Strategies for defining chemical connectivity between streams and wetlands

Abstract

Methods for characterizing wetland-to-stream chemical connectivity were developed to help regulators define jurisdiction and wetland managers prioritize their use of resources. Chemical connectivity here is based on historic stream water quality found using publically available databases and analyzed in a Geographic Information System (GIS). Although stream data was readily available, wetland data was not abundant. Interpolation methods were therefore developed using observed water quality data points in streams and projecting them to adjacent wetlands. The different interpolation methods were compared using their root mean square error (RMSE) and local polynomial interpolation (LPI) for chloride data and Universal Kriging for specific conductance data was found to typically yield the best results. To also address the lack of actual wetland water quality data a relative site suitability analysis approach using GIS was developed to determine monitoring locations for generating additional data. The key environmental variables identified that relate to connectivity and potential health of the wetlands include hydrology and land use. In additional to conservative water quality parameters, the idea of measuring fluorescence-based excitation and emission matrix (EEM) is introduced. This is a rapid assessment source tracking tool for identifying the natural organic matter (NOM) in different waters. EEM trends through two drinking water treatment plants demonstrate the consistency of the EEM signature and shows that only the more aggressive chemical activities cause notable changes.