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At least 1,117 records · Page 62Linked to original sources
USGS2020

Landscape and climatic influences on actual evapotranspiration and available water using the Operational Simplified Surface Energy Balance (SSEBop) Model in eastern Bernalillo County, New Mexico, 2015

The U.S. Geological Survey, in cooperation with the Bernalillo County Public Works Division, conducted a 1-year study in 2015 to assess the spatial and temporal distribution of evapotranspiration (ET) and available water within the East Mountain area in Bernalillo County, New Mexico. ET and available water vary spatiotemporally because of complex interactions among environmental factors, including vegetation characteristics, soil characteristics, topography, and climate. Precipitation data from the Parameter-Elevation Regressions on Independent Slopes Model (PRISM) ( P ) were used in conjunction with actual ET ( ETa ) data from the Operational Simplified Surface Energy Balance (SSEBop) model to estimate available water ( P – ETa ) at 100-meter (m) resolution in the study area. Maps, descriptive statistics, boxplots, regression analyses (continuous data), and multiple comparison tests (categorical data) were used to characterize P , ETa , and available water and their relations to topographic, soil, and vegetation datasets in the East Mountain area. Five categories of the natural land-cover type (evergreen forest, shrub, herbaceous, deciduous forest, and mixed forest) and four categories of developed land-cover type specific to residential intensity (developed open, developed low, developed medium, and developed high) were analyzed individually and in interaction with multiple elevation, tree canopy, and soil texture classes. Annual mean P in 2015 in the East Mountain area was 608 millimeters (mm), and annual mean ETa was 543 mm (89 percent of annual P in 2015), indicating that in 2015, a spatial mean of about 65 mm of water was available for runoff, soil moisture replenishment, or groundwater recharge. Monthly ETa was greatest in July and smallest in January. The intervening months did not show smooth temporal or consistent spatial changes from month to month. Months with lower ETa (January to March, October to December) also tended to have greater available water, indicating that soil moisture (water supply) and potential ET (water demand) may have been out of phase. Regression analyses showed that monthly ETa data had the highest correlation with annual ETa among the atmospheric, topographic, soil, or vegetation datasets, particularly during the early and late growing season (March, April, May, and September). In contrast, monthly P was highly variable and not as highly correlated with annual ETa . Among landscape variables, correlations with annual ETa were highest for tree canopy cover (coefficient of determination [R 2 ] = 0.46). Correlations between ETa and other landscape variables were lower (R 2 = 0.06–0.19): available soil water in the top 100 centimeters, soil bulk density of layer 1, slope, sand content of soil layer 1, soil depth, available soil water in the top 25 centimeters, leaf area index, aspect eastness, and elevation. Evergreen forest areas had the highest annual median ETa , followed by mixed forest, open residential areas, and deciduous forest. Available water typically was higher in landcover types with lower ETa : herbaceous cover, followed by deciduous forest, high-intensity developed areas, and shrub. Deciduous forest had the second highest median available water, despite having the fourth highest ETa , because deciduous forest had greater P than most other areas. Annual median ETa typically was greatest in the second highest elevation band (2,401–2,800 m above the North American Vertical Datum of 1988 [NAVD 88]), and lower in the highest elevation band (2,801–3,254 m above NAVD 88), despite having greater P , likely because of decreased tree canopy cover or a shift from evergreen to deciduous trees at the highest elevations. Annual median ETa increased with tree canopy cover, regardless of landcover type. ETa correlation was higher with tree canopy than with leaf area index or normalized difference vegetation index. This result indicates that it is important to include the thermal band (from satellite multispectral data) in vegetation indices used to describe ETa , perhaps to account for the influence of energy limitation or water limitation on ET. Of all natural landcover types, finer soils had the most available water, whereas coarser soils had the least available water. Relations of soil type with P – ETa were different than with ETa , indicating ET and available water have a complex response to differences in soil type. Further modeling would be useful in determining soils’ infiltration, storage, conductivity, and plant-water availability relations to individual storms for each position in the landscape, as well as the corresponding effects of these processes on ET and available water. The best multivariate linear model for annual ETa had an R 2 value of 0.62. Monthly ETa models had R 2 values between 0.16 and 0.65. Models usually, but not always, performed best during the growing season. These results indicate that even the best multivariate linear models cannot explain a notable amount of the variability in ET. The monthly ETa models with the highest correlations (August and September) followed a July having almost twice the mean precipitation for July (1981–2010), which indicates that a soil-moisture variable is needed to more accurately model monthly ETa . Further study is needed to better characterize this system, the variables that affect ET and available water, and the partitioning of available water into runoff, soil moisture storage, and groundwater recharge.

New Mexico↗
USGS2007

Deriving a light use efficiency model from eddy covariance flux data for predicting daily gross primary production across biomes

The quantitative simulation of gross primary production (GPP) at various spatial and temporal scales has been a major challenge in quantifying the global carbon cycle. We developed a light use efficiency (LUE) daily GPP model from eddy covariance (EC) measurements. The model, called EC-LUE, is driven by only four variables: normalized difference vegetation index (NDVI), photosynthetically active radiation (PAR), air temperature, and the Bowen ratio of sensible to latent heat flux (used to calculate moisture stress). The EC-LUE model relies on two assumptions: First, that the fraction of absorbed PAR (fPAR) is a linear function of NDVI; Second, that the realized light use efficiency, calculated from a biome-independent invariant potential LUE, is controlled by air temperature or soil moisture, whichever is most limiting. The EC-LUE model was calibrated and validated using 24,349 daily GPP estimates derived from 28 eddy covariance flux towers from the AmeriFlux and EuroFlux networks, covering a variety of forests, grasslands and savannas. The model explained 85% and 77% of the observed variations of daily GPP for all the calibration and validation sites, respectively. A comparison with GPP calculated from the Moderate Resolution Imaging Spectroradiometer (MODIS) indicated that the EC-LUE model predicted GPP that better matched tower data across these sites. The realized LUE was predominantly controlled by moisture conditions throughout the growing season, and controlled by temperature only at the beginning and end of the growing season. The EC-LUE model is an alternative approach that makes it possible to map daily GPP over large areas because (1) the potential LUE is invariant across various land cover types and (2) all driving forces of the model can be derived from remote sensing data or existing climate observation networks.

