Remote Sensing in the Great Basin
The Saline Lake Integrated Water Availability Assessment is enhancing data collected on the ground with current and historic data collected from far above using satellite remote sensing.
Saline Lakes are terminal, meaning they don’t have surface water outflows. The amount of water they contain at a given time can vary drastically depending on precipitation events, water use, and evaporation rates. The lakes are remote and large, making them difficult and expensive to access or survey from the ground. These characteristics make the use of satellite-based remote sensing a cost-effective approach to visualize and measure changes in water extent and volume over time.
In the Saline Lakes Integrated Water Availability Assessment, our goal is to improve the understanding of terminal saline lake dynamics with remote sensing data and innovations.
Project objectives:
- Generate time series data of lake/wetland inundation patterns
- Estimate lake volume change over time
- Map historic dynamics of water bird habitat extents
- Enhance understanding of conditions at intensive study sites
- Extend what we learn at intensive sites to other lakes in the Great Basin
Products and tools
Dynamic Surface Water Extent (DSWE)
The USGS developed an approach to provide Analysis Ready Data (ARD) on earth surface water extent changes over time and space through satellite remote sensing - without requiring the user to be an expert in complex remote sensing. Importantly, this approach targets areas entirely covered by water (open water) and areas where individual ground satellite measurements are mixtures of water with vegetation and/or soil. The USGS and NASA are each operationally generating ARD products based on the USGS method and product design. These are being further analyzed to meet the objectives of this project:
The USGS DSWE product is generated from the Landsat Archive (1984 – present) and openly distributed via EartherExplorer. Any location on earth is imaged by Landsat every 8 – 16 days depending on the number of Landsat satellites in orbit at a time. This data record begins in 1984 and continues to the present.
- NASA DSWx is generated from a wider variety of remote sensing systems that scan the earth more frequently but have shorter lengths of record than USGS DSWE.
- DSWx-HLS uses Harmonized Landsat Sentinel inputs, imagery from Landsat, and European Space Agency (ESA) Sentinel-2 satellites that NASA modifies to be comparable to Landsat imagery. This results in much higher frequency of surface water data for a given location (2 days on average). Forward production of DSWx-HLS began in 2023, and NASA is working to extend this near-global product back to 2016.
- DSWx-S1 is created from synthetic aperture radar (SAR) data collected by ESA’s Sentinel-1 satellites. Beginning in 2024, the satellites scan the earth every 12 days, or more often when multiple satellites are working.
- Another product in the DSWx suite, DSWx-NI, will be based on the NASA’s NISAR satellites' SAR.
Although DSWE products based on Landsat and Sentinel-1 have some cloud/smoke penetration, these SAR-based products provide “all-weather” observation capabilities for DSWx.
US Federal agencies also have limited access to high- and very high- spatial resolution commercial imagery by request through the Department of Defense. Some high-resolution data lack the spectral range of the openly distributed government data (Landsat, Sentinel, and NISAR) but image the globe on nearly a daily basis. The very-high resolution commercial data are only obtained by request as needed. All these data are used, along with data collected in the field, to assess the accuracy of surface water extent estimates from DSWE and DSWx products captured at nearly the same time.
DSWE/DSWx Derivatives
Derivatives of DSWE time series data yield useful information for a variety of purposes. One derivative known as “proportions” is the frequency of observed inundations over a selected time period, expressed as a percentage. We can calculate proportions by individual or combined DSWE water classes. The visual below shows total surface water, which includes open water and partial surface water combined. We generate these time series for all the 22 lakes in the assessment.
Time series of annual total surface water levels in Lake Owens, California from 1990 to 2025 derived from DSWE. Grey to white tones represent water free rough to flat terrain, respectively. The range of colors from light green to dark blue represent increasing periods of inundation within each year as measured at the scale of individual 30-meter by 30-meter ground areas of the Lake and surrounding impoundments.
Accomplishments
- Created an image database for the terminal lakes from multiple government and commercial satellite sources.
- Generated 24-year records for select lakes from finer-temporal resolution Landsat DSWE total surface water observations.
- Made public 41-year records on annual surface water proportions for all the continental US through an interactive dashboard.
Current research focus
We are developing and testing methods of estimating lake volume change and water bird habitat extent dynamics by combining DSWE/DSWx with bathymetry in the lakes and the topography surrounding them.
