Project planners and managers need to understand the hazards in the places where they work. Development and disaster workers do not need to be hazards specialists themselves, but they ought to understand hazards’ main features, seeking help from experts where necessary. General information on different types of hazard is available in textbooks and manuals, but in field projects and programmes more location-specific data are needed. Hazards should also be seen in a broader context, as part of eco-systems and the environment in general.
Specialised scientific hazards research tends to focus on single hazards. However, operational agencies need to take a broader approach, for two main reasons. First, vulnerable communities often face multiple hazards. Second, one type of hazard event may set off others: for example, heavy rainfall may trigger landslides; earthquakes can rupture gas pipes, causing fires. These are called secondary or cascading hazard events.
To identify past, present and potential hazard events and estimate their impacts, planners need information on their characteristics, causes, location, frequency, magnitude and severity, and the damage they might cause to property, communities and the environment. They also need to be aware of hazards outside the project area that might affect it (e.g. by cutting off transport links or power supplies), and how hazards occur through natural physical processes and human activities (e.g. deforestation causing slope instability or rapid water run-off).
Hazard exposure and intensity will change over time. Planners should understand historical trends and probable future changes, as well as current situations. This is particularly relevant to climate change (see Chapter 1), which may have a significant effect on the frequency and intensity of some natural hazard events. Data collection and analysis should begin early in the project cycle and continue throughout, generating more detailed information in the process. Significant hazard threats should be identified at the earliest possible stage in order to set priorities. Hazard assessments must not stand alone but should be integrated into the overall planning process. The amount of information needed and its format will vary according to the type of hazard and project, the stage of the planning process and the accessibility and relevance of hazards data. Project planners want information that is accurate, reliable and intelligible, but must also be realistic about the time and resources needed to collect and analyse data, and the types and quantities of information required.
Hazards data are largely quantitative or spatial and can take many forms, such as geological hazard maps showing fault lines or unstable slopes liable to cause landslides; hydrological maps of flood-prone areas; wind, rainfall and sea-surface temperature data; recordings of seismic activity from monitoring stations; and local rainfall and flood level records. A high level of accuracy and detail can be obtained visually (for example in geological mapping and satellite images) and prediction (for instance modelling rainfall run-off, the movement of floodwaters and flood inundation areas). Maps are widely used in hazard identification and assessment. They can provide accurate records of the location, probable severity and occurrence of hazards, and display this information clearly. They can be at any scale or level, making them useful for national or local disaster planning. They can be technologically sophisticated (e.g. geographical information systems: see Chapter 8) or created by community participation using whatever local materials are to hand (see Chapter 6). Maps can also be useful for communicating hazards information to decision-makers and communities at risk, but they often need interpreting for non-specialists, who may not be used to seeing information presented in this form, and for educated users who may be unfamiliar with the particular formats and symbols used (see Chapter 10).
Project planners will usually need to collect different kinds of information to build up a comprehensive picture of the relevant hazards and their impacts. Hazards information can be found in many places and obtained in many ways. The principal types of information provider are:
Much information about the location, frequency and impact of hazards can be found in sources such as historical records (oral and written), archaeological findings, professional reports and research studies, damage reports and old newspaper and magazine articles. A great deal of such information is available online and from open-access sources (this includes geospatial information such as maps and satellite images). Even a basic atlas will contain some geological and meteorological data; information on weather and rainfall is generally distributed through media channels (press, TV, radio) and online; and data from academic research are often in the public domain. That said, specialists may be needed to interpret hazards information, and it is advisable, therefore, to bring scientific specialists into the planning process at an early stage.
In some countries information may be restricted. Access to information from official sources is usually controlled by disclosure regulations. Maps are sometimes considered militarily sensitive and high-resolution maps in particular may not be publicly available. Government or industry hazard and risk maps may be considered too commercially or politically sensitive to share. Even in countries with relatively open access to information, obtaining it may require time-consuming bureaucratic procedures. Information on technological hazards is likely to be hard to find because many of the sources of such hazards are commercial industrial operations such as factories. Official enquiries or health and safety assessments may have produced relevant reports, and environmental groups may be a useful source of information. Poor countries find it difficult to collect and maintain data sets because of cost and skills shortages; the provision and maintenance of seismic monitoring equipment, for example, may be beyond the resources of local or national governments.
It is important to identify gaps, inconsistencies or ambiguities in the evidence, and very important to remember that all hazards assessment contains an element of uncertainty. It can be a complicated process because it combines different kinds of information. For example, in studying a landslide-affected site, scientists would want to look at past history, slope steepness, bedrock type, rainfall and vegetation patterns and land use. In other cases, there may be limitations in the current state of scientific knowledge. Forecasting of volcanic eruptions, for example, is a highly advanced science, but volcanoes are complex geophysical phenomena and difficult to understand, so that even the most sophisticated monitoring systems may not be able to predict individual eruptions precisely. Experts may also disagree over interpretations of scientific evidence, including probabilistic calculations of hazard events.
In many cases project planners will have to use incomplete or out-of-date data sets. For example, in the 1990s the Kathmandu Valley Earthquake Risk Management Project accepted at the start the need to work in conditions where data were lacking. Instead of carrying out further research, the project used previously collected geological and seismological information, matched this to the current state of infrastructure and the built environment and adapted an existing loss estimation method to the Kathmandu context.+A. M. Dixit et al., ‘Hazard Mapping and Risk Assessment: Experiences of KVERMP’, Proceedings: Regional Workshop on Best Practices in Disaster Mitigation: Lessons Learned from the Asian Urban Disaster Mitigation Program and Other Initiatives, 24–26 September 2002, Bali, Indonesia (Bangkok: Asian Disaster Preparedness Center, 2002), http://pdf.usaid.gov/pdf_docs/pnadk776.pdf.
It is not always necessary to rely on sophisticated technologies and outside specialists. Visual surveys by experienced people can identify areas at risk from landslides; simple stream gauges or flood marks can be used to monitor rising water levels and identify areas likely to be flooded; and local people’s knowledge of hazards is often more accurate and extensive than outsiders appreciate (see Chapters 6 and 7). Many community projects carry out participatory surveys such as transect walks, community mapping and seasonal calendars to supplement more formal scientific information. It is increasingly recognised that the production and sharing of hazard and risk knowledge in these contexts should be a collective effort, including people at risk, implementing agencies and scientists, although considerable effort and patience may be necessary to create working relationships and increase levels of trust.+E. Visman, Knowledge Is Power: Unlocking the Potential of Science and Technology To Enhance Community Resilience Through Knowledge Exchange, Network Paper 76 (London: ODI, 2014), http://www.odihpn.org/hpn-resources/network-papers.
Analysis of long-term trends and future uncertainty may also be required, for example in the context of climate change. Scenario planning may be helpful in understanding possible future changes, especially in the absence of predictions and reliable data; tools for carrying out participatory scenario planning with communities are available.+See for example A. Addison and M. Ibrahim, Participatory Scenario Planning for Community Resilience (Milton Keynes: World Vision UK, 2013), http://www.preventionweb.net/english/professional/publications/v.php?id=34947.