its capacity. Special maps are prepared for such occasions that are referred to as 'contraflow maps'. An example is give
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Evacuation maps 7.1 Germany – Hamburg
For the city of Hamburg, detailed information is available on the internet on the activities that are being implemented for the purpose of flood protection. Maps are available for several parts of the city on flood hazard and the evacuation routes. On Figure 7.1 a detailed map is shown of part of the city (Wilhelmsburg) with an indication of the evacuation zones corresponding to different water levels (6.5m and 7.5m), the location of evacuation locations (‘Fluchtburgen’, indicated with ‘F1….8’), emergency residences (‘Notunterkünfte’, indicated with ‘N1…4’) and busstops (‘H’) from where evacuation busses will depart. The maps are accompanied by an extensive description of the expected situation in case of flooding and detailed advice to the general public how to act in such circumstances. This is a good example of a well-planned information package for urban population in a very large city. The information is well-presented and easily accessible, although the files themselves may prove large for slow-speed internet connections.
Figure 7.1 Part of the map with flood protection and evacuation zones of the city of Hamburg with (German) legend
53 http://fhh.hamburg.de/stadt/Aktuell/behoerden/stadtentwicklung-umwelt/bauen-wohnen/hochwasserschutz/start.html 54 http://fhh.hamburg.de/stadt/Aktuell/behoerden/inneres/katastrophenschutz/service/merkblaetter/start.html
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7.2 Japan In Japan municipalities are obliged to inform their inhabitants on the flood risk conform the Flood Fighting Act, established in 2001. Since 2005 the municipalities are also obliged to take a pro-active attitude by distributing flood risk and inundation maps freely among the inhabitants in order to increase the flood-preparedness and, as a secondary goal, to contribute to the spatial planning within the municipality. The flood maps are prepared in two steps: 1. the Ministery of Land, Infrastructure and Transport and the prefecture (for resp. nationwide and regionally adminstred river basins) determine the flood-prone areas; 2. the municipalities produce the Flood Hazard Maps. The flood maps are produced following a nationwide standard that is determined by the Ministry, which e.g. establishes the inundation depth classes (0 – 50, 50 – 100, 100 – 200, 200 – 500 & > 500 cm) and the corresponding colour codes. The choice of those depth classes is based on ‘human characteristics’: • 0 – 50 cm: most houses will stay dry and it is still possible to walk through the water; • 50 – 100 cm: there will be at least 50 cm of water on the ground floor and electricity will have failed by now; • 100 – 200 cm: the ground floor of the houses will be flooded and the inhabitants have either to move to the first floor or evacuate; • 200 – 500 cm: both the first floor and often also the roof will be covered by water. Consequently evacuation is the logic choice of action now. The same applies, evidently, for the depth class > 500 cm. Similar to the situation in e.g. the Netherlands, the flood inundation maps are based on hydrodynamic calculations for several scenarios of possible locations of dike failure. The final map is based on the scenario that would cause the maximum number of victims, i.e. a worst case approach. The return period of the flood that is shown on the maps depends on the region as a function of potential damage. Once such maps have been made on municipal level, the municipality adds local information that is relevant for evacuation, such as the location of shelters, important buildings, evacuation routes, etc., as well as information on the items that should be taken along during an evacuation. On some maps space is left for the user to draw a personal evacuation route map based on the particular situation of the person or family. All the maps are distributed free of charge to the public on scales of 1:5.000 to 1:10.000, and in some cases they can be downloaded from the internet. It is the task of the municipality to keep the maps up to date. Examples of flood maps that are available to the public are shown in Figure 7.2 for the city of Toshima, using the depth inundation classes mentioned above. As in most cases the legend is only given in Japanese, although in some cases an English legend is provided. Further information on the preparation of the map is given on the internet55. On this site all relevant information is given necessary for evacuation in case of flooding, including the addresses of the shelters. Other examples are shown in Figure 7.3 and Figure 7.4. Especially the latter gives indications of shelters, temporary shelters (which probably have fewer resources for a long duration stay), boundaries of evacuation areas, the location of flood warning speakers and, contrary to general custom, an indication of roads that should NOT be used for evacuation. The map also provides expected flood depths, although no indication is given to which return period this applies, and the limits of a recent historical flood. Although this map has some interesting features that are hardly ever found in other evacuation-type maps (like the earlier mentioned location of ‘flood warning speakers’), the topographical layout on the scale presented is not sufficiently clear to be used in practical situations. It may be used, though, for preparation purposes as a training for flood situations. Further information can be found on the internet56.
55 http://www.city.toshima.tokyo.jp/english/bousai/hazardmap/index.html 56 http://www.icharm.pwri.go.jp/html/docu/jan_20_22_2004_ws/pdf_output/hiroki.pdf
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Figure 7.2
Part of flood depth map for the city of Toshima in Japan
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Figure 7.3
Evacuation map for the Japanese city of Sukagawa
Figure 7.4
Example of a flood hazard map with indications of evacuation roads
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7.3 Netherlands An example of an evacuation map in the Netherlands is shown in Figure 7.5 for polders along the Rhine river near Germany. This maps shows clearly the mandatory evacuation routes, including indication of one-way converted roads, closed entrances and exits, and are a easy to interpret by the general public. In Figure 7.6 the simulation of the expected flood extension for the region of “Land van Maas en Waal” (see also Chapter 4.14) is translated into a decision-support map that shows the areas that will either remain dry, reach a water level that leaves the first flood of dwellings dry and those areas that will reach such water depths that evacuation will be required. In order to take decisions on the best evacuation routes, a map is produced that shows the time of arrival of the inundation front with a depth of 50 cm at the various types of infrastructure (especially roads, see Figure 7.7). Depending on the decision up till which depth roads or other escape routes are still safe to use, maps with the arrival time of dfferent inundation depths can be produced.
