INCORPORATION OF AGRICULTURAL TERRACING WITHIN LANDSCAPE EVOLUTION MODELS

Humans are now the primary geomorphic agents on Earth, though they have been a significant factor in sediment transport for thousands of years, especially since the introduction of agriculture. Few landscape evolution models (LEM) factor human agency as part of geomorphic change; models that do include human land use within vegetation parameters or tillage modules lack the ability to model the more complex anthropogenic processes, such as agricultural terrace construction and maintenance. Agricultural terraces are an important factor in landscape evolution since they reduce sediment transport downslope, but also add complexity to their simulation due to increased occurrence of landslides when terrace walls fail because of lack of maintenance. Terraces are found worldwide in a variety of climates and land uses; thus, a LEM that includes terracing must be adaptable to a variety of climatic and land use parameters.

This research is an initial step towards the inclusion of agricultural terracing within LEMs by testing how (1) spatial resolution of terrain data affects implementation of terrace location and (2) variation in temporal parameters of terrace maintenance and time to wall failure implemented within the model runs influences the evolution of a hypothetical landscape. A landscape with steeply sloping terrain is utilized to simulate hypothetical terracing within a Mediterranean-type climate. Effects of varying terrace maintenance parameters are tested on both empirical and process-based LEMs to compare how well landscape evolution as a result of agricultural terracing is simulated within each model. The results for each of the model scenarios are compared for sediment loss, terrain steepness, and morphology against the unaltered landscape and among models. This research implements agricultural terracing within LEMs and provides the basis for inclusion of dynamic human decisions regarding terracing within these and other models of landscape evolution.