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1. Definition
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Name
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AQUIFER OVER-EXPLOITATION
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Brief definition
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Aquifer over-exploitation
is a significant cause water resources deficiency
due to bad management.
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Unit of measure
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hm³ of water/year
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Spatial scale
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Sub-region
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Temporal scale
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Annual
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2. Position within the
logical framework DPSIR
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Type of Indicator
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Pressure
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3. Target and political
pertinence
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Objective
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Identification
and mapping of ESAs, predicting the areas in which
the degradation process will be more important. Prioritisation
of mitigation actions to combat desertification.
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Importance with
respect to desertification
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Environmental effects of aquifer over-exploitation:
- increase in
depth of water table,
- decrease in
flow of rivers and springs,
- soil salinization,
- ground water
pollution,
- subsidence
and landslide processes.
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International
Conventions and agreements
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Secondary objectives of the indicator
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To generate a map of aquifer over-exploitation at
sub-watershed scale.
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4. Methodological description
and basic definitions
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Definitions and
basic concepts
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In the Spanish
dry areas the ground water is pumped up for urban
water supply and irrigated crops. In some of those
areas, the ratio between the aquifer exploitation
rate and the aquifer recharge rate is greater than
one.
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Benchmarks Indication
of the values/ranges of value
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Classes of aquifer exploitation:
- exploitation
> recharge,
- recharge
> exploitation > 0.8·recharge,
- local problems
of over-exploitation,
- without problems
of over-exploitation.
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Methods of measurement
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Assessment of
water consumption, estimation of the decrease in river
and spring flow, ground water monitoring and appraisal
of the recharge rate.
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| Limits
of the indicator |
Difficulties
in the measurement of the quantity of water pumped up
from aquifers. Illegally irrigated crops. In drought
situations controlled aquifer over-exploitation might
be allowed by certain water administrations. At the
end of the drought, conditions should be changed to
enable the aquifer to recover.
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Linkages with
other indicators
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Groundwater
depth (change in), Water quality.
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5. Evaluation of data
needs and availability
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Data required
to calculate the indicator
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Water table depth
evolution, or input/output water balance of the aquifers
over a period of time.
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Data sources
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Field and remote
sensing data.
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Availability of data from national and international
sources
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In Spain the National Water Administration keeps an
inventory and track of aquifer usage.
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6. Institutions that
have participated in developing the indicator
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Main institutions
responsible
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Dirección General
de Conservación de la Naturaleza (DGCN), Secretaría
de Medio Ambiente, Ministerio de Medio Ambiente, Spain.
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Other contributing
organizations
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7. Additional information
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Bibliography
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Programa de Acción Nacional contra la Desertificación
(DGCN, Ministerio de Medio Ambiente, Spain).
Desertification
Indicators for the European Mediterranean Region (Enne,
G. and Zucca,C. 2000).
Libro
Blanco de las Aguas Subterráneas (Ministerio de Industria
y Energía, Spain, 1994).
Libro
Blanco del Agua en España (Ministerio de Medio Ambiente,
Spain, 1998).
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Other references
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Contacts Name
and address
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Leopoldo Rojo
Serrano <LRojo@mma.es>
Dirección General de Conservación de la Naturaleza
Ministerio de Medio Ambiente
Gran Vía de San Francisco 4
28005 Madrid (Spain)
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