical variables were examined for each sample. Spatial patterns of salinity and nitrate were mapped using fitted variograms. The nitrate spatial distribution shows that nitrate pollution is a persistent problem affecting a wide area of the aquifer. The hydrochemical investigations and cluster analysis reveal four significant clusters of groundwater zones. Five main factors were extracted, which explain >77% of the total data variance. These factors indicated that the chemical characteristics of the groundwater were influenced by rock-water interactions and anthropogenic factors. The identified clusters and factors were validated with hydrochemical investigations. The geogenic factors include the dissolution of various minerals (calcite, aragonite, gypsum, anhydrite, halite and fluorite) and ion exchange processes. The anthropogenic factors include the impact of irrigation return flows and the application of potassium, nitrate, and phosphate fertilizers. Over time, these anthropogenic factors will most likely contribute to further declines in groundwater quality.

Groundwater Characteristics and Pollution Assessment Using Integrated Hydrochemical Investigations GIS and Multivariate Geostatistical Techniques in Arid Areas

In arid areas, groundwater quality is an important concern for human life and natural ecosystems. Rapid economic development impacts greatly on limited groundwater resources. This study examines the impacts of natural and anthropogenic contaminations on groundwater quality by integrating hydrochemical investigations, GIS and multivariate geostatistical techniques. Major and trace elements in groundwater were analyzed to evaluate the shallow alluvial aquifer connected to the fractured basement aquifer in the Jazan area of Saudi Arabia (KSA). Results show that the groundwater of the aquifer inland is generally under free conditions and is declining with time, while in the coastal areas, there is a disturbance of the groundwater balance resulting in upward leakage of deep saline water and seawater intrusion. Groundwater types are varied from calcium bicarbonate to sodium chloride, reflecting meteoric water recharge to seawater influence. The pollution risk is high, since the water table is shallow and the aquifers are highly permeable. Urbanization has put stress on groundwater quality due to wastewater contamination from pit latrines and leakage from the unrehabilitated sewage system. Chemical equilibrium and saturation indices were calculated, showing that most of the water samples were under-saturated with respect to anhydrate, aragonite, calcite, dolomite, gypsum and halite mineral phases. This affects carbonate and evaporite minerals in the aquifer, causing ground subsidence and sinkholes in the coastal area. Factor and cluster analyses were used to classify and examine the processes affecting groundwater quality. The main factors impacting on the groundwater hydrochemistry were identified as: dissolution of several minerals, evaporation, human impact, mixing between geothermal and other waters as well as rainfall recharge.

Proposed hydrostratigraphical classification and nomenclature: application to the Palaeozoic in Saudi Arabia

Abstract Despite the need of stratigraphers and hydrogeologists for a hydrostratigraphical classification, such widely accepted classification is lacking and was ignored by the 1983 code of the North American Commission on Stratigraphical Nomenclature (NACSN). This study is an attempt to fill this vacuum. A simple and universally applicable hydrostratigraphical classification scheme is introduced here which takes into consideration the physical properties of the rocks, especially porosity and permeability, in addition to other variables such as thickness of the unit and its areal extent. The proposed hydrostratigraphical classification is a hierarchical scheme composed of two types of hydrostratigraphical units: aquizones and aquitards, which differ significantly in their intrinsic permeabilities. Aquizones include five ranks which are named in ascending order: subaquifer, aquifer, superaquifer, aquagroup and aquasystem. The aquifer is the fundamental unit. Aquitards are divided into mini-aquitards, meso-aquitards and mega-aquitards differing in their thicknesses and lateral continuities. Hydrostratigraphical units are easier to recognise on geophysical logs than lithostratigraphical units; they have fewer boundaries and therefore, it is easier for hydrogeologists to identify them. To test the applicability of the proposed classification the Palaeozoic succession of Saudi Arabia has been chosen to illustrate such an application. The stratigraphical interval between the Precambrian Arabian Shield aquifuge below and the Lower Triassic Sudair mega-aquitard above is named here the Najd Aquasystem, whose boundaries largely coincide with those of the Palaeozoic Erathem. The Najd Aquasystem, in turn, is divided into two aquagroups called the Buraydah below and the Widyan above and separated by the 600 m-thick Qusaiba Mega-aquitard.The Buraydah Aquagroup is composed of two superaquifers: the Saq and the overlying Hail, whereas the Widyan Aquagroup is divided into two superaquifers named the Jalamid below and the Rafhah above. Each of these superaquifers is composed of two named aquifers separated from each other by aquitards of different ranks. the hydrogeological characteristics of each aquifer were briefly discussed.

Combined geo‐electrical and hydro‐chemical methods to detect salt‐water intrusion

Purpose – Salt‐water intrusion has always been a source of contamination in coastal aquifers that hinders sustainable groundwater development. Classical techniques to detect its occurrence are costly and time consuming. The application of combined geo‐electrical and hydro‐chemical methods is cheaper, executable in reasonable time, and successfully applied in mapping the interface between saline and fresh groundwater. The current study aims at detecting and delineating salt‐water intrusion in the downstream part of Wadi Gizan in southwest Saudi Arabia using geo‐electrical and hydro‐chemical methods.Design/methodology/approach – The case study area is the downstream part of Wadi Gizan in southwestern Saudi Arabia. Geo‐electrical data were obtained from field measurements using both Shlumberger and Wenner procedures. A number of 65 groundwater samples were collected and analysed for its total dissolved solids and major ionic composition.Findings – The results show variations in the resistivity of the water‐b...

