Front Page Water Erosion2Slides presenting information about soil erosion by water

 

FactsheetFront cover

RECARE Soil Erosion by Water Fact sheet

 

WP2 Reportcover

RECARE Soil Threat Review report providing detailed information

Video about soil erosion in Spain (English subtitles) 

 What is it?

Soil erosion by water occurs when individual soil particles become detached and are then transported and deposited. There are 4 main types of erosion by water:

i) splash erosion;
ii) sheet erosion;
iii) rill erosion; and
iv) gully erosion.

SplashErosion RillErosion
Splash erosion Rill erosion
SheetErosion GullyErosion
Sheet erosion Gully erosion

 Where does it occur?

The extent to which land is at risk of soil erosion by water in Europe has been assessed by various models and expert-based approaches. These assessments differ quite considerably due to the different modelling approaches used. A number of maps have been produced identifying the risk of soil erosion by water across Europe.

ErosionRiskMap PeseraMap
Risk of soil erosion by water across Europe based on erosion plot data2  Risk of soil erosion by water across Europe based on PESERA model predictions3

What are the effects?

Effects-of-soil-erosion

There are numerous effects of soil erosion which can occur on-site or off-site, further away from the source of erosion.

On-site erosion effects include:

    • Loss of soil fertility from field affecting crop yields
    • Destruction of infrastructure, such as tracks and roads
    • Pollution of watering points for livestock

Off-site erosion effects include:

    • Flash floods down stream of the erosion site
    • Water pollution
    • Sedimentation of water reservoirs

What causes it?

443px Soil erosion by water tonnes per ha per year 2010 EU 28 100 m cell size

Climate

Climate, particularly, rainfall is the primary driver of soil erosion by water. Rainfall is not only the main agent of detachment of soil particles but also the principal source of water running over the soil surface. The erosivity of the rainfall depends on the intensity and duration of a rainfall event as well as of the mass, diameter and velocity of the raindrops. In cold climate regions, however, freezing-thawing cycles can also play a key role in detachment, while snow melt can be an important additional source of runoff.

There are two main runoff generating processes:
- infiltration excess overland flow - occurs when rainfall intensity exceeds a soil’s infiltration capacity
- saturation overland flow - occurs when a soil’s water storage capacity has been exceeded.

Soil Properties
Soil properties strongly determine a soil’s infiltration and storage capacities and, thus how it responds to rainfall events. Low infiltration or storage capacities can result in excess overland flows causing soil erosion.

Human activities
Arguably, human activities have become the most important driver of soil erosion by water in modern times and places, especially those witnessing strong increases in population and/or rapid advances in slope- and landscape engineering capabilities, including inappropriate ploughing and soil compaction from heavy machinery.

How can it be measured or assessed?

The table below lists key and/or proxy indicators for soil threats identified by the RECARE project.

Soil threat

Soil Threat indicators RECARE

Soil erosion by water - area affected by soil erosion (km2) and/or extent of area affected by soil erosion (%)

- magnitude of soil erosion/deposition or sediment delivery (tons)

    ErosionPlot

                                 Erosion plot

The table below lists key indicators, the purpose of the indicator and methods used for measuring soil erosion by water.

Indicators Purpose Methods
 soil loss by water erosion     measure/estimate transport of soil particles by rainsplash/splash erosion  - splash boards as well as funnels and cups of various designs <15-20 cm 1, 5

- portable rainfall simulators 5

measure/estimate transport of soil particles by sheet flow/inter-rill erosion  - micro-plots, field rainfall simulators 1, 5
measure/estimate transport of soil particles by sheet and concentrated overland flow  - large-enough plots (“Wischmeier” plot) typically >10 m long 1, 5
produce erosion risk map  - modelling expert opinion or extrapolation of erosion plot data 2 3 4 7
 magnitude of sediment delivery measure transport of soil particles beyond the hillslope  sediment yield = streamflow’s suspended sediment concentration x discharge 8
 area affected bysoil erosion and/or deposition determine status of cumulative soil erosion  - cross-sectional area of the rills/gullies across a slope
- mapping erosion features using aerial photogrammetry, 3-D laser scanning & satellite imagery 1

 

How can it be prevented or remediated?

