Using GIS to Map Emergency Response to Municipal Flooding

Students will gain skills in making and interpreting maps, and in analyzing what would happen on the ground based on their map interpretation and the flooding scenario presented. They should gain expertise in deciding what data is important, and what data they have to combine in order to understand effects. They should gain critical thinking skills, along with an appreciation of the complexity of decision-making in a crisis. They should recognize the town as a system in which multiple factors and multiple interests have to be taken into account. Writing and presentation assignments can be included to allow students to present their proposals for shelter siting, evacuations, and prioritization of and procedure for emergency response, thus allowing them to practice constructing logical arguments, persuasion, concise recommendations, and, of course, writing and public speaking.

This was originally an exercise used in a class for teachers. The target audience of the class was science teachers teaching at middle schools and high schools. The exercise was intended for them to modify and use it with their own students. The exercise can be changed as needed to suit the level of the class, and will take different amounts of time depending on the level of the class and the extent of the questions that students will consider. It requires the use of GIS software and the availability of relevant data layers. This is a lab activity if done individually or in small groups but can also be used as a class discussion activity if appropriate.

Students should understand the concept of a watershed and have some sense of what can happen in flooding, with perhaps a prior review of water levels and timeframe for waters to rise in a historic flood in their town. Other background information needed will depend on the extent to which the teacher wishes to take the exercise. For example, some background on the health effects of sewage contamination of water supply will be useful if that part of the exercise is included.

The premise is the assumption of continuing heavy rain and the realization that parts of the town will flood and emergency measures will be needed to make sure everyone is safe. The first question is consideration of where the flooding will occur. Once that is decided, measures taken can include:

• Blocking off certain streets and changing signs and streetlight configuration to prevent people from entering flooding areas
• Making calls to warn residents in some neighborhoods or sending emergency response personnel out to assist residents
• Mapping evacuation routes through town, and planning how to facilitate evacuation
• Planning safe (dry!) shelters for people who have to leave their homes (e.g., in public buildings and churches)
• Considering whether hospitals will remain safe and reachable, and whether additional emergency treatment may be needed in the shelters or elsewhere
• Siting centers for distributions of water, food, and perhaps clothing and other necessities for people whose homes have been flooded and planning the routes by which those centers will stocked from outside the town
• Considering how to protect historic landmarks, town records, and other artifacts that are important to preserve
• Working out what possible health hazards (e.g., contamination of water supply) could be created by floodwater impact on landfills, sewage and wastewater treatment plants, animal waste lagoons, water treatment facilities, industrial storage areas for toxic chemicals, septic systems, facilities that discharge wastewater into surface water, brownfields and other contaminated sites
• Pinpointing dams and bridges that may be at risk because of high water, and predicting effects and proposing measures if they are destroyed

The exercise requires computer mapping software and substantial data showing features and topology of the town. If the school has access to ArcGIS or ArcGIS Online, either could be used, but ArcExplorer (a free version of the geographic information system software) could also be used. The municipal data needed depend on the exact formulation of the questions asked, but at minimum a base map, a topographic layer with fairly close contour lines (e.g., 20 feet), a layer of water features (rivers, streams, springs), and a street layer are needed. Other possibilities for layers that could be useful are public buildings (including schools), bridges (if not included with roads), churches, stoplights, hospitals, historic landmarks, watershed boundaries, wetlands, open space vs. residential/business/industrial areas (zoning), sites on the toxic release inventory, transportation facilities, and features that may affect public health (see list above). Such data can be obtained if your town planning board/commission has it and is willing to release it for educational activities. If that is not the case, then a mock case can be created using more readily available base, stream, and street maps, and creating layers for the other features with as much or as little completeness and regard for reality as you like.

The length of time required for the project could vary depending on the level of the student and the extent of class discussion. For teachers in a master's program, this was handed over as a project to do in pairs outside of class, after the teachers were already familiar with the software and with the concept of a watershed. It was due in about a week, in a five-week course. For a middle school class, this exercise could take the form of a discussion extending over several sessions, during which the teacher gradually reveals additional layers as the student suggestions elicit them. Then the group can discuss what measures should be taken to account for the new features, or smaller groups/individuals can work on proposals to present to the class.

Final presentations summing up the recommendations are appropriate. Maps should be included.