Pacific Southwest Research Station

Using Remote Sensing to Monitor Water Quality

Our current view of water quality in Lake Tahoe depends heavily on data records from two points within the lake and the points where some of the streams enter the lake. These point data do not provide the temporal and spatial detail needed to understand the changes taking place at different parts of the lake (such as the near-shore zone), and the linkage between the lake observations and the input sources. This study will put in place a system to utilize remotely sensed and field measurement data to quantify changes in water clarity measurements over the entire lake.

Full Title: Monitoring past, present, and future water quality using remote sensing (RS)

Proposal [pdf-191KB]

Lead Researchers: S. Geoffrey Schladow, University of California, Davis; Simon J. Hook, Jet Propulsion Laboratory (NASA/JPL)

Goals: Use remotely sensed (satellite) data to provide a quantitative management tool for lake-wide assessments of water quality and to link changes in water quality to discrete sources at the sub-watershed scale.

Sites: remote sensing of entire lake; data on water quality and meteorology from four NASA buoys in the lake and a network of 12 meteorological stations.

Timeframe: October 2007 through September 2009 (2 years)

Figure: Preliminary near-shore clarity map derived from satellite imagery (ASTER) data

Products

1. A Web-accessible repository of existing Tahoe basin RS imagery, integrated with the Coast-to-Mountain Environmental Transect (COMET) cyber-infrastructure system.
2. Tools for semi-automatically acquiring and storing future RS imagery.
3. Algorithms for characterizing the spatial variability of near-shore and offshore water clarity.
4. A description of the linkage between spatial and temporal clarity variability and changes in stream, drain, and intervening zone inputs to the lake, following storms.
5. A description of the relation between spatial and temporal variability in offshore clarity and lake mixing following wind-driven upwelling and surface current patterns.
6. A reporting system where RS-derived measures of water quality are made available on a near-real-time basis.
7. A methodology to study future changes in near-shore and offshore water clarity for any region of concern around Lake Tahoe, which can be used in water quality management decision-making and design.
8. A methodology that can either be directly applied or easily adapted to current and previous measurements acquired by other sensors, including Landsat-5 Thematic Mapper (TM), to create a long-term record of clarity to help understand the historical patterns of clarity change, of importance to present and future basin management.
9. Publication of findings in peer reviewed journals.

For more information:

NASA JPL Calibration and Validation

NASA JPL Calibration and Validation Lake Tahoe