River basins in arid and semi-arid regions worldwide serve as lifelines for ecosystems, agriculture, and human populations. However, the impacts of climate change expose them to severe stress and pose significant challenges to their management. This review and synthesis present the current state of perennial river basins in Namibia, namely the Orange, Kunene, Okavango, and Zambezi. Historical observations reveal alarming declines in river discharge, with reductions of up to 70% in the Zambezi, 60% in the Orange, 50% in the Kunene, and 40% in the Okavango River during prolonged droughts. Recent hydrological data show that they are currently experiencing declines in their respective discharges. Transboundary agreements, such as the Kunene River Agreement and participation in the Orange-Senqu River Commission (ORASECOM), are some of the initiatives incorporated in management to improve regional cooperation. The review emphasises the need for stronger climate adaptation policies and initiatives to ensure long-term water security. By synthesising hydrological data, the paper provides insights for management to safeguard the country's river basins in an era of escalating climate uncertainty, offering a novel dual perspective approach rarely applied in semi-arid Southern African context.

In this study, we present a detailed geochemical characterisation and stable isotope systematics of silver (Ag) in a mining waste facility at the Namib Lead & Zinc mine in Namibia (Africa). We examined a series of flotation tailings and ore minerals to address two principal questions: (1) the distribution, chemical form and leachability of Ag, and (2) the local Ag isotopic signature(s) and its variability in relation to Ag speciation in the solid phase, as well as the fate of stable Ag isotopes. Our findings reveal a significant correlation between Ag and Pb concentrations, indicating that galena is the primary Ag carrier. Most importantly, all mild extractions mobilised only a minimal amount of Ag (<_ 1 wt.% of the total amount). This suggests that most Ag is associated with geochemically stable phases, specifically sulphides, which are not subjected to leaching and/or intensive weathering. Unlike other isotope studies, the present research demonstrates a homogeneous Ag isotopic signal in the tailings and individual ore samples with an average S109Ag value of-0%o (+/- 0.1, 2SD). Therefore, this study provides new knowledge and clearly supports the use of Ag isotopic data to track primary Ag sources globally, not only in Africa.

Until the discovery of palaeo-placer diamond deposits in the Umkondo sediments at Chiadzwa in the Marange area, and at Charleswood farm in the Chimanimani area in 2001 and 2008, respectively, the Mesoproterozoic Umkondo Basin was the least studied sedimentary basin in Zimbabwe. Previous studies have been concentrated on coeval igneous magmatism, referred to as the Umkondo Large Igneous Province (LIP), which manifests as dolerite dykes and sills covering large areas of Southern Africa and Antarctica. This paper aims to initiate a debate about the possible provenances of diamonds in the two placer deposits. While evidence including sedimentology and geochronology suggest that the primary sources of the Marange diamonds lie somewhere in the Zimbabwe craton to the west of the Umkondo basin, different theories are proposed especially for the provenances of the Chimanimani diamonds occurring in a grit high up the stratigraphy. The proposals for the source of the Chimanimani diamonds include; that the diamonds were transported from the Mozambique Facies sediments and other older terranes lying to the east of the Umkondo basin; and that the source was from within the basin itself or its immediate surroundings. The sizes and morphologies of the Chimanimani diamonds, and the nature of associated heavy minerals, are interpreted to favour the intra-basinal source for the diamonds, or a very proximal origin. This model is also supported by the known relationships between episodes of kimberlite emplacement and the various Large Igneous Provinces (LIPs). Some of these well constrained LIPs such as the Umkondo LIPs are likely to have been associated with emplacement of kimberlites close to or within the Umkondo basin. Such kimberlites would have been the sources of the Chimanimani diamonds in particular, and the Umkondo basin in general.

