Slide 1Workshop on Common Criteria for Risk Area Identification in
the Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
A workshop in support of the Thematic Strategy for Soil
Protection
Common Criteria for Risk Area Identification in the Soil Framework
Directive
BGR, Hannover, 25 April 2007
Soil Erosion
Dick Thompson on behalf of: Bob Jones National Soil Resources
Institute Cranfield University UK
Contributors: Christine Le Bas, Josef Kozak Advisors: Olaf Düwel,
Dominique King
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Soil Erosion – points to be covered
Definitions, types, causes and consequences of soil erosion
Identifying areas at risk Conclusions
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Definition of Soil Erosion
‘Soil erosion is the wearing away of the land surface by physical
forces such as rainfall, flowing water, wind,
ice, temperature change, gravity or other natural or anthropogenic
agents that abrade, detach and remove
soil or geological material from one point on the earth's surface
to be deposited elsewhere’.
Soil erosion is normally a natural process occurring over
geological timescales; but where (and when) the
natural rate has been significantly increased by anthropogenic
activity accelerated soil erosion becomes a process of degradation
and thus an
identifiable threat to soil.
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Types of erosion
- Water - Wind - Tillage
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Water erosion
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Water erosion
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Water erosion
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Wind erosion
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Tillage erosion
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Characteristics of soil erosion
• Variable in intensity, scale & nature • Episodic – very often
event-driven • Leads to conversion of soil into
sediment • Driven by nature as well as man
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Drivers
Water Rain-splash dislodges soil particles that initially fly
through the air (saltation) Rain-flow, Rill-wash cause overland
flow Slope wash, Sheet wash cause overland flow Wave motion in
streams, rivers and lakes cause slumping of bank material
Wind Wind velocity dislodges loose soil particles that become
airborne until velocity reduces
Anthropogenic factors, such as:-
Tillage and other mechanical influences
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Surface capping
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Livestock
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Topsoil / Subsoil junction
Compaction (heavy machinery)
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
On-site Removal/redistribution of soil Loss of productivity
Reduction of soil functional capacity
Off-site Silting of lakes, reservoirs and river courses Diffuse
pollution of soil and water by contaminants and nutrients
Destruction of habitats Damage to property &
infrastructure
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Approaches
3. Combination of 1 and 2 above.
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
1. Measure soil loss from plots [ field scale] or larger areas
(resource intensive and requires long term commitment)
2. Expert judgement/field observation of soil loss from a field,
hillslope, river basin or catchment, or other spatial unit (e.g.
administrative unit)
3. Measure suspended sediment in rivers, lakes [catchment
scale]
Measuring Soil Erosion
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Weather station
Weather station
Carcassonne Site
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
We have insufficient field data and the required monitoring
networks do not currently exist so:
The assessment of erosion at European scale is only feasible by
using mathematical models
Most models attempt to combine:
1. Inherent soil erodibility & landscape (eg slope
characteristics for water erosion) - vulnerability 2. Drivers &
degree of protection provided by vegetation or crops - risk
Advise note: Soil losses estimated from computer models need
validation
- we need a monitoring network
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Tillage-cultivation practices
Land levelling, terrace construction
Climate change?
Land Use/Land cover: arable, grassland/pasture, forest,
semi-natural vegetation Land management: cropping systems,
irrigation, grazing intensity
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
DATA Sources
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Accelerated erosion by running water has been identified as one of
the most severe threats to soil in Europe.
Estimated soil loss by rill and inter-rill (water) erosion
Pan-European Soil Erosion Risk Assessment PESERA
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Is there a ‘tolerable rate’ of soil erosion?
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Some figures
Extreme events Storms can erode 50-100+ t/ha/single event
Natural erosion rates: Recent study (Wilkinson and McElroy, 2007)
Avg rate for 542million years (Phanerozoic) = 0.42 t/ha/yr Avg rate
in Pliocene (most erosive period) = 1.36 t/ha/yr Current riverine
flux to global oceans = 1.78 t/ha/yr Erosion from present day
farmland = 6.36 t/ha/yr
Tolerable erosion rates : < 1 t/ha/yr as a precaution 1.5
t/ha/yr might be acceptable ~ Pliocene = 1.4 t/ha/yr
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Summary and conclusions
Soil erosion is a significant problem in Europe It is expected to
increase under climate change Water erosion is the most widespread
form It is right that the SFD covers its control
Tolerable erosion rates - policy process to decide [but] soil loss
>1 t/ha/yr = accelerated over natural rate
Soil erosion should be monitored through a network of fully
instrumented measuring sites
should be established across Europe
Workshop on Common Criteria for Risk Area Identification in the
Soil Framework Directive, BGR, Hannover, 25 April 2007
‘Soil Erosion’
Thank you!
Danke schön!
Compaction (heavy machinery)
