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A web-based tool for ranking landslide mitigation measures
Un outil internet pour classer les techniques visant à diminuer le risque de glissements de terrain
Lacasse S., Kalsnes B.
International Centre for Geohazards / Norwegian Geotechnical Institute (NGI), Norway
Vaciago G.
1
, Choi Y.J.
2
, Lam A.
3
1
Studio Geotecnico Italiano, Milano, Italy;
2
NGI Inc., Houston, TX USA; 3GEO, Civil Engineering Development Dept, Hong Kong, HKSAR
ABSTRACT: As part of the European project SafeLand, a compendium of structural and non-structural mitigation measures for
different landslide types in Europe was prepared, and the measures were assembled into a web-based “toolbox”. The purpose of web-
based toolbox is to assist decision-making and to guide the user in the choice of the most appropriate mitigation measures. The paper
presents an overview of the toolbox features, mitigation measures considered and an example of the report for one application of the
toolbox.
RÉSUMÉ : Parti intégrante du projet européen « SafeLand », un recueil des mesures d'atténuation structurelles et non structurelles
pour les différents types de glissements de terrain en Europe a été établi. Les mesures d’atténuation ont été assemblées dans une "boîte
à outils" utilisable via internet. Le but de la boîte à outils est d'aider la prise de décision et de guider l'utilisateur dans le choix des me-
sures de diminution des risques les plus appropriées. Le document présente un aperçu des fonctionnalités de la boîte à outils, des me-
sures de diminution des risques envisagées et un exemple de rapport pour une utilisation spécifique de la boîte à outils.
KEYWORDS: Landslide, Quantitative vulnerability evaluation, Intensity, Susceptibility
1 INTRODUCTION
As part of the research done in the European project SafeLand
“Living with landslide risk in Europe: assessment, effects of
global change, and risk management strategies”, a compendium
of structural and non-structural mitigation measures for
different landslide types in Europe was prepared, and the
measures were assembled into a web-based “toolbox”.
Emphasis was placed on providing a rational and flexible
framework applicable to existing and future mitigation
measures.
The purpose of web-based toolbox is to assist decision-
making and to guide the user in the choice of the most
appropriate mitigation measures.
The mitigation measures were classified into three catego-
ries, describing whether the mitigation measures addressed the
landslide hazard, the vulnerability or the elements at risk them-
selves. The measures considered include structural measures re-
ducing hazard and non-structural mitigation measures, reducing
either the hazard, the vulnerability or the exposure of the ele-
ments at risk. The structural measures include surface protection
and control of surface erosion; measures modifying the slope
geometry and/or mass distribution; measures modifying surface
water regime - surface drainage; measures modifying ground-
water regime - deep drainage; measured modifying the me-
chanical characteristics of unstable mass; transfer of loads to
more competent strata; retaining structures (to modify slope ge-
ometry and/or to transfer stress to competent layer); deviating
the path of landslide debris; dissipating the energy of debris
flows; and arresting and containing landslide debris or rock fall.
The non-structural mitigation measures, reducing either the
hazard or the consequences: early warning systems; restricting
or discouraging construction activities; increasing resistance or
coping capacity of elements at risk; relocation of elements at
risk; sharing of risk through insurance. The measures are de-
scribed in the toolbox with fact sheets providing a brief descrip-
tion, guidance on design, schematic details, practical examples
and references for each mitigation measure. Each of the meas-
ures was given a score on its ability and applicability for differ-
ent types of landslides and boundary conditions, and a decision
support matrix was established.
The web-based toolbox organizes the information in the
compendium and provides an algorithm to rank the measures on
the basis of the decision support matrix, and on the basis of the
risk level estimated at the site. The toolbox includes a descrip-
tion of the case under study and offers a simplified option for
estimating the hazard and risk levels of the slide at hand. The
user selects the mitigation measures to be included in the as-
sessment. The toolbox then ranks, with built-in assessment fac-
tors and weights and/or with user-defined ranking values and
criteria, the mitigation measures included in the analysis. The
toolbox includes data management, e.g. saving data half-way in
an analysis, returning to an earlier case, looking up prepared ex-
amples or looking up information on mitigation measures. The
toolbox also generates a report and has user-forum and help fea-
tures.
The paper presents an overview of the toolbox features,
mitigation measures considered and an example of the report for
one application of the toolbox. The reports in the reference list
can be found on the SafeLand project website,
fp7.eu. Much more details and the descriptions of each mitiga-
tion measure along with references for each can be found in the
reports in the list of reference.
2 TOOLBOX FEATURES
The toolbox is organized to guide the user in ranking different
mitigation measures and to assist in the decision-making about
the most appropriate mitigation measures to select for a site.
The toolbox suggests the ranking of mitigation measures for a
given landslide situation. The toolbox offers an extensive menu
of different mitigation measures, and the user selects those that
he wishes to consider in the study at hand.
The toolbox documents "do’s and don’ts" and "how to". It
estimates relative costs, benefits, hazards, effectiveness and
vulnerability of each measure to mitigate hazard and/or risk.
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