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The integration of geophysical techniques with hydrological investigation is frequently used for solving different geological and environmental problems including groundwater quality and exploration and seismic vulnerability assessment. In this research, the shallow geophysical techniques comprising of electrical resistivity profiling, vertical electrical sounding, and ground magnetic were used to identify the contaminated areas lying in the upstream and downstream of Almisk Lake in Jeddah. The chemical analyses of water samples collected from the wells located in the downstream and upstream areas were used to support these results as an increase in the total dissolved solids (TDS) shows a decrease in the resistivity value. The results of geophysical techniques and hydrochemical analyses show that the TDS values are significantly higher in the upstream area of dam than those of the downstream, which suggests that the contaminating source is lying in the upstream of the reservoir. Moreover, the dam was not completely successful to block the contamination because of improper base. The hydrochemical analysis and geophysical results clearly indicate that the groundwater is not suitable for drinking and irrigation purposes.

The soil conditions variability at site strongly influence ground motions during earthquakes. The disastrous earthquakes have shown that the local site conditions are the essential factors that impact surficial ground motions. In present study, local site effects are evaluated for ground motion acceleration and amplification at Bahrah. The town is situated on quaternary alluvial wadi deposits. The ground motion time series are obtained through Spectral matching technique.. The ground motion time series and shallow Geophysical data are utilized to carry out One-dimensional simulation for equivalent linear seismic response analyses for soil layers. Results of One-dimensional site response analysis are interpolated to generate maps that account for ground motion accelerations and amplifications at top of the soil for selected spectral periods (PGA, 0.1, 0.2 and 2) for 475 years return period. The maximum value of amplification ranges upto 3.46 and acceleration upto 0.86 g. The undulation of bed rock topography and existence of deep soft sediments are reflected considerably on the results of the study area. [ABSTRACT FROM AUTHOR]

Waste management, especially dump sites, are the most important problems in developing countries. For Al Misk Lake (Buraiman Lake), there is a threatening environmental problem, as for more than ten years this lake was used for the waste disposable site of Jeddah's sewage. Now it is abandoned, but the leachout of the contaminant is still problem. A concrete dam was constructed to block the migration of contaminants from the lake. The purpose of this research is to use the results of geophysical method integrated with the hydrogeological studies in delineating the contaminant layer emanating from the seepage of sewage water from Al Misk Lake to the end of Wadi after the concrete dam. Vertical electrical sounding was applied to determine the contaminated layer thickness in front and back of the dam. Also, the water samples were collected from some wells to support the results of geophysical method. Results of the vertical electrical sounding show that there is a seepage of contaminated water in front of the dam and the thickness of the contaminated layer at the back of the dam towards lake side is more than that in the front of dam. Whereas, the hydrogeological studies also show the concentration of ions, and TDS are more in back of the dam than in the front. [ABSTRACT FROM AUTHOR]