The North Western Sahara Aquifer System (NWSAS) is characterized by unsustainable groundwater exploitation whose magnitude depends on the still unclear recharge value. It is extending over Libya, Tunisia, and Algeria, with an area of 10⁶ km². Here, we proposed an integrated approach combining Gravity Recovery and Climate Experiment (GRACE) and Global Land Data Assimilation System (GLDAS) data to reconstruct groundwater storage variations (ΔGWS) between April 2002 and July 2016. ΔGWS values are then introduced in a regional water budget equation accounting for the temporal evolution of withdrawals and natural discharge to calculate the time variations of the recharge. Yearly reconstruction of the recharge shows a large variability with alternation of net positive recharge and periods of net diffuse discharge associated with evaporation. The temporal average effective recharge value for the period of interest is 1.76 ± 0.44 mm yr⁻¹. Lag-times for the recharge to reach the water table of 45 and 100 yrs characteristic of a diffuse recharge and corresponding vadose thickness in the range 3.90 ± 3.60 and 8.60 ± 8.10 m were identified using a cross-correlation analysis between reconstructed annual recharge and annual rainfall (AR). Statistical interpretation of the relation between ΔGWS, AR, and withdrawals shows that the anthropogenic effect (groundwater extraction) is the main controlling factor (99% of explained variance) in comparison to AR variations for the ΔGWS time series under consideration. A relation between long-term recharge and average annual rainfall (AAR) suggests a recharge representing 1.8 ± 0.3% of AAR in transboundary aquifers of the Saharan belt.

Data from the Earth Gravitational Model (EGM2008) and the Earth Magnetic Anomaly Grid (EMAG2) were used to develop a continental scale crustal thickness model for Africa, and to estimate the depth to the bottom of the magnetic layer (DBML) and the geothermal gradient and heat flow. The results are: (1) the estimated DBML from the magnetic data varies from ~23.0 to ~37.2 km. The shallowest DBML values are located in the northern, eastern, and western parts of the continent, whereas the deepest values are observed in the central and southern regions. (2) The estimated crustal thickness based on gravity data varies from ~29.9 km in the northern and western parts of Africa to ~48.0 km in its southern regions, with an average thickness of 35.1 km for the whole continent. (3) The estimated heat flow varies between high values of 46–59 mW/m², observed in the northern, eastern, and western regions to low values of ~< 41 mW/m², observed in the central and southern parts of the continent. (4) The geothermal gradient values vary between 14.5 and 23.6 °C/km (5) The East African rift zone is underlain by shallow DBML characterized by high heat flow values that vary between 42 and 59 mW/m² (6) The heat flow anomalies in Egypt and Libya may be associated with the zone of the Pelusium megashear system, and it shows heat flow values that vary between 36.3 and 59.0 mW/m². The current study has taken advantage of the availability of the EGM2008 and EMAG2 datasets to map crustal thickness variations and DBML beneath the continental landmass of Africa.

The antimony tri-sulphide (Sb₂S₃) films were prepared by thermal evaporation technique. Four thicknesses (300, 521, 643 and 789 nm) were investigated. X-ray diffraction (XRD) analysis showed the amorphous structure of Sb₂S₃ films. Optical analyses revealed that Sb₂S₃ films exhibited optical energy gap between (1.98–1.16 eV) relaying on the film thickness. The films absorption coefficient was found to be higher than 2 × 10⁴ cm⁻¹(above its related optical energy gap) which makes these films reliable absorbers in photovoltaic applications. Optical constants were analyzed using Swanipole's method. The dark dc conductivity measurements of Sb₂S₃ thin films were conducted in the temperature range 298–503 K. The conduction mechanize was analyzed via Mott's variable -range hopping in three dimensions model. The correlated conductivity mechanize with increasing film thickness changed from extended