IMPACT ASSESSMENT OF LANDSLIDE EVENTS
AND THREE TEST CASES
Francesca Ardizzone
Consiglio Nazionale delle Ricerche Istituto per la Protezione Idrogeologica
CNR IRPI
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OUTLINE
!  Introduction.
!  Definition of Landslide Impact: a literature overview.
!  The three test cases of landslide impact assessment in
LAMPRE.
!  A focus on a case study: Data, Analysis and Results.
!  Problem and Conclusion.
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INTRODUCTION
!  Landslides are responsible for significant loss of life,
injury to people and damage to structure and,
infrastructure.
!  The assessment of the vulnerability is a topic that is
growing in importance. Research and tools to analyse
landslide impact assume a fundamental role.
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IMPACT DEFINITION
!  We examined scientific literature, technical reports and
other informative material related to impact.
!  We analysed how different researcher and technicians
deal with the problem of the impact of landslide event
worldwide.
!  We prepared a database of scientific and technical
papers using Google scholar and google.
LANDSLIDE IMPACT
IMPACT LANDSLIDE ON STRUCTURES AND
INFRASTRUCTURES
LANDSLIDE VULNERABILITY
LANDSLIDE COST EVALUATION
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IMPACT DEFINITION
!  The result is an excel file that lists 75 titles.
!  For the 75 studies we noted:
main topic category
study geography region
inventory type
landslide types and number
triggering event type and date
type of human structure or infrastructure involved
type of impact
cost evaluation
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IMPACT DEFINITION
!  The majority of the studies refer to landslide impact in
terms of Vulnerability; the concept of Physical Impact
between landslide and element at risk recurs only 10
times. Only 18 papers deal with the cost evaluation.
Category
Description
#
C
Cost‐damage impact
evaluation
18
I
Physical impact evaluation
10
R
Risk
21
V
Vulnerability
26
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IMPACT DEFINITION
!  The research shows that the concept of landslide
impact, includes a variety of interpretations.
!  There is not a unique definition of impact but it contains
several possible approaches and analysis.
!  The assessment of landslide impact on urban setting
spans from few papers that deals with a physical
interaction between landslides and infrastructure to
several papers, which deal with vulnerability and risk.
!  The cost estimation changes case by case from an expost analysis to an analysis of cost and benefit.
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IMPACT DEFINITION
IMPACT Physical DIRECT Economic BUSINESS INTERRUPTION Social Other INDIRECT EVENTO DE DISEMINACIÓN Y CAPACITACIÓN, 19-22 ENERO 2015
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THE LAMPRE TEST CASES
IMPACT PHYSICAL Collazzone study area (Umbria, Central Italy) Snowmelt event 1 January 1997 DIRECT COST Acquasanta Terme and Roccafluvione (Marche, Central Italy) Rainfall and snowmelt events Nov.-­‐Dec. 2013 Tramuntana Range (Majorca, Spain) Cold and wet winter in the period 2008-­‐2010 EVENTO DE DISEMINACIÓN Y CAPACITACIÓN, 19-22 ENERO 2015
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THE ITALIAN TEST CASE
!  Between November and December 2013:
•  10 – 13th of November 2013: heavy rainfall.
•  25 – 29th of November 2013: snowfall and sudden
snowmelt.
•  2nd of December 2013: heavy rainfall event.
CUMULATIVE RAINFALL
10-13 NOV
25 NOV-1 DEC
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THE ITALIAN TEST CASE
!  Between November and December 2013:
•  10 – 13th of November 2013: heavy rainfall.
•  25 – 29th of November 2013: snowfall and sudden
snowmelt.
•  2nd of December 2013: heavy rainfall event.
These events are not rare.
Past similar events: 2005, 2009, 2011, 2012
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THE ITALIAN TEST CASE
Acquasanta Terme and
Roccafluvione were
affected by several
landslides.
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THE ITALIAN TEST CASE
A large number
Acquasanta
Terme
of roads
and
Roccafluvione
connecting
smallwere
rural
affected by several
settlements
were damaged
landslides.
and
people were isolated.
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DATA
!  Data used for the analysis:
•  Event Landslides Inventory Map (ELIM).
•  Road Network Map (RNM).
•  Cost Data (CD).
(estimation cost data provided by
Municipalities for reimbursement)
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ELIM
!  The ELIM was prepared in two steps:
1.  For an area of 200 km2 field surveys were carried
out to identify the landslides and a map was
prepared.
2.  The map was carefully verified in the GIS
laboratory to obtain a detailed ELIM.
!   More than 1,500 slope failures were mapped including
earth flows, slide-earth flows, slides, rock-falls and
complex slides.
SOIL
SLIDE
EARTH
FLOW
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ROCK
FALL
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ELIM
About 900
landslides were
recognized
Landslide
poligons
Hydrographic
network
Municipal
boundary
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ELIM
Municipality
Acquasanta
Terme
Roccafluvione
Landslides Landslides Landslides
Landslides
(#)
Area (m2) density (#/km2) with damage
540
898
321,810
496,914
3.91
14.85
122
184
% Landslides
with damage
23
20
Field surveys were focused also to estimate qualitatively
the damage along the roads:
Aesthetic (Minor)
Functional
(Medium)
Structural (Severe)
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RNM
!  We elaborated a digital Road Network Map (vector format)
for Acquasanta Terme and Roccafluvione using:
•  The Web Feature Services (WFS) of the Italian
Ministry of the Environment.
