UNIVERSITA DEGLI STUDI DI PERUGIA DIPARTIMENTO DI CHIMICA, BIOLOGIA E BIOTECNOLOGIE LAKE TRASIMENO BETWEEN PAST AND FUTURE Alessandro Ludovisi e-mail : alessandro.ludovisi@unipg.it
Lake Trasimeno
The past
Copper Age (5000 y b.c.) Bronze Age (3500 b.c.) Etruscan-Roman Period Century VII b.c V A.D. XI XII Century Present XIV Century XV - XIX Century Water levels of Lake Trasimeno from the Copper Age to present, based on archeological data (Gambini, 2002) and relation with climate Climate cold warm wet dry
1420 Emperor Claudius (41-54 d.c.) Hystorical water management in Lake Trasimeno Braccio Fortebraccio da Montone Burzigotti et al., 2003 - modified
1482 1898 Consorzio Bonifica del Trasimeno Pope Sisto V Hystorical water management in Lake Trasimeno Burzigotti et al., 2003 - modified
Altitude (m a.s.l.) Average lake depth (m) Hydrometric level and average depth of Lake Trasimeno during the last century Outlet restructuring 261 260 259 258 257 Withdrawal licensing Outlet threshold 7 6 5 4 256 3 255 2 254 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
LAKE TRASIMENO 1958 La crisi del 1958 8
THE ARTIFICIAL LOWERING OF LAKE WATERS IN THE FIRST HALF OF THE 20 th CENTURY CAUSED A PROGRESSIVE (AND IRREVERSIBLE ) SHIFT TOWARDS A CONDITION OF SHALLOW LAKE! affecting, in particular: Water column stratification and mixing, and thus: Water transparency and colour Amount of suspended solids in the water column Bottom oxygenation Nutrients cycling Trophic state Sedimentation rates Salt accumulation Macrophyte coverage..and thus, the whole lake biocoenosys!
TSS (mg l -1 ) a Average lake depth (m) SEDIMENT RESUSPENSION IN SHALLOW WATERS 0.0 0.2 0.4 7 6 0.6 5 0.8 Shallow lakes 4 a=surface lake fraction subjected to resuspension (Carper & Bachman, 1984) a=f(d, W, A) 1.0 25 20 1890 1900 1910 1920 1930 1940 1950 1960 3 D=average depth W=wind speed (10 Km h -1 ) A= winf fetch Gaino et al. (2012) Hydrobiologia 15 10 1890 1900 1910 1920 1930 1940 1950 1960 Estimated historical trends of the theoretical fraction of the lake surface subject to resuspension and Total Suspended Solids (TSS ) in a central site exposed to a wind of 3 m s -1
1898 1957-64 Consorzio Bonifica del Trasimeno Ministero dei Lavori Pubblici Hystorical water management in Lake Trasimeno Burzigotti et al., 2003 - modified
Altitude (m a.s.l.) Average lake depth (m) Hydrometric level and average depth of Lake Trasimeno during the last century 261 260 259 258 Outlet restructuring Withdrawal licensing Restriction rules for withdrawals Catchment basin enlargment Outlet threshold 7 6 5 257 4 256 3 255 maximum level minimum level 254 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2
LAKE TRASIMENO 2003
HISTORICAL DATA SERIES Sampling site ARPA Umbria Water quality data collected monthly since 1990 Hydrobiological Station - Università di Perugia Daily meteorological data since 1955 Water quality data collected in several monthly sampling surveys since1958 S.I.G.L.A. meteorological stations managed by the Province of Perugia Half-hourly data collected since 1988
mm PRECIPITATION 1100 1000 900 800 Annual value linear trend 700 600 500 400 300 Critical precipitation (Dragoni, 1982) Hydrological crisis 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 Ludovisi & Gaino (2010) Journal of Limnology
C AIR TEMPERATURE 16 15 14 1980 2010 ΔT= +1.4 C ~ +0. 5 C/decade 13 12 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 Ludovisi & Gaino (2010) Journal of Limnology
