Low-Frequency Periodicities in Panama Rainfall Runoff

Abstract

Power spectra of daily river runoff for the Rio Chagres show strong peaks at one-year and half-year intervals, typical of tropical monsoon conditions. They do not, however, show any significant power to be associated with any of the other accepted or hypothesized periodicities, i.e., for synoptic, lunar tide, quasi-biennial or sunspot cycle scales. Daily measurements from seven watersheds, covering areas from 35?393 mi2 and lengths of record from 13?57 years, were analyzed; thus, statistical significance is assured.