HR: 0800h
AN: H11F-0365    [Abstracts]
TI: Enhanced Thematic Mapper Plus Analyses of Chlorophyll-a Concentration and Distribution in Small Kettle Lakes, Southern Minnesota
AU: * Hoppie, B
EM: bryce.hoppie@mnsu.edu
AF: Department of Chemistry and Geology, Minnesota State University, TN242, Mankato, MN 56001 United States
AU: Roost, B
EM: brad.roost@mnsu.edu
AF: Aquatic Biologists, Inc., N4828 US Hwy 45, Fond du Lac, WI 54935 United States
AB: Spatial and temporal variability of lake water quality is well defined; however, due to costs and logistical constraints, multiple assessments of water quality are rarely obtained in Minnesota lakes. For improved resource management, an integrated assessment of whole-lake surface water quality is needed. Sequential spatial descriptions of water quality variability will facilitate characterizing physical, chemical, and biological processes in lakes and help to identify sources of external and internal nutrient loading within individual lakes. Our study focused on surface water properties in six small southern Minnesota meso-eutrophic, eutrophic, and hypereutrophic lakes. Our protocol included obtaining multiple, georeferenced in-lake and laboratory-based assays of surface water quality within 24 hours of each Enhanced Thematic Mapper Plus (ETM+) overpass during the summer of 2001. Lake water data (including chlorophyll-a, total phosphorus, water transparency, and total suspended solids) were regressed against temporally and spatially equivalent three-by-three pixel averages of singular and combined ETM+ spectral bands. A simple linear regression of chlorophyll-a analyses from water samples and corrected ETM+ Band 2 data provided the strongest correlation (R$^{2}$ = 0.96) among the available data. The chlorophyll-a concentrations from processed ETM+ data in each lake exhibit up to three orders of magnitude greater variance than those derived from water sample data. Furthermore, ETM+ results illustrate distinctive patterns of chlorophyll-a distribution among lakes of similar trophic status that are not present in water sample data. Thus, it appears ETM+ data provide better characterizations of overall chlorophyll-a concentrations and distribution relative to multiple-sample in-lake water analyses in small kettle lakes.
DE: 6969 Remote sensing
DE: 1845 Limnology
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting