Skip to main content
Advanced Search

Filters: Tags: phreatophytes (X)

21 results (18ms)   

View Results as: JSON ATOM CSV
Evapotranspiration rates and the ground water component of evapotranspiration at a site in Colorado's San Luis Valley that is dominated by shrubby phreatophytes (greasewood and rabbitbrush) were compared before and after a water table drawdown. Evapotranspiration (ET) rates at the site were first measured in 1985–1987 (pre-drawdown) when the mean water table depth was 0.92 m. Regional ground water pumping has since lowered the water table by 1.58 m, to a mean of 2.50 m. We measured ET at the same site in 1999–2003 (post-drawdown), and assessed physical and biological factors affecting the response of ET to water table drawdown. Vegetation changed markedly from the pre-drawdown to the post-drawdown period as phreatophytic...
thumbnail
The groundwater discharge area (GDA) in Tule and part of Sevier valley represents the area where discharge from evaporation by open water or bare soil and transpiration from phreatophytic plants exceeds the volume of water contributed by precipitation. The GDA was delineated during field reconnaissance of the study area using techniques similar to those used in previous studies throughout Nevada and eastern Utah.
thumbnail
The mean MSAVI image is based on two Landsat 5 Thematic Mapper (TM) scenes representing midsummer conditions in 2007 and 2008. MSAVI was calculated for each image which were then combined by calculating the mean for each pixel in the scenes. The resultant MSAVI image was used to estimate vegetation assemblages (ET units) within a mapped groundwater discharge area.
thumbnail
This dataset, created in support of USGS Scientific Investigations Report 2020-5075, Estimates of Groundwater Discharge by Evapotranspiration, Stump Spring and Hiko Springs, Clark County, Nevada, 2016-18, represents a Normalized Difference Vegetation Index calculated for vegetated areas in the Hiko Springs groundwater discharge area. Vegetated areas within the GDA are composed of phreatophytic shrubs interspersed with xeric vegetation and bare soil. The GDA was delineated by visual interpretation of 1-meter National Agriculture Imagery Program (NAIP) aerial imagery acquired in May of 2015. Areas of channel scour within the GDA resulting from a flood event in September 2015 were delineated from a 2016 1.84-meter...
thumbnail
This USGS data release, supporting USGS Scientific Investigations Report 2020-5075, Estimates of Groundwater Discharge by Evapotranspiration, Stump Spring and Hiko Springs, Clark County, Southern Nevada, 2016–18, consists of five datasets - Normalized Difference Vegetation Indexes (NDVI) and a mapped groundwater discharge areas (GDA) for two spring areas, and a two-class land cover classification for Stump Springs and the Area of Critical Environmental Concern (ACEC) adjacent to Stump Springs. The mapped GDAs are the area within each spring’s riparian area where discharge from evaporation by open water or bare soil and transpiration from phreatophytic plants exceeds the volume of water contributed by precipitation....
thumbnail
This dataset, created in support of USGS Scientific Investigations Report 2020-5075, Estimates of Groundwater Discharge by Evapotranspiration, Stump Spring and Hiko Springs, Clark County, Nevada, 2016-18, represents the groundwater discharge area (GDA) for the Stump Springs riparian area and Area of Critical Environmental Concern (ACEC). Vegetated areas within the GDA are composed of phreatophytic shrubs interspersed with xeric vegetation and bare soil. The GDA was delineated by visual interpretation of 1-meter National Agriculture Imagery Program (NAIP) aerial imagery acquired in May of 2015. The ACEC boundary was determined by the Bureau of Land Management.
thumbnail
This dataset, created in support of USGS Scientific Investigations Report 2020-5075, Estimates of Groundwater Discharge by Evapotranspiration, Stump Spring and Hiko Springs, Clark County, Nevada, 2016-18, represents a Normalized Difference Vegetation Index calculated for vegetated areas in the Stump Spring groundwater discharge area (GDA) and Area of Critical Environmental Concern (ACEC). Vegetated areas within the GDA are composed of phreatophytic shrubs interspersed with xeric vegetation and bare soil. The GDA was delineated by visual interpretation of 1-meter National Agriculture Imagery Program (NAIP) aerial imagery acquired in May of 2015. The NDVI was calculated from a June 2017 WorldView 2 image resampled...
thumbnail
This dataset, created in support of USGS Scientific Investigations Report 2020-5075, Estimates of Groundwater Discharge by Evapotranspiration, Stump Spring and Hiko Springs, Clark County, Nevada, 2016-18, represents a two class land cover classification consisting of moderate to dense vegetation and bare to sparsely vegetated areas within the Groundwater Discharge Area and Area of Critical Environmental Concern boundaries for Stump Spring, Nevada. The classification is based on a 2015 1-meter National Agricultural Imagery Program (NAIP) image and a maximum likelihood classification algorithm provided in ENVI software (https://www.harrisgeospatial.com/docs/Classification.html#ClassSupervised).
thumbnail
This USGS data release consists of three data sets used as the basis for estimates of groundwater discharge from evapotranspiration in Tule Valley and part of Sevier Valley, UT. The data sets are a mapped groundwater discharge area (GDA), a mean modified soil adjusted vegetation index (MSAVI), and evapotranspiration (ET) units derived from the MSAVI within the GDA. The GDA represents the area within each valley where discharge from evaporation by open water or bare soil and transpiration from phreatophytic plants exceeds the volume of water contributed by precipitation. The GDA was delineated during field reconnaissance of the study area using techniques similar to those used in previous studies throughout Nevada...
thumbnail
This data set represents evapotranspiration (ET) units based on a 2017-2018 summer mean modified soil adjusted vegetation index (MSAVI). The MSAVI information was used to partition Tule Valley and part of Sevier Valley, UT into six discharging ET units (playa; open water; very sparse desert shrub; sparse-to-dense desert shrub; grassland; and dense meadow and marshland), and scale estimates of groundwater evapotranspiration (ETg) to the basin level. ET units represent generalized groupings of vegetation and soil conditions. The units are constrained by a groundwater discharge area (GDA) which represents the area where discharge from evaporation by open water or bare soil and transpiration from phreatophytic plants...
Groundwater dependent ecosystems (GDEs) rely on near-surface groundwater. These systems are receiving more attention with rising air temperature, prolonged drought, and where groundwater pumping captures natural groundwater discharge for anthropogenic use. Phreatophyte shrublands, meadows, and riparian areas are GDEs that provide critical habitat for many sensitive species, especially in arid and semi-arid environments. While GDEs are vital for ecosystem services and function, their long-term (i.e. ~ 30 years) spatial and temporal variability is poorly understood with respect to local and regional scale climate, groundwater, and rangeland management. In this work, we compute time series of NDVI derived from sensors...


