Namibia is an arid country in Southern Africa. It frequently experiences a state of freshwater deficit and must employ a range of measures to manage this scarce resource sustainably and equitably. The Ministry of Agriculture, Water and Land Reform coordinates the water sector. A state-owned enterprise, NamWater, is the bulk water supplier and manages large water infrastructure. The country follows a policy of integrated water resource management and has devolved some of the decision-making on water issues to river basin level. Transboundary catchments are managed through legal agreements and multinational permanent commissions representing the basin states. Technologies such as dams in ephemeral rivers, intra- and inter-basin water transfer schemes, reclamation of wastewater to potable standards, artificial aquifer recharge, desalination, and conjunctive use of various water sources are employed to supply water to consumers. Water demand management, particularly education, information, restrictions and tariffs, curbs wasteful use of water.

The Farm Klein Boesman, south of Dordabis in the Khomas Region of Central Namibia, is situated on the ecotone between the Central Highlands/Central Plateau and the southern Kalahari. Whereas a considerable amount of information is available for the Kalahari Duneveld in South Africa, little is known of the same ecosystem in Namibia, specifically the northern extent of this ecosystem. We stratified the farm according to visible terrain features identified on aerial images, aided by a Shuttle Radar Topography Mission (SRTM) digital terrain model. Based on these initial stratification units, 35 minipits and/or soil augerings were done to sample the typical soil units. From these, soil samples were analysed for soil chemical and physical properties. In addition, 158 relevés were compiled across all initial stratification units. These were classified with modified Two-Way Indicator Species Analysis (TWINSPAN) using a synusial approach. From the results we described and mapped twelve landform and ten soil units, as well as six vegetation associations, of which two were subdivided into two and three subassociations each. We compare these associations with related vegetation types described in the Khomas Hochland as well as in the Kalahari Gemsbok National Park (KGNP) in South Africa. Although several similarities to units described for the KGNP were identified, several discrepancies were also identified, necessitating a thorough revision of the vegetation descriptions for the greater southern Kalahari.

Reliable national-scale, multi-depth soil property maps remain scarce across much of Africa, particularly in arid regions. Here, we present the first national-scale digital soil mapping (DSM) for Namibia: sixteen physical and chemical soil properties predicted on a 90 m prediction grid for three depth intervals (0–30, 30–60 and 60–100 cm). The framework draws on 4958 legacy profiles and augerings and 65 covariates, including locally produced datasets that capture soil–environment relationships not fully represented by global covariates. A semi-automated workflow combined Random Forest modelling in Google Earth Engine with R-based depth harmonisation, Boruta-feature selection and hyperparameter tuning. Performance and bootstrap variability were quantified over 20 bootstrap iterations per property–depth combination, with pedological evaluation and independent validation. pH was the most consistently predicted property, and base saturation, sand and silt captured useful broad spatial patterns, whereas bulk density, organic carbon, phosphorus, magnesium and clay were less predictable, and electrical conductivity and sodium showed low predictive skill. Performance generally declined with depth, and bootstrap variability was highest in sparsely sampled regions and deeper layers. Against independent samples from arable land, root mean square error was lower than SoilGrids in all 14 property–depth combinations evaluated and lower than iSDA in 8 of 12. Predicted patterns were consistent with known Namibian soil–landscape relationships and pedogenic processes, except for sodium. National-scale DSM is therefore feasible in data-sparse arid environments when harmonised legacy data are combined with global and locally relevant covariates, using simple but operationally robust methods. The products are intended for national and regional assessment, rather than site-specific decisions, and the modular workflow supports future updates and is potentially adaptable to other data-limited regions.

The Namibian Soil Profile Database contains 4960 entries, all samples with geographic coordinates. Each soil property presents a different number of observations, which decreases with depth. To perform the Digital Soil Map of Soil Organic Carbon (SOC) up to 30 cm, 1298 sample points were used. The covariates used in the model were composed from land cover, geology, terrain characteristics extracted from the digital elevation model and remote sensing data. Most of the covariates carry 30 m of spatial resolution. The Random Forest model implemented in Google Earth Engine (GEE) was applied with an external validation split of 80/20 %. As the second validation layer, samples from the Namibian tier of the Soils4Africa project were applied. The use of GEE facilitated the generation of a SOC distribution map for Namibia at a spatial resolution of 30 × 30 m. The highest amounts of SOC are stored in the central region of Namibia, with SOC values ranging from 0.1 to 1.9 %. The map is suitable for national and regional decision-making, offering a baseline for determining SOC stocks, monitoring changes in SOC, assessing the effects of bush encroachment/thickening and bush control, and for agriculture implications. Mapping of soil properties in other depths are scheduled for the near future.

This article introduces the various water resources available to Namibia, an arid country in southern Africa. With low and extremely variable annual rainfall and high evaporation rates, surface water is scarce. Permanent rivers are only found along the southern and northern borders. Ephemeral rivers flow for short periods after thundershowers and few reach the ocean. Many ephemeral rivers sink into the gravelly and sandy riverbeds, where they feed alluvial aquifers. Groundwater is the only water source for about 80% of the territory. Dams were built in ephemeral rivers to create artificial lakes that play an important role in water provision for urban areas, irrigation schemes and mines. Despite the extreme aridity, Namibia has a variety of wetland habitats, including five Ramsar sites.