Groundwater Flow and Heat Transport in Wetlands: Transient Simulations and Frequency-Domain Analysis

Background/Need:
Reliable estimates of inflows to a wetland and hydrogeologic parameters can be crucial for understanding wetland hydrology as well as the sustainability of constructed wetlands. Yet inflows are spatially heterogeneous and time-dependent, and their characterization is not trivial. Groundwater models are one method for scaling point measurements up to the site scale, but the information provided by measured heads is frequently insufficient to find unique parameter values. That insufficiency can be overcome by including flux data or by jointly inverting head and temperature measurements. Including heat transport in the model could result in different time scales than are traditionally considered dominant in groundwater flow. Frequency analysis of head and temperature data can characterize these time scales and facilitate the model construction.
Objectives:
The objectives of this project were: 1) to use a set of synthetic models to demonstrate the utility of including temperature data with traditional head data to constrain estimation of parameters important for groundwater flow modeling, 2) to use frequency-domain analysis to characterize a head and temperature data set collected at a wetland in Wilton, Wisconsin, and relate this characterization to proper model construction, and, 3) to apply the approach to simulating flow and heat transport at the Wilton wetland.