Land and Water Development Division Water Resources, Development and Management Service - PowerPoint PPT Presentation

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Title: Land and Water Development Division Water Resources, Development and Management Service


1
Land and Water Development DivisionWater
Resources, Development and Management Service
AQUASTAT
Key water resources statistics
by Karen FRENKEN
International Work Session on Water Statistics,
Vienna, Austria, 20-22 June 2005
2
Water resources
Review of world water resources by country
  • Internal, external surface water and groundwater
  • Country dependency on water from other countries
  • Flows reserved by treaties
  • Calculation spreadsheets with rules and
    guidelines for accounting water resources
  • Regional overviews of the water resource situation

3
Key words
  • Presents country-level information
  • Deals with renewable water resources
  • Concentrates on the physical assessment of
    internal and external renewable water resources
  • Presents of picture of the natural state and
    current situation, taking into account existing
    uses of water
  • Combines field-based approaches with modeling
    approaches

4
Renewable water resources
  • Internal Renewable Water Resources (IRWR)
  • External Renewable Water resources (ERWR)
  • Natural Renewable Water Resources (NRWR)
  • Actual Renewable Water Resources (ARWR)
  • Exploitable Water Resources

5
Internal Renewable Water Resources
IRWR R I (QOUT QIN) R Surface
runoff, generated from endogenous
precipitation I Groundwater recharge,
generated from endogenous precipitation QOUT
Groundwater drainage into rivers (typically,
baseflow of rivers) QIN Seepage from rivers
into aquifers A simple addition of surface water
and groundwater would lead to an overestimation
of the renewable water resources. (Qout Qin),
called Overlap, is the exchange between surface
water and groundwater or the common part of
surface water and groundwater. Humid countries O
? Very arid and coastal areas O ?
6
Internal renewable water resourcesin theNile
Basin
7
External Renewable Water Resources
ERWRNATURAL SWIN SWPR SWPL
GWIN ERWRACTUAL SW1IN SW2IN SWPR SWPL
SWOUT GWIN SW1IN Surface water entering the
country which is not submitted to treaties SW2IN
Surface water entering the country, which is
secured through treaties SWPR Accounted flow
of border rivers SWPL Accounted part of
shared lakes SWOUT Surface water leaving
country, reserved by treaties for downstream
countries GWIN Groundwater entering the
countries Actual ERWR may vary with
time. Established rules to compute the different
components of the external water resources
8
Total Renewable Water Resources
TRWRNATURAL IRWR ERWRNATURAL
TRWRACTUAL IRWR ERWRACTUAL While IRWR can
be added up, TRWR can not
9
Dependency ratio
Dependency ratio IRWR/(IRWRIWR)x100 IWR
SW1IN SW2IN SWPR SWPL GWIN SW1IN
Surface water entering the country which is not
submitted to treaties SW2IN Surface water
entering the country, which is secured through
treaties SWPR Accounted flow of border
rivers SWPL Accounted part of shared
lakes GWIN Groundwater entering the
countries The dependency ratio does not consider
possible allocation of water to downstream
countries Indicator varies theoretically between
0 and 100 percent
10
(No Transcript)
11
Matrix of transboundary flows
12
The potential of models
  • Relying on country information alone does not
    ensure consistency between countries
  • A model, using available information, presents a
    homogenous methodology for computing the water
    balance across a continent
  • The model developed is simple and performed
    entirely within the GIS environment
  • It has been tested on Africa and will next be
    used on Asia
  • Combined use of country-based data and global
    water-balance modeling can enhance the overall
    reliability of the results

13
Assessment of the resultsreflections
14
Country information
  • Critical analysis is necessary to ensure
    consistency between different data collected
  • Gathering data from different sources highlights
    similarities, but also contradictions
  • Little information available on humid Africa
  • Many studies done on arid climates, but access to
    information is sometimes restricted for strategic
    reasons
  • No consistency can be ensured at regional level
    on period of reference, duration, etc.

15
Natural water resources
  • Hydrological approach (measurements,
    extrapolation, modeling) is not perfect. Natural
    versus actual upstream versus downstream
  • Metadata needed on methods used, validity of
    results, etc.
  • Time reference problem (reference period,
    frequency of occurrence)
  • Spatial reference problem (maps, region, country,
    basin)
  • Water quality problem (definition, classes,
    changes during flow)

16
Exploitable water resources
Natural resources are quantified exclusively on a
hydrological basis, which is necessary. However,
not all natural water is accessible. Need to
quantify exploitable or manageable water
resources as a function of
  • technical-economic criteria affordable cost of
    development and exploitation
  • Environmental criteria exclusion of water that
    needs to be conserved for nature
  • geopolitical criteria sharing of water between
    countries

Minimum of consensus between the countries of
each large region in the world needed in order to
have water statistics that are comparable and
respond better to the demands
17
Secondary and non-conventional sources of water
  • Secondary resources refers to return of primary
    water into the system, thus becoming available
    for use again. It is the interaction between
    resource and use in a same area without
    increasing the natural resource. Example
    agricultural drainage water
  • Wastewater reuse refers to the reuse of urban or
    industrial wastewater (with or without
    treatment), increasing the overall efficiency of
    use of water (extracted from primary sources)
  • Desalinized water refers to the production of
    freshwater by desalinization of brackish water or
    saltwater
  • Inter-basin water transfer, transporting water
    between different river basins. Examples
    Highlands water project in Southern Africa,
    importation of water in Israel from Turkey

18
Concluding remarks
Adaptation of water statistics to information
needs should be well targeted. Always ask
question for whom and for what use they are
intended
It is advisable to regionalize the efforts to
improve water statistics as a function of the
needs, which are far from uniform in the world
19
Thank you
Web site http//www.fao.org/ag/aquastat
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