Cross-sectional index (25 m grid data) (WMS service)

The vertex area index represents a combined relief parameter of “relative hang position” and slope inclination. It is primarily used for the determination of vertex areas (relatively shallow sites). As a side effect, mean values of the vertex area index usually indicate slopes or flattening (e.g. terraces, geest slabs), medium to high values point to valley floors and very high values on steep slopes in relative low position (e.g. terrace arches and steep notches). It is calculated using the following formula: Vertex range index = relHP + N where: relHP = Relative hang position (inverted) N = slope inclination (slopes > 60° -> = 60°, exponent = 0.4, standardised to 0.0 to 1.0) By incorporating the slope inclination, the relief parameter “Relative hangposition” is modified so that flattening in relative top position of the relief has very low values and there is a mostly abrupt increase in the vertex area index at the transition to the slopes. Definition and calculation method: Köthe 2007, realised by SAGA module of sciLands GmbH and SAGA module “Grid Calculator”