Figure 7.5
Example of an evacuation map for the Netherlands with indication of obstructions and lane direction and closed entrances and exits
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Figure 7.6
Basis for decision making on evacuation (expected inundation depth)
Figure 7.7
Time of arrival of the inundation front of 50 cm depth at infrastructure (roads/elevated areas)
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7.4 USA 7.4.1
Mississippi
Similar to the comments made on insurance maps, there are a number of very interesting examples of evacuation maps that can be used as examples for the development of evacuation maps in Europe. In the USA the evacuation routes are published both by state and central on a clickable map of the entire country57. In the maps from the USA reference is often made to the ‘contraflow’ principle, i.e. the reversing of the normal traffic flow direction to change an ordinary two-direction road into a one-direction (evacuation) road to increase its capacity. Special maps are prepared for such occasions that are referred to as ‘contraflow maps’. An example is given in Figure 7.8 for a part of the State of Mississippi58 and a detailed map of a road crossing prepared by the Mississippi Department of Transport is shown in Figure 7.959.
Figure 7.8
Hurricane evacuation routes in Mississippi state with indication of ‘contraflow’ roads
57 http://www.ibiblio.org/rcip/evacuationroutes.html#sbs 58 http://www.gomdot.com/cetrp/hurricane_evac_routes.pdf 59 http://www.gomdot.com/cetrp/hurricane_evac_routes.pdf
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Figure 7.9
Example of detailed maps prepared for road crossings in case of ‘contraflow’ situations
7.4.2
Florida
The State of Florida produces a number of very clear and attractive evacuation maps. An example is shown in Figure 7.10. This evacuation map is accompanied by a text with an indication of the ‘best’ evacuation route for each of the villages in the region. The colours refer to expected hurricane / storm surge force (category 1 – 5)
Figure 7.10
Evacuation map for a part of Florida60
60 http://www.firstcoastnews.com/weather/stormtrack/evacuation_map.aspx
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7.4.3
Louisiana – New Orleans
Evidently after the impact of the hurricane Katrina, New Orleans has become a focus of attention in terms of flood prevention. Detailed evacuation maps are available for the all of the state of Louisiana (see e.g. Figure 7.11)61, with for each road crossing a special map that indicates the contraflow plan and detailed instructions for the evacuation by car (Figure 7.12).
Figure 7.11
Part of an evacuation map for Southwest Louisiana
61 http://www.dotd.state.la.us/maps/
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Figure 7.12
Detail of contraflow at a road crossing (reference to map on Figure 7.11) and detailed instructions
Another example of an evacuation map for the city of New Orleans, including a phased evacuation plan, is given in Figure 7.13. Very detailed instructions are available in case of a hurricane threat, with emergency shelter information points, agency contact information, radio frequencies, a guide on how to make a ‘family communication plan’ and even a chapter on ‘preparing your pets’.
Figure 7.13
Part of evacuation map of area of New Orleans with phased evacuation plan
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7.4.4
California – Sacramento
A very interesting example of a combination of a flood depth map and a combined rescue / evacuation map is available for the County of Sacramento in California, including the city of Sacramento itself. Various detailed maps showing hypothetical levee breaks, inundation levels and the time it would take for waters to rise in affected neighbourhoods, and rescue and evacuation zones have been made available on the internet62. For a specific failure location two types of maps can be downloaded: • Flood Depth Maps: show where the water would flow over time and how deep it would get given the hypothetical flooding scenario. • Rescue and Evacuation Route Maps: show rescue areas, evacuation areas, and potential evacuation routes. − Rescue areas, in red, indicate places where water has the potential to reach a depth of at least one foot after two hours from the time of a levee failure. People would not be able to drive out and likely would be stranded and require rescue. − Evacuation areas, in yellow, indicate places, depending on where the levee breech occurs, that could fill from 1 to 26 feet of water within 10 days, giving most people time to get out safely. Flood depth details are specified on each map. − This map also portrays potential evacuation routes (in green) and which evacuation routes would become inundated over time. A total of 18 sets of maps are available. Examples of both types of maps, with the corresponding legends, for the American – River Arden region, are shown in Figure 7.14 and Figure 7.15. Detailed maps are also available for some of the other States in the USA, especially New Jersey63 and South Caroline64, but provide no extra information compared to the maps already shown in this Chapter.
62 http://www.msa.saccounty.net/waterresources/floodready/?page=maps 63 http://www.nj.gov/njoem/plan/evacuation-routes.html 64 http://www.dot.state.sc.us/getting/evacuation.shtml
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Figure 7.14
Flood depth map of the county of Sacramento, with indication of location of hypothetical levee failure and inundation process in time
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Figure 7.15
Rescue and evacuation route map of the county of Sacramento, with indication of location of hypothetical levee failure and passable routes in time
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