Geometry of the Magma Chamber and Curie Point Depth Beneath Hawaii Island: Inferences From Magnetic and Gravity Data

This study used land gravity and airborne magnetic data to investigate the depth to the magmatic chamber and map the heat flow distribution beneath the active volcanoes of Hawaii Island using the Curie point depth (CPD) and gravity modeling. Obtaining some of the ground-based geophysical measurements was problematic due to accessibility limitations; therefore, this study used available data. The CPD and magnetic data were used to map the depth to the bottom of the magnetic layer by calculating the depth to the Curie isotherm (540°C) beneath Hawaii Island. The spectral peak method was used to calculate the depths to the shallow and deep magnetic sources for the entire island, and the CPD was calculated using the centroid method. A two-dimensional density model for two Earth layers was constructed using forward modeling of the gravity data. A large plume of dense intrusive material was observed beneath the three adjacent volcanoes of Mauna Loa, Mauna Kea, and Kilauea, and two small chambers were found to be located beneath the Kohala and Hualalai volcanoes. Based on the gravity modeling results, the depth to the magma layer varied from 0.5 to 10 km, and the heat flow was higher close to the volcanic eruption zones. The current study is informative and cost effective for the world’s most active volcanic areas.Water Resource

The Groundwater Flow Behavior and the Recharge in the Nubian Sandstone Aquifer System during the Wet and Arid Periods

The Nubian Sandstone Aquifer System (NSAS) is made up of three major sub-basins: Kufra, Dakhla, and the N. Sudan Platform. It is one of the world’s largest groundwater systems. The aquifer’s hydrologic setting, connectivity of its sub-basins, and groundwater flow across these sub-basins are currently unclear. To address these issues, we used a combined approach that included: (1) a regionally calibrated groundwater flow model that mimics early (>10,000 years) steady-state conditions under wet climatic periods and later (<10,000 years BP–1960; 1960–2010) transient conditions under arid climatic periods; and (2) groundwater ages (36 Cl,81 Kr) and isotopic (18 O,2 H) data. The NSAS was recharged on a regional scale in previous wet climatic periods; however, in dry periods, its outcrops are still receiving local modest recharge. A progressive increase in36 Cl groundwater ages was found along groundwater flow directions and along structures that are sub-parallel to the flow direction. The NE–SW Pelusium mega shear zone is a preferential groundwater flow conduit from the Kufra to the Dakhla sub-basin. The south-to-north groundwater flow is hampered by the Uweinat–Aswan basement uplift. The findings provide useful information about the best ways to use the NSAS.Water Resource

Monitoring Mass Variations in Iraq Using Time-Variable Gravity Data

Iraq is facing a water shortage due to water scarcity and anthropogenic activities. The recent advance in technologies in geophysical methods has made groundwater monitoring possible. Time-variable gravity data and outputs of the climatic model, as well as rainfall data, are integrated to investigate the spatio-temporal mass variations caused by groundwater changes over Iraq. The findings are: (1) For the entire study period (04/2002–12/2020), Period I (04/2002–12/2006), Period II (01/2007–12/2017), and Period III (01/2018–12/2020), the study region had an average annual precipitation rate of 223.4, 252.5, 194.2, and 311.6 mm/y, respectively. (2) The average Terrestrial Water Storage variations (ΔTWSs) varied from −5.79 ± 0.70 to −5.11 ± 0.70 mm/y based on the three different gravity solutions with a mean of −5.51 ± 0.68 mm/y for the entire investigated period. (3) For Periods I, II, and III, the average ΔTWS fluctuation was calculated to be +6.82 ± 1.92, −6.20 ± 1.17, and +28.58 ± 12.78 mm/y, respectively. (4) During the entire period, Periods I, II, and II, the groundwater fluctuation was averaged at −4.86 ± 0.68, +2.47 ± 2.20, −3.79 ± 1.20, and −4.63 ± 12.99 mm/y, respectively, after subtracting the non-groundwater components. (5) At the beginning of the 2007 drought during Period II, a decline in rainfall rate, and significant groundwater withdrawal during Period III all appear to have contributed to groundwater depletion. The Euphrates and Tigris Rivers, as well as the Mesopotamian plain, receive water from the running streams created by the ground relief. The area of the Mesopotamian plain, which has a thicker sedimentary sequence that can reach 9000 m, is found to have a positive TWS signal, indicating that its groundwater potential is higher. The integrated approach is informative and cost-effective.Water Resource

Application of Time-Variable Gravity to Groundwater Storage Fluctuations in Saudi Arabia

