The Rain Anomaly Index (RAI) and the Wavelet Analysis (WA) were used to study the rainfall variability in different regions of the Mundaú river basin. ANA (Water National Agency) monthly rainfall data over the basin (States of Alagoas and Pernambuco) for the period 1955 to 1991 were used. The analysis were performed for three regions of this basin: High Mundaú (HM), Medium Mundaú (MM) and Low Mundaú (LM). Analyses of the RAI annual series show distinct temporal variations among these regions, except for the predominance of dry years during the beginning of the analysis period. Therefore, in some years the large scale phenomena might have the same effect on the three regions of the Mundaú basin, and have not on another. For WA and for each region a precipitation index calculated as the average of the normalized anomaly series of the stations was used. The results showed that the rainfall variability is defined by temporal multi-scales localized in certain time intervals. However, the ENSO related interannual variability and the decadal variability influenced the local rainfall variability. From these results, it is aimed that the Mundaú river basin would have more information for the management of its water resources and climate monitoring.
Wavelet Analysis; Pacific Decadal Oscillation; ENSO; Rainfall Anomaly Index
