W. F. Hunt, R. W. Skaggs, G. M. Chescheir, D. M. Amatya 1
The current method of assessing wetland hydrologic status by measuring water tables requires long periods of monitoring to provide reliable results. Reference Wetland simulations (RWS) can be used to increase the reliability of assessments based on short-term water table monitoring.
This study was conducted to develop and test alternative methods of comparing measured water table records with the RWS to determine wetland hydrologic status. The following three methods were developed and tested: the Water Table Difference (WT Diff) Method, which compares water tables of the Reference Wetland with the land in question when water tables of both are within a certain depth of the surface; the Duration Method, which makes the above comparison only after the water tables of at least one had been within 30 cm of the surface for a minimum of five days; and the Volatility Method, which compares how much the two water tables fluctuate when within a defined depth of the surface. The methods were tested in a simulation study involving four soils with drainage intensities varying from very wet to relatively dry. All three methods yielded accurate results with the Volatility Method being the most accurate predictor. Only 1.7% of the assessments made with the Volatility Method were in error. The Duration Method and WT Diff methods followed closely with around 6% error each. Based on these findings it appears that the comparison methods can be used with the RWS to correctly interpret short-term water table records for assessing wetland hydrologic status.