Agricultural and Forest Meteorology↗
USGS1996

Status of ground-water resources at U.S. Navy Support Facility, Diego Garcia; summary of hydrologic and climatic data, January 1993 through September 1995

This report contains hydrologic and climatic data that describe the status of ground-water resources at U.S. Navy Support Facility, Diego Garcia. Data presented are from January 1993 through September 1995, although the report focuses on hydrologic events from July through September 1995. Cumulative rainfall for July through September 1995 was about 15 inches which is 32 percent less than the mean cumulative rainfall of about 22 inches for July through September. July and August are within the annual dry season, while September is the start of the annual wet season. Mean cumulative rainfall is calculated for the fixed base period 1951-90. Ground-water withdrawal during July through September 1995 averaged 888,500 gallons per day. Withdrawal for the same 3 months in 1994 averaged 919,400 gallons per day. Patterns of withdrawal during the third quarter of 1995 did not change significantly since 1993 at all five ground-water production areas. At the end of September 1995, the chloride concentration of the composite water supply was 51 milligrams per liter, well below the 250 milligrams per liter secondary drinking-water standard established by the U.S. Environmental Protection Agency. Chloride concentrations of the composite water supply from July through September 1995 ranged between 42 and 68 milligrams per liter. Chloride concentration of ground water in monitoring wells at Cantonment and Air Operations continued to increase since April 1995, with water from the deepest monitoring wells increasing in chloride concentration by as much as 2,000 milligrams per liter. A fuel leak at Air Operations caused the shutdown of ten wells in May 1991. Four of the wells resumed pumping for water-supply purposes in April 1992. The remaining six wells are being used to hydraulically divert fuel migration away from water-supply wells by recirculating about 150,000 gallons of water each day.

Open-File Report↗
USGS2026

Gambel’s quail (Callipepla gambelii) nest site selection and habitat use in Oracle Junction, Arizona

Gambel’s quail ( Callipepla gambelii ) is the most widespread, abundant, and heavily harvested species of game quail in Arizona. Gambel’s quail population dynamics in Arizona are strongly influenced by seasonal weather conditions. This is particularly relevant for Gambel’s quail management as drought conditions are expected to increase in Arizona, and this may exacerbate inter-annual variation in Gambel’s quail abundance and recruitment. The goal of this study is to provide information on Gambel’s quail population demographics, habitat use, and movement to inform land management decisions for Gambel’s quail in southeast Arizona in a way that mitigates the effect of drought. We used multiple trapping methods to capture Gambel’s quail from February–July 2024 and February–15 May 2025. We found noose mats (n = 57) to be more effective than drop traps (n=14) in capturing Gambel’s quail, with multiple types of walkin traps proving ineffective. We deployed 33 GPS backpack transmitters on female Gambel’s quail to monitor their movements and locate nests. We documented eight mortalities of tracked quail from apparent predation. Quail home range sizes ranged from 3 ha-100 ha (mean = 25 ha) in 2024 and from 7–57 ha (mean = 29 ha) in 2025. We identified four nest sites with 6-15 eggs and all nests were predated. We collected vegetation measurements at nest and brood sites and corresponding random points to examine nest and brood site selection although our small sample sizes limited our ability to make inferences about Gambel’s quail habitat selection.

Arizona↗
USGS2001

Effects of urbanization on streamflow in the Atlanta area (Georgia, USA): A comparative hydrological approach

For the period from 1958 to 1996, streamflow characteristics of a highly urbanized watershed were compared with less-urbanized and non-urbanized watersheds within a 20 000 km2 region in the vicinity of Atlanta, Georgia: In the Piedmont and Blue Ridge physiographic provinces of the southeastern USA. Water levels in several wells completed in surficial and crystalline-rock aquifers were also evaluated. Data were analysed for seven US Geological Survey (USGS) stream gauges, 17 National Weather Service rain gauges, and five USGS monitoring wells. Annual runoff coefficients (RCs; runoff as a fractional percentage of precipitation) for the urban stream (Peachtree Creek) were not significantly greater than for the less-urbanized watersheds. The RCs for some streams were similar to others and the similar streams were grouped according to location. The RCs decreased from the higher elevation and higher relief watersheds to the lower elevation and lower relief watersheds: Values were 0.54 for the two Blue Ridge streams. 0.37 for the four middle Piedmont streams (near Atlanta), and 0.28 for a southern Piedmont stream. For the 25 largest stormflows, the peak flows for Peachtree Creek were 30% to 100% greater then peak flows for the other stream. The storm recession period for the urban stream was 1-2 days less than that for the other streams and the recession was characterized by a 2-day storm recession constant that was, on average, 40 to 100% greater, i.e. streamflow decreased more rapidly than for the other streams. Baseflow recession constants ranged from 35 to 40% lower for Peachtree Creek than for the other streams; this is attributed to lower evapotranspiration losses, which result in a smaller change in groundwater storage than in the less-urbanized watersheds. Low flow of Peachtree Creek ranged from 25 to 35% less than the other streams, possibly the result of decreased infiltration caused by the more efficient routing of stormwater and the paving of groundwater rechange areas. The timing of daily or monthly groundwater-level fluctuations was similar annually in each well, reflecting the seasonal recharge. Although water-level monitoring only began in the 1980s for the two urban wells, water levels displayed a notable decline compared with non-urban wells since then; this is attributed to decreased groundwater rechange in the urban watersheds due to increased imperviousness and related rapid storm runoff. Copyright ?? 2001 John Wiley & Sons, Ltd.

