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A multidisciplinary approach to reduce flooding
risks in the careful management of civil defence
plans first results in Laveno on the Lago
Maggiore shoreline (Lombardy-Italy)
Fabio Luino, Paolo Fassi Mariano
Lerbini Consiglio Nazionale delle Ricerche,
Istituto di Ricerca per la Protezione
Idrogeologica, Sezione di Torino, Strada delle
Cacce 73 10135 TORINO Italy www.irpi.to.cnr.it

Antonella Belloni Regione Lombardia, Direzione
Generale Opere Pubbliche, Politiche per la Casa
e Protezione Civile, Via Fara 26 20100 MILANO
Italy www.protezionecivile.regione.lombardia.it
Abstract Within the framework of the INTERREG
IIIA-Program Italy-Switzerland (2002-2006), the
Region of Lombardy and the CNR-IRPI of Turin are
carrying out a project to develop a
hydrogeological risk management system along the
Lombardy shore of Lago Maggiore. This research
analyses 17 municipal territories along a coastal
stretch of about 56 km. The main objectives of
the study are to determine the limits of
flood-prone areas, the developing time of
hydrometric increases, and the influence of
major tributaries, in order to design new and
functional civil defence plans.   Keywords
floods, urban planning, GIS, Lago Maggiore,
Lombardy, Italy.
The historical investigation allowed us to
uncover evidence of at least 16 inundations to
have struck the territory of Laveno during the
last 30 years (Tab. 1).
Table 1 30-year history of floods in the Laveno
municipal territory.
1. Introduction Lombardy is one of the Italian
regions most affected by hydrogeological
processes. In recent decades, landslides, debris
flows and floodings throughout the territory have
caused severe damage, often involving villages
and towns. The number of processes seems to be on
the rise, and the losses mount higher year after
year. This does not seem due to a real climatic
change, but rather to the presence of structures
and infrastructures, especially those built since
the 1960s, when urban expansion unregulated by a
correct land-use policy began to occupy the
natural expansion zones of the floodwaters 1, 2,
3. More often than before, technical public
bodies now request multidisciplinary analysis
studies for the definition of flood-prone areas
and the provision of guidelines to revise
existing urban planning and to design future
urban development in particular.
Figure 4 Urban planning mosaic map of the
Laveno municipal area the land-use planning
categories are indicated by different colours.
3.4. The differential flood risk map By
classifying a land area and subdividing it into
uniform urbanized and land-use zones, a
qualitative analysis can be made to evaluate the
expectable potential damage. In fact, to obtain
the risk level to which a territory is exposed,
not only should a more detailed scale be used,
but a structural survey of the buildings is
necessary in order to evaluate their
vulnerability to damage. A critical value was
subsequently assigned to the 8 categories
according to parameters such as the presence or
concentration of people over 24 hours or at
particular hours of the day the presence of
machineries, properties or social-recreational
activities and/or the loss of profit from damage
to agricultural zones. The 8 categories were then
unified into 4 classes of different levels of
flood hazard exposure HIGH level - categories A
and B MEDIUM level - C and D LOW level - E and
F VERY LOW level - G and H. To obtain a correct
correlation between the hydraulic hazard of the
two flood prone areas along the lake and rivers
and the exposure level of the urbanized zones, a
"risk matrix" was created (Fig. 5).
2. Study area Lago Maggiore, Italys second
largest lake (210 km²), lies at the foot of the
Alps, on the borders between Piedmont, Lombardy
and Switzerland. The lakes large catchment basin
(6598 km²) includes the valleys of the Ticino and
Toce rivers (the principal tributaries), the
Maggia and the Tresa torrents. It also receives
water from the lakes of Lugano, Orta, Varese and
Mergozzo. Its only distributory is the Ticino,
which leaves the lake at Sesto Calende and then
flows into the Po below Pavia. Only the most
northerly end (42,6 km²) lies within Swiss
territory. Our study analyses the Lombardy
shoreline, from Pino sul Lago Maggiore hamlet
(North) to Sesto Calende town (South), comprising
17 municipal territories along a coastal stretch
of about 56 km.
3.2. Hydraulic and geomorphological studies A
digital elevation model of the Laveno area (1-m
cell) was constructed and a hydraulic model
applied. The hydraulic study was supported by a
geomorphological analysis that can reveal any
morphological modifications likely to contribute
to the development of inundations. The
geomorphological study was carried out by
photointerpretation analysis of snap-shots taken
from 1954 to 2000. The reliability of the
evidence from the aerial photographs was verified
by field surveys conducted along the shoreline.
The two studies were then joined to identify the
areas with different waters depths two strips
along the shoreline were identified (Fig. 3). The
first marks the zone usually flooded during
ordinary inundations, while the larger strip
marks the zone struck by catastrophic events,
like that of October 2000.
