The region is under constant threat from El Niño and La Niña (ENSO) phenomena, affecting water availability, causing heavy rains, flooding and damage to agricultural infrastructure and housing. The objective of the study is to determine the frequencies of hydrological events (flow), using the Fourier and Wavelet method to understand river dynamics. For this research project, hydrological data (flow) information was collected from the INAMHI platform for the period (1991–2013). The discrete Fourier transform was performed, which transforms from the time domain to the frequency domain, identifying more precisely the dominant frequencies of the signals for stations H166, H167 and H188. It was found enough similarity in exactly two peaks. The first and most pronounced peak starts at frequency 11 to 11.5 (events/12 years) and the second peak starts at frequency 22.6 to 23.0 (events/12 years) approximately, the higher the peak, the stronger the frequency component. The most representative results were the significance curve for the period of 1 year indicating 1 (event/year) which means annual return of rainfall and high flows and the period of 0.5 years or half a year indicating 2 (events/year) representing the existence of seasonal heavy rains and dry seasons. The combination of both methods provides a more complete view of the temporal evolution of climatic events and their relationship with the frequencies observed in the hydrological station data in the Toachi river basin.