This working paper looks at a geographical feature that, to our knowledge, has not been investigated in Spain so far, terrain ruggedness. Using geographical information systems and two public access digital elevation models we construct a terrain ruggedness index that quantifies topographic heterogeneity, and is based on the slope with neighborhood cells.

Focusing on the higher resolution Digital Elevation Model, we show that ruggedness and altitude are almost completely unrelated and both variables have a very different spatial distribution. The main conclusion is that the ruggedness index provides a summary of a useful geographical feature of the landscape, in the same way as altitude or proximity to the coast. In addition, the Digital Terrain Model of ruggedness can be used to obtain average values of ruggedness at any level of geographical aggregation we desire, such as regions or municipalities.