Hydrologic thresholds of ecosystem resiliency: Have wetlands on the Anoka Sand Plain changed over time?

Abstract

Wetlands have long been used as an indicator for changes in climate and land use because they are sensitive to environmental changes and are connected to surficial and deeper aquifers. In Anoka County, Minnesota, USA, a monitoring network has been established and maintained since 1997 to track trends in wetland hydrology. A combination of data including water level from these wetlands, precipitation from local gages, pan evaporation data, and historical land use, including a measure of runoff flashiness, were analyzed through regressions and k-means. Results did not detect any clear trends, though some p-values showed potential. A clear statistical trend in the measured hydrologic parameters would suggest exceedance beyond historical thresholds of natural hydrologic variation and suggest the need to better protect wetland environments. The findings can be used to inform future management and regulatory decisions for wetland environments set in sandy soils. This is particularly important for Anoka County because most wetlands are intrinsically connected to the surficial Anoka Sand Plain Aquifer, which overlays deeper aquifers which are used for drinking water and are highly sensitive to pollution.