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At least 919 records · Page 51Linked to original sources
USGS1983

Inventory and analyses of information for flood plain management in North Dakota

Governmental units that have been identified as having flood hazard areas but do not have detailed base flood information are required to use the "best available data" to regulate new development or expansion of existing development in flood prone areas. Information for flood plain management has been identified for 95 governmental units in North Dakota and includes the determination of what data are available regarding flood hazards, hydraulics, and hydrology, and a review of these data to determine their adequacy for use in flood plain management.

North Dakota↗
USGS2022

Hydrogeologic characterization of the San Antonio Creek Valley watershed, Santa Barbara County, California

The San Antonio Creek Valley watershed (SACVW) is located in western Santa Barbara County, about 15 miles south of Santa Maria and 55 miles north of Santa Barbara, California. The SACVW is about 135 square miles and encompasses the San Antonio Creek Valley groundwater basin; the SACVW is separated from adjacent groundwater basins by the Casmalia and Solomon Hills to the north, and the Purisima Hills to the south. At the western, downstream part of the valley, uplifted, consolidated rocks cause groundwater to discharge at land surface at Barka Slough. Since the late 1800s, groundwater has been the primary source of water for agricultural, military, municipal, and domestic uses. Groundwater withdrawal by pumping exceeded the amount of water replenishing the aquifer system during water years 1948–2018, causing groundwater-level declines of more than 150 feet in parts of the valley and reducing base flow at Barka Slough. Reliance on groundwater for agricultural water use (primarily for the irrigation and frost protection of vineyards, and fruit and berry crops) continues to strain the sustainability of the groundwater system. Through a cooperative agreement, the Santa Barbara County Water Agency and Vandenberg Space Force Base invited the U.S. Geological Survey to address declines in groundwater levels, develop a better understanding of the hydrogeologic system, and provide tools to help evaluate and manage the effects of future development of the San Antonio Creek Valley groundwater basin within the encompassing San Antonio Creek Valley watershed (SACVW). The objectives of this study were to (1) refine the hydrogeologic framework of the San Antonio Creek Valley watershed, (2) quantify the hydrologic budget of the valley, and (3) develop hydrologic modeling tools to evaluate and aid in managing the groundwater resource. This report focuses on the first and second objectives to construct a hydrogeologic framework and characterize the historical and present-day hydrologic conditions of the SACVW during water years 1948–2018. As part of the second objective, work included quantifying the hydrologic budget and evaluating the hydrogeologic system using a combination of existing data and geologic and hydrologic data collected for this study. The groundwater-flow system in the SACVW consists of five hydrogeologic units. These separate water-bearing units were identified based on hydrogeologic properties, such as sediment grain size, vertical-head differences in multiple-depth, monitoring-well sites, long-term groundwater level responses to pumping and climate, and the chemical character of groundwater and groundwater age in the mostly semi-consolidated to unconsolidated basin-fill sediments. The hydrogeologic units that comprise the different aquifers vary in their lithologic composition. The upper and lower aquifers (upper Paso Robles Formation, and lower Paso Robles Formation and Careaga Sandstone, respectively) are relatively coarse grained and are comprised of sand, gravel, and clay; the middle confining unit (the middle Paso Robles Formation) is relatively fine grained and is comprised of primarily clay, silt, and sand. The Pezzoni-Casmalia and Los Alamos faults, which are inferred to transect the SACVW between the western and eastern areas of the valley floor, do not appear to substantially affect the groundwater system. Present-day recharge to the study area occurs primarily as infiltration from precipitation and streams in the upland areas of the Casmalia Hills and Solomon Hills, and along the main channel of San Antonio Creek. Reported estimates of annual natural recharge during water years 1948–2018 generally ranged from about 5,000 acre-feet to more than about 30,000 acre-feet. Stable and radioactive isotopes show that groundwater from the lower aquifer is old and probably was recharged as infiltration from precipitation and streams in the eastern upland areas of the Solomon Hills; however, the infiltration and recharge from these sources probably does not occur under present-day climatic conditions. Anthropogenic