Author(s): Cesar Quishpe-Vasquez; Matilde Garcia-Valdecasas Ojeda; Emilio Romero-Jimenez; Juan Jose Rosa-Canovas; Patricio Yeste-Donaire; Yolanda Castro-Diez; Maria Jesus Esteban-Parra; Sonia Raquel Gamiz-Fortis

Linked Author(s): Emilio Romero-jiménez, Juan José Rosa-Cánovas, Yolanda Castro-Díez, María Jesús Esteban-Parra, Sonia Raquel Gámiz-Fortis

Keywords: Seasonal predictability; Streamflow; Ecuador; SST; Tropical Pacific

Abstract: Seasonal variability of streamflow plays an important role in the development and management of the water resources of most of the world regions. Particularly, the South American continent is currently showing increased water stress. Additionally, it is well known that sea surface temperature (SST), particularly in the tropical Pacific region, it is one of the most convenient variables to be used as a predictor for the climate of Ecuador. Its location on the equatorial coast of the eastern Pacific, places it directly in the center of the area where El Niño phenomenon presents the most pronounced intensity. In this sense, in recent years numerously efforts have been initiated in the country to determine the influence of ENSO on the behavior of hydrometeorological variables, such as precipitation, temperature and streamflow in Ecuador. The main goal of this work is to explore the feasibility of the seasonal prediction for the Ecuadorian streamflows and the development of prediction models for them. For this end, the role of the tropical Pacific SST, taking into account the different ENSO patterns, has been investigated using the singular value decomposition (SVD) method. SVD is a multivariate technique that identifies coupled modes of variability between the anomalies of the SST and the streamflows. For forecasting purposes, seasonal delays (from 1 to 4 seasons) between the fields were stablished (SVD_Lag), and the leave one out cross-validation scheme was applied. Results show that the two main variability modes of the tropical Pacific SST, associated with the canonical and Modoki El Niño, can be used for the prediction of the February-March-April (FMA) and June-July-August (JJA) streamflows with up to three lag seasons. For the streamflow in FMA, it is found that the mode associated with El Niño Modoki is the one that presents the greatest contribution compared to the mode associated with El Niño canonical and this skill extends up to one year in advance. Finally, the experiment of combining both modes (canonical and Modoki) allows predicting the streamflow of FMA with one year of anticipation in localities placed mainly in the Andes region, while the streamflow of JJA can be predicted up to three seasons in advance in localities sited in the coastal region of Ecuador. ACKNOWLEDGEMENTS: This research has been carried out in the framework of the projects B-RNM-336-UGR18, funded by FEDER / Junta de Andalucía - Ministry of Economy and Knowledge, and the project CGL2017-89836-R, funded by the Spanish Ministry of Economy and Competitiveness with additional FEDER funds.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022856

Year: 2022