Hydrological Processes↗
USGS2010

Thermal Imaging of the Waccasassa Bay Preserve: Image Acquisition and Processing

Thermal infrared (TIR) imagery was acquired along coastal Levy County, Florida, in March 2009 with the goal of identifying groundwater-discharge locations in Waccasassa Bay Preserve State Park (WBPSP). Groundwater discharge is thermally distinct in winter when Floridan aquifer temperature, 71-72 degrees F, contrasts with the surrounding cold surface waters. Calibrated imagery was analyzed to assess temperature anomalies and related thermal traces. The influence of warm Gulf water and image artifacts on small features was successfully constrained by image evaluation in three separate zones: Creeks, Bay, and Gulf. Four levels of significant water-temperature anomalies were identified, and 488 sites of interest were mapped. Among the sites identified, at least 80 were determined to be associated with image artifacts and human activity, such as excavation pits and the Florida Barge Canal. Sites of interest were evaluated for geographic concentration and isolation. High site densities, indicating interconnectivity and prevailing flow, were located at Corrigan Reef, No. 4 Channel, Winzy Creek, Cow Creek, Withlacoochee River, and at excavation sites. In other areas, low to moderate site density indicates the presence of independent vents and unique flow paths. A directional distribution assessment of natural seep features produced a northwest trend closely matching the strike direction of regional faults. Naturally occurring seeps were located in karst ponds and tidal creeks, and several submerged sites were detected in Waccasassa River and Bay, representing the first documentation of submarine vents in the Waccasassa region. Drought conditions throughout the region placed constraints on positive feature identification. Low discharge or displacement by landward movement of saltwater may have reduced or reversed flow during this season. Approximately two-thirds of seep locations in the overlap between 2009 and 2005 TIR night imagery were positively re-identified in 2009. These results indicate a 33 percent chance of feature omission in the 2009 imagery. This assessment of seep location and distribution contributes to an understanding of the underlying geology, the role of fault and fracture patterns, and the presence of both interconnected and constrained flow paths in the region. The maps and evaluations will enhance Park management efforts, interpretation of Park resources, and increase understanding of the combined effects of land and water use on the coastal lowlands, estuarine habitats, and natural resources of WBPSP.

Open-File Report↗
USGS2007

Summary of Optical-Backscatter and Suspended-Sediment Data, Tomales Bay Watershed, California, Water Years 2004, 2005, and 2006

The U.S. Geological Survey, in cooperation with Point Reyes National Seashore, is studying suspended-sediment transport dynamics in the two primary tributaries to Tomales Bay, Lagunitas Creek and Walker Creek. Suspended-sediment samples and continuous optical backscatter (turbidity) data were collected at three locations during water years 2004?06 (October 1, 2003?September 30, 2006): at two sites in the Lagunitas Creek watershed and at one site in the Walker Creek watershed. Sediment samples were analyzed for suspended-sediment concentration, grain size, and turbidity. Data were used to estimate mean daily and annual seasonal suspended-sediment discharge, which were published in U.S. Geological Survey Annual Water-Data Reports. Data were utilized further in this report to develop field-based optical-backscatter calibration equations, which then were used to derive a continuous time series (15-minute interval) of suspended-sediment concentrations. Sensor fouling and aggradation of the channel bed occurred periodically throughout the project period, resulting in data loss. Although periods of data loss occurred, collection of optical sensor data improved our understanding of suspended-sediment dynamics in the Lagunitas Creek and Walker Creek watersheds by providing continuous time-series storm event data that were analyzed to determine durations of elevated sediment concentrations (periods of time when suspended-sediment concentration was greater than 100 mg/L). Data derived from this project contributed baseline suspended-sediment transport information that will be used to develop and implement sediment total maximum daily loads for Tomales Bay and its tributary watersheds, and provides supporting information for additional total maximum daily loads (pathogens, nutrients, and mercury) and restoration efforts for four federally listed aquatic species that are affected directly by sediment loading in the Tomales Bay watershed. In addition, this project provided an opportunity to evaluate the suitability of using optical data as a surrogate for more traditional labor-intensive methods of measuring suspended-sediment transport in steep coastal watersheds.

