1. Towards a Water Scarcity & Drought Indicator System (WSDiS)
Maggie Kossida – ETC/Water

2. Presentation Outline Water Scarcity Indicators for Awareness Rising
Relevant Water Stress Indicator (RWSI)
Storage Indicator (St)
Water Use per sector (WUs)

3. Relevant Water Stress Indicator (RWSI)
Key Message
Designed to depict the balance between natural renewable water resources and abstraction, in order to assess the prevailing water stress conditions in a catchment.
Refinement of the WEI and other relevant indicators (e.g. WAI, WSI etc.)
Provides more accurate metrics of evaluating the relevant water scarcity in a catchment, since it considers the “true” volume of water which is available for exploitation accounting for environmental requirements and returned water
In line with WFD (The level of stress or relevant water scarcity in a catchment changes if we subtract an amount of water that is not actually available for abstraction since it needs to be left in the catchment to maintain its ecological status)

4. Relevant Water Stress Indicator (RWSI)
RWSI = ABS / RWA
Relevant Water Stress Indicator (RWSI) = Percent of Total Freshwater Abstracted over the total Renewable Water Availability
Where:
ABS = Total Freshwater Abstracted
RWA = Renewable Water Availability
Metrics: annual (or monthly if available) values should be plotted and compared to the Long Term Annual Average (LTAA) of the last 20 years or the longest timeseries
available to assess the trend.
Spatial scale: River basin (RB) or WFD River Basin District (RBD)
Temporal scale: Annual, monthly if possible

5. Relevant Water Stress Indicator (RWSI)
Methodology
a. Calculation of Renewable Water Availability (RWA)
RWA = P – Eta + I – WR + R
Where:
Precipitation (P) = [total volume of all forms of precipitation which falls over the catchments in hm3]
Actual Evapotranspiration (ETa) = [total volume of water which evapotranspirates over the whole catchments area in hm3]
External Inflow (I) = [total volume of water in hm3 flowing into the catchment from upstream and/or neighboring catchments, refers both too surface and groundwater inflows as a sum]
Water Requirements (WR) = [minimum volume of water in hm3 that needs to be sustained: for environmental purposes and/or treaties]
Returned water (R) = [volume of abstracted water that is discharged to the catchment’s fresh water resources either before use as losses or after use, e.g. hydropower, in hm3. Discharges to the sea are excluded.)

6. Relevant Water Stress Indicator (RWSI)
Methodology
b. Calculation of Freshwater Abstraction (ABS)
ABS = ABS_SW + ABS_GW
Where:
Total Freshwater Abstraction (ABS) = [total volume of all freshwater abstracted regardless of source and type of water supply system from the catchment’s freshwater sources in hm3]
Total Freshwater Abstracted from surface water resources (ABS_SW) = [total volume of freshwater abstracted from the catchment’s surface water resources only, regardless of the type of water supply system in hm3]
Total Freshwater Abstracted from groundwater resources (ABS_GW) = [total volume of freshwater abstracted from the catchment’s groundwater resources only, regardless of the type of water supply system, in hm3]

7. RWSI vs. WEI Differences: Hydropower vs. Return (ET losses)
Annual, monthly vs. LTAA
Water Requirements (WR): environmental + other (e.g. treaties in transboundary RBs)

8. RWSI vs. WEI
Comparing the two indicators we can see that the EI depicts more unsustainable conditions as the annual availability is over exceeded by abstraction, and this trend is increasing over the years making the system more vulnerable.
Years 1998, 1999, 2002, 2005, 2006, 2007, 2008 difference ranges from 20-50%

9. Relevant Water Stress Indicator (RWSI)
Comments
Provides better metrics of the actual water stress conditions in comparison with other relevant indicators/indices
The parameters of the RWSI are requested under the WISE-SoE#3 reporting (except the WR)
The calculation of environmental water requirements (EWR) is not globally established, and there may be differences in the implemented methodologies, yet member states have calculated EFs on the basis of the WFD RBMPs reporting.
The indicator is relatively easy to calculate and straightforward to use.
The indicator can readily be integrated with other indicators at the same scale and used for water management purposes, or to better assess the drivers and impacts of water scarcity.
It is particularly meaningful to evaluate the RWSI together with an indicator on Storage

