Colombia: Floods related to La Niña - Operation Update no. 1, DREF Operation n° MDRCO018


A. Situation analysis

Description of the disaster

The Colombia Red Cross Society (CRCS) created an Emergency Plan of Action to prepare and respond to the likely effects of the 2021 La Niña phenomenon in Colombia. As a preventive activation plan, it entails actions that the National Society conducts before a potential emergency related to the La Niña phenomena during the 2021 rainy season. The CRCS will be ready to respond when the likely emergency event occurs.

Forecast-based trigger mechanism

The National Society will do conduct a staggering trigger mechanism that is forecast-based. The first trigger was met with the January 2021 IDEAM forecast (monthly bulletin no. 11) that indicated a 60 per-cent probability of rainfall above average values in the Caribbean and Andean regions. The second trigger would be the UNGRD and the IDEAM issuing a red flood risk alert for flooding in La Guajira, Magdalena and/or Norte de Santander departments.
This second trigger initiates the early response activities.

La Niña is a phenomenon composed of positive weather anomalies in some places and negative weather anomalies in others. In Colombia, the positive anomalies usually manifest as an increase in rainfall in the Andean, Caribbean, and Pacific regions, as well as the Plain Foothills of the Eastern Plains, while the negative anomalies present by a decrease in the sea surface temperatures in the eastern areas of the Orinoquía and Amazonia. The latest forecasts for 2021 made by the World Meteorological Organization (WMO)regarding rainfall behaviour in Colombia during the first quarter, indicated a 65 per cent probability that La Niña conditions would continue from February to April 2021, and a 57 per cent probability that conditions will worsen due to increased precipitation throughout the first half of 2021. This increase in rainfall and its impact on the rise in emergencies is beginning to be seen in various departments. In the Pacific Region, specifically, the departments of Nariño, Cauca, Valle del Cauca, and Chocó, the significant increase in rainfall seen from the last week of February to the second week of March has led to several declarations of public calamity. Almost 80 per cent of Valle del Cauca department has been affected by higher-than-historical-average rains. In Antioquia, three heavy rainfall events have caused landslides with damaged roads, bridges, and aqueducts.

The IDEAM models for March and April coincide with international forecasts predicting higher-than-average precipitation levels in the western Caribbean region, some areas in the central Andean region, and the central-western Eastern Plains by 10 40 per cent. In the longer term, rainfall above average by 10 to 20 per cent is forecast for May in most of the country.

Projections suggest that the first rainy season in Colombia will likely affect many people in April and May. During this period, population centres in La Guajira, Magdalena, Norte de Santander departments, and many others across the country are affected by increases in rainfall, mainly because they are located in areas at risk of flooding or landslides.
There is a risk that homes will be destroyed, which generates the need for sites to accommodate or shelter people, and that people's ability to move will be restricted because of the damage to highways, bridges, and roads. Flooding directly affects food security, as it affects the crops that provide food to the areas affected and reduces food availability both in markets and for households. The floods also disrupt work activities in communities within affected areas, cutting off families' income. Communities are exposed to hazards associated with decreased access to safe water, which can cause illnesses and an increase in insects that are vectors for disease.