Euro-Mediterranean Seminar on New Technologies
applied to the Management of Disasters Risks
Madrid, 6/8 October 2003
Figure 1 Map of the study area the Lombardy
shore of the Lago Maggiore
3. Methodology Building on prior studies of other
zones in Lombardy, the CNR-IRPI Research
Institute of Turin has applied a
multidisciplinary approach to identify
flood-prone areas along the Lago Maggiore
shoreline. The three steps comprise 1)
historical research of past flooding data 2)
hydraulic and geomorphological studies 3) urban
planning analysis. Each analysis produces a
different map (Arcview-GIS). The results of the
different maps are joined to create a flood-prone
area map.
Figure 5 - Risk matrix used to join the four
classes to different exposure level of the
urbanized zones with two flood prone areas
located along the Lago Maggiore shoreline.
The superimposition of the urban planning mosaic
map over the historical, hydraulic and
geomorphological maps automatically highlighted
the areas with different risk levels along the
Lago Maggiore shoreline (Fig. 6), thus producing
7 different areas with 4 different risk levels.
3.1. Historical research of past flooding
data The historical research was carried out at
various resource sites a) state technical office
archives contain many unpublished reports on past
inundations, with useful information about flood
dynamics and timing, discharges, hydrometric
levels, flooded areas, water depths in the towns,
number of victims, amount of damage b) municipal
libraries hold papers, technical and historical
books regarding Lago Maggiore c) newspaper and
periodical libraries collect national and local
newspaper articles d) municipal archives of the
17 villages examined. All gathered data were
analysed, verified and successively implemented
and chronologically listed. Many interviews with
local inhabitants were also conducted. From these
data, a historical map (Fig. 2) of all damaged
sites was constructed.
Figure 3 Hydraulic and geomorphological map of
the Laveno municipal area. Blue vertical
sketching marks the area inundated in the past by
ordinary floods red vertical sketching shows
flood-prone areas during catastrophic events.
3.3. Urban planning analysis The goal of the
urban planning analysis was to differentiate
between the purposes of the present land-use, to
improve knowledge of the existing building
property, to define criteria of compatibility
with the future urban development. The first step
was to collect the current urban planning maps
with their technical codes, cadastral maps and
aerophotogrammetry maps at scales of 12000 and
15000. The Regional Technical Map was used as
cartographical base supported by the municipal
cartographies of the urban planning at 12000
scale. An in-depth study of the 17 municipalities
was carried in prepration for the construction of
the mosaic land-use maps, at least for the areas
near the shore. The urban planning mosaic is
generally composed of 8 categories defined by
their principal functions (Fig. 4)   A)
Residential settlement existing and foreseen
residential areas B) Hotel/Residences and
Tourist Facilities residences, hotels, spas,
etc. C) Public Services Areas municipal
buildings, barracks, schools and hospitals,
churches, dumping areas and storage platforms,
etc. D) Sport Areas, Utilities and Standards
public gardens, parks, athletics grounds, private
and public sport clubs, etc.). All areas occupied
by roads, railways and cemeteries are marked in
the same color E) Industrial and Handicraft
Areas existing and foreseen industrial,
craftmade and commercial buildings F)
Agricultural Areas agricultural activities. In
these areas old farms can be renovated and the
building volume slightly expanded G) Woods
natural regional areas, grassland, pastures H)
Lacustral and Fluvial Zones natural areas along
the lake and river banks defined as
flood-safeguard zones. Only the first 4
categories (residential settlement, tourist
facilities, public service and sport/standard
areas) are present in the Laveno urban area near
the shoreline.
Figure 6 Laveno final map indicating the
shoreline areas with different risk levels.
4. Findings  Historical research has evidenced
that the clear increase in flood frequency in
northern Italy since the 1960s can be traced to
several factors, foremost of which is the growth
of human pressure from unregulated urbanization
encroaching into wide natural river areas. A
multidisciplinary approach comprising historical
investigation, hydraulic and geomorphological
studies provides a valid method to identify
flood-prone areas. The superimposition of an
urban planning mosaic map over a map of the
flood-prone areas is, without doubt, a
fundamental step in the identification of highest
flood risk. A multidisciplinary approach can also
be used for the in-depth analysis of a territory
that has far too often suffered from rapid and
unregulated change. The research results should
provide evidence for the formulation of
guidelines for the revision of existing urban
planning and of future urban development in
particular ultimately, the aim is to forecast
risk scenarios. Only in this way will it be
possible to draw up new and functional civil
defence plans.
Figure 2 Laveno historical map. Sites damaged in
the past are highlighted. The labels refer to the
year of the event.
geologist/researcher of National Research
Council E-mail F.Luino_at_irpi.to.cnr.it