hese
tent.
ntire
as at
ct to
and
or a
d be
10se
ined
t to
the
lere
red
ncy
use
ion
oes
ita
the
the
the
ic,
the
OW
'se
Banchini, Giovanni
Knowledge, in real time, of the environmental situation immediately after the disaster to plan disaster aid and
emergencies
Knowledge of the environment in quasi real time to plan the first reconstruction activities or the eventual
provisional relocation of damaged installations
Knowledge of the environment in due course for the definitive planning of the reconstruction or of the post
event normalization and, after, for a documentation of what was done
AN EXAMPLE: THE SARNO RIVER EVENT OF 1998
On 5-6 May 1998, following intense rains in the region of Campania a series of landslides developed on the
carbonate slopes of the upper basin of the Sarno River involving the communities of 4 municipalities. The landslides
occurred in the form of quick mudflows following the existing drainage channels. Starting at the drainage divides the
mudflows reached very high velocities as they progressed downstream eventually arriving at the plains where they
spread as fans and struck directly various urban centers and industrial areas with disastrous effects. More than 160
people died. The first slides started in the late afternoon of 5 May, continuing all night. About 100 slides were
recorded;. some of the flows spanned 3km in length. More than 200 000cubic meters of mud flowed over a relief of
800m.
The Compagnia Generale Ripreseaeree, alerted to the existing conditions as reported by the media on the
evening of 5 May, had a photogrammetric plane ready on the morning of 6 May and a photogrammetric survey was
conducted as soon as light conditions permitted it. The flight was carried out under rain flying below the cloud cover.
The first photographic material was in the hands of the Protezione Civile, the civil defense agency of Italy, the same
afternoon.
The before-the-event geographical information on an area brings on the ever present problem of map updating.
It is a general cartographic problem which becomes particularly significant in hazards prone areas for which the
availability of up to date information on roads and infrastructures in general is fundamental both during the prevention
phase and for post event planning as in the development of a general evacuation plan. Under these circumstances a
product based on little cost and quick production is much to be preferred to an optimal but dated conventional
cartography be that numerical or analogic. For the Sarno River event the most up to date product comprised the b/w
aerophotogrammetric coverage of Italy flown in 1994 by the CGR. An orthophoto of part of the area struck by the slide
is shown in figure 1. Though taken at 11 000m above the ground the quality of the photography of the survey is such
that products at the scale of 1: 10 000 can be derived without any problem. Conditions portrayed on this image can be
considered to be those existing just before the disaster save for the construction of a few houses and perhaps one or two
small industrial plants.
Knowledge on real time of the situation immediately after the event requires a high degree of efficiency,
competence, and quickness of response on the part of those organizations charged with defending against the disaster.
Technically the only valid response to the need of information is the photogrammetric product, whether the classic
aerial nadiral photo or, for a better grasp of the details of the structures involved, with panoramic low level
photographic coverages from airplanes or helicopters. A possible alternative is represented by high resolution satellite
images which however fail if clouds are present and are anyhow available only if the satellite happens to be passing
over the area at the right moment. For the Sarno area the data available for civil defense consisted of the ad hoc material
collected as the main event had just taken place.
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 109