Scientific Investigations Report↗
USGS2013

Comparison of water consumption in two riparian vegetation communities along the central Platte River, Nebraska, 2008–09 and 2011

The Platte River is a vital natural resource for the people, plants, and animals of Nebraska. A recent study quantified water use by riparian woodlands along central reaches of the Platte River, Nebraska, finding that water use was mainly regulated below maximum predicted levels. A comparative study was launched through a cooperative partnership between the U.S. Geological Survey, the Central Platte Natural Resources District, the Nebraska Department of Natural Resources, and the Nebraska Environmental Trust to compare water use of a riparian woodland with that of a grazed riparian grassland along the central Platte River. This report describes the results of the 3-year study by the U.S. Geological Survey to measure the evapotranspiration (ET) rates in the two riparian vegetation communities. Evapotranspiration was measured during 2008–09 and 2011 using the eddy-covariance method at a riparian woodland near Odessa, hereinafter referred to as the “woodland site,” and a riparian grassland pasture near Elm Creek, hereinafter referred to as the “grassland site.” Overall, annual ET totals at the grassland site were 90 percent of the annual ET measured at the woodland site, with averages of 653 millimeters (mm) and 726 mm, respectively. Evapotranspiration rates were similar at the grassland site and the woodland site during the spring and fall seasons, but at the woodland site ET rates were higher than those of the grassland site during the peak-growth summer months of June through August. These seasonal differences and the slightly lower ET rates at the grassland site were likely the result of differing plant communities, disturbance effects related to grazing and flooding, and climatic differences between the sites. The annual water balance was calculated for each site and indicated that the predominant factors in the water balance at both sites were ET and precipitation. Annual precipitation for the study period ranged from near to above the normal precipitation of 640 mm. Substantial precipitation fell in May and October 2008 that caused flooding along the Platte River in May of this especially wet year. There was a deficit in precipitation compared to ET at both sites in 2009 and 2011, leading to a net groundwater use of greater than 140 mm per year at the woodland site and greater than 55 mm per year at the grassland site. This indicates that the net annual groundwater use or recharge depends predominately upon the relation between ET and precipitation in these riparian areas with shallow soil layers above the groundwater table. Prior research at the woodland site provided four additional annual water balances dating back to 2002 for comparison with the study period at the woodland site. Perhaps most striking in this comparison was the 25-percent increase in annual ET for 2008–09 and 2011 despite precipitation totals and potential ET rates that were within the range of those measured in 2002–05. As a result, the water balance indicates that groundwater was discharged 2 of the 3 years of the study. This likely was caused by higher groundwater levels and a healthier plant community in 2008–09 and 2011 relative to the drought-affected years of 2002–05. As a result of these changes, the crop coefficients developed for riparian woodlands during the prior research underestimated 2008–09 and 2011 annual ET rates by an average of 35 percent. Though new crop coefficients were developed by this study, the importance of soil-moisture stress and plant community successional dynamics need to be considered when applying these coefficients at other riparian sites or into the future. Nonetheless, their development and the data on which they are based may provide improved understanding of water consumption by riparian grasslands and riparian woodlands along the central Platte River.

Nebraska↗
USGS2011

Report of the River Master of the Delaware River for the period December 1, 2006–November 30, 2007

A Decree of the Supreme Court of the United States, entered June 7, 1954, established the position of Delaware River Master within the U.S. Geological Survey (USGS). In addition, the Decree authorizes diversions of water from the Delaware River Basin and requires compensating releases from certain reservoirs, owned by New York City, to be made under the supervision and direction of the River Master. The Decree stipulates that the River Master will furnish reports to the Court, not less frequently than annually. This report is the 54th Annual Report of the River Master of the Delaware River. It covers the 2007 River Master report year—the period from December 1, 2006, to November 30, 2007. During the report year, precipitation in the upper Delaware River Basin was 46.72 inches (in.) or 107 percent of the long-term average. Combined storage in Pepacton, Cannonsville, and Neversink Reservoirs was high on December 1, 2006. Reservoir storage remained high throughout the winter, declined seasonally during the summer, and began to recover in mid-October. Delaware River operations throughout the year were conducted as stipulated by the Decree. Diversions from the Delaware River Basin by New York City and New Jersey were in full compliance with the Decree. Reservoir releases were made as directed by the River Master at rates designed to meet the flow objective for the Delaware River at Montague, New Jersey, on 123 days during the report year. Releases were made at conservation rates—or rates designed to relieve thermal stress and protect the fishery and aquatic habitat in the tailwaters of the reservoirs—on all other days. During the report year, New York City and New Jersey complied fully with the terms of the Decree, and directives and requests of the River Master. As part of a long-term program, the quality of water in the Delaware Estuary between Trenton, New Jersey, and Reedy Island Jetty, Delaware, was monitored at various locations. Data on water temperature, specific conductance, dissolved oxygen, and pH were collected continuously by electronic instruments at four sites. In addition, selected water-quality data were collected at 19 sites on a twice–monthly basis and at 3 sites on a monthly basis.

Delaware;Pennsylvania;New York↗
USGS2026

Miocene evolution of the Humboldt Current

Diatom records from the East Pisco Basin (EPB) of southern Peru and offshore Ocean Drilling Program (ODP) Hole 682 A reveal stepwise increases in the primary productivity of the Humboldt Current during the middle and late Miocene. Although diatoms are present back through the late middle Eocene, successively enhanced diatom production occurs during the Miocene in four steps. The first step between 14.2 and 13.8 Ma marks the onset of diatom deposition in the Pisco-0 sequence. A second step at ∼12.9 Ma coincides with a major drop in global sea level during which diatom deposition ceased in the EPB but continued in ODP 682 A as well as in Chile, Ecuador, and Colombia. Beginning at 10.4 to 10.0 Ma, a major increase in diatom sedimentation rates in both the EPB and in ODP 682 A signals an abrupt intensification of the Humboldt Current productivity, which may be related to the closure of the Central American Seaway to deeper water circulation. A fourth step coincides with the transgressive deposition of the diatom-rich Pisco-2 sequence at 8.4 Ma and is enhanced by the onset of the global Late Miocene Biogenic Bloom (8.0–4.5 Ma). Between 7 and 6 Ma, common subtropical diatoms in ODP 682 A contrast with high diatom deposition rates in the EPB, suggesting variable El Niño-La Niña conditions. During this time, fossil vegetation evidence from southern Peru supports the presence of seasonal periods of enhanced rainfall typical of El Niño conditions. The Miocene trend of increasing sea mammal diversity in the EPB parallels these steps, further supporting stepwise enhancement of primary productivity in the Humboldt Current during the Miocene.

