Impact of the 2010–2011 La Niña phenomenon in Colombia, South America: The human toll of an extreme weather event

Abstract The 2010–2011 La Nina (positive phase of El Nino) phenomenon affected four million Colombians, ∼9% of the total population, and caused economic losses of approximately US $7.8 billion, related to destruction of infrastructure, flooding of agricultural lands and payment of government subsidies. We analyzed the spatial patterns of effects on the population, measured as the number of affected persons in each municipality normalized to the total municipal population for 2011, using global (Moran's I index) and local (LISA) spatial autocorrelation indicators, and multiple regression analyses (OLS and ML spatial error model). The spatial autocorrelation analysis revealed two regional clusters or “hotspots” with high autocorrelation values, in the lower Magdalena River Valley (Caribbean plains) and lower Atrato Valley (Pacific lowlands). The regression analyses emphasized the importance of the spatial component as well as the variables related to hazard exposure and social vulnerability. Municipalities in “hotspots” show: (1) a high degree of flooding, as they are located on the Magdalena and Atrato River floodplains, and (2) high social vulnerability, suggested by low values of the ICV (national living conditions index).