In the Middle East, water shortage is becoming more and more serious due to the development of agriculture and industry and the increase in population. Saudi Arabia is one of the most water-consuming countries in the Middle East, and urgent measures are needed. Therefore, we integrated data from Gravity Recovery and Climate Experiment (GRACE), and other relevant data to estimate changes in groundwater storage in Saudi Arabia. The findings are as follows: 1) Average annual precipitation (AAP) was calculated to be 76.4, 90, and 72 mm for the entire period, Period I (April 2002 to March 2006) and Period II (April 2006 to July 2016), respectively. 2) The average TWS variation was estimated to be −7.94 ± 0.22, −1.39 ± 1.35, and −8.38 ± 0.34 mm/yr for the entire period, Period I and Period II, respectively. 3) The average groundwater storage was estimated to be +1.56 ± 1.35 mm/yr during Period I. 4) The higher average groundwater depletion rate was calculated to be −6.05 ± 0.34 mm/yr during Period II. 5) Both soil texture and surface streams in the study area promote lateral flow and carry surface water to the Arabian Gulf and the Red Sea. 6) During Period II, average annual recharge rates were estimated to be +9.48 ± 2.37 and +4.20 ± 0.15 km3 for Saudi Arabia and the Saq aquifer, respectively. 7) This integrated approach is an informative and cost-effective technique to assess the variability of groundwater resources in large areas more efficiently.Water Resource

Detection of Mineralization Zones Using Aeromagnetic Data

Every day, mining corporations grow and develop over Egypt’s Eastern Desert in search of gold, silver, and other metals. Mineral resources in Egypt are a powerful tool for increasing national income. In this study, we are interested in mineral exploration, such as gold and porphyry deposits, using aeromagnetic data, applying various processing techniques such as First Vertical Derivative, Total Horizontal Gradient, Analytical Signal, Tilt Derivative, and the center of exploration targeting. The study area is located at the Central Eastern Desert, which includes the Barramiya, Abu Marwa, and Abu Mireiwah regions. The analysis of the delineated structural trends shows that the N–S, NW–SE, and NE–SW are the most effective directions for managing deposits in the investigated area. A minor trend is also shown in the E–W direction and corresponds to the alteration zones reported by geology and prior investigations. Mineralization zones occur most frequently at the contact between ophiolitic serpentinite, sediments, and other rock types. This study intends to add more about the use of the recently developed technology of CET grid analysis for mineral exploration and structural interpretation across the Central Eastern Desert. The CET porphyry analysis map shows locations where several occurrences of porphyry deposits are probable. The newly discovered spots are similar to the area’s usual deposit sites. This study proves that aeromagnetic data are significant in mineral exploration since they are useful for the discovery of the structure and shear zones controlling the mineralization zones.Water Resource

Hydro-Geochemical Applications and Multivariate Analysis to Assess the Water–Rock Interaction in Arid Environments

Thirty groundwater samples were taken from Assiut’s northern outskirts. The physicochemical properties of these samples were investigated. For the evaluation of water–rock interaction, the saturation index (SI), chloro-alkaline indices (CAI1 and CAI2), Gibbs ratios for cations and anions (GC and GA), principal component analysis (PCA), and hierarchical cluster analysis (HCA) were used. (1) With the exception of five samples that were supersaturated, the rest of the groundwater samples were under-saturated with carbonate mineral dissolution (calcite, dolomite, and aragonite) and evaporite mineral dissolution (anhydrite, gypsum, halite, and sylvite). (2) The presence of ion exchange between alkali elements (Na+ + K+) and earth alkaline elements (Ca2+ + Mg2+) is explained by the positive values of the chloro-alkaline indices. (3) In four groundwater samples, negative chloro-alkaline indices suggest reverse ion exchange and an increasing alkali element content. (4) The Gibbs diagram demonstrates that, with the exception of four samples that reflect saline groundwater, the majority of the groundwater samples are freshwater recharging from the fresh surface water in the research area. (5) Groundwater types include Ca-HCO3 (11%), Mg-HCO3 (48%), Na-HCO3 (23%), Mg-Cl (13%), and Na-Cl (3%). (6) The alkali, earth alkaline elements, and sulphate are the key controls on groundwater salinity, according to PCA and HCA. (7) The somewhat saline groundwater in the research area’s western desert margins should not be used since it poses a health danger to people.Water Resource

Geophysical investigations for the identification of subsurface features influencing mineralization zones

The numerous hydrothermal alteration zones and subsurface structures affecting the mineralized deposits of the Dungash region were identified using aeromagnetic data. The Center of Exploration Targeting (CET) approach and several filters, such as reduction-to-pole, Tilt derivative, First Vertical Derivative, Horizontal gradient map, Downward continuation, analytical signal methods, regional, and residual separation, were used to analyze the aeromagnetic data. The research region is impacted by several structural trends running in the N-S, E-W, NW-SE, and NE-SW directions, and these trends are strongly related to the gold mineralization and surrounding hydrothermal alteration zones. In the NW-SE direction, four alteration zones have been identified. The research region's northern and eastern regions have shallower basement relief, with depths of only approximately 100 m, and those depths show that the area is rootless. Conversely, the basement relief and surface depths are lower in the study region's western and southern regions. The routes taken by the ascending hydrothermal fluids can be seen as aeromagnetic lineaments at the hydrothermal alteration zones. Mineralization appears to be linked to structural lineaments, as evidenced by airborne magnetic data. For gold prospecting, the aeromagnetic technique seems to be the most effective and efficient geophysical method because gold is typically found in severely deformed shear zones and faults.Water Resource