Humboldt Current↗
USGS2014

Report of the River Master of the Delaware River for the period December 1, 2007-November 30, 2008

A Decree of the Supreme Court of the United States, entered June 7, 1954, established the position of Delaware River Master within the U.S. Geological Survey (USGS). In addition, the Decree authorizes diversions of water from the Delaware River Basin and requires compensating releases from certain reservoirs, owned by New York City, to be made under the supervision and direction of the River Master. The Decree stipulates that the River Master will furnish reports to the Court, not less frequently than annually. This report is the 55th Annual Report of the River Master of the Delaware River. It covers the 2008 River Master report year, the period from December 1, 2007, to November 30, 2008. During the report year, precipitation in the upper Delaware River Basin was 49.79 inches (in.) or 114 percent of the 67 report-year average. Combined storage in Pepacton, Cannonsville, and Neversink Reservoirs remained high from December 2007 to May 2008. Reservoir storage decreased seasonally from June to late October, then increased gradually through the end of November. Delaware River operations during the year were conducted as stipulated by the Decree. Diversions from the Delaware River Basin by New York City and New Jersey were in full compliance with the Decree. Reservoir releases were made as directed by the River Master at rates designed to meet the flow objective for the Delaware River at Montague, New Jersey, on 107 days during the report year. Releases were made at conservation rates—rates designed to relieve thermal stress and protect the fishery and aquatic habitat in the tailwaters of the reservoirs—on all other days. During the report year, New York City and New Jersey complied fully with the terms of the Decree, and directives and requests of the River Master. As part of a long-term program, the quality of water in the Delaware Estuary between Trenton, New Jersey, and Reedy Island Jetty, Delaware, was monitored at various locations. Data on water temperature, specific conductance, dissolved oxygen, and pH were collected continuously by electronic instruments at four sites. Data on water temperature and specific conductance were collected intermittently at one site. In addition, selected water-quality data were collected at 19 sites on a twice-monthly basis and at 3 sites on a monthly basis.

Delaware;New Jersey;New York;Pennsylvania↗
USGS2016

Federal collaboration in science for invasive mammal management in U.S. National Parks and Wildlife Refuges of the Pacific Islands

Some of the most isolated islands in the Pacific Ocean are home to US National Parks and Wildlife Refuges. These islands are known for flora and fauna that occur nowhere else, but also for invasive species and other factors which have resulted in the disproportionate extinction of native species. The control of invasive mammals is the single most expensive natural resource management activity essential for restoring ecological integrity to parks in the Hawaiian Islands, American Samoa, and the islands of Guam and Saipan. Science-based applications supporting management efforts have been shaped by longstanding collaborative federal research programs over the past four decades. Consequently, feral goats (Capra hircus) have been removed from >690 km2 in National Parks, and feral pigs (Sus scrofa) have been removed from >367 km2 of federal lands of Hawai‘i, bringing about the gradual recovery of forest ecosystems. The exclusion of other non-native ungulates and invasive mammals is now being undertaken with more sophisticated control techniques and fences. New fence designs are now capable of excluding feral cats (Felis catus) from large areas to protect endangered native waterfowl and nesting seabirds. Rodenticides which have been tested and registered for hand and aerial broadcast in Hawai‘i have been used to eradicate rats from small offshore islands to protect nesting seabirds and are now being applied to montane environments of larger islands to protect forest birds. Forward-looking infrared radar (FLIR) is also being applied to locate wild ungulates which were more recently introduced to some islands. All invasive mammals have been eradicated from some remote small islands, and it may soon be possible to manage areas on larger islands to be free of invasive mammals at least during seasonally important periods for native species.

Conference Paper↗
USGS2006

Concentrations, fluxes, and yields of nitrogen, phosphorus, and suspended sediment in the Illinois River basin, 1996-2000

