Detecting and mapping subsurface utilities in urban areas is crucial for identifying defects or damages in drinking and sewage pipes that can cause leaks. These leaks make it difficult to accurately characterize the pipes due to changes in their reflective properties. This study focused on detecting leaks originating from underground pipes and distinguishing between these various types of pipes. It also aimed to create a visual fingerprint model that displays the reflection characteristics of these pipes during different leak conditions, enabling efficient maintenance and handling procedures on the pipes. To achieve this, a finite-difference time-domain (FDTD) method was used to simulate two types of pipe materials with and without leak areas to construct different scenarios. Additionally, a ground-penetrating radar (GPR) field survey was conducted using a 600 MHz antenna in a part of the El Hammam area on Egypt’s northwest coast. The simulated images produced with numerical modeling were compared with the radar profiles obtained using GPR at particular locations. The numerical simulations and radar profiles demonstrated the noticeable influence of water leaks from the different pipes, wherein the reflection of saturated soil waves was interrupted due to the presence of saturated soil. Envelope and migration techniques were employed in a new application to accurately distinguish between different pipe types, specifically focusing on leak areas. The strong correlation between the real radar profile and the specific signal of a water pipe leak in the simulated models suggests that GPR is a reliable non-destructive geophysical method for detecting water pipe leaks and distinguishing between the different pipe materials in various field conditions. The simulated models, which serve as image-matching fingerprints to identify and map water pipe leaks, help us to comprehend reality better.

Since the early 1960s, near-surface seismic refraction tomography (SRT) has been extensively used as a non-invasive and cost-effective geophysical method to characterize complex geological structures for landslide investigation. This geophysical technique is able to characterize the slope material, the sliding surface's geometry, the landslide mass movement, the physical properties of media, and the water saturation effects on the slope. Therefore, this method has become an appropriate method due to the increasing progress of novel algorithms and the improvements of field-data collection systems. In this paper, we attempt to review the essential research that investigated various types of landslides influenced by water saturation and landslide materials and identified in various areas, since the year 2000. Significant conclusions obtained by applying different survey strategies and data processing algorithms in seismic refraction surveys are widely discussed concentrating on the advantages and disadvantages of this method. The main results obtained by the few available studies applying time-lapse SRT (TLSRT) are particularly analyzed.

In this study, we investigated the stability and reactivation of preexisting Tonghua landslide deposits in China, including the adjacent stable slope. We used an integrated approach, combining a multichannel analysis of surface waves (MASW) and electrical resistivity tomography (ERT). We used ERT to determine groundwater seepage paths, weathering conditions, water content, and the depth to bedrock. High-resolution two-dimensional (2D) shear-wave velocity MASW images, on the other hand, played an essential role in detecting both horizontal and vertical compositions, disjointedness, and sliding surfaces related to lithological borders. Based on seismic models, we considered four geological layers encountered in the stable slope, including fractured (gravel) and weathered (phyllite) materials, as a sliding mass. We combined the 2D resistivity profiles obtained to create pseudo-three-dimensional ERT images to estimate water-saturated and unsaturated masses. From the tomography results, we identified different preexisting deposits, including buried arable clay deposits, old accumulated earthflow deposits, a water accumulation zone, and a fissure runoff. Based on the resistivity results, the bottom of the earthflow deposits is susceptible to water, and oversaturation can reactivate the earthflow.

Groundwater quality assessment is of utmost importance for water security in arid areas, such as south of Wadi El-Farigh due to deficiency of recharge, high evaporation rates and groundwater demand for agricultural and drinking utilities. The physicochemical parameters of 25 groundwater samples were investigated. Major ion occurrence was sequenced as Na⁺ ˃ Ca²+ ˃Mg²⁺ ˃K⁺ and Cl⁻ ˃ SO₄^2- ˃HCO3 ⁻ ˃ CO₃ ^2- . The main groundwater hydrochemical facies was the (Na⁺+K⁺) (Cl⁻ + SO₄²-) type. The studied samples were fresh to brackish and weakly alkaline in nature. The chloro-alkaline indices demonstrate the exchange of Ca²⁺ and Mg²⁺ in groundwater with Na⁺ and K⁺ from the rock. The water quality index revealed that 80% of samples were appropriate for drinking, 8% were classified as poor, and 12% excellent. Depending on the calculated sodium absorption ratio, the studied samples were categorized as excellent for irrigation. All samples have a good level of residual sodium carbonate. The sodium absorption ratio and electric conductivity were plotted on the diagram of U.S. salinity laboratory and revealed that the moderate and high salinity with low sodium absorption ratio values could cause a negative impact on the crops. It is concluded that, silicate weathering, ion exchange and halite dissolution are the key factors affecting the chemical composition of water in the area of interest. So, the best solution would be to cultivate crops that are resistant to high salinity.