Abstract

PIERRE, Francis  and  TIRADO, María. Influence of ENSO on precipitation in the watershed of Yacambú River and Quíbor Depression, Lara State, Venezuela. Bioagro [online]. 2007, vol.19, n.1, pp.41-52. ISSN 1316-3361.

The influence of El Niño/Southern Oscillation (ENSO) on the amount and distribution of rainfall was studied in the watershed of Yacambú River (WYR) and in the Quíbor depression (QD) (Lara State, Venezuela), one of the most important areas in vegetable production of the country. Annual and monthly rainfall data were analyzed to determine variations in the amount of rain occurred for El Niño and La Niña years in relation to the Normal years. For WYR, there was a tendency to increased rainfall during El Niño years (3.10 % overall mean), but a decrease was registered during La Niña years (11.24 %). For QD there was a tendency to decreased rainfall during El Niño (17.68 %); for La Niña, Quíbor station showed a tendency to increased rainfall, but Guadalupe station a tendency to decreased rainfall. These opposite responses were attributed to the different recording periods between both stations. For WYR differences (P≤0.05) were registered in May in Miracuy station between El Niño and Normal years, and in Caspito station between La Niña and Normal years. For QD differences (P≤0.05) were detected in September in Quíbor station between La Niña and Normal years. It seems that for WYR El Niño exerts a positive influence on the amount of rainfall, and La Niña a negative effect. For QD the influence is negative during El Niño. For La Niña years, the results did not show a clear trend.

Keywords : climatic variability; irrigation.