Disaster risk assessment is an important part of disaster management planning. It provides the foundation and direction for the plan identifying what disaster risk reduction measures can be implemented. The South African National Land Cover dataset (https://egis.environment.gov.za/) provides a valuable resource for disaster management planning. The data can be used for many applications. Disaster risk assessment is the focus of this article where the impact of hazards or possible disastrous events is calculated by measuring the impact on land cover. The discussion below shows a few examples where land cover data can be used in disaster risk assessment.
Catchment areas for towns/cities, shopping centres/commercial activities using urban gravity models such as the Huff Model. The figure on this page is the catchment area for the Sandton City shopping centre in Johannesburg. Size of the shopping centre and distance to possible consumers were used to determine the attractiveness of the centre. The probability of consumers visiting the centre was calculated and mapped. Darker red represents a higher probability. The same methodology can be used to identify catchment areas for rural towns.
Suitable location analysis can be done for many land uses. For example, the figures on this page show suitable locations for residential development in the Sasolburg area. Multicriteria Land Suitability Evaluation, Analytical Hierarchy Process and PairWise Comparison with GIS techniques are used to identify suitable locations. The three (3) small figures show the data input for the analyses. The top one represents residential growth; the middle figure residential and vacant residential properties and the last one the proximity to schools. The dark blue areas in the bigger figure show the most suitable locations for residential development.
Flood risk mapping as part of flood risk assessment is an important part of a floodplain management system. Floodplain management A little about floodplain management. Already in 1996 Miller et al., stated that majority of damages appeared to result from unwise use of floodplain areas, it became increasingly clear that careful land use planning, in combination with engineering, architectural and hydrologic measures, could be employed to avert local flood damage. Floodplain management is defined as “… a decision-making process whose goal is to achieve appropriate use of the nation’s floodplains. Appropriate use is any activity or set of activities compatible with the risk to natural resources (natural and beneficial functions of floodplains) and human resources (life and property) …”. The basic challenge of the flood problem is the development of a set of management strategies which can permit more intensive use of floodplains and yet minimise potential damages (Milliman, 1984). Floodplain management system Floodplain Management System is a system that exists of different actions that together form a structure to manage a flood plain (“Floodplain Development Manual” which was published by the New South Wales Government in 1986 and updated in 2005). The system is shown in the following figure. Floodplain Risk Management Committee The main aim of such a committee is to assist a municipality in the development and implementation of a flood plain management plan. The floodplain management committee can be a sub-committee of the municipalities Disaster Management Advisory Forum. Flood study Flood studies define the nature and extent of possible flood events. The first action is the demarcation of the flood plain through hydrological and hydraulic studies. Demarcation of areas in the floodplain It is necessary to divide the floodplain into categories descriptive of the impact that development may have on floodwater and the impact that floodwater may have on development. This will include land use and land cover assessments. Flood plain management studies Flood plain management studies are undertaken to identify and evaluate the effectiveness of suitable measures. Measures can be classified as structural and the latter as non-structural measures. Flood risk assessment must be completed to evaluate measures. The figure below shows the results of flood damage estimation for Upington, Northern Cape. The possible damage can now be used in cost benefit analysis to determine the most appropriate measures. Flood plain management plans Before a floodplain management plan can be drawn up, it must be assured that the plan measures up to specific criteria. Objectives can include: The use of land that is prone to floods must be planned and managed in such a way that it is compatible with the calculated frequency and extent of floods. Land that is prone to floods must be managed in such a way that social, economic and ecological costs and benefits are considered. Plan Implementation A project implementation plan must be developed and executed. In South Africa this must be done through the IDP process.
Introduction An important part of disaster management is the communication of information to stakeholders. It can by disaster management practitioners and/or the public. Mechanisms to do this must keep up with the times. The question is also what format of reporting will enhance the ability to utilize data or information from disaster risk assessments? What happen to the hardcopy reports after the assessment? Does in gather dust in the cabinet? How fast can you retrieve information from the report? Can you easily link information from the report to a specific location? Can you apply your own thinking to do analysis on the data in the report? This post is about the investigation if story maps, as used in ESRI online, can be used for reporting results of disaster risk assessment. Story maps What is story maps? “Esri Story Maps let you combine authoritative maps with narrative text, images, and multimedia content. They make it easy to harness the power of maps and geography to tell your story.” https://storymaps.arcgis.com Disaster risk assessment’s story is about the description of hazards and risks and showing the possible impact areas including communities, environment and infrastructure. What better way to describe the impact by doing it with maps linked to a narrative describing the impact. This is where story maps comes in. Example The following images show screenshots of a story map. The story starts with a dashboard show some information of possible risk per ward in the Mangaung Metropolitan Municipalities area of jurisdiction. This dashboard is interactive and depends on information from risk assessments. The following tab shows the risk value per ward. The third map shows the location of possible water pollution points in the municipality. A narrative is added to describe the map which can include for example disaster risk methodology, recommendations and/or standard operational procedures.