NAVAL: a Computer-Based Tool for Avalanche Risk Scenarios Definition

International Snow Science Workshop Grenoble – Chamonix Mont-Blanc - 2013 NAVAL: a computer-based tool for avalanche risk scenarios definition Massimiliano Barbolini*, Francesco Stefanini & Lisa Bonomi FLOW-ING S.r.l., La Spezia, Italy ABSTRACT: The software NAVAL has been developed in order to support avalanche experts and decision makers to promptly define and visualise probable avalanche risk scenarios over a region in rela- tion to given meteorological and snow-cover conditions. The software includes a cartographical data- base with avalanche outlines, historic events information and tools for definition of potential hazard and risk scenarios. The user is driven through different choices concerning avalanche frequency, release zone altitude and exposure, avalanche size and is helped in the decision process by built-in tools, such as snow precipitation data analyser and external links with current avalanche and meteorological bulletins. As a function of user choices NAVAL acts a filter over the avalanche data-base in order to visualize on different cartographic or photographic bases the most probable avalanches, that is the hazard scenario. Combined to each hazard scenario, information about exposed elements – that is elements at risk – might be easily visualized in order to evaluate the most appropriate preventive measures. NAVAL allows users to export and save any generated risk scenario in a web-gis format (*.kml). Visualization of "kml" format on the Google EarthTM platform makes it easier to store the data and to share the information about avalanche risk scenarios with a wider variety of users. The data- base about avalanches and exposed elements can be straightforwardly updated as new information are made available. First implementation of NAVAL software has been done with respect to an Italian alpine valley in cooperation with the local Mountain Community which is in charge of operational avalanche risk management. KEYWORDS: risk management, avalanche risk scenarios, computer-based tool, google earthTM 1 INTRODUCTION 2 SOFTWARE DESCRIPTION Mayor alpine valleys usually encompass a NAVAL software has been released for Win- wide variety of avalanche problems, including dows operating system platforms: it can be in- avalanches of different frequency, size, release stalled on Windows XP, Windows Vista, Win- zone altitude and exposure. It is also the case dows 7 (32 and 64 bit). that many different types of exposed elements might be affected, such as villages, hamlets and 2.1 How program is built isolated houses, roads, railways and power NAVAL interface comes on a very simple lines. As a result, potential risk scenarios result- structure and a straightforward user interface ing from specific hazard conditions might be ex- (Figure 1). tremely differentiated and their definition over The main viewport is the two-dimensional traditional maps could be a troublesome chal- planimetric map built on three different layers. A lenge. set of keyboard commands allows the user to NAVAL is a computer-based program spe- dynamically scroll through the map of the project cifically designed for the definition and visualisa- area. Meanwhile, selection and information but- tion of potential avalanche risk scenarios. The tons allow the user to investigate each carto- software is especially suited for most complex graphic data. and challenging situations, where it could repre- sent an useful support to consultants and decision makers in avalanche risk analysis and management. A brief description of the software is given (§ 2) with respect to its first practical implementation (§ 3). ______________________ * Corresponding author address: Massimiliano Barbolini, FLOW-ING s.r.l. La Spezia, ITALY tel: +39 (0)187 500158; fax: +39 (0)187 529777; Figure 1. Screenshot of main NAVAL user inter- email: [email protected] face. 278 International Snow Science Workshop Grenoble – Chamonix Mont-Blanc - 2013 In the avalanche layer all the avalanches are dow (Figure 3); from this pop-up, also pictures of compiled as vector elements. The cartographical past avalanches con be visualised, when avail- layer is a raster layer made of geo-referenced able. raster maps with contour lines, road network, water network, lifeline network and buildings. The layer with aerial photography, where available, is a raster layer of ortophotos of the project area. Cartographical maps and aerial photography’s are of crucial importance to help the users analysing the interaction between avalanche events and exposed elements. The creation of an avalanche risk scenario is approached through the filters menu installed in the secondary viewport, on the right screen side (Figure 1). The geographical filter (Figure 2a) allows the Figure 3. An example of NAVAL’s avalanche user to select avalanches with regards to a spe- property pop-up window. cific region, valley or municipality, according to the enquiry needs. 2.2 How data are stored The avalanche properties filter (Figure 2b), With reference to a certain project area, ava- allows the user to narrow the avalanche selec- lanches are stored as vector data, polylines or tion with respect to the features of the expected polygons depending on the nature of carto- avalanche events. Selection is based on the graphical information available. following avalanche properties: release zone Technical attributes for a vector are stored in exposure and altitude, avalanche size and ava- a spreadsheet called “avalanche data table” lanche frequency. (available from the secondary viewport, on the Avalanches can be selected on the base of bottom-right screen side, see Figure 1). Each their potential damages attribute as well: the row in the table is an avalanche, each field re- user could in fact filter avalanches also with re- calls an avalanche property. spect to the elements at risk potentially affected Stored avalanche properties include: (roads, houses, lifelines). - geographical information (location of the avalanches, with respect to region, province, valley and municipality of belonging); - release area information (identification of the main attributes of avalanche’s release area: altitude of the highest point of release and release area exposure); - avalanche frequency (is characterised by three different options: annual, once every 1 to 3 years, on average; periodic, once every 3 to 30 years, on average; rare, events which occur with an average frequency lower than once every 30 years); - avalanche size (is characterised according to European avalanche size classification in four classes, depending on track length: (a) (b) small, medium, large and very large, see www.avalanche.org). Figure 2. NAVAL main filter menus: (a) geo- NAVAL automatically combines the cartographical filter; (b) avalanche properties filter. graphic information about avalanches with information stored in the “avalanche data table”: it The selections applied in the filter menu (by is thus possible to find records in the table by the “apply filter” button, see Figure 2) will take selecting avalanches on the map, and find ava- action in the main viewport resulting in the visu- lanches on the map by selecting records in the alization of the resulting avalanche scenario. table. On a given avalanche scenario, when any Historical records for each avalanche are avalanche vector data is selected on the plani- stored in a separate spreadsheet called “history metric map, avalanche properties and historical data table”. Each row is a past avalanche event, data will be shown on a pop-up information win- with main linked properties as follows: ID of the 279 International Snow Science Workshop Grenoble – Chamonix Mont-Blanc - 2013 avalanche, the date and time of the event, a based on an empiric relationship obtained brief description of the avalanche, including me- from statistical analysis of avalanche historic teorological condition, snow cover information, data (at present calibrated only for the test release altitude, features of deposit and ele- area, see § 3), which gives for the three fre- ments affected. Also interview with witnesses quency classes (annual, periodic, rare, see § and photos of the event are included, when 2.2) an estimate of the critical value of new available. snow for avalanche release as a function of altitude, the tool provides the user with an 2.3 How program works alert or alarm status for avalanches with a specific frequency (see Figure 4). The creation of an avalanche risk scenario with NAVAL software is the result of a progres- sive filtering procedure which reflects the choices of the user concerning current avalanche danger and more likely avalanche features. In particular, during his expert analysis the user is driven by the program through evaluation choices concerning geographical area of inter- est, expected avalanche frequency, expected starting zones altitude and exposure, expected avalanche size. In the different phases of the decision process the user is supported by built- Figure 4. Screenshot of “snow precipitation data in tools, represented by (a) external links with analyser”, customised with respect to monitoring current avalanche and meteorological bulletins stations available in Valsesia valley (see § 3). and (b) a snow precipitation data analyser (see For automatic stations also a link to web page § 2.4). with real time data is provided. As a function of user choices NAVAL acts a filter over the overall avalanche data-base in NAVAL is able to produce unlimited ava- order to visualize on different

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