1. Statistical dimensions of fresh water of JQ-IW and REQ-Water
ESTP Water Statistics Vienna 2016
Arnulf Schönbauer
THE CONTRACTOR IS ACTING UNDER A FRAMEWORK CONTRACT CONCLUDED WITH THE COMMISSION

2. Renewable freshwater resources
JQ-IW: Table 1 REQ: Table 1

3. Objective
brings water use in relation with natural water availability  is water use sustainable?
… aims at taking stock of fresh water resources available on the national territory, and of the different flows (inflow and outflow) of which they are composed.
Comparable between different countries
Display national trends of development

4. Schematic of national water balance
P precipitation
Qi external inflow
Eta actual evapotranspiratoin
Qo total outflow from the territory
R net recharge into aquifers
C water consumption
P-ETa = D (internal flow)
P and Q are usually the only variables with a representative number of observations

5. Statistical Dimensions JQ–IW (Mio m3)

6. Statistical Dimensions REQ (Mio m3)

7. Methodology
integration of spatio-temporal processes from incomplete, discrete data  requires extended hydrological expertise
generally available from national hydrological or meteorological services
Wide range of hydro-meteorological regimes, e.g.

8. Methodology
Reference period: generally the calendar year Jan-Dec, but where snow and soil water storage is significant  hydrological year! (e.g. Nov – Oct)
Long term annual averages (LTAA): average of >= 30 consecutive years

9. ETa and Internal Flow
Actual Evapotranspiration: Total volume of evaporation from the ground, wetlands and natural water bodies and transpiration of plants.
Internal Flow: Total volume of river runoff and groundwater generated, in natural conditions, exclusively by precipitation into a territory. The internal flow is equal to precipitation less actual evapotranspiration and can be calculated or measured.

10. Other Definitions
Total Freshwater Resources: Internal flow plus actual external inflow.
Groundwater available for annual abstraction: Recharge less the long term annual average rate of flow required to achieve ecological quality objectives for associated surface water. The theoretical maximum of groundwater available is the recharge.

11. Freshwater Resources 95% out of time
Portion of the total freshwater resource that can be depended on for annual water development during 19 out of 20 consecutive years, or at least 95 per cent of the years included in longer consecutive periods. This item yields information about the average annual long-term availability of freshwater for use in human activities.

12. Groundwater available for annual abstraction
groundwater which is not needed for ecological discharge and is also economically and technically extractable
to be estimated individually for every aquifer (a “groundwater body” according to the EU WFD)
precise assessments for all aquifers in a country will likely not be available, especially if there is no water shortage
EU members: amount of water which can be extracted from the groundwater body without violating good quantitative status of the groundwater body, according to the WFD

13. Actual evapotranspiration ETa
Measurement error
good results only at lysimeters „grass reference evapotranspiration“ – empirical relationships for different land cover  hardly ever useful for national water balance
Spatial representation: only few stations, good coverage with meteorological stations for indirect estimation (of ETp!)
Time representation: some methods work with monthly data

14. Actual evapotranspiration ETa
Modelling error
depends on model
From water balance equation: depending on climatic conditions, ETa might have a large relative error due to differencing large numbers with considerable error
Process-based water balance models: good results

15. Aquifer recharge
Measurement error: no direct measurements; state of groundwater system usually monitored by groundwater table observation (WFD!)
Spatial representation: for larger aquifers sufficient
Time representation: bi-weekly or monthly data
Modelling error: estimation of recharge needs comprehensive numerical groundwater modelling for each aquifer (coupled surface water / groundwater models)

16. Summary on Resources
Water balance figures are derived from hydrological modelling approaches
Expertise from hydrological services required
Use synergies with other reporting duties (EU WFD) to save efforts and to improve consistency
document of the database used and the methods applied, including spatial coverage and reliability of estimates

17. Annual freshwater abstraction by source and by sector
JQ-IW: Table 2
REQ: Table 2

18. Statistical Dimensions JQ -IW (Mio m3)

19. Statistical Dimensions JQ -IW (Mio m3)

20. Statistical Dimensions REQ (Mio m3)

21. JQ-IW: Table 3 REQ: Table 2
Water losses
JQ-IW: Table 3 REQ: Table 2

22. Statistical Dimensions JQ –IW + REQ

23. Water made available for use
JQ-IW: Table 3

24. Statistical Dimensions JQ -IW (Mio m3)

25. Statistical Dimensions JQ -IW (Mio m3)

26. Statistical Dimensions JQ -IW (Mio m3)
Total water made available for use
WAU= FS + FG + NfW - RW -Exp + RuW + Imp + DsW

27. Water use by supply category and by sector
JQ-IW: Table 4 REQ: Table 3

28. Statistical Dimensions JQ -IW (Mio m3)

29. Statistical Dimensions JQ -IW (Mio m3)

30. Statistical Dimensions JQ -IW (Mio m3)

31. Statistical Dimensions REQ (Mio m3)

32. References
Data Collection Manual for the OECD/Eurostat Joint Questionnaire on Inland Waters; (2014) version 3.1, Eurostat
NACE Rev. 2, Statistical classification of economic activities in the European Community, Methodologies and Working paper, Eurostat, ISBN , 2008