map background search result map search result map Evapotranspiration Units, Groundwater Discharge Area, and 2007-2008 Summer Mean Vegetation Index for Tule Valley and part of Sevier Valley, Utah Groundwater Discharge Area for Tule Valley and part of Sevier Valley, Utah Scaled Modified Soil Adjusted Vegetation Index for Tule Valley and part of Sevier Valley, Utah Evapotranspiration Units for Tule Valley and part of Sevier Valley, Utah Geospatial Data to Support Estimates of Annual Groundwater Discharge by Evapotranspiration from Areas of Spring-Fed Riparian Vegetation, Stump Spring and Hiko Springs, Clark County, southern Nevada Combined Groundwater Discharge Area and Area of Critical Environmental Concern for Stump Spring, NV Normalized Difference Vegetation Index for Vegetated Areas of the Groundwater Discharge Area, Hiko Springs, NV Maximum Likelihood Vegetation Classification for the Combined Groundwater Discharge Area and Area of Critical Environmental Concern, Stump Spring, NV Normalized Difference Vegetation Index Corresponding to Vegetated Areas in the Combined Groundwater Discharge Area and Area of Critical Environmental Concern, Stump Spring, NV Combined Groundwater Discharge Area and Area of Critical Environmental Concern for Stump Spring, NV Normalized Difference Vegetation Index Corresponding to Vegetated Areas in the Combined Groundwater Discharge Area and Area of Critical Environmental Concern, Stump Spring, NV Maximum Likelihood Vegetation Classification for the Combined Groundwater Discharge Area and Area of Critical Environmental Concern, Stump Spring, NV Normalized Difference Vegetation Index for Vegetated Areas of the Groundwater Discharge Area, Hiko Springs, NV Groundwater Discharge Area for Tule Valley and part of Sevier Valley, Utah Geospatial Data to Support Estimates of Annual Groundwater Discharge by Evapotranspiration from Areas of Spring-Fed Riparian Vegetation, Stump Spring and Hiko Springs, Clark County, southern Nevada Evapotranspiration Units, Groundwater Discharge Area, and 2007-2008 Summer Mean Vegetation Index for Tule Valley and part of Sevier Valley, Utah Scaled Modified Soil Adjusted Vegetation Index for Tule Valley and part of Sevier Valley, Utah Evapotranspiration Units for Tule Valley and part of Sevier Valley, Utah