Water insecurity is shaped not only by water availability but also by governance and service systems, an issue that is increasingly pressing in cities. In the African policy context, the Africa Water Vision 2063 and Policy, positions water security and safe sanitation as central to achieving Agenda 2063. Framing household water insecurity through reliability and spatial equity, speaks directly to these continental aspirations. This study examines household water insecurity in three Namibian towns, (Ongwediva, Rundu, and Windhoek), which differ in their hydroclimatic conditions and water supply systems. Drawing on the 12-item Household Water Insecurity Experiences (HWISE) scale and supplementary survey data, we examine how the severity of household water insecurity varies across towns and across socio-spatial groups within each town. The findings show significant between- and within-town differences. Windhoek, the capital city and economic hub of the country, faces severe physical water scarcity. Respondents in Windhoek report lower water insecurity scores, which could be explained by the city’s long-standing investment in augmenting the water supply and consistent promotion of water demand management strategies. Rundu, the second-largest town, is located in a water-rich basin (the Okavango Basin) and has the highest household water insecurity scores. These findings could result from inadequate and ageing water infrastructure and institutional constraints that affect the continuity of supply. In Ongwediva, relatively high levels of service coverage do not fully protect households from insecurity, as the system remains vulnerable due to its dependence on a long-distance transboundary transfer corridor that is affected by other factors, such as power cuts. In town comparisons reveal that informal and higher-density suburbs tend to have higher insecurity scores than other residential areas. These findings suggest that household water security is rarely the result of hydrology alone. Infrastructure constraints, institutional capacity, and climate variability often intersect in ways that shape the reliability of water services.

Groundwater plays a critical role in urban water security across African cities, yet its management is often fragmented amid rapid urbanization, population growth and climate variability. This study provides an overview of groundwater development approaches in Lusaka (Zambia) and Windhoek (Namibia), two cities with contrasting hydrogeological settings but similar water security challenges. Through a comparative review of literature and secondary data, the study identifies knowledge gaps and transferable strategies. In Lusaka, over 50% of potable water is drawn from a vulnerable karst aquifer increasingly stressed by population growth. In contrast, Windhoek manages its aquifer as a strategic storage reserve by incorporating artificial recharge systems that inject over 2.8 million m3 annually. The city further strengthens water security through potable water reuse which contribute about 30% of supply. This integrated approach has enabled Windhoek to diversify water sources, enhance resilience to climatic and population pressures, and optimise the use of water resources in a semi-arid environment. Key lessons include the need for aquifer protection in rapidly urbanizing areas, the role of managed aquifer recharge, efficient water use, source diversification, and robust regulatory frameworks. The findings underscore the importance of regional knowledge exchange and climate-adaptive groundwater policies to safeguard urban groundwater sustainability.

Land use and land cover (LULC) change serve as a major control on groundwater recharge, especially in urbanizing regions. This study assessed the impacts of LULC change on recharge to the Lusaka Aquifer, Zambia, between 1990 and 2022 using an Earth Observation (EO) based Water Balance Method (WBM). Recharge estimates were evaluated using the Water Table Fluctuation (WTF) and empirical methods for consistency and plausibility assessment. Results indicated a substantial decline in seasonal recharge from 212.7 mm in 1990 to 147.7 mm in 2022 driven by expansion of built-up areas (830.49%) and loss of forest cover (67.10%). Pronounced reductions in recharge occurred in 2004/05 (61.61 mm) and 2018/19 (55.14 mm), while the largest deviations between the simulations occurred in 2007/08 (108.12 mm) and 2016/17 (110.50 mm). Spatial patterns of recharge were strongly controlled by LULC and lithology. Carbonate formations exhibited the highest recharge (>350 mm) under forest and vegetated cover, in contrast, granitic terrains consistently showed low recharge (<10 mm) regardless of land cover and Schist formation showed moderate recharge, with values exceeding 150 mm under vegetation but experienced marked decline in built-up areas (<50 mm). Comparison of WBM and WTF recharge estimates revealed consistent spatial patterns, though magnitudes differed by lithology: in dolomite, WBM estimated 227.95 mm compared to 291.67 mm from WTF; in limestone, 122.14 mm versus 123.45 mm; and in schists, 158.34 mm versus 82.00 mm. This corresponded to relative differences of -21.85%, -1.06%, and 93.09%, respectively. Recharge from empirical methods further corroborated the declining trends captured by WBM and reflected temporal variability linked to precipitation. Overall, the findings demonstrate the robustness of EO based water balance approach for quantifying recharge variability in data-scarce aquifers and highlight the critical role of LULC management in sustaining groundwater recharge under ongoing urban expansion. It also showed the importance of using multiple, conceptually distinct methods to reduce structural uncertainty in recharge estimation.

