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1. Definition
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Name
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DROUGHT (Spanish
NAP)
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Brief definition
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According to the
World Meteorological Organization "an area is
affected by drought when the annual precipitation
is lower than 60 % of the normal values, at least
during 2 consecutive years in more than 50 % of its
area".
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Unit of measure
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% of the normal
mean annual precipitation values.
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Spatial scale
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Regional
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Temporal
scale
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Annual
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2. Position within the
logical framework DPSIR
3. Target and political
pertinence
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Objective
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Identification
and mapping of ESAs. Prioritisation of mitigation
actions to combat desertification.
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Importance with
respect to desertification
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Environmental
effects of droughts:
- water
table depth increase,
- decrease
in river flow,
- water
pollution,
- soil
and water salinization,
- soil
pollution by fertilizers
- increase
in soil erosion risk,
- increase
in wild and forest fires risk,
- damage
in forests,
- vulnerability
of vegetation to other damaging agents (pests, fires,
wind, etc.)
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International
Conventions and agreements
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As the UNCCD establishes,
drought is "the naturally occurring phenomenon
that exits when precipitation has been significantly
bellow normal recorded levels, causing serious hydrological
imbalances that adversely affect land resource productions
systems".
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Secondary
objectives of the indicator
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To
predict the areas in which the degradation process
will be more important.
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4. Methodological description
and basic definitions
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Definitions and
basic concepts
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In arid, semi-arid
and dry sub-humid areas, the annual rainfall is scarce
and its distribution during a year is very variable.
This fact is the cause of a soil hydric deficit during
several months. In addition, in those areas there
are frequent and long periods of time in which annual
precipitation is more scarce than the normal recorded
levels.
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Benchmarks Indication
of the values/ranges of value
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According to the
World Meteorological Organization "an area is
affected by drought when the annual precipitation
is lower than 60 % of the normal values, at least
during 2 consecutive years in more than 50 % of its
area".
|
|
Methods of measurement
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Comparison of
the annual precipitation with the mean annual precipitation
calculated from the rainfall sets recorded for several
years (30) in the same area.
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Limits of the
indicator
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Linkages with
other indicators
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Rainfall,
Vegetation
cover, Water quality,
Groundwater depth
(change in), Aquifer
over-exploitation, Soil salinity index and Fire
risk.
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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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The data required
are the annual rainfall statistics for several years
to calculate the average annual precipitation.
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Data sources
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Meteorological
data sets (at least for 30 years).
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Availability of
data from national and international sources
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Available from
Meteorological Services or directly from field stations.
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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).
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Other references
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Inventario UE-ECE
de daños forestales (IDF) en España (DGCN, Servicio
de Protección de los Montes contra Agentes Nocivos,
Ministerio de Medio Ambiente, Spain).
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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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