Distribution of local landforms at head and end points of gullies on different grid spacing

Abstract

Local landforms described by signs of curvatures can be considered as potential indicators of gully formation. However, the role of these landforms is not generally investigated in literature. Hence, the goals of the present research are: (i) identification of the relationships of land surface attributes at the head and end points of gullies with the size of these gullies, at different grid spacings of a digital elevation model (DEM); (ii) explanation of the frequency of occurrence (FO) of local landforms.Investigations were conducted on the example of 439 gullies of the Hronská pahorkatina Hill Land in Slovakia. The sizes of the gullies were described by their area and perimeter. Altitude, slope steepness, maximal catchment area (MCA) and curvatures were calculated at the head and end points of these gullies. 12 types of main local landforms (MLLFs) were identified by the signs of six curvatures. For calculation of land surface attributes, a set of DEMs with grid spacings at every 10m interval from 10m to 100m was prepared.At the head points of gullies, significant Spearman's rank correlation coefficients (rs) show that MCA and curvatures related with gully size at DEM grid spacings from 10m to 30m. At the end points, such relationships are observed at all grid spacings. A negative rs between gully size and slope steepness is obtained. At the head points, it is demonstrated that the large gullies reached more flat locations in comparison with small gullies. At the end points, negative rs indicates that large gullies are characterized by flatter outlets in comparison with small gullies. The FO of MLLFs at the head and end points of gullies – relative to their frequency for the whole DEM – indicate that only four types of MLLF are systematically related to gully occurrence.