The Southern African Development Community (SADC) Member States adopted regional gender instruments that set targets for gender equality and were subsequently domesticated through national policies, including Namibia’s National Gender Policy (2010-2020). This study examines the extent to which the Department of Water Affairs (within the Ministry of Agriculture, Water and Land Reform at the time of study) has translated formal gender equality commitments into substantive gender mainstreaming practices beyond policy rhetoric. Using a mixed-methods design, we combined document review with an online survey adapted from the International Labour Organisation gender audit framework. Forty-nine staff members responded (32% response rate). Results indicate persistent institutional constraints: 87.8% of respondents reported no formal training on gender equality in policy or programming, while confidence to perform core gender mainstreaming functions remained very low (2-5%), alongside high non-response across proficiency items. Institutional support mechanisms were weak, with 89.8% reporting no periodic support from gender focal points. At sector level, Namibia’s AMCOW WASSMO Indicator 6.6 score declined from 44% (2019) to 33% (2024), suggesting that earlier policy-alignment gains were not sustained. Document review further identified no explicit budget allocations for gender mainstreaming within reviewed annual budgets (2018-2022), indicating limited fiscal institutionalisation. Interpreted through Gender and Development and institutional theory, the findings point to structural decoupling, weak incentives, and limited systematic embedding of gender requirements in planning, budgeting, monitoring, and programme design. We recommend establishing a dedicated gender mainstreaming unit, instituting gender responsive budgeting with tracked allocations, and strengthening applied capacity through mandatory training linked to performance and reporting. Further research should examine accountability architectures that can accelerate measurable gender outcomes across the SADC water sector.

Local diversity of soil units and properties in a semi-arid tropical climate is controlled by a number of interacting factors, whose contribution to the final form of individual soil characteristics is often difficult to discern. The present study focuses on a detailed assessment of five diverse soil profiles located in the flat foothills of the Otavi Mountains in northern Namibia. A multi-proxy approach consisting of clay mineralogy, micromorphology and geochemical analyses was used to disentangle the drivers of an extraordinary local pedodiversity and to identify the patterns of recent and relict pedogenesis. Significant differences in profile stratigraphy were observed in the soils studied, represented by more weathered Chromic Cambisols and humus-rich soils with mollic horizons (Haplic Phaeozems, Calcic Kastanozem) and vertic features (Vertic Phaeozem). Complex lithology with a dominant influence of unconsolidated sediments of mainly fluvial origin, duration of pedogenesis and subtle changes in local topography and hydric soil regimes were identified as the main factors for the sharp transitions between the patches of each soil group. The studied soils differed significantly in the proportions of clay minerals and iron forms, partly inherited from the allochthonous soil-forming material, and partly developed in-situ. More intensive processes of soil weathering and clay translocation were retarded by limited leaching and base-saturated soil solution. The development of the vertic features was mainly conditioned by the localization of the profile in a minor local depression with prolonged water stagnation and abundance of the finest clay fraction rich in expanding clays. The formation of the thick mollic horizons was probably related to the former dominance of grassland vegetation and further enhanced by stabilization of soil organic carbon by various processes. Specific features that indicate a change in vegetation and a decreasing intensity of redox processes suggest a gradual aridification of the environment in the study region.

Landcover transformations exert pressure on aquifer systems by disrupting natural recharge, yet the extent of these impacts remain poorly understood. This study investigated impacts of land use and land cover (LULC) change on groundwater recharge potential zones (GRPZ) on the Lusaka Aquifer System. Geospatial techniques were combined with multi-criteria decision analysis to delineate GRPZs for the years 1990-2022 with seven thematic layers. Results indicated that built-up areas expanded significantly from 70.13 km2 to 652.60 km2 (830.49 %) while forest and cropland declined by 593.81 km2 (67.10 %) and 258.65 km2 (33.54 %) respectively. The transition matrix showed that built-up areas had a gain of 25.26 % of the total study area, largely sourced from cropland (10.37 %), forest (8.13 %), and vegetation (5.55 %). Forest cover underwent notable transformations with a loss of 25.75 %. Cropland exhibited the highest degree of persistence, with 11.19 % remaining unchanged. The areal coverage of GRPZ showed that low and moderate recharge zones increased by 134.21 km2 (27.17 %) and 39.14 km2 (3.13 %) respectively. In contrast, high and very high zones declined by 164.90 km2 (33.33 %) and 8.47 km2 (74.48 %). Analysis of built-up area expansion on GRPZs revealed notable encroachments on low, moderate and high recharge zones by 127.28 km2, 332.02 km2 and 106.65 km2 respectively. This study highlights the ongoing shifts in recharge potential areas driven by urbanization, indicating a continued trend that increases the risk of reduced aquifer recharge and long-term groundwater depletion. The spatial overlap between built-up expansion and recharge potential zones indicates a disconnect between LULC change and groundwater management.

