SARNO (ITALY) LANDSLIDES: DIFFERENT METHODOLOGIES OF DATA ACQUISITION 
M. Barbarella*, M. Fiani** 
* DISTART - University of Bologna (Italy) 
** 1st. di Geodesia, Topografia e Idrografia - Universitary Naval Institute of Naples (Italy) 
Commission VI, Working Group 3 
KEY WORDS: Surveying, GPS network, Datum transformation, DEM 
ABSTRACT 
On May 1998 a large number of landslides struck five villages in the south of Italy. The landslides present a large 
extent of the area which was invaded by mud, the amount of material displaced and the difficulty of access and transit. 
We are requested to determinate the volume of the material moved in the shortest possible time. 
To draw the post-event surface a number of surveys on the ground have been performed by means of different 
instrumentation, select according to the local morphology of the landslide. To get the course of the surface before the 
event has been necessary to use a pre-existing cartography and, on a landslide, of the photograms of a performed flight 
a few before the event. The cartography has been rasterized and vectorized with half-automatic methods seeds to get the 
contour lines. 
From these different numerical models have been drawn some grids to perform the calculation of the volumes included 
the two surfaces. Some algorithms of DEM interpolation have been analyzed on a grid to evaluate the effect of the 
interpolator in different cases. Finally the volumes of removed ground have been evaluated. 
1. INTRODUCTION 
On May 1998 a large number of landslides struck five 
villages in the south of Italy; many people died and 
considerable material damages occurred. 
An interdisciplinary workgroup was set up in order to 
study the phenomenon. In the same region nearly two- 
hundred other villages run the same risk. 
As regard the topographic surveys, these landslides 
present the following characteristics: the extent of the 
area which was invaded by mud, the amount of material 
displaced and the difficulty of access and transit, 
especially where the ground is very steep (near the 
detachment zones). 
Other people belonging to research group asked to us to 
make urgent surveys in order to obtain the present shape 
of the ground surface which was invaded by mud, the 
localization of the unsteady ground which might be 
dangerous, the calculation of the volume displaced. 
A vast amount of surveys has been necessary in order to 
know the new morphology of the ground after the event. 
It was not possible to make a photogrammetric survey 
immediately because of problems concerning the time, 
territorial jurisdiction and financial difficulties for the 
flight and plotting costs and so on. Therefore a few field 
surveys were carried out immediately 
A photogrammetric flight at low altitude was planned 
both for the niches and for some flow channels. 
Of course, it was not possible to survey in such a way all 
the landslides because of time, funds and personnel. 
Altogether eleven mudslides, concerning four villages, 
were surveyed on the ground; right those ones which 
were declared to be both the most important for the 
studies and the most dangerous. At the same time the 
research of the pre-landslide cartography began with the 
aim of identifying the changes in topographic shapes and 
to have some indication about the volume of material 
displaced. 
2. SURVEYING METHODOLOGIES 
The morphology of the ground changes a lot along the 
landslide. Towards the mountain the slope arrives until to 
50°-60° and there are many zones which are not 
practicable on foot or dangerous. 
Owing to different morphology of the ground which 
interested by the mudslides, some different survey 
methodologies were utilized in order to obtain the actual 
shape of ground. This especially refers to a landslide 
which interests Sarno’s village, called SA60. 
In details: 
Kinematic GPS, with antenna mounted on special 
vehicles in some zones, handy held in others (on the 
SA60 landslide). 
Classic total station; for precision surveys to make on 
the detaching niches, the operator was sometimes 
assured by means of a rope (figure 1). 
A special total station, called MDL, was utilized in 
upstream zones and in those ones which are not 
easily practicable on foot. 
The harshness of the ground makes the kinematic survey 
with antenna in hand fatiguing and not very productive. 
The motorized kinematic GPS survey is convenient in the 
medium-low zone of the landslide. The utilized 
caterpillar lorry goes through easily (slope until to 60°- 
70°) and fastly (10-15 Km/h in level stretches).