Fig 1.
Location and topo-climatic characteristics of Namibia.
White lines indicate borders between three aridity zones: semiarid (aridity index ~ 0.2 to 0.371), arid (aridity index ~ 0.03 to 0.2), and hyperarid (aridity index ~ 0.006 to 0.03).
Fig 2.
Relationships between the seven soil databases used in this study.
The following databases were considered: DSMW, NAMSOTER, SOTERSAF, HWSD, SoilGrids1km, SoilGrids250m, and WISE30sec. See the text for full names and versions of the soil databases. “Field and Lab Soil and Terrain Data” are based on data collected at discrete points on the ground; “Geospatial Data” are derived mostly from remotely sensed products and cover areas as opposed to points.
Table 1.
Key characteristics of topsoil texture map data sources.
Fig 3.
Dominant topsoil textures in Namibia according to the soil databases used in this study.
The panels show: a) full field dataset (1,102 samples), b) spatially uncorrelated subset of field data 327 samples), c) DSMW, d) NAMSOTER, e) SOTERSAF, f) HWSD, g) SoilGrids1km, h) SoilGrids250m, and i) WISE30sec. See the text for the full names and versions of the databases.
Table 2.
Allocation of field samples among soil textural classes in the full field data set and the spatially uncorrelated random subset of field data.
Fig 4.
Soil texture triangle (top) and relative areal coverage of dominant topsoil texture types according to the seven map data sources (bottom).
The map data sources include DSMW, NAMSOTER, SOTERSAF, HWSD, SoilGrids1km, SoilGrids250m, and WISE30sec. See the text for full names and versions of the map data sources.
Fig 5.
Overall agreement and disagreement between map and field data.
See the section on “Topsoil Texture Map Accuracy Assessment” for a definition of overall agreement and disagreement. See the text for full names and versions of the map data sources.
Fig 6.
Absolute disagreement between map and field data at the topsoil texture category level.
See the section on “Topsoil Texture Map Accuracy Assessment” for a definition of absolute disagreement. SiC, SiCL, and Si are not shown because these were not represented in any of the field samples or maps. See the text for full names and versions of the map data sources.
Fig 7.
Relative disagreement between map and field data at the topsoil texture category level.
See the section on “Topsoil Texture Map Accuracy Assessment” for a definition of relative disagreement. SiC, SiCL, and Si are not shown because these were not represented in any of the field samples or maps. Cases with complete relative quantity disagreement are those in which a soil texture was present in the field data and not the map data (i.e., C, SiL, L, CL, SCL, SL, LS, or S) or in which the map data included categories not present in the field data (i.e., R or ND). See the text for full names and versions of the map data sources.
Fig 8.
User’s and producer’s accuracies of the different topsoil texture categories in the maps and overall map accuracies.
See the section on “Topsoil Texture Map Accuracy Assessment” for definitions of user’s and producer’s accuracies. SiC, SiCL, and Si are not shown because these were not represented in any of the field samples or maps. See the text for full names and versions of the map data sources.
Fig 9.
Spatial distribution of correctly and incorrectly classified locations.
Panels a-g) show correctly and incorrectly classified locations in: a) DSMW, b) NAMSOTER, c) SOTERSAF, d) HWSD, e) SoilGrids1km, f) SoilGrids250m, and g) WISE30sec. Panel h) shows regions in which locations are often classified correctly (C1, C2, and C3) or incorrectly (I1, I2, and I3). See the text for full names and versions of the map data sources.