Determination of hydrochemical processes and classification of hydrochemical facies for the Sakakah Aquifer, northeastern Saudi Arabia

Abstract The Sakakah Aquifer is a hydrostratigraphical unit that is being exploited in the northeastern part of Saudi Arabia (Sakakah region). This area has received increasing attention since 1965, when economic reserves of phosphorite deposits were discovered. The population of the area, as well as demand for groundwater, has increased since then. Therefore, hundreds of groundwater wells were drilled, tapping the Sakakah Aquifer and other water bearing units. Groundwater of the Sakakah Aquifer was found to range in quality between fresh (potable) water and relatively saline water (TDS exceeds 3000 ppm). In the present study, several hydrochemical techniques were used to classify water type facies and to determine the hydrochemical processes controlling the water quality variations. Firstly, the classification of water type facies was done through the use of Durov diagrams. Secondly, the hydrochemical processes were determined by observing the water quality changes down-gradient. This is done by constructing hydrochemical cross-sections. Thirdly, the stoichiometric balance was checked by utilizing the x-y relationships between the major dissolved constituents. The Sakakah groundwater was classified into three distinct facies. Water type I is a calcium bicarbonate water with Na becoming important. This water type is believed to be recharge water of recent origin. Water type III is relatively saline sodium chloride water. This water is believed to be fossil water of old origin residing in the interstices. Water type II represents a mixture of the previous two types. Several hydrochemical processes have an influence on the Sakakah Aquifer groundwater facies. The most influential of these processes are mixing and ion-exchange. Oxidation occurs in the low salinity zone, as O enriched recharge water reaches the aquifer through fault planes and fracture zones. Therefore, the structural complexity of the study area also plays an important role in controlling water quality. Finally, reduction reactions may occur in isolated cases and do not represent a trend of any kind.

Utilizing potential field data to support delineation of groundwater aquifers in the southern Red Sea coast, Saudi Arabia

In this paper potential field data are interpreted to map the undulation of the basement surface, which represents the bottom of the water bearing zones, and to delineate the tectonic framework that controls the groundwater flow and accumulation in the southern Red Sea coastal area of Saudi Arabia. The interpretation reveals that the dominant structural trend is a NW (Red Sea) trend that resulted in a series of faulted tilted blocks. These tilted blocks are dissected by another cross-cut NE trend which shapes and forms a series of fault-bounded small basins. These basins and the bounded structural trends control and shape the flow direction of the groundwater in the study area, i.e. they act as groundwater conduits. Furthermore, the present results indicate that volcanic intrusions are present as subsurface flows, which hinder the groundwater exploration and drilling activities in most of the area; in some localities these volcanic flows crop out at the surface and cover the groundwater bearing formations. Furthermore, the gravity and magnetic data interpretation indicates the possible existence of a large structural basin occupying the southeastern side of the study area. This basin is bounded with NW and NE trending faults and is expected to be a good host for groundwater aquifers; thus it is a promising site for hydrogeological investigation.

Upconing and Saline Water Intrusion and the Need for Water Conservation in the Lower Part of Wadi Fatimah, Western Saudi Arabia

Shallow aquifers were exploited in western Saudi Arabia a long time ago in history. In the last five decades, and under the conditions of an increasing supply of water, many new wells were drilled at relatively deeper intervals than the hand-dug wells of the time. In the downstream part of Wadi Fatimah, and over time, more saline water has been brought up in a number of wells. Overexploitation of groundwater for industrial and agricultural purposes has led to the appearance of two phenomena responsible for the salinization-upconing and saline water intrusion. Upconing occurs in separate pockets while saline water encroachment affects the lower part of Wadi Fatimah and the area towards the Red Sea coast. This article deals with the identification and delineation of areas affected by each of the two phenomena. The methodologies used in this work are mainly hydrogeological and hydrochemical. Resistivity surveys helped in delineating the fresh water-saline water interface. Methods to control upconing and saline water intrusion are suggested to safeguard the aquifer from further contamination. Effective conservation measures are recommended for the protection of groundwater resources in Wadi Fatimah.

Desalination of Seawater Using Geothermal Energy for Food and Water Security: Arab and Sub-Saharan Countries

Abstract Future war will be fought for water. The number of water stressed countries around the world is increasing exponentially with growing population and demand for food. This especially true with respect to Gulf Cooperation Council, Middle East and North Africa, and sub-Saharan countries. Food imports by these countries will exceed > 100 million tons from current 68 million tons. Countries are craving to get into virtual water trade to secure food. These countries have ample geothermal energy resources lying unexploited. An excellent example is Kenya which is able to generate 1228 million kWh electricity from geothermal and another 27,800 million kWh is waiting to be developed. Other countries too have similar geothermal resources waiting to be developed. Governments should adopt suitable energy policies and given priority to develop geothermal energy. The desalinated water could be sold at

Extreme Natural Hazards, Disaster Risks and Societal Implications: Natural hazards in Saudi Arabia

As the name implies Natural Hazards are naturally occurring events that can endanger human lives and property. During the past few decades the losses to life and property from natural hazards have increased many folds mainly due to the increase in human population resulting in the inhabitation of areas prone to hazards. Saudi Arabia is quite prone to different kinds of natural hazards. The North western region of the kingdom is prone to earthquakes and volcanic hazards whereas the central and western region of the kingdom is exposed to floods especially during events of heavy rainfall. Landslides are a common phenomenon in the inhabited mountainous regions of the south west. Dust storms are quite common in the central and the eastern regions of the Kingdom. Pollution of natural resources specially groundwater has also been seen in the kingdom in the recent years especially around the wadis and agricultural farms where the extensive use of fertilizers for increasing agricultural yields have resulted in polluting the aquifers. Different government agencies and various universities having been working on these issues, to mitigate these hazards and also educate the people. The SGS Chair on Natural Hazards established at the King Saud University is one such effort in addressing this subject. Due to the 2009 Jeddah flood disaster more emphasis is being given to tackle the problems related to hydrological hazards. Similar events like this have the potential to affect other major cities of the Kingdom.