Concentrations, spatial and temporal variations, and fluxes of nitrogen, phosphorus, and suspended sediment were determined for 16 streams in the Illinois River Basin, Illinois from October 1996 through September 2000. Water samples were collected through the National Water-Quality Assessment's Lower Illinois River Basin (LIRB) and Upper Illinois River Basin (UIRB) Study Units on a monthly to weekly frequency from watersheds representing predominantly agricultural and urban land, as well as areas of mixed land-use. Streams in agricultural watersheds had high concentrations and fluxes of nitrate nitrogen, whereas streams in predominantly urban watersheds had high concentrations (above background levels) of ammonia nitrogen, organic nitrogen, and phosphorus. Median concentrations of nitrate nitrogen and total phosphorus were similar at the two Illinois River sampling stations (Illinois River at Ottawa, Ill. and Illinois River at Valley City, Ill.) that represented the downstream points of the UIRB and LIRB Study Units, respectively, and integrated multiple land-use areas. Concentrations of nitrogen were typically highest in the spring and lowest in the fall in agricultural watersheds, but highest in the winter in urban watersheds. Phosphorus concentrations in urban watersheds were highest in the fall and winter, but there was minimal seasonal variation in phosphorus concentrations in agricultural watersheds. Concentrations of nitrate and total nitrogen were affected primarily by non-point sources and hydrologic factors such as streamflow, storm intensity, watershed configuration, and soil permeability, whereas concentrations of phosphorus were affected largely by point-source contributions that typically have little seasonal variation. Seasonal variation in hydrologic conditions was an important factor for seasonal variation in nutrient concentration. Fluxes and yields of nitrogen and phosphorus forms varied substantially throughout the Illinois River Basin, and yields of specific nutrient forms were determined primarily by upstream land uses. Yields of nitrate nitrogen were highest in predominantly agricultural watersheds, whereas yields of phosphorus and ammonia nitrogen were highest in urban watersheds with wastewater effluent contributions. Yields of both total nitrogen and total phosphorus were similar at the two Illinois River stations representing the integrated UIRB and LIRB Study Units. Concentrations of suspended sediment ranged from 1 to 3,110 milligrams per liter (mg/L), with median concentrations generally higher in the UIRB. Suspended-sediment concentrations were highest and most variable in the LaMoine River Basin. The median concentration of suspended sediment in the Illinois River at Valley City, Ill. (155 mg/L) was twice as high as that at Ottawa, Ill. (80 mg/L). Fluxes of suspended sediment generally corresponded to watershed size and yields from agricultural watersheds were larger than yields from urban watersheds. The flux in the Illinois River at Valley City, Ill. (4,880,000 tons per year) was approximately four times the flux in the Illinois River at Ottawa, Ill. (1,060,000 tons per year).

Scientific Investigations Report↗
USGS2001

Occurrence and distribution of pesticides in streams of the Eastern Iowa Basins, 1996-98

The U.S. Geological Survey began collection of water samples in streams of the Eastern Iowa Basins in 1996 for the analysis of pesticides and pesticide degradates as part of the National Water Quality Assessment Program (NAWQA). This study provides some of the first large scale monitoring data on pesticides and pesticide degradates in Eastern Iowa. Three hundred and forty-four samples were collected from 1996-98 to document the occurrence, distribution, and transport of pesticide compounds. Pesticide analysis included 80 pesticide compounds and 10 pesticide degradates. The Eastern Iowa Basins study encompasses about 50,500 square kilometers (19,500 square miles) and is drained by four major rivers--the Wapsipinicon, Cedar, Iowa, and Skunk. Agriculture accounts for approximately 93 percent of the land use in the study area. The most commonly detected pesticides were those most heavily used on crops. The triazine (atrazine and cyanazine) and chloroacetanilide (alachlor, acetochlor, and metolachlor) pesticides are some of the most heavily used (by weight) historically and during the period of data collection 1996-98. Atrazine and metolachlor were detected in all samples. Acetochlor, alachlor, and cyanazine were detected in more than 70 percent of all surface-water samples. Few non-agricultural herbicides were detected. One exception, prometon was detected in more than 80 percent of the samples at very low concentrations (less than 0.1 micrograms per liter). Pesticide degradates were some of the most frequently detected pesticide compounds in the study. Four pesticide degradates--metolachlor ethane sulfonic acid (metolachlor ESA), alachlor ethane sulfonic acid (alachlor ESA), metolachlor oxanilic acid (metolachlor OA), and acetochlor ethane sulfonic acid (acetochlor ESA) were detected in more than 75 percent of the samples. A few insecticides that may pose potential risk to aquatic invertebrates were detected in streams from May through September, the months when most application normally occurs. Carbofuran was the most commonly detected insecticide (16 percent of all samples). Although detected in less than 20 percent of all samples, carbofuran was detected in 68 percent of the samples in June. When present, carbofuran concentrations were generally less than 0.80 micrograms per liter. Chloropyrifos was detected in about seven percent of the samples. As with other insecticides, chlorpyrifos was detected most frequently in June (30 percent). The highest concentration was 0.06 micrograms per liter. Diazinon, a common urban insecticide found in other NAWQA studies throughout the Nation, was detected in only 2 percent of the samples in the Eastern Iowa Basins study. Pesticides were found to occur in mixtures with several compounds rather than individually. Four or more parent pesticide compounds were detected in 91 percent of the water samples and seven or more parent compounds were detected in 46 percent of the water samples. Four or more pesticide degradates were detected in 93 percent of the water samples and seven or more pesticide degradates were detected in 46 percent of the water samples. Commonly applied parent pesticide compounds (acetochlor, alachlor, atrazine, cyanazine, and metolachlor) were generally detected at low concentrations with median concentrations ranging from 0.01 to 0.22 micrograms per liter. The median concentrations for the pesticide degradates were larger than their parent compounds. Median concentrations for the pesticide degradates ranged from 0.07 to 3.7 micrograms per liter. Acetochlor, alachlor, atrazine, cyanazine and metolachlor pesticides compounds were present at least an order of magnitude or higher in the late spring and summer than at other times of the year. The maximum measured concentrations for acetochlor, atrazine, cyanazine and metolachor were approximately 11 to 48 micrograms per liter (the maximum for alachlor was 0.56 micrograms per liter). In contrast, maximum measured concentrations for the total pesticide degradates were lower than their parent compounds and ranged from approximately 0.7 to 12 micrograms per liter. The maximum measured concentration of a single pesticide compound was for atrazine at 48 micrograms per liter. Seasonal patterns of atrazine, acetochlor, alachlor, cyanazine, and metolachlor generally show peak concentrations following application in May and June and decreasing during remainder of the growing season. In addition, a small secondary peak in atrazine, acetochlor, alachlor, cyanazine, and metolachlor concentrations occurred at all sites in late winter. This secondary peak may be attributed to early "winter thaw" that can release pesticide residue from soil, making pesticides available to be transported to surface water by snowmelt and early spring rains. Pesticide degradates account for a significant portion of the total pesticide load at all sites. Eighty-one percent of the total pesticide load in samples from Iowa River near Rowan, Wolf Creek near Dysart, and the Iowa River at Wapello were as pesticide degradates. The pesticide degradates for the triazine compounds tended to follow the load pattern of the parent pesticide compounds closely throughout the year. In general, the degradate loads calculated for the triazine compounds were smaller than loads calculated for their parent pesticides. The loads for the chloroacetanilide degradate compounds were larger than those for the parent pesticides. The loads for alachlor were found to be small or nonexistent. Alachlor has been heavily used in the past, but since 1995 has been largely replaced by acetochlor or other herbicides. The loads for all degradates were higher than the parent compounds during the winter months. Overland flow may be diminished during the winter months, but shallow sub-soil drainage and ground-water flow may be a source of many pesticide degradates during the late fall and winter. Occurrence of pesticide compounds varied by landform region. The triazine herbicides, atrazine and cyanazine and their degradates were present in significantly greater concentrations in the Southern Iowa Drift Plain (predominantly loess soils) than either the Des Moines Lobe or the Iowan Surface (predominantly till soils). Less atrazine and cyanazine are applied to till soils because of pH and organic carbon content. Alachlor, metolachlor, and acetochlor have often been used to offset triazine pesticide reductions in area with till soils.