Water conductivity at 25 C (ms cm -1 ) WATER QUALITY CHANGES Total Dissolved Solids (kg 10 6 ) SALINITY 1800 1600 1400 Annual value Maximum Mean Minimum 340 330 320 310 300 1200 290 1000 800 600 280 270 260 250 240 R 2 = 0.77 p<0.0001 400 1970 1980 1990 2000 2010 230 1990 1995 2000 2005 Periods with water levels under the outlet threshold YEAR Accumulation rate = 3.310 3 tons year -1 Ludovisi & Gaino (2010) Journal of Limnology
Total Alkalinity ( mg L -1 CaCO 3 ) WATER QUALITY CHANGES 0.00 1.00 ALKALINITY SO 4 2-0.25 [ Polynomial Regression 1989-2006 for Data1_Alcmin: Y = A + B1 * X 0.75 Cl - 200 0.75 0.50 1969 Parameter Value Error A -2395.33953 455.34856 B1 1.27839 0.22826 R-Square(COD)SD N P 0.63538 9.56663 20 <0.0001 0.50 0.25 180 160 140 120 Annual value Maximum Average Minimum 1970 1980 1990 2000 2010 YEAR Ludovisi & Gaino (2010) Journal of Limnology Polynomial Regression for Data1_Alcmed: Y = A + B1 * X Parameter Value Error A -1583.80976 385.69726 B1 0.88023 0.19334 1.00 0.00 0.00 0.25 0.50 0.75 1.00 R-Square(COD)SD N P 0.53521 8.1033 20 2.4664E-4 HCO 3 - + CO 3 2- Polynomial Regression for Data1_Alcmax: Y = A + B1 * X Parameter Value Error The change in the ionic A -232.07957 540.60124 B1 0.21162 0.271 balance due to salt R-Square(COD)SD N P 0.03277 11.35775 20 0.44501 accumulation has caused an increase in alkalinity
ph WATER QUALITY CHANGES D.O. (mg l -1 ) 10 9 8 ph 1970 1980 1990 2000 2010 Annual value Maximum Mean Minimum Polynomial Regression for Data1_pHmed: Y = A + B1 * X Weight given by Data1_pHerr error bars. Parameter Value Error A 21.19367 3.54945 B1-0.00633 0.00178 R-Square(COD)SD N P 0.35531 6.35695 25 0.00166 17 Maximum 16 Polynomial Regression for Data1_pHmax: Mean Y = A + B1 * X Minimum 15 14 13 12 11 10 9 8 7 6 Parameter Value Error A 36.05187 15.05388 B1-0.01353 0.00756 R-Square(COD)SD N P 0.12225 0.43267 25 0.08666 Polynomial Regression for Data1_pHmin: Y = A + B1 * X Parameter Value Error A -13.83996 7.05535 B1 0.01108 0.00354 R-Square(COD)SD N P 0.29851 0.20278 25 0.00472 DISSOLVED OXYGEN 5 1960 1970 1980 1990 2000 2010
SRP (mg L -1 ) Secchi depth (m) Total Phosporous (mg l -1 ) Chlorophyll a ( g l -1 ) WATER QUALITY CHANGES 0.20 0.18 0.16 0.14 0.12 0.10 0.08 0.06 0.04 0.02 0.00 0.10 0.08 0.06 0.04 Annual value Maximum Mean Minimum Eutrophy Mesotrophy 1960 1970 1980 1990 2000 2010 Annual value Maximum Average Minimum TROPHIC STATE AND TRANSPARENCY 4 3 2 60 50 40 30 20 10 0 Annual Value Maximum Mean Minimum Eutrophy Mesotrophy 1960 1970 1980 1990 2000 2010 Mesotrophy Eutrofphy Annual value Maximum Mean Minimum 0.02 1 0.00 1960 1970 1980 1990 2000 2010 Ludovisi & Gaino (2010) Journal of Limnology 0 1960 1970 1980 1990 2000 2010
SEDIMENT RESUSPENSION AND WATER TRANSPARENCY Secchi depth (m) Average lake depth (m) 14 16 18 4 TSS (mg l -1 ) 20 22 3 a=surface lake fraction subjected to resuspension (Carper & Bachman, 1984) a=f(d, W, A) D=average depth W=wind speed (10 Km h -1 ) A= winf fetch Gaino et al. (2012) Hydrobiologia 24 26 4 3 2 1 0 1960 1970 1980 1990 2000 2010 1960 1970 1980 1990 2000 2010 2 Annual value Maximum Mean Minimum
THE FUTURE SCENARIOS
IPCC Assessment Report 2007 (AR4) Average changes for temperature ( C) and precipitation (%) projections from a set of 21 global models for the A1B scenario. Predicted differences are for the period 2080-2099 with respect to the averages 1980-1999.
