Northampton Electronic Collection of Theses and Research

‘Local gradient’ and between-site variability of erosion rate on badlands in the Karoo, South Africa

Favis-Mortlock, D., Boardman, J., Foster, I. D. L. and Greenwood, P. (2018) ‘Local gradient’ and between-site variability of erosion rate on badlands in the Karoo, South Africa. Earth Surface Processes and Landforms. 43, pp. 871-883. 0197-9337.

Item Type: Article
Abstract: Site-average values of local gradient, defined as the steepest slope angle measured at a point, are a powerful predictor of long-term rates of soil loss as measured by erosion pins on the non-channel floor portions of ten badland study sites in the Karoo area of South Africa. Local gradient may be easily measured using a smartphone clinometer. The successful use of local gradient here is in strong contrast to the previous failure of other site-specific attributes, including other measures of gradient and relief, to explain between-site variation in erosion rate on these study sites. Each measurement of local gradient may be thought of as a sample of the site’s microtopography. Microrelief is a strong determinant of the emergent patterns of inter-channel overland flow, and hence of the patterns of inter-channel erosion by flow. Local gradient changes most rapidly during the initial stages of channel incision. When channels are established, local gradient changes more slowly leading to almost-parallel retreat of channel sidewalls. A sensitivity analysis suggests that measurements of local gradient are not all equal with regard to prediction of long-term erosion rate. A greater share of predictive power is contributed by measurements made on very steep or vertical channel side wall areas, and a lesser share is contributed by measurements made on interfluves.
Uncontrolled Keywords: Karoo, badlands, clinometer app, local gradient, microtopography, soil erosion
Creators: Favis-Mortlock, David, Boardman, John, Foster, Ian D L and Greenwood, Philip
Faculties, Divisions and Institutes: Faculties > Faculty of Arts, Science & Technology > Environmental Science
Date: 30 March 2018
Date Type: Publication
Page Range: pp. 871-883
Journal or Publication Title: Earth Surface Processes and Landforms
Volume: 43
Number of Pages: 13
Language: English
ISSN: 0197-9337
Status: Published / Disseminated
Refereed: Yes

Actions (login required)

Edit Item Edit Item