Jean-Claude Thomas, Dan Sechrist
Developed algorithms for extrapolation of in-situ evapotranspiration measurements using statistical summaries of TM data
Produced map of evapotranspiration with l00m resolution for south Florida for the image date of 3/21/96
Tested and eliminated the possibility of transferring TM developed statistical techniques to AVHRR for improved temporal resolution
Developed spectra for samples of cattail, sawgrass, periphyton, and open water through in situ measurements
Developed co-registered, georeferenced data sets from TM, SPOT, AVHRR, STATSGO SOILS, and climate stations in GIS format
Calibration of TM and AVHRR data sets to radiance, reflectance, and apparent surface temperature
Development of procedures for statistical sampling and analysis of any georeferenced data set using a combination of GIS, image processing, and advanced statistical software
Fieldwork for this effort has included the collection of high-resolution reflectance spectra for a great number of vegetation and land surfaces. Also, vegetation biomass and other structural characteristics have been sampled at intensive field study sites. Along with other ground data such as water level, elevation, and land cover type, these data are being used to test the efficacy of data fields and vegetation maps derived from the remotely sensed data. Data from numerous airborne and satellite imaging systems have been georeferenced and pre-processed to facilitate data fusion and analysis. Databases of different temporal and spatial solutions (depending on extent) that depict changes in vegetation amount and vigor (through vegetation indexes) have been developed for small areas like the Everglades Nutrient Removal project area and the entire South Florida region. A vegetation map of the Southern Inland and Coastal Systems (SICS) model study area has been developed for the application of spatially distributed fields of vegetation flow resistance. A similar map is currently being produced for the Tides and Inflows to Mangroves of the Everglades (TIME) study area. Data from several different remote-sensing systems and in situ data collections have been fused for the development of other map products to include vegetation density, surface reflectance, and inundated areas, as well as the development of visually enhanced satellite image maps. Finally, spatial analysis of derived variables has been undertaken to address issues of scale important in aggregation for hydrodynamic modeling.
Satellite Image Mapping in the Big Cypress area
This task will produce a 1:100K satellite image map of Big Cyrpress area that will abut the two previous satellite image maps created through this project (i.e., The Southern Everglades and Northern Everglades image maps).
The image fusion and other cartographic procedures developed through this research project will be applied using additional data acquired for the region of the Big Cypress preserve. Procedures that produce tonal and resolution qualities that match those of previous image maps will be used so that one mosaic can be made of all the data for the region of South Florida below Lake Okeechobee. The image maps previously created have been widely used as an outreach and planning tool. The development of the map for the Big Cypress region is a logical conclusion to pre-restoration image map production. The requirement to match previous satellite image map characteristics makes the near-term execution of this task critical.
Given low topographic gradients and subtle topographic variations in South Florida, vegetation affects the distribution and fate of surface water. Means of parameterizing hydrologic models to account for this influence have not been established. While point-measured flow resistance has been linked to vegetation characteristics measured at the same points, methods of spatially extrapolating and populating hydrodynamic models with flow resistance values has not been completed. The objective of this task of the project is to correlate vegetation characteristics that can be measured using remote sensing with characteristics that have been shown to influence flow resistance and use spatial analysis techniques to generate spatially distributed fields of vegetation flow resistance for use in hydrodynamic models of the TIME model domain.
Planned work for this year: 1) Link high-resolution remote sensed indices of vegetation characteristics with point-based measurements of vegetation characteristics. This will be accomplished using previously collected vegetation and remotely sensed data using multiple regression techniques.
2) Develop relationships between high-resolution remotely sensed vegetation indices and satellite-based (coarser resolution) vegetation indices.
3) Use spatial analysis to extrapolate vegetation index models throughout the TIME model domain using multi-date satellite imagery.
4) Populate hydrodynamic models with spatially distributed, multidate flow resistance indices based on the extrapolated vegetation parameters.
5) Evaluate model performance with and without fields of vegetation flow resistance.
