International Strategy for Disaster Reduction
Latin America and the Caribbean   

Newsletter ISDR Inform - Latin America and the Caribbean
Issue: 13/2006- 12/2006 - 11/2005 - 10/2005 - 9/2004 - 8/2003 - 7/2003 - 6/2002 - 5/2002 - 4/2001- 3/2001



Community-Operated Early Warning Systems
In Central America

Juan Carlos Villagran De Leon, Department Of Applied Physics, Galileo University
Guatemala City, Guatemala

Central America is a region prone to natural hazards of various kinds. Earthquakes have devastated communities and social infrastructure throughout the countries these past decades. Floods and hurricanes have taken their toll on coastal plains, and volcanic eruptions and landslides have also played a role, in more localized regions, but with lasting impacts.

As a result of the many disasters, the Central American countries have embarked on a regionally tailored plan to mitigate natural disasters, encompassing the creation of national institutions devoted to the subject, funding or co-funding projects to mitigate natural disasters, and grasping the UN Programme for natural disaster mitigation, with CEPREDENAC (Center for Natural Disaster Prevention of Central America) as the leading sub-regional institution devoted to disaster prevention.

All Central American countries now devote attention to the reduction in risks or disasters through specific institutions devoted to this task, known as National Emergency Councils, Civil Defense Agencies, or National Civil Protection Institutions. Their task is to reduce the risk via mitigation, preparation, and prevention.

Community Operated Early Warning Systems:

Considering that most disasters have impacted rural areas, where climatic and hydrological information is not yet accessible on time, simple, community-operated early warning systems for floods have been designed and implemented in various watersheds throughout Central America by scientist and students of the Applied Physics Department at Galileo University. These systems are based on these standard, but simple actions: Measure rainfall, Measure river levels, Determine if floods are possible via simple protocols and Execute emergency plans if floods are possible

These systems are set up using a standard radio network to link the various voluntary observers throughout the watershed with authorities and volunteers in the flood-prone communities. The observers located throughout the watershed measure and transmit rainfall and river level data to a local center where the data is analyzed and a forecast is made concerning probable floods. This center then transmits via the same radio network the information to the communities in the flood plains and to local authorities.

Technical Designs of the Early Warning Systems

These community-operated early warning systems have been designed with several criteria in mind:

  • Instrumentation supplied to the observers must be simple and practical, so that people with minimal education can use it effectively.
  • The instrumentation to be implemented must be replaceable on a quickly basis and at a reasonable cost, so than the system can work on a continuous basis.
  • The instrumentation to be implemented must contemplate the use of standard batteries as a main source, or at least as a back-up mechanism, as during major floods electrical power outages can be common.

Rainfall is measured with standard, plastic rain-gauges (Tru-Check brand gauges, 6 in. capacity), river level is measured via a simple, electronic instruments which display the level of the river in digital fashion (one digit from 0 – 9 indicating the various levels) with an audible alarm adapted for the case of floods occurring late at night (developed and constructed by personnel of the Applied Physics Department).

With these ideas in mind, early warning systems are implemented via a sequence of phases, which can be grouped into two components: a technical component dedicated to instrumentation and the measurement of weather conditions for the forecasting of floods, and a social component dedicated to the set up of the communal organization required to ensure that the early warning system will be operated properly. Both components can be organized in phases.

The technical component can be organized as follows:

Phase 1: research on the local historical weather conditions, to determine return periods for floods, amount of rainfall required to flood communities, and determination of river levels associated with floods at various points throughout the watershed.
Phase 2: visits to the watershed to determine optimal points to measure rainfall and river levels, which contemplate both hydrological conditions, as well as potential operators of the instruments.
Phase 3: acquisition and deployment of instrumentation in the selected sites.
Phase 4: testing and calibration of the instrumentation.

In contrast, the social component must be organized according to rules and regulations dictated by municipal authorities, as well as by national disaster reduction institutions. In general, these institutions are responsible for the safety and well being of the population, and thus, must be included in the various activities related to the early warning system. Several phases can be pointed out:

Phase 1: coordination between the national disaster reduction institution, municipal leaders and volunteers to implement the system in a coordinated fashion.
Phase 2: set-up of committees to execute the various tasks involved, such as training, community organization and emergency response.
Phase 3: implementation of workshops to train committee members on the specific instances related to the operation of the early warning system.
Phase 4: implementation of strategies to convey information to the general public in relation to the system, and to foster relations with members of the community to generate a social awareness about the early warning system and its virtues.
Phase 5: involvement of community leaders and members of the community in various committees related to emergency planning.
Phase 6: implementation of workshops to train community members in the various tasks required to complete the early warning system, such as hazard and vulnerability mapping, emergency planning and coordination, posting of evacuation routes, search and rescue activities, shelter implementation and management, crisis management, and interinstitutional coordination.
Phase 7: testing of the system via simulations and tests.

In general deputies of the national and municipal emergency committees carry out these phases, as they possess the knowledge and experience to execute the related activities. In contrast, the technical component can be implemented by technical consultants, supported by technical personnel of the national emergency committee to ensure that guidelines are being followed with respect to system operation. The various systems throughout Central America have been set up within a period of six to eight months to ensure the all phases are carried out. Additionally, the involvement of the national disaster reduction agency has been a key point to promote local sustainability.

Initial Results:

Systems of this type have been implemented in Guatemala in six watersheds, in Honduras in three watersheds, and in individual watersheds in Costa Rica, El Salvador, and Panama. Funding for these systems has been provided by ECHO (European Community Humanitarian Office), SIDA (Swedish International Development Agency), OAS (Organization of American States), and via government loans (Guatemala).

Among the various lessons to be learned from these experiences, the following deserve special consideration:

  • Community-operated early warning systems are providing information concerning river floods to local authorities and to members of the communities on a daily basis.
  • Community-operated early warning systems tailor-made taking into account social and cultural conditions of the local population have been readily accepted and operated by members of the community.
  • Community-operated early warning systems have provided communications in cases of emergencies not related to floods, because the communication network is readily accessible to the communities. In this respect, the linking with the national disaster reduction agency aids communities in solving social problems of various kinds.
  • Community-operated early warning systems are easier to set up and maintain than costly telemetric systems.


Community-operated early warning systems are offering local authorities in flood-prone communities an alternative to the national, centralized weather information systems. This alternative is fostering community involvement, and is creating an awareness about the possibility of addressing local problems with local solutions and local involvement.

The extreme simplicity of these systems makes it easy to be applied in typical watersheds of small dimensions throughout Central America (watersheds encompassing a few thousand square kilometers at most).
These systems are also providing a platform for the future implementation of prevention and mitigation measures in a process called risk-reduction management. This innovative process is being set-up within the national institutions devoted to civil defense in case of natural disasters and will soon be implemented in rural areas.

Further information can be requested at the following address:
Departemento de Física Aplicada
7ª Avenida Final, Zona 10
Guatemala City, Guatemala
Central America
Tels: (502) 331-4948, 360-3531, 360-3541, 360-3551
Fax: (502) 331-1645