SEA LEVEL REAL TIME MONITORING SYSTEM IN THE NORTHEASTERN ITALY

Transcription

1 Workshop on Real-time Transmission and Processing Techniques: Improving the Global Sea Level Observing System s contribution to multihazard warning systems Intergovernmental Oceanographic Commission of UNESCO Paris, France 5 June 2007 SEA LEVEL REAL TIME MONITORING SYSTEM IN THE NORTHEASTERN ITALY Maurizio Ferla National Agency for Environmental Protection and Technical Services VENICE LAGOON SERVICE ( Ruga dei Oresi, Venezia Tel fax e_mail: maurizio.ferla@apatvenezia.it

2 mm/y mm/y mm/y (natural) 9 cm 100 years induced 1.0 mm/y Coastal areas at risk from storm surge and sea-level rise in North-eastern Italy over 300 km of low sedimentary shores the continuity of the coasts is interrupted by several rivers and lagoons sea bottom gradients varying from 2-11 m/km coastal defence structures along 60% of the coasts km 2 below m.s.l. are subjected to reclamation works Tide excursion: 1 m (normal) - > 2 m (storm surge) SUBSIDENCE natural + induced

3 cm SEA LEVEL RISE annual mean sea level Venice - Punta Salute moving average of period 11 tide gauge sea level rise from 1890 to years sea level trend VENICE 28.0 cm 2.4 mm/year TRIESTE 14.6 cm 1.26 mm/year Tide gauge station Trieste cm TRIESTE VENICE Trieste - Molo Sartorio tide gauge annual mean sea level km

4 STORM SURGES Adriatic Sea: 800 km long ~100 km large Semi-closed basin South-easterly winds (sirocco) BORA SIROCCO

5 STORM SURGES Adriatic Sea: 800 km long BORA ~100 km large Semi-closed basin South-easterly winds (sirocco) SIROCCO Worst cases of exceptionally high tides recorded in Venice - Punta Salute 1 st case 4 November cm 2 nd case 22 December cm 3 rd case 1 February cm 4 th case 15 January cm 5 th case 12 November cm 6 th case 16 April cm 7 th case 16 November cm 8 th case 15 October cm 9 th case 3 November cm 10 th case 6 November cm 11 th case 8 December cm 12 th case 17 February cm 13 th case 5 November cm 14 th case 26 November cm 15 th case 22 December cm 16 th case 24 November cm cm ZMPS Venice - Punta della Salute tide gauge cm h 9.40 recorded sea level /11/ /11/ /11/2002 astronomical tide

6 SEA STORMS 4 th November 1966 Maximum estimeted wave height H s = mt (S-SE) H s = mt (N-NE) RIVER FLOODS Peak level River beds increasingly high Soil sinking in the reclaimed areas Adige river - Cross section n 189

7 Daily Tide Bulletin for short term sea level prediction in the city of Venice

8 Data transmission scheme Centrale Ripetitore Prov. BOLZANO Stazione RETE APAT - Venezia Prov. TRENTO Regione VENETO RETE INTEGRATA DEL TRIVENETO Regione FRIULI V.G. APAT VENEZIA MAG. ACQ. VENEZIA Visentin Rialto Ondametro Piattaforma CNR Chioggia Diga Sud Foce Po Collegio Morosini Murano Diga Sud Lido Punta della Salute National Civil Defence real time monitoring system Sharing meteorological, hydrological, tidal and sea waves data. Observed variables: Water levels (sea, rivers, lakes) Wind speed and direction Atmospheric pressure Rainfall Humidity Solar radiation Waves

9 Italian Oceanographic Network (National Agency for Environmental Protection and Tchnical Services) 26 gauges located into the main Italian harbours -Sea level -Wind speed/direction -Atm pressure -Water temperature -Air temperature

10 REAL TIME TIDE GAUGE 25 stations within the Venice Lagoon and along the Northern Adriatic coastline. Instruments: tide floating/ultrasonic sensor. 8 gauge equipped with atmospheric sensors (anemometer/barometer/air temp.) Sampling/transmission interval: 10 minutes Local recording system: 1 memory card; 1 paper recording drum: 2 tide gauge each station -> to avoid loss of information Data dissemination Web-site:

11 REAL TIME SEA LEVEL MONITORING SYSTEM IN THE NORTHERN ITALY APLICATIONS: STORM SURGE FORECAST sea level = astronomical tide + surge (residual) Astronomical tide forecast Meteorological tide and seiche

12 Storm Surge Prediction - Statistical models Linear, autoregressive, based on the least squares theory. Predictors: observed sea level and pressure. Coefficients: calculated by means of a 25-years database ( ). Δh ( τ ) ( τ ) ( t+ τ ) = ( ai Δh( t i) + bi p( t i) ) forecasted surge in Venice at τ lag observed sea level (or surge) observed and forecasted pressure Observed data Sea level (t - 30) : Venice (RTLV) Atmospheric pressure (t - 12): Venice, Bari, Genova, Alghero (ECMWF) Forecast Atmospheric pressure (t + 144): Venice, Bari, Genova, Alghero (ECMWF)

13 STORM SURGE PREDICTION THE DETERMINISTIC APPROACH Hydrodynamic model Based on Finite Element Grid: S.HY.F.E.M. (CNR ISMAR Venice) ISONZO TAGLIAMENTO LIVENZA PIAVE SILE LAGUNA DI Mare VENEZIA Adriatico Spatial domain: Adriatic Sea and Venice Lagoon; F.E. GRID (8072 nodes e elements); Spatial resolution (10 meters - 60 Km) Forcing: wind speed/direction and atm pressure (ECMRWF). Model calibration: Recorded tide level along the coastline; Friction coefficient at the bottom and at sea surface;

14 Local winds effects into the lagoon of Venice 8/12/1992 Storm surge 6/11/2000 Storm surge North-easterly winds (bora) South-easterly winds (sirocco)

15 APPLICATION IN THE FUTURE: MOBILE GATES MANAGEMENT AT THE ENTRANCES OF THE VENICE LAGOON (under construction) ECMWF= European Centre for Medium ECMWF UGM = Weather Forecast Uffic io Generale di Meteorologia Weather forecast and real time data acqusition SMER Venezia UGM SMER = (Aeronautica Militare) Servizio Meteorologico Regione Emilia -Ro magna Local Water Levels Measurements Synop data Storm Surge Classification and Sequence of Decisions MOBILE BARRIERS OPERATION Classification of high water events At 24 to9 hours in advance f 97 (90) f 3 (10) Class 1 cl = +75 to +100 Class 2 cl = +65 At 6 to 3 hours in advance f 2 (2) f 48 (44) f 45 (42) f 2 (2) Class 1AV cl = +80 Class 1A cl = +100 Class 1B cl = +90 Class 1BV cl = +75 cl = closing level f = percent frequency of occurrence, between brackets refers to a 20 cm rise in mean sea level

16 Workshop on Real-time Transmission and Processing Techniques: Improving the Global Sea Level Observing System s contribution to multihazard warning systems Intergovernmental Oceanographic Commission of UNESCO Paris, France 5 June 2007 SEA LEVEL REAL TIME MONITORING SYSTEM IN THE NORTHEASTERN ITALY THANK YOU Maurizio Ferla National Agency for Environmental Protection and Technical Services VENICE LAGOON SERVICE ( Ruga dei Oresi, Venezia Tel fax e_mail: maurizio.ferla@apatvenezia.it