This review examines state-of-the-art practices in water harvesting and groundwater recharge, emphasizing their crucial role in sustainable water resource management. Groundwater, a crucial resource for drinking and agricultural water, is facing depletion due to the combined effects of urbanization, climate change, and unregulated extraction. This paper provides a comprehensive overview of contemporary knowledge on water harvesting and recharge, using a systematic four-step methodology to identify and analyze relevant studies from databases like Google Scholar, Scopus, and ScienceDirect. It categorizes water harvesting techniques, such as rainwater, flood water, and groundwater harvesting, and evaluates their effectiveness in enhancing recharge. Both natural and artificial recharge methods are explored, highlighting their role in improving groundwater levels and water quality. This study also reviews recharge estimation techniques and their applicability across hydrogeological contexts. This paper promotes a balanced approach to address issues of water scarcity by integrating water harvesting into groundwater management strategies. This integration aims to build resilience against climate change-driven environmental damage. Recommendations are provided to enhance the sustainability of these practices, with a particular focus on arid and semi-arid regions where water demand is rising. Overall, this study underscores the significance of water harvesting and recharge in promoting long-term resource sustainability.

The management and monitoring of the quality of water resources in the Mekelle area are challenging, due to both geogenic and anthropogenic impacts. The extent of these impacts and the sources of pollution in this area have not been thoroughly investigated. In this article, a mapping of water resources vulnerability was carried out using the DRASTIC method and a modified DRASTIC vulnerability map was produced. Single-parameter and map-removal sensitivity analyses were performed on the relevant rates and weights. A final DRASTIC vulnerability index, varying from 54 to 140, was divided into four vulnerability classes: low (225.7 km²), medium (302.8 km²), high (307.2 km²), and very high (187.6 km²); the values in the parentheses indicate the corresponding areal coverage of each class. Similarly, a modified DRASTIC vulnerability index, ranging from 91 to 192, was divided into four vulnerability classes: low (166.4 km²), medium (266.8 km²), high (338.0 km²), and very high (252.2 km²) Nitrates were used to validate both models. in which moderate positive correlations (with Pearson’s correlation coefficient, r) of 0.681 and 0.702 were calculated for the DRASTIC and modified DRASTIC indices, respectively. A comparison of the two maps showed that significant sources of pollution are located in areas with high to very high vulnerability. The results of this research work can be used for the protection and monitoring of groundwater resources in the Mekelle area.

This study provides a comprehensive analysis of the groundwater potential of hard rock aquifers in five diverse African case study areas: Lake Tana Basin and Beles Basin in northwestern Ethiopia and Mount Meru in northern Tanzania (comprising volcanic aquifers); the Mekelle area in northern Ethiopia and Jifarah Plain in Libya (consisting of sedimentary aquifers). The evaluation of recharge, transmissivity, and water quality formed the basis of qualitative and quantitative assessment. Multiple methods, including water table fluctuation (WTF), chloride mass balance (CMB), physical hydrological modeling (WetSpass), baseflow separation (BFS), and remote sensing techniques like GRACE satellite data, were employed to estimate groundwater recharge across diverse hydrogeological settings. Topographic contrast, fractured orientation, lineament density, hydro-stratigraphic connections, hydraulic gradient, and distribution of high-flux springs were used to assess IGF from Lake Tana to Beles Basin. The monitoring, sampling, and pumping test sites took into account the high hydromorphological and geological variabilities. Recharge rates varied significantly, with mean values of 315 mm/year in Lake Tana Basin, 193 mm/year in Mount Meru, and as low as 4.3 mm/year in Jifarah Plain. Transmissivity ranged from 0.4 to 6904 m²/day in Lake Tana Basin, up to 790 m²/day in Mount Meru’s fractured lava aquifers, and reached 859 m²/day in the sedimentary aquifers of the Mekelle area. Water quality issues included high TDS levels (up to 3287 mg/L in Mekelle and 11,141 mg/L in Jifarah), elevated fluoride concentrations (>1.5 mg/L) in 90% of Mount Meru samples, and nitrate pollution in shallow aquifers linked to agricultural practice. This study also highlights the phenomenon of inter-basin deep groundwater flow, emphasizing its role in groundwater potential assessment and challenging conventional water balance assumptions. The findings reveal that hard rock aquifers, particularly weathered/fractured basalt aquifers in volcanic regions, exhibit high potential, while pyroclastic aquifers generally demonstrate lower potential. Concerns regarding high fluoride levels are identified in Mount Meru aquifers. Among sedimentary aquifers in the Mekelle area and Jifarah Plain, limestone intercalated with marl or dolomite rock emerges as having high potential. However, high TDS and high sulfate concentrations are quality issues in some of the areas, quite above the WHO’s and each country’s drinking water standards. The inter-basin groundwater flow, investigated in this study of Beles Basin, challenges the conventional water balance assumption that the inflow into a hydrological basin is equivalent to the outflow out of the basin, by emphasizing the importance of considering groundwater influx from neighboring basins. These insights contribute novel perspectives to groundwater balance and potential assessment studies, challenging assumptions about groundwater divides.