Iowa↗
USGS2025

Leveraging wildfire to augment forest management and amplify forest resilience

Successive catastrophic wildfire seasons in western North America have escalated the urgency around reducing fire risk to communities and ecosystems. In historically frequent-fire forests, fuel buildup as a result of fire exclusion is contributing to increased fire severity. The probability of high-severity fire can be reduced by active forest management that reduces fuels, prompting federal and state agencies to commit significant resources to increase the pace and scale of fuel reduction treatments. However, lower severity areas of wildfires also have the potential to act as “treatments,” and even catastrophic fires with large areas of high severity can still have substantial areas of lower severity fire that may be improving forest conditions locally. We quantified active management and wildfire severity across yellow pine and mixed conifer (YPMC) forests in the Sierra Nevada of California over a 22-year period (2001–2022). We did not detect increases in the area treated through time, but the area of beneficial wildfire (low to moderate severity) increased substantially, exceeding active treatment area in 8 of 22 years. Overall, beneficial wildfire treated ~17% more area than all treatments combined, and roughly four times more area than fire-related treatments alone. We then used disturbance history to evaluate resistance to high-severity wildfire and forest loss across the YPMC range. Of the 2.3 million ha YPMC of forests in 2001, 20% lost mature forests due to high-severity fire by 2022, which is nearly half of all YPMC area burned. Most of the landscape (47%) remains at risk of high-severity fire because it had no restorative disturbances, but 33% of the study area has some level of resistance to high-severity wildfire. In these areas, resistance will need to be enhanced and maintained over time via active management or managed wildfire, but these treatment needs will likely outpace capacity even under optimistic implementation scenarios. Given limited resources for implementing active management and the likelihood of a more fiery future, incorporating beneficial wildfire into landscape-level treatment planning has the potential to amplify the impact of active management treatments.

California, Nevada↗
USGS2023

Status and trends of total nitrogen and total phosphorus concentrations, loads, and yields in streams of Mississippi, water years 2008–18

To assess the status and trends of conditions of surface waters throughout Mississippi, the U.S. Geological Survey, in cooperation with the Mississippi Department of Environmental Quality (MDEQ), summarized concentrations and estimated loads, yields, trends, and spatial and temporal patterns of total nitrogen (TN) and total phosphorus (TP) at 20 stream sites in MDEQ’s ambient water-quality monitoring network and 2 stream sites in the U.S. Geological Survey’s National Water-Quality Assessment Project’s monitoring network. Comparison of streamflow at the time of water-quality sample collection to flow-duration curves for each site showed that samples were relatively evenly spread over a wide range of flows, indicating that load estimations were representative of a wide range of flows. Relation of streamflow to concentrations of TN and TP varied among sites and land use. Sites with high agriculture land use in the drainage basin tended to have a positive correlation between streamflow and concentration, suggesting influence of event-driven nonpoint-source runoff. Sites near urban (developed) areas tended to have a negative correlation between streamflow and concentration, suggesting chronic point-source influences during low-flow conditions. Sites with high forest land use and lower agriculture and urban (developed) land use showed little to no association between streamflow and concentration. Seasonal distributions of concentrations of TN and TP also corresponded closely with variations in land use. Sites near urban (developed) land had the highest concentrations in late summer and fall, sites with a high percentage of agricultural land had the highest concentrations in the spring, and sites that were primarily forested or with little developed land did not exhibit substantial changes in concentration across seasons. Eight sites had statistical likelihoods for upward trends of TN loads, and seven sites had statistical likelihoods for downward trends. Trends in TN loads at six sites were considered “about as likely as not,” meaning that a site has an equal chance of having an upward or downward trend. Trend results of mean annual flow-normalized loads of TP for the period of analysis (2008–18) showed that 16 sites had upward trends, 3 sites had downward trends, and 2 sites were considered “about as likely as not.” Results from our study were compared to results from existing regional models to assess accuracy of predictions at a local scale. Comparisons of yields predicted from 2012 regional-scale SPAtially Referenced Regressions on Watershed attributes (SPARROW) to results from this study showed the 2012 SPARROW-predicted estimates varied in consistency with results from this study. The 2012 SPARROW-prediction model underestimated TN yields, more often and by a slightly larger degree, more than it overestimated TN yields. The 2012 SPARROW-predicted model tended to underestimate yields at study sites with higher yields. All four sites in the predominantly agricultural area of northwest Mississippi, locally known as the Mississippi Delta, were underestimated by 2012 SPARROW. For TP, yield comparisons at sites with lower yields were consistent, yields at sites with midrange yields tended to be overestimated by SPARROW, and yields at sites with high yields tended to be underestimated by SPARROW. TP yields at four sites in the Mississippi Delta were underestimated by the 2012 SPARROW-predicted model. Results of select sites from our study were also compared to other published load estimates from an earlier time period to evaluate possible trends. Comparison of TN yields at four sites and TP yields at three sites from the study-derived estimates to estimates made from data spanning 1993–2004 showed decreasing TN yields at all four sites and decreasing TP yields at two of three sites, with increasing yields of TP at the Yazoo River lower site. Also, a third comparison of the TN and TP yields of the Yazoo River lower site of this study to estimates made from data spanning 1996–97 showed decreasing TN yields but similar TP yields. This suggests that TN yields may have decreased over the last 20–30 years, but TP yields remain constant or are increasing.

