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1. Definition
| Name |
IRRIGATION
INTENSITY AND SEAWATER INTRUSION |
| Brief definition |
The presence
of seawater intrusion in aquifers in coastal areas. |
| Unit of measure |
Subjective
classification |
| Spatial scale |
|
| Temporal scale |
|
2. Position
within the logical framework DPSIR
| Type of Indicator |
State or Impact
(depending on the process analyzed) |
3. Target and
political pertinence
| Objective |
The
objective of the indicator is to assess the effects of groundwater
abstraction (for irrigation processes or other uses) on the
hydro geological process of seawater intrusion. |
| Importance
with respect to desertification |
Large areas
of the Mediterranean coastline have been reported to be affected
by saltwater intrusion. The main cause is groundwater over-abstraction
for public water supply. Irrigation is the main cause of groundwater
over-exploitation in agricultural areas. Saltwater intrusion
processes leads to poor quality groundwater, which can lead
to soil salinization problems and soil degradation processes
when this water is used in agriculture. If this groundwater
is to be used as fresh water it needs de-salinization, which
makes it more expensive. Sometimes the groundwater is too saline
to be used at all. |
| 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 |
Contribution
to the definition and mapping of ESAs and evaluation of the
desertification risk of an area. |
4. Methodological
description and basic definitions
| Definitions
and basic concepts |
The rapid expansion in
groundwater abstraction over the past 30 to 40 years has supported
new agricultural and socioeconomic development in regions
where alternative surface water resources are insufficient,
uncertain or too costly. Over-abstraction leads to groundwater
depletion, loss of habitats and deteriorating water quality.
It is a significant problem in many European countries. One
of the impacts is the intrusion of saltwater into aquifers.
In 9 out of 11 countries where coastal overexploitation was
reported to exist, saltwater intrusion is the consequence.
The exploitation of coastal aquifers always produces a lowering
of the water table levels, balanced by sea level in the coastal
strip. When the extracted volumes are greater than the recharge,
even on a local basis, a salinisation process begins in the
aquifer as the seawater flows under the land. In the light
of this, the management of coastal aquifers is conditioned
by the need to determine the maximum permissible penetration
limit for each particular aquifer.
The problem of aquifer
contamination by seawater intrusion, together with the extent
and seriousness of the problem, is mainly conditioned by three
factors: the difference between the respective densities of
the fresh and salt water, the hydrodynamic properties of the
aquifer, and the flow that the aquifer discharges into the
sea. The first two factors are intrinsic to the seawater intrusion
problem regardless of the climate in the region. Furthermore,
these two parameters are fixed, and cannot be modified by
the usual anthropogenic activity. The flow that the aquifers
discharge into the sea is conditioned by natural conditions
(from rainfall) or artificial recharge (mainly from irrigation)
and by pumping. Therefore, anthropogenic actions can bring
about some modifications.
 |
source:
http://www.solinst.com/Res/papers/101C4Salt.html |
|
| Benchmarks
Indication of the values/ranges of value |
Presence/absence
of salt water intrusion. |
| Methods of
measurement |
The presence
of salt water intrusion must be studied under local conditions.
The depletion of groundwater levels and the change in water
quality can indicate the appearance of the problem. The depletion
of the groundwater level is the first step in the process. |
| Limits of the
indicator |
Information
about aquifer characteristics is necessary. Water quality must
be monitored. |
| Linkages with
other indicators |
Groundwater
depth (change in), Water quality,
Aquifer over-exploitation,
Water use policy/law |
5. Evaluation
of data needs and availability
| Data
required to calculate the indicator |
Variation
in groundwater levels. Water quality, water composition. |
| Data sources |
Data can be
obtained from irrigation applications, groundwater exploitation
managers or official statistics |
| Availability
of data from national and international sources |
Usually available
at national, regional or local levels. |
6. Institutions
that have participated in developing the indicator
| Main
institutions responsible |
University
of Murcia
|
| Other contributing
organizations |
Agricultural
University of Athens, Universities of Lisbon, Basilicata, Amsterdam,
Leeds |
7. Additional
information
| Bibliography
|
EEA, 2003. Indicator Fact
Sheet: (WQ03b) Saltwater intrusion
Estrela T., Marcuello
C.and Iglesias A. 1996. Water resources. Problems in Southern
Europe. An overview report. European Topic Centre on Inland
Waters. European Environment Agency
|
| Other references |
Valdés,J.B. &
Maddock,T., 2003: Water resources management in Semi-Arid
Regions: The United States Southwest. In A. Pulido y A. Vallejos
(Eds): Gestión y contaminación de recursos hídricos.
Publicaciones de la Universidad de Almería. Almería,
37-54
Collin,J.J.; Margat, J.,
193: Overexplotaition of water resources: overreaction or
an economic reality? Hydroplus, No 36: 26-37
Custodio,E., 1992: Hydrogeological
and hydrochemical aspects of aquifer overexplotaition. In
Selected Papers in Hydrogeology. International Association
of Hydrogeologits. Heise, Hannover, Vol.3: 3-28Custodio,E.,
2000: The complex concep of overexploited aquifer. Papeles
del Proyecto Aguas Subterráneas. Serie A, No 2. Fundación
Marcelino Botín. Madrid, 62 pp
|
| Contacts
Name and address |
University of Murcia
Jorge García Gómez email: jorgegg@um.es
Pr. Francisco López Bermúdezemail: lopber@um.es
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