The reprocessing of metallurgical wastes to recover much-needed metals such as copper not only ensures an adequate supply of metals but also contributes to the cleaning of the environment. A copper smelter in Namibia accumulated significant amounts of spent refractory bricks that are enriched with metal values including copper. This supposedly waste material can potentially serve as a supplement to the ore concentrate, as a smelter feedstock for this toll smelter. Representative samples of crushed bricks, designated as Sample 1 and Sample 2, were used for mineralogical characterisation and flotation test work. The assays for Sample 1 and Sample 2 were 14% Cu and 18% Cu, respectively. Microscopy results identified various copper phases including metallic Cu, bornite, malachite and chalcopyrite. Batch flotation tests were conducted to investigate the effect of grind size (P80 of 53, 75 and 106 μm), pulp pH (natural pulp pH, 10, 10.5 and 11) and collector (potassium amyl xanthate, PAX) dosage (70, 100 and 130 g/t) on the recovery of copper, concentrate grade and weight recovery. In some tests, a co-collector (dithiophosphate, DTP) and sulphidiser (Na2S) were also added in the quest to maximise the recovery of copper. Based on the test conditions investigated in this study, the grind size is the key variable affecting the recovery of copper. The best copper recovery of 86% (with a weight recovery in the range of 42 to 45% (w/w) and concentrate grade of 37% Cu) was achieved for the finest grind size of 53 μm. The reagent suite that yielded the best recovery was 70 g/t PAX with no addition of the sulphidiser while the pH was 10. There is scope for developing the process routes to recover other valuable metals such as iron, lead and zinc that are also in the spent bricks, as well as potential reuse of the spent bricks (after recovering valuable metals) to make new refractory bricks.

The Groot Aub (GA) settlement depends entirely on groundwater for domestic purposes and other development activities. Development activities are mainly agriculture, such as animal husbandry, chicken farming and crop farming using irrigation. However, these activities have the potential to contaminate the groundwater system. A total of 87 groundwater samples were collected from the boreholes in the study area during the dry and wet season. Water quality parameters (pH, salinity, total dissolved solids (TDS), electrical conductivity (EC) and hydrochemistry (Na+ > Ca2+ > Mg2+ > K+, and HCO3− > SO42− > Cl−) of 5 boreholes and 1 reservoir tank were analysed. The dominant cations were attributed to cation exchange processes as a coupled exchange of Na+ + K+ replacing Ca2+; and Na+ replacing Mg2+ ions in the rock–water interactions. The HCO3− anion is attributed to underlying rich carbonate rocks in the study area and chemical reactions between groundwater and silicate minerals. TDS ranged from 639.01 to 1 998.96 mg/L. The microbial levels as indicated by heterotrophic plate count (HPC) values exceed the limits imposed by the local Namibian and WHO drinking water regulations. The Piper diagrams showed a mixed water type of mainly HCO3− and SO42− anions and Na+ and Ca2+ > Mg2+ cations. The study shows that the elemental composition of the groundwater is impacted significantly by primarily anthropogenic activities and secondarily geogenic processes. Based on the results of this study it is recommended that a buffer zone be created between human activities and production boreholes to avoid further groundwater contamination.

A Canberra coaxial High Purity Germanium (HPGe) gamma-ray spectrometry detector was used to measure activity concentrations of radionuclides in commonly used building materials in Swakopmund, Namibia. The activity concentrations in, Bq.kg−1, for 226Ra, 232Th and 40K in all sample groups of building materials (cement, sand, cement bricks and roof tiles) were found to be in the range of 18.002–499.266, 14.069–132.508 and 162.794–1747.260, respectively. The average activity concentration of 40K was found to be two times higher than the critical level of 500 Bq.kg−1 in sand, cement bricks, clay bricks and roof tiles. The measured activity concentrations were used to estimate average dose rates and radiological hazard parameters. The absorbed dose rate (D) both due to indoor and outdoor exposure was higher than the international acceptable safe limits in all sample groups while the annual effective dose equivalent (AEDE) due to indoor exposure was higher in sand, cement bricks and clay brick samples. AEDE due to outdoor exposure was within acceptable safe limits for all sample groups. Radium equivalent (Raeq), external hazard (Hex) and gamma (Iγ) hazard indices were found to be higher than the acceptable safe limit only in clay bricks samples. The internal hazard (Hin) index was only higher than the acceptable safe limit in cement and clay bricks while the alpha (Iα) index was higher in sand, cement bricks and clay bricks. The Excess Lifetime Cancer Risk (ELCR) exceeded the acceptable safe limits in all sample groups. Our study showed that most of the computed radiological parameters were significantly higher than prescribed safe limits in most of the samples and therefore may pose a health risk to the inhabitants of Swakopmund.

