研究目的
The objective of this research was to develop and evaluate relationships between hyperspectral remote sensing and lake water quality parameters—chlorophyll, turbidity, and N and P species.
研究成果
The research demonstrated that hyperspectral remote sensing can accurately estimate most water quality parameters in Mark Twain Lake, with chlorophyll a, turbidity, total N and P, and dissolved NO3–N and PO4–P all estimated with R2 ≥ 0.7 using proximal sensing. Aerial hyperspectral sensing was slightly less accurate but still viable for water quality assessment. The study highlighted the importance of collecting calibration samples at each sensing date for accurate remote sensing estimates, especially for nutrients.
研究不足
The study found that extrapolation of estimation models to dates other than those used to calibrate the model greatly increased estimation error for some parameters, indicating the need for collection of calibration samples at each sensing date for the most accurate remote sensing estimates of water quality. Additionally, the accuracy of aerial hyperspectral sensing was somewhat less than proximal sensing for the two measurement dates where both were obtained.
1:Experimental Design and Method Selection:
The study involved collecting proximal hyperspectral water reflectance data on seven sampling dates and aerial hyperspectral data on two dates from Mark Twain Lake. Water samples were analyzed for chlorophyll, nutrients, and turbidity. Reflectance indices and full-spectrum methods (partial least squares regression) were used to develop relationships between spectral and water quality data.
2:Sample Selection and Data Sources:
Seven sampling sites were identified where highway bridges crossed arms of the lake, with multiple sampling stations established at each site. Water samples and spectral data were collected under generally clear sky conditions.
3:List of Experimental Equipment and Materials:
Equipment included an ASD FieldSpec Pro FR field spectrometer for proximal sensing, AISA pushbroom sensors (AISA Classic and AISA Eagle) for aerial hyperspectral imaging, and YSI 6600 or 6920 Sonde for turbidity measurements.
4:Experimental Procedures and Operational Workflow:
Field spectrometer data were collected at each sampling station, and water samples were obtained within 30 minutes of spectral data collection. Aerial hyperspectral images were acquired and processed for two dates.
5:Data Analysis Methods:
Previously reported reflectance indices and partial least squares regression (PLSR) were used to analyze the relationships between spectral data and water quality parameters.
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