•  Regional Technical maps (CTR) of Regional
Government.
!  Roads were classified in two classes:
•  Main Roads (MR, under the State responsibility).
•  Secondary Roads (SR, under the Municipality
responsibility).
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RNM
MR
SR
ROAD
ACQUASANTA
TERME (KM)
ROCCAFLUVIONE
(KM)
MAIN
(MR)
63.4
36.53
SECONDARY
(SR)
124
204.21
TOTAL
187.4
240.74
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CD
The two municipalities provided different information
about the damage and the related direct cost .
Acquasanta Terme
13 damaged roads
For each road
ü  the economic estimation of the damage,
ü  the number of landslides that hit the road,
ü  the length of damaged road.
Roccafluvione
97 damaged roads
For each road
ü  the economic estimation of the damage.
The economic information were stored
in PostreSQL, an open source
enterprise DBMS.
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ANALISYS
The Road Network Map (RNM), the Event
Landslide Inventory Map (ELIM), the Cost Data
(CD)
!  The analysis was aimed at quantifying the cost:
•  for each landslide,
•  for each linear meter of damaged road,
•  for each square meter of landslide.
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ANALISYS
!  Using the ELIM we intersected the landslides with the
RNM using a 6 meter buffer around each road.
INTERSECTION
LANDSLIDE
ROAD
BUFFER
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ANALISYS
!  A total of 642 intersections was obtained.
Intersections Landslides
#
#
Acquasanta
Terme
Roccafluvione
Landslide area
(m2)
219
213
75,495
423
384
175,066
Note that a single landslide could intersect
the same road more than one time.
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ANALISYS
Cost for
Acquasanta
Terme
Roccafluvione
Terme
Each
Landslide
642 Intersections
from GIS analyses
Linear meter
Square meter
Cost data
from municipalities
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ANALISYS
Square
meter
Acquasanta Terme
Linear
meter
Road
# Landslides
Linear meter
Square meter
30,000 €
Cost €
Cost €
Cost €
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ANALISYS
Acquasanta Terme
Cost for each linear meter
12 10 8 6 4 2 0 y = 8E-­‐06x R² = 0,7126 y = 8E-­‐06x R² = 0,8043 0 500000 1000000 1500000 Landslides area (m2) Cost es?ma?on (€) 15000 Cost for each square meter
y = 0,0087x R² = 0,8882 10000 Damage length (m) # Landslides Cost for each landslide
250 y = 0,0002x R² = 0,8828 200 150 100 y = 8E-­‐05x R² = 0,6411 50 0 0 500000 1000000 1500000 Cost es?ma?on (€) Good correlation
5000 0 0 200000 400000 600000 800000 1000000 1200000 1400000 Cost es?ma?on (€) From cost
data
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From GIS
analysis
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ANALISYS
Acquasanta Terme
Cost
Landslide Linear meter
Mean Value 152,936 € Mean Value 96,700 € Square meter
149 €/m2 5,197 €/m EVENTO DE DISEMINACIÓN Y CAPACITACIÓN, 19-22 ENERO 2015
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ANALISYS
Roccafluvione
Cost for each landslide
25 Damage length (m) # Landslides 20 y = 2E-­‐05x R² = 0,41671 15 10 5 0 Landslide area (m2) 0 100000 200000 300000 400000 500000 600000 Cost es?ma?on (€) Cost for each square meter
8000 7000 6000 5000 4000 3000 2000 1000 0 Cost for each linear meter
140 120 y = 0,0002x R² = 0,29549 100 80 60 40 20 0 0 100000 200000 300000 400000 500000 600000 Cost es?ma?on (€) y = 0,0077x R² = 0,1327 0 200000 400000 600000 From GIS analysis Cost es?ma?on (€) EVENTO DE DISEMINACIÓN Y CAPACITACIÓN, 19-22 ENERO 2015
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ANALISYS
! Roccafluvione case study suggests that the landslide
event inventory map does not represent the
phenomena that produce damage along the road
network.
WHY?
!  The cost estimated by the Municipality included
damages caused by the meteorological event and not
only by the landslides.
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PROBLEM
!  When many landslides affected large areas, it is very
difficult to collect complete data regarding damage and
costs.
!  Data from public documents frequently differ in quality
and amount, even for very close municipalities.
!  The available documents frequently give the total
amount of costs or do not make difference between
landslides or other kind of damaging events
!  The costs provided by the municipalities are estimates
and this adds an uncertainty degree to the analysis.
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CONCLUSION
!  A methodology was elaborated to estimate the
cost: (i) for each landslide, (ii) for each linear meter
of damaged road, (iii) for each square meter of
landslide.
!  The results are different between the two
municipalities since the cost data were different.
!  To control these differences we need other case
studies i.e. other areas and type of roads.
!  The results of this ex-post analysis could be useful
for ex-ante analysis.
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THANK YOU FOR THE ATTENTION
[email protected]
…….and thank to
Bruce Malamud, Paola Reichenbach, Rosa Mateos, Federica Fiorucci
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