Multispectral Satellite Bathymetry for Turbid Water Depth
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Solution Overview
Problem
Existing methods for determining water depth using satellite data are inaccurate due to varying water turbidity, which affects the reliability of depth measurements, especially in areas with different turbidity levels, leading to incorrect depth readings even in flat sea floors or where actual depths are the same.
Innovation Solution
A method that uses multispectral satellite data to estimate water depth by minimizing the differences between modeled and sensed radiance values over time, accounting for changing turbidity by varying the assumed depth, bottom cover, and water constituents, without requiring calibration with SONAR measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If satellite data is used to determine water depth, then the cost and time of surveys are reduced, but measurement precision deteriorates due to varying water turbidity
Solution Approach 1:
The patent applies parameter changes by utilizing multiple wavelengths (spectral parameters) of satellite data to characterize water turbidity. By measuring radiance at different wavelengths and analyzing spectral signatures, the system dynamically adjusts for variations in water constituents (chlorophyll, suspended sediments, colored dissolved organic matter) to maintain depth measurement accuracy despite changing turbidity conditions.
Solution Approach 2:
The patent introduces an intermediary approach by using spectral analysis as a mediator between satellite radiance measurements and depth determination. The system processes radiance data through spectral unmixing and constituent concentration calculations to derive accurate depth values, effectively bridging the gap between raw satellite data and reliable bathymetric measurements in turbid waters.
2Measurement precision
If ship-based bathymetric surveys are used, then measurement precision is maintained, but productivity decreases due to high cost and time consumption
Solution Approach 1:
The patent replaces the mechanical ship-based survey system with a satellite-based optical remote sensing system. Instead of physically deploying ships with SONAR equipment to map each area, the invention uses multispectral satellite imagery to obtain bathymetric data over large regions simultaneously, dramatically increasing survey coverage while maintaining accuracy through spectral analysis techniques.
Solution Approach 2:
The patent applies universality by designing a satellite-based system that can simultaneously perform multiple functions: determining water depth, characterizing water turbidity, identifying bottom type, and mapping large geographic areas. This multi-functional approach replaces the specialized ship-based SONAR system with a single satellite platform that achieves broader applicability and higher productivity.
3Productivity
If existing satellite bathymetric methods are used, then productivity is improved, but reliability deteriorates in areas with varying turbidity
Solution Approach 1:
The patent applies dynamics by implementing a dynamic model that accounts for temporal and spatial variations in water constituents. The system uses spectral analysis to detect changes in turbidity parameters (chlorophyll concentration, suspended sediment, colored dissolved organic matter) and dynamically adjusts depth calculations accordingly, ensuring reliable measurements across different locations and time periods.
Solution Approach 2:
The patent incorporates feedback mechanisms by using spectral signatures as indicators of water quality conditions. The system continuously monitors spectral characteristics to assess turbidity levels and feeds this information back into the depth inversion algorithm, allowing real-time compensation for varying water properties and maintaining measurement reliability across diverse environments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate determination of water depth despite varying turbidity, providing reliable measurements without the need for costly and time-consuming ship-based surveys, and can update depth charts regularly, even in remote areas.
Implementation Method 1
The satellite measures radiation from the sun that is reflected from the earth
Implementation Method 2
substances in the water, and the water surface roughness absorb the sun's radiation
Implementation Method 3
factors that scatter and absorb the sun's radiation
Data Source
AI summary
Satellite data is used to determine water depth by accounting for the changing turbidity of the water over time and without requiring calibration using SONAR measurements. Radiance values at multiple wavelengths sensed at both a first time and a second time are stored in a database. Modeled reflectance values are calculated for a defined surface area on the water based on an assumed depth, assumed water constituents and assumed bottom cover. A plurality of differences between the modeled reflectance values and the reflectances sensed at the two times are calculated. A bathymetry application module minimizes the sum of the differences between the modeled and sensed subsurface reflectances by varying the assumed depth, bottom cover and water constituents. The differences are weighted based on wavelength before being summed. The depth that results in the minimized sum of the differences is the estimated depth, which is displayed on a graphical user interface.