|
1. Definition
| Name |
EROSION
RISK (RDI) |
| Brief definition |
A quantitative
estimate of the long term average rate of land erosion at a
site of interest. |
| Unit
of measure |
Tonnes
Ha-¹ year-¹ |
| Spatial scale |
|
| Temporal
scale |
|
2. Position
within the logical framework DPSIR
3. Target and
political pertinence
| Objective |
To
provide a measure of the expected rate of water erosion for
a given small area (generally 1 km²). The PESERA/RDI model
is used to make the estimate. |
| Importance
with respect to desertification |
Overland
flow runoff occurs where the intensity and duration of rainstorms
exceeds the capacity of the soil to infiltrate the rain. The
volume of runoff, combined with the topography and soil strength
(erodibility) determine the volume eroded during a storm, and
the erosion risk is the cumulative effect of storms over a period.
Water erosion is widely considered to be the most serious desertification
hazard in Europe. |
| International
Conventions and agreements |
The
UNCCD emphasizes that combating desertification must be tackled
within the general framework of actions to promote sustainable
development. |
| Secondary
objectives of the indicator |
As
well as indicating the general level of erosion expected, the
erosion risk can be used to allocate resources for mitigation
or further research. It can also be used to investigate the
expected impact of land use or climate change scenarios. |
4. Methodological
description and basic definitions
| Definitions
and basic concepts |
The
PESERA/RDI model is used to make a physically based estimate
of the erosion risk, combining three components which are multiplied
together:
- Erosivity, derived
from climate and soil properties, determines the power of
the runoff to transport sediment
- Topographic index,
estimated from local relief (standard deviation of heights
within a 1 km radius)
- Soil erodibility, estimated
from soil characteristics, primarily texture.
|
| Benchmarks
Indication of the values/ranges of value |
Erosion
risk normally takes values between 0.1 and 100 T Ha-¹ yr-¹.
Replacement of organic topsoil may take place at up to 5 T Ha-¹
yr-¹, but replacement of mineral soil by weathering generally
occurs at 1 T Ha-¹ yr-¹ or less, so that values of
more than 2-5 T Ha-¹yr-¹ generally lead to progressive
loss of soil and associated fertility. |
| Methods
of measurement |
The
index is calculated within the PESERA/RDI model. Estimates may
be compared with experimental field plot data and with more
detailed models such as WEPP or LISEM. |
| Limits
of the indicator |
The
indicator is applicable only to erosion by running water. It
contains routines for estimating loss under snow and freezing
conditions. |
| Linkages
with other indicators |
Erosivity
(RDI), Runoff Threshold
(RDI) |
5. Evaluation
of data needs and availability
| Data
required to calculate the indicator |
The
main data sets required are as follows. Data should be interpolated
to a regular grid, generally at 250-1000m.
- Daily rainfall for
>=10 years.
- Monthly means for temperature
and potential evapotranspiration
- Digital Elevation Model
- Soils map (European
Soils Data Base or better)
- Land use (e.g. CORINE),
or monthly remotely-sensed land cover
|
| Data
sources |
Necessary
data are usually available and accessible to researchers, but
meteorological data may be expensive. |
| Availability
of data from national and international sources |
Data
can be obtained from various regional, national or international
institutions involved in the collection and the analysis of
meteorological and soils data. The 90 m SRTM DEM is available
from the EROS data centre free of charge. |
6. Institutions
that have participated in developing the indicator
| Main
institutions responsible |
University
of Leeds |
| Other
contributing organizations |
Catholic
University of Leuven, Agricultural Univ of Athens, ISRIC Wageningen,
CSIC/EEZA Almeria, INRA Orleans, Universities of Basilicata,
Lisbon and Murcia. |
7. Additional
information
| Bibliography
|
Kosmas,
C., Kirkby, M. and Geeson, N. 1999. Manual on: Key indicators
of desertification and mapping environmentally sensitive areas
to desertification. European Commission, Energy, Environment
and Sustainable Development, EUR 18882, 87 |
| Other
references |
Kirkby,
M.J., Y. Le Bissonais, T.J. Coulthard, J. Daroussin and M.L.
McMahon, 2000. The development of Land Quality Indicators for
Soil Degradation by Water Erosion. Agriculture, Ecosystems and
Environment, 81, 125-36
Kirkby, M.J., Jones, R.J.A.,
Irvine, B., Gobin, A, Govers, G., Cerdan, O., Van Rompaey,
A.J.J., Le Bissonnais, Y., Daroussin, J., King, D., Montanarella,
L., Grimm, M., Vieillefont, V., Puigdefabregas, J., Boer,
M., Kosmas, C., Yassoglou, N., Tsara, M., Mantel, S., Van
Lynden, 2004. G. Pan-European Soil Erosion Risk Assessment:
The PESERA Map, Version 1 October 2003. Explanation of Special
Publication Ispra 2004 No.73 (S.P.I.04.73). European Soil
Bureau Research Report No.16, EUR 21176, 18pp. Office for
Official Publications of the European Communities, Luxembourg.
|
| Contacts
Name and address |
Mike
Kirkby, School of Geography, University of Leeds, LS2 9JT, UK
mike@geog.leeds.ac.uk |
|
