1. Arno River Basin Authority
Ing. Bernardo Mazzanti
Bruxelles, 5-6th march 2012
Test Annual Equations
Test Annual Equations for separate SW and GW
Calculate the water deficit based on the hydrological balance for a long timeserie
Calculate the supplementary indicators water demand/water abstraction
Correlate calculated WEI+ with SPI
Calculate WEI+ without Environmental Flow
Draft methodology for threshold definition
Provide a memo for assumptions and proxies
Provide expert view on usefulness, capabilities and limitations

2. Case study: Arno river basin
Basin surface: 8228 sq. km
Water balance for SW (distributed model, daily aggregation)
Water balance for GW (lumped model for 17 water bodies, monthly scale)
Period:
Min discharge: 2,2 mc/s (aug 1931)
Max discharge: 2290 mc/s (nov 1966)
Annual average total abstraction: 660 Ml mc

3. Test Annual Equations 1 4

4. Test Annual Equations 8

5. Test Equations for separate SW and GW1 SW GW

6. Test Equations for separate SW and GW4 SW GW

7. Test Equations for separate SW and GW8 SW GW

8. Calculate the water deficit based on the hydrological balance for a long timeserie

9. Correlate calculated WEI+ with SPI4

10. Calculate WEI+ without Environmental Flow2 3 2 4

11. Draft methodology for threshold definition
10% perc.
Q355 4

12. Draft methodology for threshold definition

13. Assumptions and proxies
Data
Confidence
Precipitation
High
Evapotranspiration
Moderate
Storage SW
Storage GW
Low
Water use/return – irrigation
Water use/return – industry
Moderate (high number of withsmall wihdrawals)
Water use/return – water supply
Environmetal flow
High (stated by law; Basin Plan)
Water supply
Irrigation
Industry

14. Usefulness, capabilities and limitations of tested WEI+ estimates
Eq. 1, 4, 8 seem to give best results (higher variability between dry and wet years)
Opt. 1: simple, robust formula
Opt. 4: Eflow in the numerator, as "requested water"
Opt. 8: small DS values doesn't influence results
SW/GW estimates could bring a deeper look in exploitation description (even if internal flow attribution to SW/GW is coupled with higher uncertainty)
No clear correlation with SPI index
Only a lower threshold seems to be derived from discharge analysis (i.e. WEI+<20% means no critical condition)

15. Monthly exercise

16. Monthly exercise