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Pacific Southwest Research Station
Tahoe Science Projects supported by SNPLMA
Remote sensing of Lake Tahoe's nearshore environment
Erin Lee Hestir, University of California, Davis
The goal of this research is to use remotely sensed data to retrieve fine sediment, chlorophyll, and colored dissolved organic matter (CDOM) concentrations from the water column in the near shore, and to map the distribution of periphyton (attached algae), aquatic macrophytes (submerged plants), clam beds in the nearshore of Lake Tahoe and variations in sediment type. High spatial resolution multispectral satellite imagery, moderate spatial resolution multispectral satellite imagery, and airborne hyperspectral imagery will be used. We will investigate both empirical and model-driven methods to map fine sediment, chlorophyll, and CDOM concentration, macrophyte communities, clam beds, periphyton, and substrate type. The empirical approach will first classify the optically shallow near shore into the different bottom classes using the field data and spectral library first to train and then (independently) validate the classifier. This analysis allows the development of statistical correlations (e.g., regression modeling) whereby reflectance information can be used to predict the probability of the concentration of water quality constituents above a particular bottom type. Upon successful development, the statistical model can then be used to predict water quality in each image pixel given the reflectance value of that pixel. The second approach will use a radiative transfer model that simulates remote sensing reflectance of water given inputs of different aquatic optical properties. One of the key deliverables of the project is a cost-benefit analysis of remote sensing approaches for monitoring the nearshore environment and a manual for implementing remote sensing analysis for monitoring the nearshore environment.
Relation to Other Research Including SNPLMA Science Projects
The value of remote sensing technologies for evaluation and monitoring in the Lake Tahoe Basin has also been widely recognized, and an increasing number of remote sensing datasets are being acquired over the basin. NASA has been operating a remote sensing validation site at Lake Tahoe for over a decade and recently the Tahoe Regional Planning Agency (TRPA) and U.S .Geological Survey have purchased high spatial resolution satellite imagery of the Tahoe Basin. Dr. Schladow and Dr. Steissberg (UC Davis TERC) and Dr. Hook (NASA-JPL) have completed a SNPLMA Round 7-funded project, "Monitoring past, present, and future water quality using remote sensing (RS),"aimed at using remote sensing to quantify changes in lake-wide distributions of Secchi depth and chlorophyll distribution. The large pixel size has limited the application to areas outside the nearshore; however, there will be considerable benefit to this project based on what was learned. Several previous SNPLMA science studies will inform this project, including: 1) "Predicting and managing changes in near-shore water quality," 2) "Natural and human limitations to Asian clam distribution and recolonization-factors that impact the management and control in Lake Tahoe," and 3) "Development of a risk model to determine the expansion and potential environmental impacts of Asian clams in Lake Tahoe," as well as a project funded by the US Army Corps of Engineers that is conducting a baseline assessment of benthic species and developing recommendations for future assessments.
Expected date of final products:
|Last Modified: Nov 12, 2014 03:51:19 PM|