Mississippi↗
USGS2016

Dispersal limitation does not control high elevational distribution of alien plant species in the southern Sierra Nevada, California

Patterns of elevational distribution of alien plant species in the southern Sierra Nevada of California were used to test the hypothesis that alien plant species invading high elevations around the world are typically climate generalists capable of growing across a wide elevational range. The Sierra Nevada has been heavily impacted for more than a century and a half, first by heavy grazing up into high elevation meadows, followed by major logging, and finally, by impacts associated with recreational use. The comparative elevational patterns of distribution and growth form were compared for native and alien plant species in the four families (Asteraceae, Brassicaceae, Fabaceae, and Poaceae) that contribute the majority of naturalized aliens in the study area. The distribution of realized climatic niche breadth, as measured by elevational range of occurrence, was virtually identical for alien and native species, with both groups showing a roughly Gaussian distribution peaking with species whose range covers a span of 1500–1999 m. In contrast to alien species, which only rarely occurred at higher elevations, native species showed a distribution of upper elevation limits peaking at 3000–3499 m, an elevation that corresponds to the zone of upper montane and subalpine forests. Consistent with a hypothesis of abiotic limitations, only a few alien species have been ecologically successful invaders at subalpine and alpine elevations above 2500 m. The low diversity of aliens able to become established in these habitats is unlikely due to dispersal limitations, given the long history of heavy grazing pressure at high elevations across this region. Instead, this low diversity is hypothesized to be a function of life history traits and multiple abiotic stresses that include extremes of cold air and soil temperature, heavy snowfall, short growing seasons, and low resource availability. These findings have significant implications for resource managers.

California↗
USGS2015

Future wave and wind projections for United States and United-States-affiliated Pacific Islands

Changes in future wave climates in the tropical Pacific Ocean from global climate change are not well understood. Spatially and temporally varying waves dominate coastal morphology and ecosystem structure of the islands throughout the tropical Pacific. Waves also impact coastal infrastructure, natural and cultural resources, and coastal-related economic activities of the islands. Wave heights, periods, and directions were forecast through the year 2100 using wind parameter outputs from four atmosphere-ocean global climate models from the Coupled Model Inter-Comparison Project, Phase 5, for Representative Concentration Pathways (RCP) scenarios 4.5 and 8.5 that correspond to moderately mitigated and unmitigated greenhouse gas emissions, respectively. Wind fields from the global climate models were used to drive a global WAVEWATCH-III wave model and generate hourly time-series of bulk wave parameters for 25 islands in the mid to western tropical Pacific for the years 1976–2005 (historical), 2026–2045 (mid-century projection), and 2085–2100 (end-of-century projection). Although the results show some spatial heterogeneity, overall the December-February extreme significant wave heights, defined as the mean of the top 5 percent of significant wave height time-series data modeled within a specific period, increase from present to mid-century and then decrease toward the end of the century; June-August extreme wave heights increase throughout the century within the Central region of the study area; and September-November wave heights decrease strongly throughout the 21st century, displaying the largest and most widespread decreases of any season. Peak wave periods increase east of the International Date Line during the December-February and June-August seasons under RCP4.5. Under the RCP8.5 scenario, wave periods decrease west of the International Date Line during December-February but increase in the eastern half of the study area. Otherwise, wave periods decrease throughout the study area during other seasons. Extreme wave directions in equatorial Micronesia during June-August undergo an approximate 30° clockwise rotation from primarily west to northwest. September-November RCP4.5 extreme mean wave directions rotate counterclockwise by approximately 30 to 45° in equatorial Micronesia; September-November RCP8.5 extreme mean wave directions within equatorial Micronesia rotate clockwise by approximately 20 to 30°. Extreme wind speeds decreased within both scenarios, with the largest decreases occurring in the September-November season. Extreme wind directions under RCP4.5 rotated clockwise by more than 60° in equatorial Micronesia during the September-November season and by approximately 30° during June-August. RCP8.5 extreme wind directions rotated counterclockwise during September-November within the same region by 30 to 50° and clockwise by 30 to 40° at one island. The spatial patterns and trends are similar between the two different greenhouse gas emission scenarios, with the magnitude and extent of the trends generally greater for the higher (RCP8.5) scenario.

Micronesia, Pacific Ocean↗