AQUASTAT FAO’s global information system on water and agriculture Food and Agriculture Organization of the United Nations Land and Water Division Water Resources Statistics by Karen FRENKEN AQUASTAT Programme Coordinator Eurostat seminar for EECCA countries on water statistics Almaty, Kazakhstan, September 2012

Water resources Internal and external surface water and groundwater Dependency of a country on water from other countries Flows reserved by treaties Calculation spreadsheets with rules for accounting water resources Regional overviews of the water resources situation Review of world water resources by country:

Key words  Presents country-level information  Deals with renewable water resources  Concentrates on the physical assessment of internal and external renewable water resources  Takes into account agreements and treaties between countries  Includes many metadata  Combines field-based and modeling approaches

Renewable Water Resources  Internal  External  Natural  Actual  Total

Internal Renewable Water Resources IRWR = R + I – (Q OUT – Q IN ) R = Surface runoff, generated from endogenous precipitation I = Groundwater recharge, generated from endogenous precipitation Q OUT = Groundwater drainage into rivers (typically, baseflow of rivers) Q IN = 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 = 

Internal renewable water resources (IRWR) in the Nile Basin

External Renewable Water Resources ERWR NATURAL = SW IN + SW PR + SW PL + GW IN ERWR ACTUAL = SW 1 IN + SW 2 IN + SW PR + SW PL – SW OUT + GW IN SW IN = Surface water entering the country SW 1 IN = Surface water entering the country, which is not submitted to treaties SW 2 IN = Surface water entering the country, which is secured through treaties SW PR = Accounted flow of border rivers SW PL = Accounted part of shared lakes SW OUT = Surface water leaving country, reserved by treaties or agreements for downstream countries GW IN = Groundwater entering the countries Actual ERWR may vary with time Established rules to compute the different components of the external water resources

Total Renewable Water Resources TRWR NATURAL = IRWR + ERWR NATURAL TRWR ACTUAL = IRWR + ERWR ACTUAL While IRWR can be added up, TRWR can not

Dependency ratio Dependency ratio = IRWR/(IRWR+IWR)x100% IWR = SW 1 IN + SW 2 IN + SW PR + SW PL + GW IN IWR = Incoming water resources (water resources entering the country) SW 1 IN = Surface water entering the country, which is not submitted to treaties SW 2 IN = Surface water entering the country, which is secured through treaties SW PR = Accounted flow of border rivers SW PL = Accounted part of shared lakes GW IN = 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

Matrix of transboundary flows

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  It takes into consideration upstream withdrawals (but shows results at basin and not country level)  The model developed is simple and is performed entirely within the GIS environment  Combined use of country-based data and global water-balance modeling can enhance the overall reliability of the results

Assessment of the results and reflections

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 regions, especially 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 reverence, duration, etc.

Natural water resources  Hydrological approach - measurements, extrapolation, modeling - not perfect; natural versus actual; upstream versus downstream  Metadata needed - 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

Exploitable water resources 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 Natural resources are quantified exclusively on a hydrological basis, which is necessary. However, not all natural water is accessible. It is needed to also quantify the ‘exploitable’ or ‘manageable’ water resources as a function of:

Other sources of water  Secondary freshwater: Water previously withdrawn and returned to rivers and groundwater, thus becoming available for use again. Examples: agricultural drainage water returned; returned (treated) wastewater  Non-conventional sources of water: These include  Direct use of treated wastewater  Direct use of agricultural drainage water  Desalinated water: 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

Adaptation of ‘water statistics’ to information needs should be well targeted. Always ask question for whom and for what use they are intended Minimum of consensus between the countries of each large region in the world is needed in order to have water statistics that are comparable and respond better to the demands 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 Concluding remarks

Thank you!