Community Based Flood Early Warning Systems


How does it work?

Early warning systems are an important component of disaster risk management strategies, which assess flood risk and provide warnings when a flood is imminent or already occurring. For this, the system monitors the river water level and conveys this information to downstream communities through a transmission system. The CBFEWS instrument co-developed and implemented by ICIMOD consists of three units: a data acquisition unit at the riverbank upstream, a data upload unit at a caretaker’s house upstream at a safe distance from the river, and a GSM alarm unit downstream for the vulnerable communities.
installed CBFEWS sites in the HKH

Information flow

Disseminating and communicating risk information to the concerned communities and authorities is an integral part of the CBFEWS. When the flood signal is detected upstream, it needs to be disseminated instantly so that people can prepare and respond to it. Warning information must be clear and brief. The major components of information dissemination are presented below.

Source of early warning

Early warning information comes from individuals or organizations that generate a risk message and send it to the concerned authorities and vulnerable communities. The caretaker is the main source of information. The information generated by the instrument must be verified by the caretaker to generate correct flood early warning information. Every bit of information delivered from the source needs to be reliable, timely, and consistent. The source person needs to correctly type out the trigger message for the alarm units. Furthermore, the caretaker should formulate a clear and standardized warning message so that the intended recipients can fully understand the message and act accordingly.

Recipients of early warning

Warning recipients are nodal persons downstream who are part of the communication network. These nodal persons receive the warning message from different channels (e.g. directly from the source, such as a caretaker or other concerned authorities) and instantly communicate it to at-risk households. There may be various levels of recipients depending on the distance of the vulnerable settlement along the river and the urgency of delivering the information.

Early warning message

The warning message from the source to the intended recipients could be textual (SMS), verbal/audio (siren, telephone, megaphone), or visual (flag, sign). Warning messages should be concise, understandable, consistent, and tailored to the specific needs of the intended recipients. Our CBFEWS has three warning levels that can be interpreted in the following manner:

Warning Level Colour code Siren signal Interpretation Action
Level 1 Blue No siren Normal water levels Stay alert and on standby
Level 2 Yellow Beeping sound Stay alert: Water level is rising Activate communication chart; alert downstream recipients to be prepared
Level 3 Red Continuous ringing Flood is coming Alert downstream recipients to evacuate
Communication channel

A communication channel is a network of people created for information dissemination. An efficient and reliable communication network is important for CBFEWS to function properly. A well-drilled communication channel, particularly between upstream (caretakers) and downstream (authorities and communities) actors, is of utmost importance for efficient and timely flow of correct information. Such a channel should be formed at the initial stages of implementing the system through stakeholders’ consultations and meetings with local government officials and influential leaders in the village.

cbfews workflow

Key actors and their roles and responsibilities

The major actors in the CBFEWS communication network are the caretaker or gauge reader; local disaster management authorities; village/panchayat heads and influential leaders; scientific or relief organizations; the media; and vulnerable communities. Each and every actor should have predefined roles and responsibilities that they should perform before, during, and after the disaster. The major actors and their roles and responsibilities are listed below.

  • Maintain (check, clean, troubleshoot) and monitor flood early warning instruments
  • Monitor flood levels, keep records of flood events, and disseminate flood warnings to the concerned authorities and people
  • Regularly report on the status of the instruments to the concerned authorities and communities
Local disaster management authorities
  • Monitor and cross-check the situation and circulate information to the concerned organizations and downstream focal persons
  • Deploy flood response or rescue teams such as the army, police, and civil authorities to the affected areas
  • Circulate information to different media organizations
Focal person (recipient of information) in downstream vulnerable villages
  • Receive flood warning and communicate it to communities
  • Make sure that each and every member of the community receives the warning information
  • Coordinate and disseminate information to different people who are responsible for different tasks (early warning, rescue, first aid).
Local media
  • Alert at-risk communities by broadcasting or publishing flood warning and information
  • Inform the community about ongoing relief and response activities
  • Coordinate with relief organizations
Flood risk management committee

In the absence of a community group that can deal with flood risks, a flood risk management committee can be formed through common consensus. Such a committee can enhance local capacity to withstand flood impacts in an organized way. Flood risk management committees can not only unite the whole community and strengthen their capacity but also provide authority and leadership for dealing with local flood-related issues. The committee can have several sub-committees such as an early warning, communication, and information group; first aid and heath group; evacuation and rescue group; and shelter management and logistics group. The major roles and responsibilities of a flood risk management committee are as follows:

  • Plan, implement, and monitor flood-related issues
  • Coordinate and establish a network with external agencies and stakeholders
  • Coordinate with upstream communities
  • Coordinate with local people and assign them different responsibilities
  • Prepare a flood preparedness plan
Other actors

The private sector, Red Cross Society, police, army, influential leaders, and local teachers are other actors involved in disseminating the early warning.

What next for CBFEWS?

The system still needs to be further customized at the local level and outscaled to many more flood-vulnerable rivers and tributaries. ICIMOD’s work with communities has focused on ensuring continued operation, system maintenance, and community buy-in. Ensuring long-term operation requires financial sustainability, annual maintenance, compensation for caretakers, regular stakeholder meetings, and strong upstream–downstream collaboration.

Promoting ownership of the system among nodal agencies could enhance sustainability and facilitate the system’s full ownership by communities. For this, CBFEWS needs to be included in annual disaster management strategies and upscaled in all flood-prone areas. A network of these instruments would further improve the flood preparedness of communities. The private sector can also contribute to enhancing the technology and improving the instrument’s accessibility.



For more details on CBFEWS

Community Based Flood Early Warning System Resource Manual : Revised Edition for Telemetry Based Instrumentation

The Hindu Kush Himalayas (HKH) make up one of the most dynamic and complex mountain systems in the world. The region is known to be extremely fragile and prone to natural hazards, which are exacerbated by climate change.

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