Different measures are available to control soil erosion by water. The most appropriate measure to use is dependent on the local situation, but the key principle is maximisation of rainfall infiltration in soils in situ.

Agronomic measures

 Vegetative measures  Structural measures  Management measures
Contour cropping  Vegetative cover  Terracing  Integrated management of micro-catchment
Mulching & residue management  Vegetative strips  Dams & silt fencing  Policy, law and regulation
Tillage management  Grassed waterways  Stone bunds  
Strip contour cropping  Temporary and permanent seedings  Impoundment  
     Gravel access path  

 

ResidueManagement VegetativeStrips Vines terraces
Agronomic measures - residue management Vegetative measures - vegetative strips Structural measures - terracing

SoilThreatsChartHow does it interact with other soil threats?

Soil erosion by water can have an important impact on other soil threats especially on a decline in soil organic matter (SOM), flooding risk, and a decline in soil biodiversity.

How does it affect soil functions?

  • biomass production - direct effect, for example by removal of seeds, or indirectly by reducing rooting space for plant support and reducing available soil water and soil nutrient pool
  • gene pool - if the removal of an organism by runoff is significant in terms of its existing population
  • physical heritage - from changes in the aspect of the landscape, particulary from gully erosion raw materials – providing for example use of sands accumulated in river beds for civil construction purposes.
  • cultural heritage - the removal and re-deposition of archaeological artefacts as well as through the burial of archaeological artefacts under eroded sediments.

Soilfunctions

References

1 Morgan, R.P.C., 2005. Soil erosion and conservation. Blackwell Publishing Ltd., Bodmin. ISBN 1-405-1781-8, 304 pp
2 Cerdan, O., Govers, G., Le Bissonnais, Y., et al., 2010. Rates and spatial variations of soil erosion in Europe: A study based on erosion plot data. Geomorphology 122, 167-177.
3 Kirkby, M.J., Jones, R.J.A., Irvine, B. et al. 2004. Pan-European Soil Erosion Risk Assessment: The PESERA Map, Version 1 October 2003.
4 Panagos, P., Borrelli, P., Poesen, J., Ballabio, C., Lugato, E., Meusburger, K., Montanarella, L., Alewell, .C. 2015. The new assessment of soil loss by water erosion in Europe. Environmental Science & Policy. 54: 438-447
Jones, A., Panagos, P., Barcelo, S. et al. 2012: The state of soil in Europe. EUR 25186 EN – Joint Research Centre. JRC Reference Reports, Publication Office of the European Union, Luxembourg, ISSN 1018-5593, 71 pp.
6 Huber, S., Prokop, G., Arrouays, D., et al., 2008. Environmental assessment of soil for monitoring. Volume I indicators & criteria. EUR 23490 EN/1, Office for the Official Publications of the European Communities, Luxembourg, DOI 10.2788/93515, 339pp
7 Stolte, J., Tesfai, M., Øygarden, L., Kværnø, S., Keizer, J., Verheijen, F., Panagos, P., Bilbao, C and Hessel, R., (2015). Soil threats in Europe. JRC Technical Report.
8 OECD, 2013. Soil. Water and wind erosion. In: OECD Compendium of Agri-environmental Indicators. OECD Publishing. http://dx.doi.org/10.1787/9789264186217-9-en..
9 Vanmaercke, M., Maetens, W., Poesen, J., et al., (2012). A comparison of measured catchment sediment yields with measured and predicted hillslope erosion rates in Europe. J. Soils Sediments 12(4), 586–602. 
10 Chappell, A. Baldock, J. Sandermand, J. (2016) The global significance of omitting soil erosion from soil organic carbon cycling schemes. Nature Climate Change 6, 187–191

 

Useful links

  • A RECARE video link to a presentation explaining soil erosion can be viewed here.

 

Soil erosion by wind is another problem occurring across Europe, usually as a consequence of cultivation when fields are left exposed for a period of time. Iceland is a special case having soils especially prone to wind erosion due to their physical properties that interact with climatic factors, as is reflected in the fact that about 40% of the land area suffers from wind erosion.  

                                           Wind Erosion

Soil erosion by wind in Iceland

                       

 Front Paage Wind Erosion2

 

 

 

 

 

 

 

Slides providing details about soil erosion by wind