1. Introduction to landslides Case study: Vaiont landslide
Cees van Westen
International Institute
for Aerospace Survey and Earth Sciences
(ITC), Enschede, The Netherlands.
Landslide case study Vaiont
Introduction to GIS

2. Location NE Italy, 100 km N of Venice Confluence with the River Piave.
Landslide case study Vaiont

3. Geological cross section
Landslide case study Vaiont

4. Arch dam
The Vaiont dam, a dome-shaped shell, is one of  the highest  arch dams in the world, being 265 m high with  a 160  m chord, which spans a very deep and narrow gorge.
The rock on both sides of the gorge had been skilfully reinforced.
Landslide case study Vaiont

5. Paleoslide
A paleo landslide existed in the area, along the side of the reservoir.
The landslide was not recognized during the investigation phase.
Landslide case study Vaiont

6. Rising the lake level
February - November 1960: the  water level in the reservoir rose from 580 m to 650 m
September - November 1960: movements of about 3.5 cm a day: lower reservoir  down  to  600 m.
: rock slide (  m3) slid  into the lake within about ten minutes
in 1962  the reservoir  rose   to  700 m.
In 1963, it  slowly oscillated  between 700 and 650 and back to 713,  never reaching  the dam crest (at 722.5).
In the final days before  the catastrophe, the velocity of the slide reached 20 to 30 cm a day.
Landslide case study Vaiont

7. Overview of landslide area
Landslide case study Vaiont

8. Flooding caused by the event
Vaiont dam
Landslide case study Vaiont

9. The dam still stands
It was overtopped by m water during the slide
Landslide case study Vaiont

10. Airphoto 1954: before dam construction
Landslide case study Vaiont

11. Airphoto 1962: after dam construction but before the event
Piave river
Dam
Longarone
Landslide case study Vaiont

12. 1964
Landslide case study Vaiont

13. Airphoto 1984 Longarone Dam Landslide Piave river
Landslide case study Vaiont

14. Detail area in 1962
Landslide case study Vaiont

15. Detail landslide in 1984
Landslide case study Vaiont

16. Objectives The assignment has the following objectives:
Make a photointerpretation of three periods:
1. Before construction (1954): recognise the paleolandslide
2. After construction (1962): map lake extend
3. After the landslide (1964 or 1984): map the new situation
GIS work:
Calculate the total volume of water in the reservoir prior to the landslide
Calculate the volume of water that was removed from the reservoir during the landslide
Calculate the total volume of eroded materials of the landslide
Calculate the total volume of accumulated materials of the landslide
Calculate the total volume of the landslide.
Landslide case study Vaiont

17. Landslide mapping
Landslide case study Vaiont

18. Input data The input data consists of
Airphotos: 1954, 1962, 1964 and 1984
Beforeco: a segment map with the contours before the landslide happened
Before: a segment map with other information before the landslide happened
Afterco: a segment map with the contours after the landslide happened.
Carte3: a polygon map with unique ID polygons, linked to a table with geological , geomorphological and landslide information.
Landslide case study Vaiont

19. Digital contour lines
Landslide case study Vaiont