**2. Data**

222 Studies on Environmental and Applied Geomorphology

• Derive the "behavior" of the DEMs over different terrain, using multiple tests, to observe their "internal coherence", which is referred to here as "relative assessment". This assessment is especially relevant to geomorphologists, as actual land surface processes do not have a direct bearing on absolute elevation alone, these can also be appropriately studied if relatively to each other the individual elevation grids resemble appropriate elevation change! This topic has hardly been addressed in literature so far! • Determine implications of the accuracy of the products for hydrological and

The study is conducted for two sites in Ghana (Figure 1). These sites fall in different agro climatic zones, have different elevation ranges and differ in landcover. Site 1, which climatologically falls in the Guinea Savannah zone (northern Ghana), has an elevation range of about 400 m. It is fairly flat, with an average slope of 0.90. The major landcover types are deciduous woodland (55 %) and shrubland (36 %). Site 2 lies between two climatic zones – moist semi-deciduous forest and transitional zones. It has an elevation range of about 780 m, with an average slope of 3.30. Though also fairly flat, this site has a range of mountains that borders the Volta Lake. The dominant landcover types are forest (52 %) and

selected.

**1.2 Study sites** 

environmental modeling.

woodland/shrubland (34 %).

Fig. 1. Map of the study sites

absolute comparison. DEMs over different topography and land cover have been