Integrated Geophysical Assessment of Groundwater Potential in Southwestern Saudi Arabia

Saudi Arabia is seeking fresh groundwater resources to face the increase in anthropogenic activities. The groundwater storage variations and occurrence were investigated and the surface and subsurface structures influencing the groundwater resources in the research area were defined using a combined study of Gravity Recovery and Climate Experiment, aeromagnetic data, and electrical resistivity data with other relevant datasets. Results are: The groundwater storage fluctuation is calculated at −0.34 ± 0.01 mm/yr during the period 04/2002-12/2021. The area is receiving an average annual rainfall rate of 117.6 mm during the period 2002 to 2019. Three structural trends, defined in the directions of NS, NNW, and NNE are cutting the sedimentary cover and the basement rocks. The sedimentary cover ranges from 0 to 1.2 km thick. Vertical electrical sounding results indicate three main geoelectric layers: the surface geoelectrical layer of higher resistivity values (428-9626 Ω. m) is made up of unconsolidated Quaternary sediments; the water-bearing layer of saturated sands with a resistivity range between 5.1 and 153 Ω. m and with depths vary from 1 to 94 m, and highly fractured basement rocks with resistivity values ranging from 813 to 6030 Ω. m. The integrated results are useful in providing a comprehensive image of the study area’s surface and subsurface structures, as well as groundwater potential in the southwestern part of Saudi Arabia. Our integrated approach provides a reproducible model for assessing groundwater potential in arid and semiarid areas.Water Resource

Geophysical and Remote Sensing Assessment of Chad’s Groundwater Resources

Because of climate change and human activity, North and Central Africa are experiencing a significant water shortage. Recent advancements in earth observation technologies have made widespread groundwater monitoring possible. To examine spatial and temporal mass fluctuations caused by groundwater variations in Chad, gravity solutions from the Gravity Recovery and Climate Experiment (GRACE), climatic model outputs, and precipitation data are integrated. The results are as follows: (1) The investigated region experienced average annual precipitation (AAP) rates of 351.6, 336.22, and 377.8 mm yr−1, throughout the overall investigation period (04/2002–12/2021), Period I (04/2002–12/2011), and Period II (01/2012–12/2021), respectively. (2) Using the three gravity solutions, the average Terrestrial Water Storage Variations (ΔTWS) values are estimated to be +0.26 ± 0.04, +0.006 ± 0.10, and +0.64 ± 0.12 cm yr−1, for the overall study period, periods I, and II, respectively. (3) Throughout the full period, periods I, and II, the groundwater storage fluctuations (ΔGWS) are calculated to be +0.25 ± 0.04, +0.0001 ± 0.099, and +0.62 ± 0.12 cm yr−1, respectively after removing the soil moisture (ΔSMS) and Lake Chad water level trend values. (4) The country receives an average natural recharge rate of +0.32 ± 0.04, +0.068 ± 0.099, and +0.69 ± 0.12 cm yr−1, throughout the whole period, Periods I, and II, respectively. (5) The southern mountainous regions of Erdi, Ennedi, Tibesti, and Darfur are receiving higher rainfall rates that may recharge the northern part of Chad through the stream networks; in addition to the Lake Chad and the higher rainfall over southern Chad might help recharge the central and southern parts of the country. (6) A preferred groundwater flow path from the Kufra (Chad and Libya) to the Dakhla basin (Egypt) appears to be the Pelusium mega shear system, which trends north-east. The findings suggest that GRACE is useful for monitoring changes in groundwater storage and recharge rates across large areas. Our observation-based methodology provides a unique understanding of monthly ground-water patterns at the state level, which is essential for successful interstate resource allocation, future development, and policy initiatives, as well as having broad scientific implications for arid and semiarid countries.Water Resource

Use of insulation based on nanomaterials to improve energy efficiency of residential buildings in a hot desert climate

Building insulation based on nanomaterials is considered one of the most effective means of reducing energy consumption in the hot desert climate. The application of an energy-efficient insulation system can significantly decrease the energy consumed via a building’s air-conditioning system during the summer. Hence, building insulation has become an interesting research topic, especially with regards to the use of insulation based on nanomaterials due to their low U-values. In the present study, the use of nano vacuum insulation panels (VIPs) or polystyrene foam in the walls enabled a significant reduction in the annual energy consumption, a savings of 23% compared to the uninsulated wall in a study in New Aswan City. The application of nanogel glazing to the windows (two layers of clear glass filled with the nanogel) achieved approximately 11% savings in annual energy. This savings, twice that obtained by using double-glazed windows, could be due to the low U-value of nanogel compared to the U-values of argon or air. The embedded nanogel layer between two layers of argon and two layers of single clear glass showed a significant reduction in annual energy consumption, saving 26% compared to the use of a single layer of glass. Moreover, the integration between this window and embedded walls with 50 mm of polystyrene foam exhibited a significant improvement of energy efficiency by 47.6% while presenting the lowest value of simple payback period (SPP). This research provides a way for buildings to be insulated to make them more energy efficient as well as attractive from the economic standpoint.Water Resource