Impact of the ENSO phenomenon on dissolved oxygen at two stations on the Cauca River-Colombia: 1985 to 2015.

Climate variability is one of the main challenges faced by mankind, and understanding its relationship with water quality will generate knowledge that will enable the development of early adaptation strategies and the integral management of water resources. This study assessed the impact of the different intensities of the "El Niño-Southern Oscillation" (ENSO) climate phenomenon on Dissolved Oxygen (DO) from 1985 to 2015, at two monitoring stations on Cauca River. Spatial-temporal variation analysis of DO was performed using descriptive and inferential statistical techniques under different ENSO phases. The correlation between DO and the intensities of the ENSO phases was assessed using the Spearman correlation coefficient. No statistical differences were found in DO concentration at the two studied stations (p = 0.1164). Statical differences of DO were found depending on the ENSO phases at the Mediacanoa station (p = 0.002556); it was also found that the highest median concentrations of DO took place when La Niña was present. No correlation was found at the studied stations between the intensities of the ENSO phases and DO. The water quality of the Cauca River, at the Yotoco and Mediacanoa stations, showed very poor conditions, which has produced negative social, economic and environmental effects. [ABSTRACT FROM AUTHOR]