We report a novel discovery of a westward trend in geochemical maturity revealed by major oxides and SiO2 ratios in the Chimanimani diamondiferous sediments of the Umkondo Basin, eastern Zimbabwe. The analyses were carried out on diamond drill core samples obtained by the Zimbabwe Consolidated Diamond Company from the grits in the Lower Argillaceous Formation in Chimanimani. The origin of these sediments has been a subject of debate. Unlike the basal Marange diamondiferous deposits occurring basal to the Proterozoic Umkondo sediments, the Chimanimani grits occur within the sedimentary pile, overlying finer sandstones and underlying shales, which suggests a distinct depositional sequence. While some researchers have attributed the Chimanimani diamondiferous grits to eastward erosion and dispersal from the basal Marange diamondiferous deposits on the basin's western margin, others propose an origin from the older and metamorphosed Mozambique Facies thrust sheets in the east. This study favours a closer source for the diamonds, to the east of the current deposit, as revealed by the westward maturation of hosting grits. X-ray fluorescence (XRF) analysis of major and trace elements in the samples revealed ratios of major oxides to SiO2 ranging from 70 to 96%, indicative of mature sediments. This maturity could be attributed to a distant source for the sediments, or to hydraulic sorting within the basin. A striking westward increase in SiO2/major oxide ratios, corroborated by a decrease in SiO2/TiO2, is observed across the deposit. This trend suggests a possible source for the sediments as being to the east of the Chimanimani deposit. This appears to contradict the hypothesis of derivation of the sediments from the west, similar to the provenance of the Marange deposits.

The depletion of the ore reserves in the world necessitates the search for secondary sources such as waste products (tailings and slag). The treatment and cleaning up of such secondary sources also has a positive impact on the environment. A smelter in Namibia we examined had historic slag which accumulated over decades of its operating life, thus posing the challenge of how best to collect representative samples to evaluate and propose viable methods of recovering contained metals. In this study, analytical and mineralogical characterization of the slag was performed using X-ray fluorescence (XRF) analysis, atomic absorption spectrometer (AAS), ICP-OES, scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) analysis, and optical microscopy analysis. The chemical analyses showed that the metal values contained in the slag were mainly copper, lead, and zinc whose average contents were approximately 0.35% Cu, 3% Pb, and 5.5% Zn. About 10.5% Fe was also contained in the slag. Germanium was detected by scanning electron microscopy, but was however below detection limits of the chemical analysis equipment used. Based on the results, approximate conditions under which the different slag phases were formed were estimated and the recovery routes for the various metals were proposed. Analysis by both optical and scanning electron microscopy revealed that Zn and Fe occurred mainly in association with O as oxides, while Cu and Pb were mainly associated with S as sulphides. The slag consisted of three different phases, namely the silicate phase (slag), metallic phase and the sulphide phases. The phases in the slag were mainly silicate phases as well as metallic and sulphide phases. It was observed that the metallic and sulphide phases were dominant in the finer size fractions (−75 µm) whereas the sulphide phase was also present in the coarser size fractions (+300 µm). An important finding from the microscopy examination was that the sulphide phases were interstitial and could be liberated from the slag. This finding meant that liberation and subsequent concentration of the sulphide phases was feasible using conventional processing techniques.

Of the driest countries on the African continent, Namibia is the most arid in Southern Africa and water scarcity is perhaps its greatest challenge. Windhoek, the capital city, depends on surface water runoff; groundwater systems and recycling of grey water for its domestic, commercial and industrial water supply. However, due to high evaporation rate in the city, only 2% of the total rainfall ends up as runoff and inflow into the dams, plus another 1% that seeps into the groundwater as recharge. The city accounts for 15% of the country's population. The results show that the high population and its accompanying water demand has led to a heavy dependence on the groundwater system as precipitation has gradually decreased, both in quantity and frequency over the last thirty (30) years. The results further show that abstraction from the Windhoek aquifer is currently estimated to be 2 Mm3 per annum and is considered to be unstainable. This scenario led to a significant lowering of the groundwater table over the years. To sustain the water demand, the city has adopted artificial recharge into the aquifer. However, this has not been sufficient, and often the local authority has resorted to a drought index strategy; a water management strategy that restricts water usage. To manage groundwater with water security as a priority in an environment of climate change and a growing city population; more strategies of water storage and harvesting need to be adopted and not only rely on the dams and the Windhoek aquifer.

