Measurement of wetland hydroperiod using harmonic analysis

The pattern of water-level fluctuations in a wetland is its hydroperiod. Characterization of this pattern cannot be accomplished by measuring a single parameter, but some means of measuring hydroperiod is needed so that comparisons can be made both between wetlands and within a single wetland over time. Harmonic analysis can be used to characterize hydroperiod quantitatively by obtaining the amplitude and timing of the dominant periodic component in a time series of water levels. The utility of this method is demonstrated by investigating the link between water management in South Florida and nesting failure by wood storks in the Everglades wetland. With the quantitative measures of hydroperiod derived by harmonic analysis, I am able to demonstrate statistically the relationships between water management and hydroperiod in the Everglades and between hydroperiod and the probability of nesting failure. The simplicity and directness by which these results are achieved suggests the potential for harmonic analysis of hydroperiod as a general tool for wetland science.