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Multiscale (spatial, spectral, temporal) remote sensing of biogeochemical conditions in Nebraska Sand Hills lakes
Abstract
This dissertation applied remote sensing to several questions regarding lake water quality in the Nebraska Sand Hills. In Chapter 2, baselines of reflectivities were defined, from May to October, 1972 through 1986, as measured by the Landsat Multispectral Scanner, for 130 lakes in Garden and Sheridan Counties, NE. This yielded multispectral signatures and records of variation for the individual lakes. Chapters 3 and 4 addressed the basic problem of associating lake reflectivities with water quality parameters specific to Sand Hills lakes, using: (a) 252 bands of hyperspectral reflectance data collected with a spectroradiometer from a helicopter, (b) 7 bands of multispectral reflectance data collected by the Landsat Thematic Mapper, and (c) water quality conditions of turbidity, algal chlorophyll-a and alkalinity. Results from both chapters yielded significant correlations of turbidity and chlorophyll-a with the spectral information. A record of hyperspectral reflectance from 32 lakes was established. Chapter 5 was a cursory study on the spatial variability expressed by waterscape (landscape ecology analog) metrics within and among lakes, using reflectance classes as surrogates to aquatic habitats. Results showed that spatial metrics vary among lake spectral classes. Chapter 6 provided estimates of albedo, from hyperspectral reflectance data among lakes, and then used the results to examine the variability in lake radiation budgets. There were shifts in relative dominance between reflected shortwave and longwave components, which may be important in assessing lake impacts on local and regional climate or biological production. Each of these studies presented either new approaches to the study of water resources with remote sensing, or new and useful information about the many lakes in Nebraska's Sand Hills. Both aspects should prove useful in regional monitoring or comparisons with other regions of the world. Overall, the results provided evidence that remote sensing is a useful tool for studying water quality, and a developing science with new basic questions to be addressed.
Subject Area
Geography|Biogeochemistry|Freshwater ecology|Remote sensing
Recommended Citation
Fraser, Rolland Neil, "Multiscale (spatial, spectral, temporal) remote sensing of biogeochemical conditions in Nebraska Sand Hills lakes" (1996). ETD collection for University of Nebraska-Lincoln. AAI9637067.
https://digitalcommons.unl.edu/dissertations/AAI9637067