Armed conflicts continue to severely impact human populations and essential infrastructure, particularly water supply systems. This study examines the Yechilla area, a high-intensity battle corridor during the Tigray (between 12°15′26″ 14°57′49″ N latitude; and 36°20′57″–39°58′54″ E longitude) war (2020–2022). Using Cochran’s formula, a representative sample of 89 water schemes was selected for onsite assessment. Additional data on damages to water offices, personnel, equipment, and related infrastructure were gathered through face-to-face interviews with local officials and water professionals, onsite visits, and reviews of governmental and non-governmental archives, and previous studies. The findings reveal that 48.3% of water schemes in the study area are non-functional (does not deliver water), which is a significant increase from pre-war non-functionality rates of approximately 7.1% regionally and 21.1% nationally. Despite the Pretoria peace agreement, non-functionality levels remain critically high two years after conflict. Damage includes partial impairments, lack of technical and spare part support, complete destruction, and looting of water scheme components. The widespread destruction of civilian water infrastructure during the Tigray conflict underscores the insufficiency of existing international legal frameworks, such as the International Humanitarian Law and International Water Law, which are inadequately protecting civilians and their property. Understanding the broader consequences of armed conflicts requires examining the indirect effects and the complex interactions within and between social, economic, and environmental systems. These interconnected impacts are essential to fully grasp how conflict affects livelihoods and human security on a wider scale.

Background: Hypersaline environments are dynamic ecosystems, the chemistry of which is significantly influenced by climate change, which in turn impacts the microbiota and biogeochemical processes. This study investigates the microbiome of Lake Karum, a hypersaline lake in the Danakil Depression, Ethiopia, with a particular focus on genome-based potential of climate-relevant biogeochemical processes. Results: The microbiomes of Lake Karum sediments and waters were dominated by halophilic Archaea ( Halobacteriota ) and Bacteria ( Bacteroidota , Pseudomonadota , and Cyanobacteriota ), with significant variation in community composition among sites, reflecting geochemical heterogeneity. Despite these taxonomic differences, sediment and water metagenomes exhibited broadly overlapping functional gene profiles. Genes involved in denitrification, carbon monoxide oxidation, osmotic stress tolerance, and utilisation of osmolytes were widespread and predominantly affiliated with Halobacteriales, indicating their pivotal role in nitrogen and carbon cycling. Genome‑resolved analyses revealed substantial intrageneric variation in metabolic potential within dominant halobacterial lineages as well as bacterial candidate phyla, including Candidatus Bipolaricaulota and Candidatus Salsurabacteriota, which encode genes linked to trace-gas metabolism and nitrogen cycling. Notably, a high‑quality metagenome‑assembled genome assigned to the Candidatus Salsurabacteriota was recovered that possesses novel combinations of functional genes not previously reported for this lineage. Conclusion: This study provides a comprehensive genome‑resolved assessment of the taxonomic and functional diversity of the Lake Karum microbiome and identifies microbial taxa with the potential to drive key carbon, nitrogen, and sulfur cycling processes in a hypersaline lake. By revealing previously unrecognised metabolic capabilities within bacterial candidate phyla and highlighting intrageneric functional heterogeneity among dominant halophilic Archaea , this work advances understanding of how hypersaline microbial communities contribute to biogeochemical cycling in extreme environments.