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How to distinguish water scarcity and drought in EU water policy? Guido Schmidt & Carlos Benítez-­‐Sanz Intecsa-­‐Inarsa, Madrid Discussion Paper 1333 August 2013 This article looks at the similarities and differences between the interrelated concepts of drought and water scarcity. The authors provide a framework for defining the two terms in order to inform the development of improved EU water policy . drought;1 and due to the very similar effects of
both events, water managers, the public, and
the media often use the terms in an indistinct
manner. This lack of clarity hampers the
implementation of policies and measures
which can adequately deal with the drivers
The Global Water Forum publishes discussion papers to share the insights and knowledge contained within our online articles. The articles are contributed by experts in the field and provide: original academic research; unique, informed insights and arguments; evaluations of water policies and projects; as well as concise overviews and explanations of complex topics. We encourage our readers to engage in discussion with our contributing authors through the GWF website. and pressures of the two phenomena.2,3 The
definitions commonly used are also often too
lengthy, have contradictions and overlaps, and
do not properly explain the interrelationships
between the two events (see Understanding
water
scarcity:
Definitions
and
measurements).
Keywords: water scarcity, drought, definitions, differences, EU, water policy. A screening exercise of 123 River Basin
Management Plans (RBMPs) showed that
Water
scarcity
and
drought
are
two
interrelated but distinct concepts. Despite
widespread recognition of the important
differences between the two concepts, there is
no scientific agreement about the precise
both
water
scarcity
and
droughts
are
recognised as relevant issues by RBMPs across
the EU (see Figure 1a and b). However, the
exercise also showed that the analysis of water
quantity aspects in many RBMPs lacks
definitions of the terms water scarcity and
Suggested Citation: Schmidt, G. & C. Benítez-­‐Sanz (2013), ‘How to distinguish water scarcity and drought in EU water policy?’, GWF Discussion Paper 1333, Global Water Forum, Canberra, Australia. Available online at: http://www.globalwaterforum.org/2013/08/26/how-­‐to-­‐distinguish-­‐water-­‐scarcity-­‐and-­‐drought-­‐in-­‐eu-­‐water-­‐policy/ How to distinguish water scarcity and drought in EU water policy? adequate foundation; the quantity data used
are often insufficient; and the concepts of
water scarcity and drought are not clearly
distinguished.4
In order to improve water management in the
EU, the concepts of drought and water
scarcity need to be clearly differentiated in the
next RBMPs cycle (2015-2021) along with the
Drivers,
Pressures,
Status,
Impacts,
and
Responses for each type of event. This is
particularly important for understanding the
(different) causes of water scarcity and
drought,
determining
appropriate
policy
measures, and assessing their effectiveness.
This is because, in order to design adequate
Figure 1a. Occurrence of drought. Source:
policy
EEA (2009)
responses
to
these
events,
it
is
necessary to make a distinction between
droughts and water scarcity based on their
causes and the opportunities for action.
How to distinguish water scarcity and drought in EU water policy? Figure 1b. Occurrence of water scarcity.
closely related, and if either droughts or water
Source: EEA (2009)
scarcity pass certain thresholds, they can
significantly
In order to facilitate this aim, a set of working
definitions has been developed by the cooperative
EU
Common
Implementation
Strategy for the Water Framework Directive
Implementation process2 based on a review of
affect
the
environment
(terrestrial and freshwater ecosystems, air,
soils), the economy (agriculture and water
uses), and society (public water supplies,
welfare, recreational activities, cultural and
aesthetic values).6,7
previously used definitions and descriptions of
water scarcity and drought events.5 According
There are, therefore, a number of similarities
to the resulting definitions the two concepts
and differences between drought and water
can be distinguished as follows:
scarcity, and the key elements needed to
define and compare the two concepts are set
Drought is a natural phenomenon. It is a
out in the table below:
temporary, negative, and severe deviation
along a significant time period and over a
large region from average precipitation values
(a rainfall deficit), which might lead to
meteorological, agricultural, hydrological, and
socioeconomic drought, depending on its
severity and duration.
Water scarcity is a man-made phenomenon. It
is a recurrent imbalance that arises from an
overuse
of
water
resources,
caused
by
consumption being significantly higher than
the natural renewable availability. Water
scarcity can be aggravated by water pollution
(reducing the suitability for different water
uses), and during drought episodes.