While land cover characteristics such as vegetation density are suspected as important influences on the fate and movement of water, methods of accounting for land cover variations on rates and amounts of evapotranspiration (ET) have not yet been developed for South Florida. This research will use a combination of field and remotely sensed data to develop models of ET that more accurately reflect the spatial and temporal distribution of evaporative water loss in South Florida.
Work this year will build upon previous efforts by Jones to spatially extrapolate ET values measured at point locations through Edward German’s ET project. Research on data calibration and atmospheric correction has been undertaken for this task and a set of calibrated/atmospherically corrected satellite data has been generated. Jones and Sechrist will expand this data set so that more rigorous models can be developed and evaluated. While modeling efforts will focus on key subareas within the Everglades, data for locations in the Florida ET Network (Sumner) will also be leveraged for model development. In conjunction with the vegetation characterization activities, we will use ground-based measurements of vegetation density and biomass as calibration and validation data for remotely sensed estimates of vegetation characteristics that likely influence ET. Evapotranspiration maps (in GIS and hardcopy formats) will be produced for use in indexing ET in South Florida hydrologic models. Results will be evaluated on the basis of technical review, assessment using withheld ground data, and output impacts on hydrologic model performance.
Throughout the year, requests and opportunities arise for pilot studies to investigate the use of novel remote sensing and geospatial analysis techniques to gather information of importance to CERP objectives, water quality and flow modeling, ecological modeling, and even as an aid to other remote sensing efforts. Two specific pilot mapping activities currently planned for FY 2003 and FY 2004. The first is focused on the characterization of solution holes in the Rocky Glades. Solution holes in the that region may constitute critical refugia and other habitat. Little is known about their spatial distribution or structural characteristics. It is also not clear how water resource manipulation will impact the function of these holes. The objective of this subtask is to investigate the potential of remote sensing techniques for solution hole survey, characterization, and monitoring.
A second subtask is focused on periphytoon detection and mapping. Periphyton affects water flow, mercury methelation, and the reflectance recorded by remotely sensed imagery. Previous research has demonstrated that periphyton mapping may be possible using hyperspectral imaging techniques that are currently used operationally. The minimum objective of this pilot study is to determine whether the presence or absence of periphyton can be estimated through the use of operational remote sensing systems. A “perihyton index” is the goal. Our ability to conduct more sophisticated periphyton mapping research will be dependent on available data and collaborator resources. I f appropriate ground and remote sensing data are available, this work may be extended to included periphyton composition mapping.
This year, airborne imagery will be collected and analyzed for its efficacy in mapping the location and surface characteristics of solution holes. Airborne aerial photography will be evaluated through visual interpretation and compared against validation data collected in the field. In addition, bathymetric LIDAR data will be collected for examination in FY 2004.
1. Land surface characterization for hydrological and ecological modeling
We will complete the collection of multi-temporal leaf area index (LAI) measurements at various points within the Greater Everglades region. Methods of extrapolating LAI values from points to the region will be developed and tested. We will then use spatial analysis to characterize the spatial structure in LAI at multiple scales and use that characterization to develop and test techniques for assigning flow resistance coefficients that are adjusted for sub-cell heterogeneity to TIME model cells.
2. Greater Everglades focused Status and Trends Topical Report
Following USGS publication guidelines, we will compile and publish a USGS circular-like document using both reprinted and custom-generated papers. At present, we anticipate including the following: 1) Document introduction and overview of Everglades environmental issues/the concerted Everglades restoration project 2) Everglades vegetation history from sediment core pollen analysis 3) Modeling Everglades surface hydrodynamics 'getting the water right' 4) The impact of anthropogenic Twentieth Century land use change on sea breeze generated convective rainfall and sensible weather over the South Florida Peninsula 5) Hurricanes impacts on Everglades mangroves 6) A sampling framework for Everglades landcover change assessment 7] A sidebar regarding Satellite image maps as research, monitoring, and educational outreach tools
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Southern Everglades Satellite Image Map
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U.S. Department of the Interior, U.S. Geological Survey, Center for
Coastal Geology
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