The Saline Lake Integrated Water Availability Assessment is enhancing data collected on the ground with current and historic data collected from far above using satellite remote sensing.
Saline Lakes are terminal, meaning they don’t have surface water outflows. The amount of water they contain at a given time can vary drastically depending on precipitation events, water use, and evaporation rates. The lakes are remote and large, making them difficult and expensive to access or survey from the ground. These characteristics make the use of satellite-based remote sensing a cost-effective approach to visualize and measure changes in water extent and volume over time.
In the Saline Lakes Integrated Water Availability Assessment, our goal is to improve the understanding of terminal saline lake dynamics with remote sensing data and innovations.
Project objectives:
- Generate time series data of lake/wetland inundation patterns
- Estimate lake volume change over time
- Map historic dynamics of water bird habitat extents
- Enhance understanding of conditions at intensive study sites
- Extend what we learn at intensive sites to other lakes in the Great Basin
Products and tools
Dynamic Surface Water Extent (DSWE)
The USGS developed an approach to provide Analysis Ready Data (ARD) on earth surface water extent changes over time and space through satellite remote sensing - without requiring the user to be an expert in complex remote sensing. Importantly, this approach targets areas entirely covered by water (open water) and areas where individual ground satellite measurements are mixtures of water with vegetation and/or soil. The USGS and NASA are each operationally generating ARD products based on the USGS method and product design. These are being further analyzed to meet the objectives of this project:
The USGS DSWE product is generated from the Landsat Archive (1984 – present) and openly distributed via EartherExplorer. Any location on earth is imaged by Landsat every 8 – 16 days depending on the number of Landsat satellites in orbit at a time. This data record begins in 1984 and continues to the present.
- NASA DSWx is generated from a wider variety of remote sensing systems that scan the earth more frequently but have shorter lengths of record than USGS DSWE.
- DSWx-HLS uses Harmonized Landsat Sentinel inputs, imagery from Landsat, and European Space Agency (ESA) Sentinel-2 satellites that NASA modifies to be comparable to Landsat imagery. This results in much higher frequency of surface water data for a given location (2 days on average). Forward production of DSWx-HLS began in 2023, and NASA is working to extend this near-global product back to 2016.
- DSWx-S1 is created from synthetic aperture radar (SAR) data collected by ESA’s Sentinel-1 satellites. Beginning in 2024, the satellites scan the earth every 12 days, or more often when multiple satellites are working.
- Another product in the DSWx suite, DSWx-NI, will be based on the NASA’s NISAR satellites' SAR.
Although DSWE products based on Landsat and Sentinel-1 have some cloud/smoke penetration, these SAR-based products provide “all-weather” observation capabilities for DSWx.
US Federal agencies also have limited access to high- and very high- spatial resolution commercial imagery by request through the Department of Defense. Some high-resolution data lack the spectral range of the openly distributed government data (Landsat, Sentinel, and NISAR) but image the globe on nearly a daily basis. The very-high resolution commercial data are only obtained by request as needed. All these data are used, along with data collected in the field, to assess the accuracy of surface water extent estimates from DSWE and DSWx products captured at nearly the same time.
DSWE/DSWx Derivatives
Derivatives of DSWE time series data yield useful information for a variety of purposes. One derivative known as “proportions” is the frequency of observed inundations over a selected time period, expressed as a percentage. We can calculate proportions by individual or combined DSWE water classes. The visual below shows total surface water, which includes open water and partial surface water combined. We generate these time series for all the 22 lakes in the assessment.
Time series of annual total surface water levels in Lake Owens, California from 1990 to 2025 derived from DSWE. Grey to white tones represent water free rough to flat terrain, respectively. The range of colors from light green to dark blue represent increasing periods of inundation within each year as measured at the scale of individual 30-meter by 30-meter ground areas of the Lake and surrounding impoundments.
Accomplishments
- Created an image database for the terminal lakes from multiple government and commercial satellite sources.
- Generated 24-year records for select lakes from finer-temporal resolution Landsat DSWE total surface water observations.
- Made public 41-year records on annual surface water proportions for all the continental US through an interactive dashboard.
Current research focus
We are developing and testing methods of estimating lake volume change and water bird habitat extent dynamics by combining DSWE/DSWx with bathymetry in the lakes and the topography surrounding them.