Earth Surface Processes and LandformsEarth Surf. Process. Landforms 27, 1363–1364 (2002)Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/esp.434

EDITORIAL

The COST-623 ‘Soil Erosion and Global Change’ meeting on the Linkage of Hillslope Erosion to Sedi-ment Transport and Storage in River and Floodplain Systems took place in Almerıa, Spain, from 8 to 10September 2000. Attended by 73 scientists from 20 countries, the meeting aimed to review recent develop-ments in understanding the linkages that operate through the catchment system. The meeting addressed fourmajor issues.

1. Linking slope and channel processes. Issues raised by this session included: problems of infiltrationheterogeneity; spatial patterns of erosion processes; the difference between hydrological and sedimentconnectivity through a system, and how it changes with the scale of the system under observation; therole of local sinks within the system and the implications for looking at differences between agriculturaland non-agricultural systems, particularly in the ways that different forms of barrier are introduced intothe system, thus affecting its connectivity; the importance of not making extrapolations of erosion ratesbeyond the range of data on which they are based in a too-simplistic way; the question of whether practicalerosion estimates should be based at the rill rather than interrill scale, so that they are more identifiableto people involved in managing soil systems, such as farmers; and the need to appreciate measurementsof erosion in their context, and the uniqueness of individual sites. There is therefore the need to providea range of quantitative and qualitative information on process measurements.

2. Linking slope and channel measurements. Points identified were: models based on average rates seem towork well despite the fact that extreme events are so important in generating large amounts of sediment;the effects of base-level change on system connectivity; the interaction between channels and fan-typedeposits from slopes and side gullies and their relationship to (i) the travel distance of the particles thatmake up the deposits, (ii) the size of deposits and (iii) the timing of flows in different parts of the channelsystem; the potential for tectonics and aspect (controlling vegetation cover) to control rates of lateralmigration; the seasonality of pulses of sediment moving through the system; and how the link betweenlong and short timescales can be achieved. This last point was developed in the third session.

3. Long time-scale perspectives. Studies focused on: the relationship between vegetation and erosion onhillslopes; the effects of single events versus phases of activity; the links between climate and tectonics orclimate and human activity, depending on the timescale of observation; how the effects of extreme eventsmight vary significantly according to their timing relative to surface cover; and how vegetation structureas well as overall cover might be important in determining erosion rates.

4. Modelling and parameter scaling. The main issues addressed were: the effects of error propagation inthe modelling process; the importance of having good field data, particularly on land use and infiltration,which are often limiting factors in hydrology and erosion models; the question of whether simple, empir-ically based models might be more appropriate in some contexts, and whether physically based modelsare meaningful.

In the final session, discussion centred on how to take the research frontier forwards. It was agreed that therewere knowledge gaps in five main areas:

(1) residence times and the remobilization of eroded material within catchments in terms of:ž links between process-based and long-term studiesž relationships with the particle size of materialsž differences between these processes on hillslopes and in channelsž the relationship to coupling or connectivityž applications to practical issuesž the development of redistribution/deposition models;

Copyright 2002 John Wiley & Sons, Ltd.

1364 J. WAINWRIGHT ET AL.

(2) appropriate scales of description:ž for process understandingž for making predictions;

(3) whether it is necessary to know more about processes to make predictions;(4) the dynamics of interactions between slopes and channels at the appropriate timescales; and(5) the relationships between sediments in different parts of the system and how to evaluate these.

Hopefully, these pointers will spur further research in these areas with the collaborative enthusiasm thatwas seen at the meeting. Clearly, there is need for more of the lively debate that was concentrated on thetopics covered.

This special issue contains eight papers submitted after the meeting. These papers illustrate most of therange of topics covered in the meeting. The first three papers give examples of how field investigationscombining a variety of techniques are fundamental for furthering our understanding of the processes active indifferent environments that control the transfer of sediments from hillslopes. Coppus and Imeson present resultsfrom observations of an extreme event in semi-arid southern Bolivia, while Slattery et al. and Swiechowiczevaluate the response of more temperate areas, in the eastern USA and in Poland, respectively. The nexttwo papers deal with process understanding and methodological issues. Rejman and Usowicz demonstrateconvincingly how an incomplete understanding of erosion processes can produce erroneous interpretationsof data, while Verstraeten and Poesen present a detailed methodology for obtaining sediment budgets frompond data, including an in-depth assessment of potential errors. The final three papers present modellingapproaches. Michaelides and Wainwright focus on the hydrological linkages that underpin sediment linkagesin semi-arid settings, while Kirkby et al. provide an approach to the upscaling of hydrological data using theHydrologically Similar Surfaces (HYSS) approach. Finally, Bogena and Diekkruger provide an in-depth modelanalysis of sediment and solute transfers in a catchment in Germany. Abstracts of other papers presented atthe meeting can be found at http://www.kcl.ac.uk/kis/schools/hums/geog/res/cost.pdf.

JOHN WAINWRIGHT

ADOLFO CALVO CASES

JUAN PUIGDEFABREGAS

KATERINA MICHAELIDES

Copyright 2002 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms 27, 1363–1364 (2002)