The hydrology of the shallow lake Trasimeno

Transcription

1 The hydrology of the shallow lake Trasimeno history, forecasting and management Stefano Casadei

2 Trasimeno

3 Trasimeno lake Unesco Chair «Water Resources Management and Culture» Lake surface Km 2 Average lake depth 4.2 m Maximum lake depth 6.88 m Watershed/lake surface ratio 3.2 Water renewal time 24.4 years The Trasimeno lake is the fourth Italian lake by extension. It is placed in the north-western side of Umbria, close to the border with Tuscany, at 25,5 m above sea level; now it has an extension of about 124 Km 2 and a maximum depth not greater than 6- m. It has a perimeter of about 53 Km and an almost circular shape, it is fed by small creeks that collect rainfalls from the surrounding hills, therefore its hydrological regime has wide seasonal and pluriannual oscillations since it is driven by the precipitations occurring in that area.

4 Trasimeno history beginning XVI century Leonardo da Vinci ( ), Royal Library of Windsor. Valdichiana and Trasimeno map Leonardo da Vinci ( ), Royal Library of Windsor. Valdichiana and Trasimeno map

5 Ludovisi A

6 Benedetto Castelli, a Benedictine monk. Letter to Galileo above Lake Trasimeno, 1639, June 16. A giorni passati ritrovandomi in Perugia, dove si celebrava il nostro Capitolo Generale, avendo inteso che il lago Trasimeno per la gran siccità di molti mesi, era abbassato assai, mi venne curiosità di andare a riconoscere occultamente questa novità, e per mia particolare sodisfazione, ed anco per poter riferire a padroni il tutto con la certezza della visione del luogo... Ritornato che fui in Perugia, seguì una pioggia non molto grossa, ma continovata assai, ed uniforme, quale durò per ispazio di otto ore circa: e mi venne in pensiero di volere esaminare, stando in Perugia, quanto con quella pioggia poteva essere cresciuto il lago, supponendo (come aveva assia del probabile) che la pioggia fosse universale sopra il lago, ed uniforme a quella che cadeva in Perugia; e così preso un vaso di vetro di forma cilindrica He was the first person recorded to have invented a rain-gauge in 1639.

7 261 Unesco Chair «Water Resources Management and Culture» Hydrometric level and average depth of Lake Trasimeno du (Ludovisi A. 2012) Altitude (m a.s.l.) maximum level minimum level Catchment basin Outlet threshold enlargment Year 263 cm Average lake depth (m)

8 Drought period Drought period Unesco Chair «Water Resources Management and Culture»

9 Hydrometric level and average depth of Lake Inaugural Meeting Trasimeno 11 MARZO 2014du Altitude (m a.s.l.) maximum level minimum level Catchment basin Outlet threshold enlargment Year Average lake depth (m)

10 The catchment area before 1958 The catchment area before 1958

11 First catchment basin enlargment Tresa and Rio Maggiore rivers

12 Total catchment basin enlargment Tresa, Rio Maggiore, Moaino and Maranzano rivers km 2

13 Hydrometric level and average depth of Lake Inaugural Meeting Trasimeno 11 MARZO 2014du Altitude (m a.s.l.) maximum level minimum level Catchment basin Outlet threshold enlargment Year Average lake depth (m)

14 Historic flood, ,32 m s.l.m. Gambini, 1995 Gambini, 1995

15 At present the Trasimeno Lake is an important tourist site Unesco Chair «Water Resources Management and Culture» At present time

16 [m s.l.m.] Mounthly rainfall Level hydrometric zero Lineare (Level) [mm]

17 Montedoglio reservoir Unesco Chair «Water Resources Management and Culture» January February March April May June July August September October November December

18 The future The future Ludovisi A

19 Montedoglio reservoir Unesco Chair «Water Resources Management and Culture» Montedoglio Trasimeno Casanuova

20 Ovest system ha Montedoglio reservoir East system ha Casanuova reservoir Trasimeno Lake

21 THE MONTEDOGLIO-CHIASCIO PROJECT

22 Mitigation actions Unesco Chair «Water Resources Management and Culture» Ludovisi A

23 Thanks