Mapping Disaster Prone Areas

Mapping Disaster Prone Areas

A map is a means of representing the physical features of the earth’s surface in the form of two-dimensional image with a scale and projection system.

The human race has been making maps since the Stone Age. For example, an inscription of a map dating back to 6200 BC is on the cave wall of Catalhuyuk, an archeological site in southern Turkey.

As Yeyep Yousman points out in his book Sistem Informasi Geografis dengan MapInfo Profesional (2004), mapping is a process that involves the collection, processing and presentation of data.

Not Just an Image

A map has several functions, such as showing a location’s position in relation to other places, showing the form or measurement of physical features of the earth’s suface, showing the orientation and distance of a location, and presenting other data about the surface of the earth. A map is said to be good or ideal if its depictions of the earth’s surface. These include the distances between certain points, the area of the places depicted, delineation changes and direction routes, as well as the depiction of other physical features. Size and distance must be in accordance with the facts by using a scale as a means of comparison.

A map must also include a little, compass points to show direction, a comparison of actual measurement (the scale), legend information, the date of production, and the name of the person or the organization that made the map.

The purpose of scale is so the reader could calculate the actual distance between places on the map as they are on the earth’s surface. For example, a scale of 1:24,000 means that 1 centimetre on the map represents 24,000 centimetres (240 metres) on the surface of the earth.

There are two main types of maps. First, a topographical map, which shows the elevation of an area, with differences in elevation being represented by contour lines. Second, a topological map, which is the more common type of map, such as those in atlases used in high schools and elemtary schools.

Utilising GPS in Disaster Preparedness

The Global Positioning System (GPS) is a system of determining geographical positions by using satellite navigation technology. The full terminology for GPS is NAVSTAR GPS (Navigation Satellite Timing and Ranging Global Positioning System). This system was first used in military circles to determine geographical position and direction.

GPS takes information from satellites to provide an image of a geographical position. since the implementation of the CBDP programme in Indonesia, PMI (Indonesian Red Cross) has used GPS to conduct mapping of areas that are at risk of disasters. GPS is specifically designed to provide positining information that is accurate in three dimensions and up to date across all parts of the world. Its capacity is not affected by time or the weather. Hence a GPS unit can still receive information from satellites at night and during heavy rainfall.

By making use of GPS, PMI and local communities have carried out risk mapping in village prone to disasters. The mapping provides village residents with important information, such as which areas will suffer long-term impacts when a disaster strikes, so precise and swift action can be taken in managing the disaster.

Because GPS provides three-dimensional data, results of the risk mapping can be used as straightforward input material for all realted sides, including the government. Furthermore, a risk map can also be used to estimate the impact of future disasters. The utilisation of GPS as a form of equipment in disaster preparedness is still regarded as a relatively new process in PMI, having first been officialy used in 2004.

In using GPS, data of the earth's surface area is provided in three-dimensons. Therefore we can know the position of an area as well as its contours (highest to lowest points). In an area prone to floods, for example, we could mark which points will not be affected by the floodwaters.

Moreover, GPS also provides many other benefits. It is quite easy to learn how to operate GPS equipment, so PMI volunteers at the village level have been able to use it after receiveing training.

Results of the CBDP programme showed that members of PMI's Disaster Response Team (Satgana) became experts in GPS use after receiving special training, while villagers working with the Sibat could carry out risk mapping using GPS.

As mentioned before, GPS can always be used, regardless of the time or weather. GPS is served by about 24 satellites located 20,000 km above the survace of the earth and moving at speeds of up to 7,000 miles per hour. This gives GPS a very wide scope of global coverage.

GPS can provide precise information on a position, to the nearest meter or even millimeter. A GPS unit is quite small and therefore easy to carry.

As a device that is linked to satellites, GPS gives the latest information about an area. So when an area hits by seriuos disaster, its exact geographical position can be determined. GPS can provide its precise latitude and longitude.

Village maps made by PMI with communities at the village or district level are really quite detailed. A village's boundaries are marked in accordance with its administrative border.

By having such detailed maps, PMI will hopefully no longer encounter difficulties when conducting of assisstance, rescues and determining safe evacuation routes.

Mapping the Village

One of the most important activities of the CBDP programme is risk mapping by the community members of a village or local district. The map will include data on the risks, vulnerabilities and capacities of the village. It is considered to be a very simple and cost effective tool to collect ground level data through a baseline survey and PRA.

Before the mapping exercise starts, the community members first discuss and record their experiences of previous disasters they have faced and disasters they may face in future. This aims to provide a pictorial base for the planning process, especially for the semi-literate populace and ensures maximum community involment across gender, age, and other social devide. It has also been found to be very effective in raising awareness among the community and thereby enhancing particiaption of villagers in problem identification.

The maps generate awareness among the community about the avenues for smooth evacuation during any imminent disaster. The strategy adopted is to use locally available resources rather tahn depending on the external agencies for assisstance and support.

The community members are encouraged to draw the maps on the ground using locally available materials such as stones, sand, and various coloured powders for different items and indicators. Village leaders and prominent figures should be consulted to ensure there is consensus on the village's borders.

The initial maps drawn need not be too detailed or precisely to scale. The three types of village mapping exercises are as follows:

Resource map: resources mapping focuses on identifying locally available assets and resources that can be utilised for building the capacities of the community during and after disaters. Resources that could be included on the map are strong buildings that are considered safe meeting points when a disaster strikes, such as house of worship, school buildings and village halls. Apart from infrastructure and funds, resources could also be individuals with specific skills, local institutions and people's knowledge, as all these have the capacity to create awareness and bring about changes in the community. A resource map is threfore not limited to depicting the available resources but also shows their distribution, access and use by taking into consideration prevailing sensitiveness within the village.

Risk and Vulnerability map: In the vulnerability map, community members have to identify the hazards that their village is prone to and the possible areas that would be affected. They also demarcate the low lying areas, areas near bodies of water such as the sea and rivers, wind direction, etc. Through this mapping exercise the community members identify the location of groups at risk and the assets that require protection from various hazards.

Safe and Alternate Route map: In a similar exercise, the villagers identify safe evacuation routes and shelter areas, plateaus, etc. It would be useful to identify alternate approach routes that could be used during times of emergency. Foreknowledge of such routes will help villagers to take swift action if they have to flee a disaster.

(This article has been publish on Siaga – disaster preparedness media – Ed.04/June/2006)