Arno River Basin Authority Ing. Bernardo Mazzanti b.mazzanti@adbarno.it 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

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: 1993-2006 Min discharge: 2,2 mc/s (aug 1931) Max discharge: 2290 mc/s (nov 1966) Annual average total abstraction: 660 Ml mc

Test Annual Equations 1 4

Test Annual Equations 8

Test Equations for separate SW and GW 1 SW GW

Test Equations for separate SW and GW 4 SW GW

Test Equations for separate SW and GW 8 SW GW

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

Correlate calculated WEI+ with SPI 4

Calculate WEI+ without Environmental Flow 2 3 2 4

Draft methodology for threshold definition 10% perc. Q355 4

Draft methodology for threshold definition

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

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)

Monthly exercise

Monthly exercise