  This study presents a basin wide assessment about the spatio-temporal
variability of streamflows in Ecuador for the period 1979-2015. The influence
of the tropical Pacific sea surface temperature (SST) on stremaflow
variariability from February to April (FMA) period, as the months showing
maximum stramflow for the wet season in Ecuador, and from the June to August
(JJA), correspondign to the dry season, was analysed. First, a long-term trend
analysis was carried out by applying the Sen's slope estimator and the
Mann-Kendall test to monthly streamflow data from 45 gaging stations located in
different basins across Ecuador. While the coastal region showed the highest
generalized positive trends from July to January, the results for the Pacific
Andean area suggested a strengthening of the seasonality, presenting an overall
increase in the streamflow for all months except August, September and October,
which showed negative trends. Second, a singular-value decomposition (SVD) was
applied in order to find the main coupled variability patterns between the FMA
streamflow and the quasi-coetaneous SST (December-February, DJF) and between
the JJA streamflow and the coetaneous SST. The results revealed two main
coupled modes for DJF SST/FMA streamflow, the first associated with the
canonical El Ni\~no and the second with El Ni\~no Modoki. The latter exerted a
major influence on FMA streamflow over most of Ecuador. For JJA streamflow,
however, the pattern associated with the traditional El Ni\~no was even more
relevant. These results establish the foundations for streamflow modelling in
Ecuador based on the Pacific SST, showing the strong response of the
streamflows to different types of El Ni\~no events
