HAZARD AND RISK MITIGATION (STRUCTURAL, NONSTRUCTURAL MEASURES, INSURANCE)

New planning process for flood protection projects after severe flooding events

Markus Wyss, dipl. Bauing. ETH1

INTRODUCTION be taken into account and minimized. In light of In recent years, the Bernese Oberland has been the 70 millions Swiss Francs spent for urgent often struck by severe flooding, causing catastroph- reconstruction of river courses and 150 millions ic damage in different towns und cities. Main invested in additional river engineering and safety reasons of the events, which occurred from 2005 to projects after the events in the year of 2005, it 2011, were unfavorable weather conditions with furthermore seemed appropriate to establish a either heavy short duration precipitation or rapid special analysis and planning process. Within a few snow melting in combination with enduring days after the events, so called „local, solution precipitation. In addition, some flooding was trig- focused event analyses“ were initiated. In 2005, gered by changes in periglacial areas of the Alps six local, solution focused event analyses were due to global warming. On account of the very successfully executed under the project manage- heterogeneous topography different processes ment of the District I in the communities of Diemti- occurred reaching from debris flow in steep gullies gen, Reichenbach, Lütschental, Brienz, Meiringen/ to flooding along large rivers and lakes. Side effects Hasliberg and Guttannen. In 2011, the same often were extensive erosion and extraordinary bed process was applied in the communities of - load transport. steg, Kandergrund and . As a result of the increasing number of events, but The new process comprises immediate and coordi- also of their extent, complexity and ultimately of nated documentation as well as analysis of an event the resulting destruction, the entire process from and leads to the conceptual solution for future event analysis to planning of protection measures flood protection. Therefore and at the start of the had to be altered and optimized. Optimization was process, a complete project team is installed at each also necessary, since this intellectual work was event site including specialists in the fields of governed by difficult conditions such as extreme geology, geomorphology, hydraulics, civil engineer- time pressure in case of ongoing danger, destruc- ing as well as landscape architecture and environ- tion of life lines and infrastructures, anxious ment, and others if necessary. residents and high expectations of the public, poli- Typically, the first step is mainly performed by ticians and media with respect to solutions. geologists and morphologists − possibly even during the lasting event. They have to determine METHODOLOGY AND OBJECTIVES what triggered the event and what happened During the flooding of 2005 about 60 of the where Bernese Oberland‘s 80 communities faced limited (e.g. areas of failure and erosion scars, locations or no accessibility due to destroyed traffic ways. and quantities of bed load transport, spatial extent Subsequently, emergency work had to be per- of flooding and destruction). Simultaneously, formed with limited technical and human resourc- engineers assess the extent of damage at the river es, mainly available on site. In addition to these bed, its protection structures and at the traffic ways difficulties, some communes were further stressed and other infrastructures. Without time loss, by supply demands as well as the need for evacua- possible future event scenarios and according tion of tourists. Especially tourist destinations asked protection deficiencies are identified and concep- for immediate reconstruction of traffic and public tual protection solutions are determined in a infrastructure. Quick decisions and solutions were second step. Early cooperation and communication expected. However, the risk of wrong action had to among the different team members and also

334 | INTERPRAEVENT 2016 – Extended Abstracts IP_2016_EA032 involving the affected public, local authorities and complexity it seems to be an extraordinary short the essential cantonal and federal offices allow for a period of time. fast and effective planning. Finally, during the third Three key factors are relevant for a successful step, the preliminary design of the protection process: Immediately establishing an interdiscipli- project is carried out in a comprehensively partici- nary team allows for fast and thorough action with pative process (see Fig. 1). just-in-time interaction between the team members Local, solution focused event analyses shall there- from the beginning of the event analysis. The fore lead to: second key factor is communication. Residents as – A unitary process and the application of the well as local politicians such as municipal councils same analyses and planning principles at all are involved into the analysis and planning process. disaster sites. They personally know the key team members and – An efficient and effective project organization gain confidence as a basis for the necessary accept- by reducing interfaces. ance of the later protection project, which can have – Time gain, also related to the necessity to a significant impact on the settlement area or on communicate with public, politicians and media. residents and their private property. The early – Minimum opposition against the protection understanding of the particular natural hazard projects. process also allows for immediate and continuous information of the public, further increasing confi- FINDINGS dence and acceptance. Finally, adequate quality The execution of extensive protection projects assurance in terms of hydraulic and technical following the 2005 disaster in , Reichen- aspects as well as costs and sustainability has to be bach, Lütschental, Brienz and Meiringen/Hasliberg ensured. Peer reviews of crucial project elements was successfully finished between 2009 and 2012. performed by independent specialists or laboratory In comparison with their total costs of approx. testing as well as periodical consulting with the 105 millions Swiss Francs and especially their essential cantonal and federal offices are of major importance.

Figure 1. flow chart of the local, solution focused event analysis

KEYWORDS event documentation; event analysis; mitigation planning process; communication; Partizipation

1 Tiefbauamt des Kantons Bern, Thun, Bern , [email protected]

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