10. Relevant Water Stress Indicator (RWSI)
MS Remarks UK
EF, treaties  Not doublecount. Yes, term changed to Water Requirements (includes both, with footnote that in the case of treaties, the max of two should be deducted)
Relevant Thresholds? WEI 20%,40%, we will revise that for RWSI since EWR are included
Units of Flows? We want volumes per year or per month FI
Good, but difficult to calculate, especially abstractions, and not of use in water rich areas. Sugg: 1. Assess stress from WFD RBMPs, 2. Use RWSI on critical areas, 3. Revise assessment every 6 yrs with RBMPs update.
1. No info on water availability has been reported in the RBMPs (only some for GW). WFD not targeted to WQuantity, not real data to allow assessment
2. Considering WR can change the picture, thus the critical areas

11. Relevant Water Stress Indicator (RWSI)
MS Remarks cont. ES
Only a LTAA of water resources would be needed. Using actual -monthly or annual- RWA data would be adding information regarding dry or wet situations
Refer to Cyprus example
The average volume variation in water storages (surface and groundwater) for each month should be incorporated in the RWA equation
ΔS is incorporated in RWA
Should also incorporate the External Outflow, turning it into a ‘External Balance’ term
Assumption is made that all available freshwater could be retained in the catchment with the exemption of EWR and other existing treaties
It should also take into account desalinated water
Non-freshwater resources are not considered under RWA. Desalinated water can reduce vulnerability and should be looked as additional source, but not in the equation of RWA

12. Storage Indicator (St)
Key Message
Important for evaluating the total water availability of the catchment, especially during periods where the renewable water availability is low (either due to low precipitation or limited inflows in the catchments).
This indicator does not reflect the storage capacity (which may be higher due to infrastructure and related water works), but the actual water stored in the surface and groundwater reservoirs over the previous time step (month or year).
Combined with additional indicators on water abstraction and use the St indicator can communicate messages on how much of the stored water is used up and from which economic activity, during which periods and at what rates, thus allowing for proper water management.

13. Storage Indicator (St)
Storage (St)
Total volume of water in hm3 stored in the catchment, both in surface and groundwater reservoirs, during the reference period t
Metrics: annual (or monthly if available) values should be plotted and compared to the Long Term Annual Average (LTAA) of the last 20 years or the longest timeseries
available to assess the trend.
Spatial scale: River basin (RB) or WFD River Basin District (RBD)
Temporal scale: Annual, monthly if possible

14. Storage Indicator (St)
Methodology
St = St-1 + ΔSt
(e.g. S2010 = S ΔS2010)
Where:
Storage (St) = [total volume of water in hm3 stored in the catchment, both in surface and groundwater reservoirs, during the reference period t]
Difference in Storage (ΔSt) = [the difference in the volume of water in hm3 stored in the catchment between the reference period t and the previous period t-1, in all the surface and groundwater reservoirs]
ΔSt = P - ETa + I + R – Abs - O
ΔSt, P, ETa, I, R, Abs as mentioned previously (units in hm3)
Outflow (O) = [the total outflow from the catchment to a downstream and/or a neighboring catchment in hm3 as measured at the outlets. The total outflow includes the environmental flow releases EF]

15. Storage Indicator (St)
Comments
Many MS use this indicator but mostly broken down into surface water storage (lakes and reservoirs, snowpack) and groundwater storage (aquifers).
Data for the calculation of the St are included in the WISE-SoE#3 reporting
The change in storage (ΔSt) which is used to compute the indicator is calculated based on the parameters of the hydrological cycle, thus is supposes that hydrological balance of the area is accuraletly simulated. Yet, it can be measured as well when broken down by components (surface water storage i.e. lakes and reservoirs, groundwater, snowpack storage)
Relatively easy to calculate (for SW) and straightforward to use
Can readily be integrated with other indicators at the same scale and used for water management purposes, or to better assess and impacts of water scarcity
It is particularly meaningful to evaluate the Storage together with an indicator on water exploitation and renewable water availability.

