Soil erosion patterns: evolution, spatio‐temporal dynamics and connectivity

Abstract

Soil erosion is among the major environmental threats related to agricultural land use in Europe. Important European policies and directives, such as the Water Framework Directive, the European Commission Strategy for Soil Protection as well as agro-environmental measures address the issues of soil erosion. During recent decades, international research has contributed greatly to an improved understanding of soil erosion processes at various scales from single plots to complex watersheds. Research focus evolved from descriptive approaches over process analyses of soil-hydrological dynamics to in depth studies of the temporal interactions of rainfall soil erosion relationships. The analysis of spatial dynamics of soil surface characteristics and runoff and erosion patterns is a recent topic of soil erosion research, which is a crucial piece of the puzzle when analysing connectivity issues and when linking upland area processes of sediment production with channel processes of sediment transport. Patterns of runoff and soil erosion represent the two-dimensional response of the landscape to rainstorm events. These patterns illustrate in a complex and yet incompletely understood way the spatial variability of important soil, land use and landscape characteristics. There has been increasing recognition of the significance of such patterns for understanding and predicting erosion and its environmental impacts. For example, improved insight into the way in which patterns of runoff and soil loss evolve over time and vary with spatial scale may help us to better comprehend the value and limitations of short-term plot studies with respect to erosion in a wider, real-landscape context. A better appreciation of the role of dynamic connectivity in runoff and sediment delivery may assist in improving our estimates and surface functions of landscape response to rainfall events. Similarly, improved understanding of patterns of aeolian erosion and deposition may facilitate prediction of wind erosion’s impacts. In the framework of the European COST action 623 ‘Soil Erosion and Global Change’ two meetings focused on recent developments in understanding the influence of spatial characteristics and patterns on the hydrological and erosion response of soils and landscapes. The first meeting was held in September 2001 in Strasbourg (France) and addressed the role of dynamic soil surface characteristics for soil erosion. Selected papers from this meeting were published in Earth Surface Processes and Landforms vol. 29 (2004). The second meeting was held at the LeibnizCentre for Agricultural Landscape and Land Use Research (ZALF) in Muncheberg (Germany) in October 2002. This meeting focused on the spatio-temporal dynamics of runoff and soil erosion patterns and related connectivity parameters at scales ranging from experimental plots to watersheds. This special issue of Earth Surface Processes and Landforms contains selected papers from this meeting. The issue opens with two papers dealing with the role of semiarid vegetation patterns for spatially structuring runoff and soil erosion at hillslope scale. The first paper gives a review of recent findings on this issue (Puigdefabregas), while the second presents a simulation approach (Boer and Puigdefabregas). Three papers deal with catchment-scale analysis, the most complex presenting a mapping approach of erosion patterns as related to agricultural land use and field organization patterns (Van Dijk et al.). The approach allows the identification of linkages between driving force patterns (land use) and pressure patterns (sediment delivery) at watershed scale. The paper by Vigiak et al. presents model comparisons with respect to their performance in predicting erosion patterns at catchment scale. Ollesch et al. describe a model adaptation to soil hydrological patterns for better predicting snowmelt erosion in catchments. The last three papers deal with small experimental approaches on laboratory or field plots. Takken et al. present an in-depth study on the role of spatial discretization of hydraulic model parameters on model results. Rejman and