The study evaluated the milling kinetics of three copper ores, from a multi-mineralised deposit, which were identified as sulphide 1 (with bornite as a dominant copper mineral), sulphide 2 (mainly composed of chalcopyrite) and oxide (with malachite as a dominant copper mineral) and related the breakage parameters to the mineral composition data. Five mono-size fractions between 1000 µm and 212 µm were dry milled for short grinding times in the laboratory ball mill in order to obtain data for predicting breakage rate parameters. The analytical and mineralogical characterisation of the ores were performed using X-ray fluorescence (XRF) analysis, scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) analysis, optical microscopy analysis and X-ray diffractometer (XRD). The mineralogy data showed that quartz was the abundant gangue mineral (average for each ore was above 60% (w/w)), followed by K-feldspar minerals (orthoclase and microcline) which constituted between 4% (w/w) and 6% (w/w) and the remainder are the minor calcite and dolomite minerals which are also in the host rock. The experimental milling kinetics parameters and mineralogical data were used to assess the robustness of the heterogeneous (two-component) and homogeneous (single-component) first-order rate breakage models. The mineral composition data were used for setting up the predictions of breakage parameters in the two-component and single-component first-order breakage models. The experimental data fitted better on the two-component breakage model than the single-component breakage model. These results highlighted the influence of two groups of minerals (generally classed as valuable and gangue minerals). The breakage data showed that the selection function for the hard component (the gangue minerals) has a dominant contribution to the overall selection function of the ores, with SiA correlating fairly well with experimental Si. The parameter a in the Austin empirical breakage model was relatively similar (approximately 1) for all three ores, which confirms similar milling conditions to which the ores were subjected to. The data suggests that there is a relationship between breakage parameter α (material-specific parameter) in the Austin empirical breakage model and brittleness index βi (calculated from the mineralogical composition of the gangue phase). No clear trends could be deduced from the cumulative breakage distributions of the three ores. This highlights the complexity of developing relationships between the mineralogical composition data and breakage distributions of the ores which are extracted from the same deposit and with comparable gangue composition.

Woody plants provide natural archives of climatic variation which can be investigated by applying dendroclimatological methods. Such studies are limited in Southern Africa but have great potential of improving our understanding of past climates and plant functional adaptations in the region. This study therefore investigated the responsiveness of Dichrostachys cinerea to seasonal variations in temperature and rainfall at two sites in central Namibia, Waterberg and Kuzikus. Dichrostachys cinerea is one of the encroacher species thriving well in Namibia. A moving correlation and response function analysis were used to test its responsiveness to seasonal climatic variations over time. Dichrostachys cinerea growth rings showed relationships to late summer warming, lasting up to half of the rainy season. The results also revealed that past temperatures had been fluctuating and their influence on growth rings had been intensifying over the years, but to varying extents between the two sites. Temperature was a more important determinant of ring growth at the drier site (Kuzikus), while rainfall was more important at the wetter site (Waterberg). Growth ring responsiveness to rainfall was not immediate but showed a rather lagged pattern. We conclude that D. cinerea differentially responds to variations in rainfall and temperature across short climatic gradients. This study showed that the species, due to its somewhat wide ecological amplitude, has great potential for dendroclimatological studies in tropical regions.

By identifying fragments of DNA in the environment, eDNA approaches present a promising tool for monitoring biodiversity in a cost-effective way. This is particularly pertinent for countries where traditional morphological monitoring has been sparse. The first step to realising the potential of eDNA is to develop methodologies that are adapted to local conditions. Here, we test field and laboratory eDNA protocols (aqueous and sediment samples) in a range of semi-arid ecosystems in Namibia. We successfully gathered eDNA data on a broad suite of organisms at multiple trophic levels (including algae, invertebrates and bacteria) but identified two key challenges to the implementation of eDNA methods in the region: 1) high turbidity requires a tailored sampling technique and 2) identification of taxa by eDNA methods is currently constrained by a lack of reference data. We hope this work will guide the deployment of eDNA biomonitoring in the arid ecosystems of Namibia and neighbouring countries.