| Soil erosion refers both to an agricultural problem and a (set of) geomorphic process(es).
Agricultural scientists and geomorphologists study these processes from a different
perspective: while geomorphologists are interested in (long-term) landscape development,
soil erosion studies were mainly set up on agricultural or grazing land to assess (short-term)
soil erosion risk and the efficiency of soil conservation measures.
Due to the agricultural interest in soil erosion, there are now more data available on soil
erosion rates than on any other geomorphological process. Furthermore, a wide range of
soil erosion models exist and soil erosion processes have been studied in detail
both in the laboratory and in the field. In geomorphological research on long-term
landscape evolution, relatively little use is made of these data and models, perhaps as
they are being considered as irrelevant to landscape evolution given the relatively
short time span and small spatial scale that they usually cover. At first sight, recent
estimates of human impact on sediment fluxes in large fluvial systems seem to confirm
this view as it is estimated that the latter have risen only by ca. 10% due to human
impact.
In this presentation we investigate if and how soil erosion data and process understanding may be
useful in developing insights in long-term evolution of soil-covered geomorphological
systems. A key issue in this respect is how soil erosion data can be adequately scaled over
space and time. The latter requires appropriate models to describe sediment production and
transfer. Efforts to develop and apply such models are underway: we investigate some
possible approaches and discuss a number of issues that warrant attention, both in
terms of model development and testing as well as in terms of data collection and
interpretation. Particular attention will be given to scaling issues and to the importance of
using adequate process descriptions in long-term soil erosion models, as well as to
the importance of incorporating feedbacks between erosion processes and the soil
system.
The development of adequate long-term soil erosion models will not only benefit
geomorphology as a science. Such models will also be of great help to assess soil
erosion and its consequences for the sustainability of human societies, in particular
with respect to agricultural productivity and other ecosystem services derived from
agricultural land. Addressing these issues indeed requires an integrated, long-term
approach: geomorphologists can play a critical role in developing such an approach. |