WEI+ Results from the exercise with the Pilot RBs Maggie Kossida – ETC/Water

WEI vs. WEI+ comparison Based on the available data the following comparison between WEI and WEI+ has been made:   WEI WEI+ WEI+ vs. WEI Data source AT, country level (1961-2000) 4% 5% ↑ Eurostat, Pilot RB exercise BE, Scheldt RB (2007) 51% 37% ↓ WISE-SoE#3 CZ, Morava RB (2009) - Pilot RB exercise UK, Thames RB (1961-1990) 21% 23% EE, country level 15% 9% FI, Paimionjoki RB (2010) IT, Serchio RB (2000-2008) 7% 10% NL, country level (2007) 11% ES, Segura RB (1989-2009) 190% 161% Guidelines not followed by all participant (scale, time resolution) Additional data from HU, IT just received, and thus not yet processed

WEI vs. WEI+ comparison (cont.) WEI+ < WEI in areas where the returned water (treated and non-treated) is significant (e.g. Estonia, Segura RB, Scheldt RB due to cooling water) In the areas that returns are not major, the WEI+ may be slightly higher than the WEI, in the range of about 2%. The water requirements did not show to affect that much (in terms of resulting to a significant higher WEI+), especially when compared to the return water whose effect is far more dominant.

1. Scale issues Problem at the monthly step (summer precipitation < Eta or zero => high water stress, while previous Storage actually exists). This problem is not encountered at annual level Storage component to be added maybe the RB is too aggregated in some case WS&D events may have a very local character. the systematic calculation of this indicator may not be of relevance to non-scarce areas Preliminary assessment could be carried to find out which areas are scarce, then we can zoom in the stressed and near stress areas (similar approach to the Floods directive), while the remaining areas re-assess in X years time

2. Hydropower 3. Return water The current expression of WEI+ (ratio of abstraction over availability) should not include the hydropower abstractions, because even if this is also accounted as a return, if the amount is high (as compared to the remaining abstractions) the basin can be shown as severely stressed Possible revision of the expression of WEI+, if change from “ratio” to “deduction”, then it does not cause a problem   3. Return water Returned water (treated and non-treated) has proven to be an important parameter than can significantly reduce the water stress, especially in basins with important use of cooling water. (e.g. Scheldt 15% reduction)

4. Water requirements (WR) HU in favor, since this approach complies with the WFD Some MS comments that WR are hard to calculate, it seems though that the participants in this exercise have been able to report them. It is understood that assumptions may be associated with this calculations, that have to do with the way the MS calculate their requirements, and thus statement of these assumption is encouraged Alternative suggestions, to adopt a common proxy e.g. 20%, 40% etc. No dramatic change in the WEI+ due to the inclusion of WR has been observed.

Water Requirements (cont.) WR as % of available water (aw = internal flow + return):   WR/aw WEI+ vs. WEI AT, country level (1961-2000) 39% +1% BE, Scheldt RB (2007) 12%* -14% CZ, Morava RB (2009) 9% - UK, Thames RB (1961-1990) 26% +2% EE, country level 22% -6% FI, Paimionjoki RB (2010) 1% IT, Serchio RB (2000-2008) 30% +3% NL, country level (2007) 2% -1% ES, Segura RB (1989-2009) 7% -29% *based on assumption that is equal to the 20% of the Internal Flow

5. Storage Storage is indeed an important function not captured in the current representation of WEI+. While its effect is not very significant at annual scale, it is major in the monthly scales We had since the beginning of this work stated that the WEI+ should be looked jointly with an indicator on Storage (refer to the relevant fact sheet), yet this need becomes now more apparent. We are now thinking of possible revisions (based also on comments received by MSs) and hopefully the issue of storage will be tackled, and thus the monthly calculation will be made feasible as well

6. Data issues MS comments on non availability of data, non-harmonisation and prevailing assumptions Assumptions regarding data (gap filling, proxy calculations etc.) is not a new problem, it is common in EU, even within a MS among its different agencies who use different models, methodologies etc. (e.g. ET is calculated based on various methods, precipitation data are aggregated from point stations following different methods as well, etc. The WEI parameters are no exception to that, nor are other indicators, SoE assessments, WFD reporting etc.   Does this mean we should never try to present harmonised EU assessments? Does this mean that all reports comparing facts and figure among countries (or within a country) e.g. indicators on nutrients, pesticides, assessment of WFD status of water bodies, bathing water etc. are reflecting wrong information and the intercomparison is virtually impossible? Thus, what we must point out here is the need that under every indicator and parameter a clear statement of the assumptions, calculations and methods should be stated to avoid misinterpretation. R! be conscious of the data you report under different initiatives

7. Revised expression of WEI+ Would a revised expression of the WEI+ would be more beneficial and easy to handle?   WEI+ = Abstraction ÷ Renewable Water Availability (RWA) Possible alternatives….. RWA – Abstraction > threshold … Furthermore the Storage parameter could be integrated in the above formula…. RWA – Abstraction > threshold (related to exiting Storage) RWA + existing storage – Abstraction > threshold of sustainable yield… Suggestions on the above point are very welcome.

Country specific replies... Thank you !