While the two concepts are distinct, the
definitions demonstrate that they are also
How to distinguish water scarcity and drought in EU water policy? Aspect Drought Water scarcity Causes Natural, due to a reduction of precipitation over a certain time period. High temperatures, strong winds, low relative humidity, timing (onset, duration, and end) as well as characteristics of rain can increase the severity. Man-­‐made, due to an overuse of water resources, caused by consumption becoming significantly higher than the natural renewable availability, or pollution (reducing suitability for water uses). Occurrence Drought is a normal, recurrent feature of all climates and can happen in all parts of Europe. Its occurrence can be related to large-­‐scale changes in atmospheric circulation patterns. Due to the increase in water consumption, water scarcity is increasingly prevelant and recurrent across Europe. Duration Droughts are highly variable in their duration and can last from a few weeks to several years. Water scarcity is usually characterised by a permanent and continued degradation of water ecosystems and reduced water availability for other (economic) functions. Impacts The impacts of both are highly variable according to the occurrence, severity, and duration of the event as well as the sensitivity of the affected ecosystems, economy, and society. They are also influenced by the relative humidity of soils, capacity of storage for groundwater, and streamflow of surface waters. When occurring in already water scarce areas, droughts have the most severe effects. Spatial extent Regarding geographical extension, droughts and water scarcity can both happen at a local level or cover entire RBDs. Drought events are even reported across wide areas of the EU. Predictability Interaction Environmental thresholds Drought forecasting is currently based on statistical analysis of historical occurrences and numerical weather forecasts, with a timeframe from a few days up to several months (generating increasing uncertainty). Implementation is planned in the frame of European Drought Observatory. Water scarcity is predictable for the mid-­‐ and long-­‐term in the frame of RBMPs if adequate information on water availability and consumption and trends has been compiled, and considering the uncertainty e.g. of climate change predictions. When droughts occurr in an area characterised by water scarcity, their impact will be more severe as they are more vulnerable. Heat waves can aggravate droughts and water scarcity situations. Water scarcity can also be an effect of overexploitation due to (concurrent) drought events, but this does not apply vice versa i.e. drought is not an effect of water scarcity. (Freshwater) ecosystems are often characterised by, and adapted to, recurrent natural variations in precipitation and 1
streamflow . Nonetheless, exceptionally severe droughts or the combined impact of droughts with man-­‐made overabstraction / water scarcity can result in irreversible changes to ecosystems. Water scarcity usually affects the ecological status of ecosystems with the extent depending on duration, relevance, and the sensitivity of the ecosystem (including functions and elements). 1
Note that the case of non permanent rivers should be carefully tackled. How to distinguish water scarcity and drought in EU water policy? Aspect Costs Drought Water scarcity In general, little data is available about the precise costs of water scarcity or drought situations (for marketable sectors, like agriculture and energy). Where data is available, it should evaluate the combined effects of a drought and geographically overlapping water-­‐scarce area. Pan-­‐European Indicators The European Drought Observatory offers a combined drought indicator, based on the Standard Precipitation Index (SPI), soil moisture and the Fraction of Absorbed Photosynthetically Active Radiation (fAPAR). The Water Exploitation Index has been developed by the European Environmental Agency. A refinement to reflect consumption data and monthly/seasonal resolution is still in the testing phase (WEI+). Possible measures to prevent or mitigate effects Drought forecasting, risk prevention (e.g. insurance, climate change adaptation, increased flexibility of water usage, increased water efficiency, protection of vulnerable species and habitats, governance rules for different drought thresholds) and emergency actions (e.g. water supply). RBMPs, water management, metering and allocation, water demand management, increase water efficiency and reuse, protection of vulnerable species and habitats, pricing policies etc. DPSIR focus Responses focus on Impacts. Responses focus on Drivers, Pressures, and Impacts. Development of Drought Management Plans (DMPs), water allocation systems, and water Possible policy governance rules and regulations. Support for responses insurance systems. Financial support for emergency actions (e.g. Solidarity Funds). Reduction of pressures via sectoral policies (e.g. agriculture, energy, urban development) related to water usage (e.g. on water-­‐usage planning, water allocation and pricing systems, control) Taking into account these definitions and the differences and similarities between water scarcity and
drought events,8,9 the recent EU water policy review “A Blueprint to safeguard Europe’s waters”,
promotes action lines for both concepts over the next few years. Some of these measures include e.g.
enforcing water pricing/cost-recovery obligations under the Water Framework Directive; including
metering when relevant; completing the hydro-economic model for Europe and establishing water
accounts; developing guidance on and implementing environmental flows; applying GMES services
to detect illegal abstraction; and further developing the European Drought Observatory.10 By
recognising the distinct and interrelated aspects of water scarcity and drought, the EU is attempting
to improve water governance and implement water policies designed to tackle the particular issues of
droughts or of water scarcity when appropriate.
References
1. Mishra & Singh (2010): A review of drought concepts. Journal of Hydrology 391: 202-216
2. CIS Expert Group on Water Scarcity & Drought (2012): Working definitions of Water Scarcity and
Drought. URL: https://circabc.europa.eu/sd/d/02a234f7-ac60-4f81-bd8d-a3a0973e77d1/55171Drought-WS_Definitions_V4-27Abril2012.doc (after ECAS registration only)
How to distinguish water scarcity and drought in EU water policy? 3. Van Loon, A. F., and H. A. J. Van Lanen (2013): Making the distinction between water scarcity and
drought using an observation-modeling framework, Water Resour. Res., 49, 1483–1502,
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4. Schmidt, G. & C. Benítez-Sanz (2012): Topic report on: Assessment of Water Scarcity and Drought
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European Commission (under contract “Support to the implementation of the Water Framework
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Policy Options for Conference on Drought. URL: http://www.feem-project.net/xerochore/files/D5.1.pdf.
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Policy (COM/2012/0672 final). URL: http://eurlex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:52012DC0672:EN:NOT.
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2/2009. URL: http://www.eea.europa.eu/publications/water-resources-across-europe.
About the author(s)
Guido Schmidt is Senior Programme and Project Manager aiming to better understand, prevent and/or
solve water and environmental problems and conflicts; with a focus on water policy and planning in
water-scarce areas. Carlos Benítez-Sanz is Agricultural Engineer with over 20 years experience. His
activity in recent years has focused on water planning under the Water Framework Directive in Spain:
Ebro, Andalusian Mediterranean Basin and the Basque Country. He is also involved in supporting
works for the European Commission. Both have supported the work of the mentioned EU Expert Group.
The article is based on deliverables of the EU Expert Group on Water Scarcity and Droughts of the
Common Implementation Strategy for the Water Framework Directive, namely Working definitions of
Water Scarcity and Drought (2012), and the authors supported the Group’s work as consultants.
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