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Detecting the Zambezi River plume using observed optical properties
J R Siddorn1, D G Bowers, A M Hoguane
1Plymouth Marine Laboratory, Devon, UK. jsid@pml.ac.uk
Marine Pollution Bulletin
|November 6, 2001
Summary
Researchers mapped the Zambezi River plume using satellite data by analyzing water color and salinity. This method shows potential for tracking river plumes in coastal waters.
Area of Science:
- Oceanography
- Remote Sensing
- Water Quality Analysis
Background:
- The Mozambique Channel is influenced by the Zambezi River plume, characterized by distinct optical and salinity gradients.
- Understanding river plume dynamics is crucial for coastal ecosystem management and nutrient transport studies.
Purpose of the Study:
- To establish an empirical relationship between optical properties and salinity in the Zambezi River plume.
- To demonstrate the feasibility of using satellite imagery to map salinity and delineate the Zambezi River plume distribution.
Main Methods:
- Conducting a research cruise in the Mozambique Channel for in-situ optical, water quality, and salinity measurements.
- Developing empirical algorithms relating salinity to yellow substance absorption and reflectance ratios.
- Applying the established algorithm to SeaWiFS satellite imagery for large-scale salinity mapping.
Main Results:
- A strong negative correlation (r2 = 0.76) was found between salinity (S) and yellow substance (g440).
- An empirical algorithm was derived: S(1/2 Zsd) = 37.45-7.07(R555/R490), linking salinity to a specific reflectance ratio.
- The algorithm successfully mapped salinity on the Sofala Bank using SeaWiFS data, confirming the Zambezi plume's extent.
Conclusions:
- Remote sensing offers a viable method for mapping salinity and tracking the Zambezi River plume.
- The derived optical algorithms are effective, though high chlorophyll concentrations may affect accuracy.