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 early warning systems:
A strategy for the local management of disaster reduction
in Central America
Juan Carlos Villagrán De León, Ph.D., Director, Department of Applied Physics FISICC, Francisco Marroquín University, Scientific Advisor, National Coordination Office for Disaster Reduction (CONRED),

A volunteer observes the rain
accumulated in a pluviometer.

In recent years, Central America’s government agencies in charge of civil defense have started to engage in a transition from disaster response approach towards a new concept of risk reduction.

This transition was first made possible by the passing of laws broadening the mandate of these agencies to include not just emergency management but also disaster preparedness and risk migation. However, this has led to discussions about which would be the best strategies, institutional coordination and participation mechanisms, and conceptual models of risk reduction and management.

One strategy that has been accepted and adopted by several Central American countries to consolidate this transition is the implementation of early warning systems. The purpose of early warning systems is to warn the population about a natural phenomenon of such severity that it might cause death, injury or damage to property, housing, or infrastructure. These systems are a key component of disaster preparedness, and therefore of risk management.

All early warning systems must satisfy the operational criterion of warning the population sufficiently ahead of time to let people take at least minimum precautions. They include three components: monitoring the natural conditions related to the hazard in question, forecasting events, and warning the population. The operational integration of these components, in the case of floods, is outlined in fig. 1 below.

Monitoring is carried out in two ways. The more sophisticated approach uses automatic measuring equipment connected to a telemetric radio communications device. Local conditions are measured in real time and transmitted automatically to a national observatory in order to be analyzed at any time. This approach is commonly used in Central America by national seismology and vulcanology institutes. However, the use of sophisticated equipment requires highly qualified staff, as well as substantial funds for the acquisition and operation of these systems.

An alternative and much less complicated approach involves the direct participation of community members using very simple monitoring equipment. Station operators report the information by radio to a local forecasting center where the data can be analyzed employing simple routines.

Fig. 1
Operational scheme for early warning
systems developed to detect floods.

The Central American experience with community early warning systems has basically focused on flood warnings. In 1997, I designed and supported the implementation of a flood forecasting system for the Coyolate river basin in Guatemala, a project financed by the Swedish International Development Agency (SIDA).

In Honduras, similar systems were installed in La Masica and Arizona with European Union funding and the coordination of the Organization of American States (OAS) and COPECO.

In 1999, the RELSAT project, financed by the European Union and coordinated by the regional FEMID program, established systems in every country in Central America that follow the design of the system that was implemented at the Coyolate river.

Currently, the demand for implementing community early warning systems is growing due to the need to forecast floods locally in many places. CONRED in Guatemala is implementing this type of system in four additional basins, and the Costa Rican Risk Prevention and Emergency Management Commission is preparing a national early warning project to deal with a variety of hazards. At the regional level, the success of these systems has encouraged the Central American Natural Disaster Prevention Center (CEPREDENAC) to incorporate the issue as one of the key points of its Strategic Framework for Vulnerability and Disaster Reduction in Central America.

The advantages of using community early warning systems include the following:

  • These systems help national civil defense authorities to raise the awareness of rural communities concerning the need to launch local risk reduction activities.
  • They establish a radio communications network that allows community members to exchange social or legal information, in addition to the data on natural hazards.
  • They have very low operational costs, since the monitoring equipment is very simple and volunteers operate the system. Recent emergencies such as Hurricane Mitch showed that volunteers are ready to operate such systems around the clock to reduce the risk of a natural disaster.
A member of the local emergency committee directing an emergency simulation in Guatemala.

Community early warning systems must be designed on the basis of the conditions in which they will typically operate. Factors to bear in mind when implementing such systems in rural communities include the following:

  • The capacity of the population to operate and maintain the equipment.
  • The economic capacity of the community to acquire spare parts and other items needed to keep the equipment in operation.
  • The will of the population to operate the system.

In this sense, the equipment may be accepted or rejected based on how complex it is to operate. With this in mind, a basic infrastructure for community early warning systems for flood mitigation has been designed to meet the following requirements:

  • Low cost and local or regional availability.
  • Simplicity of use.
  • Modular integration to facilitate maintenance.

Cost and availability are essential if the system is to be maintained economically by the community with the technical advice of a national entity. Simplicity ensures that any member of the community can use the system, a key consideration in the event of an emergency.

Forecasting center in Zacatecoluca, El Salvador, part of the RELSAT project. On the wall, to the right, a simple meteorological station..

Flood forecasting requires a hydrological assessment of the basin, as well as an analysis of historical data related to meteorological conditions. The analysis makes it possible to define which months are more hazardous, how many floods can be expected on average each year, and the effect of non-cyclical phenomena such as hurricanes on coastal areas.

The hydrological analysis of the basin helps to choose the best sites to place sensors, particularly in terms of their vertical placement, which helps to determine critical levels that will lead to a flood downstream. Finally, the integration of hydrometeorological data and local experience is valuable in determining how the warning system should be designed so that it can be operated by community members.

Typical forecasting procedures begin with the information provided by a simple electronic meteorological station. The station can forecast rain and takes into account changes in atmospheric pressure, temperature and wind strength. When risk levels increase, observers in the higher reaches of the basin are asked to measure rainfall and report the results every hour to the forecasting center. Once rainfall exceeds a critical level in the space of one to three hours, the level of the river and its tributaries is measured. Since rainfall is measured consistently, a rise in the river level helps to confirm the geographic extension and the magnitude of the precipitation. When the river surpasses its critical flooding level, the forecasting center notifies the local emergency committee, which issues a public warning and activates its emergency plan.

In the case of floods in coastal areas, where the tides are a key factor, forecasts are based on data concerning both the expected tide levels and the volume of precipitation. INETER in Nicaragua and other oceanographic centers publish tide tables for each quarter, or the entire year, that can easily be checked by date. In the case of ports, the hydrological analysis is limited to the assessment of sewers and their ability to handle rainwater both at high tide and low tide.

The Local Emergency Committee

Equipment designed by the author to measure river levels. It includes a sensor with electrodes (the long tube), an interconnection cable, and an electronic measuring device. The sensor, placed on the riverbanks, sends the information to the house of the operator through a cable. In this way, the operator can measure and report the river level at any time and in all kinds of weather without having to leave his or her home.

As part of the early warning system, one or more local or community emergency committees must be appointed to carry out the various activities outlined in the local emergency plan. These activities include the following:

  • Issuing public warnings.
  • Carrying out search and rescue operations.
  • Providing first aid.
  • Establishing and managing shelters
  • Coordinating the various institutions involved in the crisis.

Generally, civil protection institutions establish these committees and train them for the activities they must carry out in their communities, including the following:

  • Disseminating information throughout the community about existing hazards and disaster preparedness and mitigation.
  • Engaging in risk mapping.
  • Developing emergency plans.
  • Defining and properly identifying evacuation routes.
  • Carrying out drills and simulations.


Community early warning systems are operational structures that enable the population to adopt measures to minimize the impact of natural disasters. In Central America, these systems are helping civil protection organizations to move away from the old-fashioned emergency response paradigm towards local risk reduction and preparedness. Implementing community early warning systems serves as an alternative to the use of expensive centralized telemetric systems, and encourage communities to play a much more active role in their own protection.

For more information, please contact:
Dr. Juan Carlos Villagrán De León
7ª Avenida Final Zona 10, Guatemala, Guatemala, C. P. 01010
Tel (502) 331-4948, Fax (502) 331-1645