SOUTHERN EUROPE / MEDITERRANEAN IPCC Assessment Report 2007 (AR4) IPCC Report 2007: Regional averages of changes for temperature ( C) and precipitation (%) projections from a set of 21 global models for the A1B scenario. Predicted differences are for the period 2080-2099 with respect to the averages 1980-1999. The signal is assumed to increase linearly with time.
SOUTHERN EUROPE / MEDITERRANEAN IPCC Assessment Report 2013 (AR5) IPCC Assessment Report 2013 (AR5): Regional averages of changes for temperature ( C) and precipitation (%) projections from a set of 42 global models for the RCP4.5 scenario. Predicted differences are with respect to the averages 1986-2005.
1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100 Temperature ( C) THE FUTURE SCENARIOS 20 19 18 17 16 T_observed T_IPCC_50 T_IPCC_min T_IPCC_max TEMPERATURE Observed (1980-2010) and simulated (1980-2099) scenarios for air temperature at Lake Trasimeno 15 14 13 The reference period (1980-1999) (+ climate signal) is replicated several times in the future Ludovisi A., Gaino E., Bellezza M., Casadei S. (2013) Aquatic Ecosystem Health & Management
1980 1990 2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100 Precipitation (mm year -1 ) THE FUTURE SCENARIOS 1000 900 800 700 600 500 400 300 200 100 P_observed P_IPCC_50 P_IPCC_min P_IPCC_max PRECIPITATION Observed (1980-2010) and simulated (1980-2099) scenarios for precipitation at Lake Trasimeno The reference period (1980-1999) (+ climate signal) is replicated several times in the future Ludovisi A., Gaino E., Bellezza M., Casadei S. (2013) Aquatic Ecosystem Health & Management
THE FUTURE SCENARIOS THE WATER BALANCE MODEL (LUMPED) Ludovisi A., Gaino E., Bellezza M., Casadei S. (2013) Aquatic Ecosystem Health & Management V ( mm / month) = ( P s S s P b S S b s C ) V d V a E Precipitation on the lake surface Precipitation on the catchment basin Runoff coefficient Outflows from the artificial outlet Withdrawals for agriculture and civil uses Evaporation (Visentini equation) Calibrated from observed data (1963-1999) E=f(T)
C MODEL CALIBRATION 0.5 Average monthly runoff coefficient in the calibration period (1963-1999 ) 0.4 0.3 0.32 (annual average) 0.2 0.1 0.0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month
Water level ( m a. s. l. ) THE FUTURE SCENARIOS 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 WATER LEVELS 2010 2015 2020 2025 2030 2035 2040 2045 2050 2055 2060 2065 2070 2075 2080 2085 258.0 257.5 257.0 256.5 256.0 255.5 255.0 254.5 254.0 253.5 253.0 252.5 252.0 Observed Scenario 1 (IPCC_P50_T50) Scenario 2 (IPCC_Pmax_Tmin) Scenario 3 (IPCC_Pmin_Tmax) LAKE BOTTOM! OUTLET THRESHOLD Ludovisi A., Gaino E., Bellezza M., Casadei S. (2013) Aquatic Ecosystem Health & Management
WATER FROM MONTEDOGLIO Since 2012 : 1-2 Mm 3 year 1 to agriculture DIRECT INPUT TO THE LAKE??
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050 2055 2060 2065 2070 2075 2080 2085 Water level ( m a. s. l. ) THE FUTURE SCENARIOS (with strong mitigation) 258.0 257.5 257.0 256.5 256.0 255.5 255.0 254.5 254.0 253.5 253.0 252.5 252.0 Observed Scenario 1 (IPCC_P50_T50) + 10 Mm -3 /year Abolition of abstraction licensing +10 Mm 3 year 1 of water input from external basins. Scenario 3 (IPCC_Pmin_Tmax) + 10 Mm -3 /year LAKE BOTTOM! OUTLET THRESHOLD Ludovisi A., Gaino E., Bellezza M., Casadei S. (2013) Aquatic Ecosystem Health & Management
LAKE TRASIMENO May 2014 the water level exceeds the outlet threshold after 25 years!