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Overview
Basics
Basics
Utilize 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 (e.g. the Incline Creek watershed) scale.
Completed
2007
2007
2010
$172,029
Patricia Maloney (pemaloney@ucdavis.edu)
10/03/2017
10/03/2017
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| Location Information | Location Notes |
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Organizations
EIP Details
EIP Basics
EIP Basics
04.01.01.0069 - P015: Monitoring Past, Present, and Future Water Quality Using Remote Sensing
Performance Measures
Expected Performance Measures
Expected Performance Measures
No expected performance measures set for this project.
Reported Performance Measures
Reported Performance Measures
No annual performance measure accomplishments entered for this project.
Funding
Expected Funding
Expected Funding
$172,029
$172,029
$0
| Total | |||
|---|---|---|---|
| Unknown or Unassigned | $172,029 | $172,029 | $0 |
| Grand Total | $172,029 | $172,029 | $0 |
Reported Expenditures
Reported Expenditures
| Total | 2010 | 2009 | 2008 | 2007 | |
|---|---|---|---|---|---|
| Southern Nevada Public Land Management Act (Pacifi... | $172,029 | $43,007 | $43,007 | $43,008 | $43,007 |
| Grand Total | $172,029 | $43,007 | $43,007 | $43,008 | $43,007 |
Photos
Other Details
Watersheds
No watersheds set for this project.
Threshold Categories
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Remote sensing (RS) technologies are being used worldwide to monitor aquatic, atmospheric, and terrestrial systems. RS provides an instantaneous synoptic overview of these systems which, when coupled with in situ measurements, can provide unmatched, cost-effective, quantitative measures of change with spatial resolutions down to the order of meters and temporal frequency better than daily.
Local and Regional Plans
No Local and Regional Plans set for this project.
Related Projects
Related Projects
No Related Projects set for this project.
External Links
No external links entered.
Notes
Notes
| 08/13/2017 9:09 PM | System | Objectives: The objective of this project is to utilize 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 (e.g. the Incline Creek watershed) scale. |
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| 08/13/2017 9:08 PM | System | Findings: • Remotely sensed “measurements” are a combination of measurements and models. Spaceborne radiometers, such as MODIS, measure the spectral distribution of radiance exiting the top of the atmosphere. Only a small fraction of the radiance measured at the sensor is water-leaving radiance. Over oligotrophic waters, such as Lake Tahoe, the atmosphere can contribute as much as 90 – 99% of the signal received by the satellite sensor. In addition, there are influences from factors such as sun glitter, whitecaps, clouds and jet contrails. Therefore, atmospheric correction must be performed on each satellite image to remove these contributions and adjust for atmospheric attenuation. In the open ocean there are well-established methods for atmospheric correction, which benefit from negligible terrestrial contributions to the atmosphere and water. Lake Tahoe by contrast has a more optically complex terrestrial atmosphere, albeit a thinner one due to its altitude, and more optically complex waters, although its low chlorophyll concentrations are similar to the pelagic ocean. Uncertainties associated with the process of atmospheric correction (i.e. how the atmosphere is modeled) are an important limitation on the accuracy of remotely sensed water quality at Lake Tahoe. • As part of this project a web-accessible database of Tahoe remotely sensed imagery has been created. This is a living database, and images are being added to it as they are acquired by MODIS. These images are atmospherically corrected, using what we believe to be the most appropriate “models” for Lake Tahoe. Instantaneous and monthly averaged Secchi disk depths and chlorophyll a values for locations corresponding to the long term UC Davis monitoring stations are calculated, as are similar values for 45 “virtual” offshore, coastal and nearshore stations around the periphery of the lake, and maps of these variables for the entire lake are produced. • Calibration of the satellite-derived Secchi depth and chlorophyll a concentration against the measured data for the lake gave a very good match, with both seasonal variations and year- to-year variations for the 8 years of data used being well represented. Annual average Secchi depth showed a slight bias, with the satellite derived values being about 1 m lower than the measured values. The cause of this bias is currently being studied. *** See www.fs.fed.us/PSW/partnerships/tahoescience for additional findings. |
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| 08/13/2017 9:05 PM | System | Management Implications: • The intent of this project was to demonstrate the use of remote sensing for measuring water quality parameters at Lake Tahoe. One of the major benefits of this approach would be that a whole-lake view of water quality changes would be possible, even extending into the nearshore where discrete sources of pollutants could be identified. • Improving our understanding of the dynamics of water quality parameters in the lake will improve our ability to manage them. • Several regions in the lake merit further study. Water quality in Carnelian Bay was lower than expected at times, while the area adjacent to Blackwood Creek showed minimal impacts near its inflow points, despite its much greater inflows. • Similarly disproportionate effects were observed along the eastern shore adjacent to the Glenbrook and Logan House Creek inflows, which were the lowest of the streamflows recorded during this study period. • The inflows along the southern shore appear to have a very large impact on lake-wide water quality. Therefore, this region needs further study to quantify the point- and non-point sources of pollution into the lake and the contribution of sediment resuspension to water clarity. |