16. Storage Indicator (St)
MS Remarks UK
Does it include storage in river systems?
No, only reservoirs and GW
Difficult to measure overall storage, especially for aquifers
True, modelling is required
Not itself a water scarcity indicator, mostly for management purposes
Stored freshwater from a previous period (e.g. winter) can decrease your vulnerability/degree of stress. It should be looked up as an “addition” to the RWA in term of water available for exploitation generated from a previous time step.
When developing the threshold of RWSI, the St should somehow be related (maybe a moving average, exceedance percentiles…)

17. Water Use per sector (WUs)
Key Message
Designed to depict the volume of water that is actually used by end users for a specific purpose within a territory, such as for domestic use, agriculture or industrial processing.
Provides accurate metrics of evaluating the water allocation between the different economic activities and their water use intensity
Provides useful information to be considered in the design of economic and policy response measures which cut across all sectors, e.g. cap and trade, voluntary trading of water rights etc.

18. Water Use per sector (WUs)
Indicator
Water Use per sector (WUs)
Where:
Water Use per sector (WUs) = Total Volume of all Freshwater Used from a specifc user sector
Metrics: annual (or monthly if available) values should be plotted and compared to the Long Term Annual Average (LTAA) of the last 20 years or the longest timeseries available to assess the trend.
Spatial scale: River basin (RB) or WFD River Basin District (RBD)
Temporal scale: Annual, monthly if possible

19. Water Use per sector (WUs)
Methodology
Total Freshwater use (WU) can be divided based on the actual economic sectors that use the resource (based on NACE classes).
Therefore, six sub-indicators may be introduced that have the same assessment, units, and spatial and temporal scale characteristics with the main freshwater use indicator:
Total Volume of Domestic freshwater use
Total Volume of Agricultural freshwater use (NACE A)
Total Volume of Mining & Quarrying freshwater use (NACE B)
Total Volume of Manufacturing freshwater use (NACE C)
Total Volume of Energy freshwater use (NACE D)
Total Volume of Services freshwater use (NACE I)
Total Volume of Other freshwater use (Other)
The SUM of the above six sub-indicators is ≤ of the Total Volume of freshwater used

20. Water Use per sector (WUs)
Comments
Water Use data are collected through the WISE-SoE#3 and Eurostat JQIWA.
Water use data are often at a different aggregation level (NUTS) and available by the statistical services, which may cause some problems of comparability. Yet, these data have been reported in the RBMPs of the WFD and thus it should be easy to obtain them
It is an open question whether these data are actually measured (by the water services and then disseminated) or calculated based on proxies.
The indicator is relatively easy to calculate and straightforward to use
The indicator can readily be integrated with other indicators at the same scale and used for water management purposes, or to better assess the drivers and impacts of water scarcity
Evaluation of water used by the different economic activities along with additional supporting socio-economic data is strongly related with issues of: Water allocation and equity, Prioritisation of conflicting water uses, Environmental cost recovery, Water pricing, Water efficiency

21. Water Use per sector (WUs)
MS Comments UK
Not an WS indicator which can explain why but not if
Yes, it is a pressure indicator for WS, but it is very important to make the distinction whether the stress is due to drought/climate conditions or anthropogenic influence
Nevertheless, the WU/capita is widely used as a WS indicator with absolute threshold values FI
Not necessary a separate indicator, could be presented under the RWSI (abstraction per sector, excluding non-consumptive water uses)
Abstraction not necessarily equals use (higher if leakage and transport losses, lower if reuse)
Non-consumptive: ref. to RWSI comment on hydropower

22. Logical relations of the proposed WS indicators
Water Use
your main anthropogenic pressure
RWSI
your degree of water stress
Storage
can decrease your vulnerability/degree of stress

23. Thank you !