Modelling Water and Tillage Erosion using Spatially Distributed Models

DOI: 10.1007/3-540-36606-7_6


Soil erosion models are valuable tools for understanding sedimentary records. In this paper, the potential use of a topography-based
model (WaTEM) for simulating long-term soil erosion and its effect of soil properties is discussed. Long-term (derived from
profile truncation) and medium-term (derived from 137Cs measurements) erosion patterns are compared with simulated patterns of water and tillage erosion. Results showed that WaTEM
is able to describe to reproduce the observed spatial pattern of long-term water erosion reasonably well. However, the 137Cs data indicated that a major change in erosion and sedimentation patterns has occurred over the last decades: the dominance
of water erosion over a time scale of several thousands of years explains the spatial pattern of soil truncation. On the other
hand, the 137Cs data indicate that the present-day pattern of soil erosion is dominated by tillage. WaTEM is also used to assess the effect
of changes in landscape structure on soil erosion. It was shown that, when shifting focus from the field to the catchment
scale, the way we represent space in distributed models affects the model performance at least as dramatically as the physical
description of the process. Finally, a model application whereby WaTEM is linked with a mass-balance model, showed that simulating
the effects of soil erosion on the redistribution of soil properties is an important issue when trying to link surface processes
and sedimentary records.

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    ABSTRACT: One of the main aims of geomorphology is to understand how geomorphic processes change topography over long time scales. Over the last decades several landscape evolution models have been developed in order to study this question. However, evaluation of such models has often been very limited due to the lack of necessary field data. In this study we present a topography based hillslope erosion and deposition model that is based on the WATEM/SEDEM model structure and works on a millennial time scale. Soil erosion, transport and deposition are calculated using slope and unit contributing area. The topography is iteratively rejuvenated by taking into account modelled erosion and deposition rates, thereby simulating topographic development backwards in time. A first attempt has been made to spatially evaluate the model, using detailed estimates for historical soil erosion and sediment deposition volumes, obtained from an augering campaign in a small catchment in the Belgian Loess Belt. The results show that the model can simulate realistic soil redistribution patterns. However, further research is necessary in order to deal with artificial flaws that cause routing problems and significantly influence results. Common problems and issues related to this type of backward modelling are also discussed.
    Geomorphology 08/2006; 78(3-4-78):250-264. DOI:10.1016/j.geomorph.2006.01.033 · 2.79 Impact Factor