The integration of remote sensing and geographic information systems for Great Lakes water quality monitoring.

摘要

This dissertation is concerned with the integration of satellite remote sensing and geographic information systems for the purpose of monitoring Great Lakes water quality. "Water quality" is defined as the physical, chemical and biological conditions that determine a water body's optical properties (i.e., its transparency and color). The utility of three operational satellite remote sensing systems, namely, the Landsat Thematic Mapper (TM), the SPOT High Resolution Visible (HRV) sensors and the NOAA Advanced Very High Resolution Radiometer (AVHRR), were evaluated as a means of estimating water quality and surface temperature. No one system was optimal for all water quality monitoring needs but the geographic information system (GIS) concept--a computerized data base of spatially registered information layers--provides a logical way of integrating the data from these various remote sensing systems.; Empirical calibration through linear regression techniques was used to relate near-simultaneously acquired satellite radiance/reflectance data and water quality observations obtained in Green Bay and the nearshore waters of Lake Michigan. Four dates of TM and one date each of SPOT and AVHRR imagery/surface reference data were acquired and analyzed (TM 7/18/84, 7/24/86, 6/9/87, 7/27/87; SPOT 10/6/86; and AVHRR 6/9/87, respectively). Highly significant relationships (R{dollar}sp2{dollar} {dollar}>{dollar} 0.80) were identified between the TM and SPOT data (both individual bands and ratio combinations of multiple bands) and secchi disk depth, nephelometric turbidity, chlorophyll a, total suspended solids (TSS), absorbance, and surface temperature (TM only). The AVHRR data were not analyzed independently but were used for comparison with the TM data. TSS appears to be the overwhelming determinant of the water volume reflectance observed in this study.; Calibrated water quality image maps were input to a PC-based raster GIS package, EPPL7. Pattern interpretation and spatial analysis techniques were used to document the circulation dynamics and model mixing processes in Green Bay. A GIS facilitates the retrieval, query and spatial analysis of mapped information (including remotely sensed imagery) and provides the framework for an integrated operational monitoring system for the Great Lakes.