|
1. Definition
| Name |
IMPERVIOUS
SURFACE AREA |
| Brief definition |
The area over
which the soil is covered by impervious materials. This includes
all kinds of buildings, roads and infrastructure but also areas
covered by plastic and used for agriculture. The use of heavy
agricultural machines and bulldozers for terrace construction
also creates impervious surfaces. |
| Unit of measure |
km² |
| Spatial scale |
Medium |
| Temporal scale |
Annual changes |
2. Position
within the logical framework DPSIR
| Type of Indicator |
Driving force,
state, impact and response |
3. Target and
political pertinence
| Objective |
Land
that is sealed no longer performs many of its former ecological
functions. Rain no longer stays were it falls to be used by
plants, but runs off the impervious surface causing problems
of flooding, erosion and sedimentation. Less soil water available
for evaporation means that the impermeable areas get hotter
and there is a reduction in the humidity of the area affected.
The objective is to have an indicator that enables the increase
in the sealed areas to be recorded. |
| Importance
with respect to desertification |
The increase of sealed
areas is seen as one of the major threats to European soils
and landscapes and this is particularly the case in the Mediterranean.
The following aspects are important for desertification.
- Sealing indicates an
increased risk of runoff, erosion and flooding.
- Sealing means that
there is a loss of biodiversity and an increase in temperature
because there is less evaporative cooling from soils.
- The areas covered by
impermeable surfaces are no longer providing the ecological
and economic functions and the goods and services associated
with them.
- The impact of soil
compaction during terrace construction is a major cause
of land degradation as it reduces the ability of the soil
to store water.
- The increase of the
impervious area is easy to measure and it is an indicator
of the pressures on the environment resulting from infrastructure
development.
- Increase in the impervious
area is an indicator of the general level of pollution and
energy use.
- The areas covered by
plastic (e.g. near Almeria in Spain) represent a special
case.
|
| International
Conventions and agreements |
Sealing has
been identified as one of the major threats to European and
other soils. |
| Secondary objectives
of the indicator |
Impervious
surface area indicates the loss of all kinds of functions (natural
water purification, water and nutrient regulation, evaporative
cooling). It is partly an explanation for the high summer temperatures
experienced in cities. |
4. Methodological
description and basic definitions
| Definitions
and basic concepts |
The
indicator can be defined as the change in area of the sealed
or impervious surface. |
| Benchmarks
Indication of the values/ranges of value |
National and
EU Environment Agencies as well as many other organisations
report this as an indicator of land use change. |
| Methods
of measurement |
The
indicator is easy to measure and calculate from available data
and monitoring programmes. In fact the EU is monitoring it and
the CORINE 2000 data base can also be used. Local information
is usually monitored by planning authorities at different organisational
levels. At the local scale, airborne laser altimetry can be
used to accurately measure changes. |
| Limits
of the indicator |
The
indicator refers to areas that are sometimes quite different
in terms of the characteristics of the impervious area. It is
useful to distinguish between different types of impervious
surface. |
| Linkages
with other indicators |
Land
use type, Erosion risk
(RDI), Infiltration
capacity, Soil erosion
(USLE), Soil quality
index, Water storage
capacity, Management
quality index, Tillage
operations, Runoff
water storage, Water
availability.
|
5. Evaluation
of data needs and availability
| Data
required to calculate the indicator |
The
field measurement determinations needed to calculate this indicator
are being systematically collected in Europe. |
| Data
sources |
European
Environment Agency, JRC, Planning authorities in different countries
and regions, CORINE. |
| Availability
of data from national and international sources |
Generally available. |
6. Institutions
that have participated in developing the indicator
| Main institutions
responsible |
Foundation
for Sustainable Development (3D-EC). In the MEDALUS project
this topic was studied by the University of Cagliari (Prof Aru
and co-workers)
|
| Other contributing
organizations |
|
7. Additional
information
| Bibliography
|
Prof. W. Burghardt Chairman
of the EU working group on soil sealing in Europe produced
a report which can be downloaded at the following site. This
is a 57 page report that provides extensive background information
regarding this issue. It is organised according to the DPSIR.
http://www.uni-essen.de/bodenkunde/links/eusoil/EUUrbansoilsapr04.pdf
|
| Other references |
See JRC remote
sensing project |
| Contacts
Name and address |
A.C. Imeson
Foundation for Sustainable Development (3D-EC), Netherlands
3de@hetnet.nl
|
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