recharge, from sources such as return flow from agricultural irrigation, municipal water systems, and wastewater effluent, was estimated to range from about 600 acre-feet in 1948 to about 6,600 acre-feet in 2018. The average annual amount of groundwater removed from the SACVW by pumping during 1948–2018 was estimated to be about 17,200 acre-feet per year, increasing from about 3,000 acre-feet in 1948 to about 32,600 acre-feet in 2018. Estimates of annual pumpage generally exceeded estimates of annual recharge beginning in the mid-1970s and continuing through 2018. The predominant direction of groundwater flow under historical and present-day conditions was from the eastern uplands in the Solomon Hills to the west along San Antonio Creek to the discharge area in Barka Slough, and from the northern uplands in the Casmalia Hills south to San Antonio Creek. Pumpage since the early 1900s and the subsequent groundwater-level declines have substantially reduced the amount of natural groundwater discharge at Barka Slough. Estimates of base flow to San Antonio Creek at the western, downstream extent of the SACVW have varied over time in response to changes in groundwater pumpage and climate; however, there was an overall decline in base flow during water years 1956–2018, decreasing from an average of about 1,700 acre-feet per year during 1956–69, to about 300 acre-feet per year during 2016–18. The long-term extraction of groundwater correlates with a decrease in groundwater levels by more than about 150 feet since the early 1940s in the eastern part of the basin near Los Alamos, and as much as about 50 feet in the upland areas and in the western part of the basin. At Barka Slough, groundwater levels have declined below land surface in some places, altering native riparian vegetation in and around the slough. Surface-water quality in the SACVW varied depending on location and the time of year the samples were collected and on the amount of annual precipitation Most groundwater in the SACVW was calcium-bicarbonate-type water with total dissolved-solids concentrations of about 500–800 milligrams per liter generally representing water naturally recharged as infiltration from precipitation and streams. Total dissolved-solids concentrations in some wells ranged from 800 to 8,000 milligrams per liter, suggesting mixing of naturally recharged infiltrated water with water associated with oil-bearing geologic formations, agricultural products, or the evaporation of shallow groundwater. Concentrations of total dissolved solids and the chemical constituents chloride, nitrate plus nitrite (as nitrogen), calcium, and magnesium at selected wells generally increased during water years 1980–2018; increasing concentrations of these constituents may be associated with the expansion of agriculture in the watershed over time and the corresponding increase in the use of nitrates and calcium- and magnesium-based fertilizers and soil additives in modern agricultural practices. The predominant direction of groundwater flow during historical and present-day conditions was from the eastern uplands in the Solomon Hills to the west along San Antonio Creek toward Barka Slough, and from the western uplands in the Casmalia Hills south to San Antonio Creek. The age of groundwater in the SACVW was evaluated using radioactive isotopes, and the flow of groundwater within the SACVW was evaluated using radioactive and stable isotopes. Modern groundwater (recharged after 1952) was generally found adjacent to San Antonio Creek and its tributaries in wells with perforated depths that averaged about 270 feet below land surface. Pre-modern groundwater (recharged before 1952) was found in wells that had average perforation depths of about 540 ft below land surface. Pre-modern groundwater identified in wells in the eastern upland area is interpreted to have had long, slow travel times to the western part of the SACVW where it was eventually discharged as base flow at Barka Slough or extracted as groundwater pumpage.

California↗
USGS1995

Evaluation of ground-water flow and hydrologic budget for Lake Five-O, a seepage lake in northwestern Florida

Temporal and spatial distributions of ground-water inflow to, and leakage from Lake Five-O, a softwater, seepage lake in northwestern Florida, were evaluated using hydrologic data and simulation models of the shallow ground-water system adjacent to the lake. The simulation models indicate that ground-water inflow to the lake and leakage from the lake to the ground-water system are the dominant components in the total inflow (precipitation plus ground-water inflow) and total outflow (evaporation plus leakage) budgets of Lake Five-O. Simlulated ground-water inflow and leakage were approximately 4 and 5 times larger than precipitation inputs and evaporative losses, respectively, during calendar years 1989-90. Exchanges of water between Lake Five-O and the ground-water system were consistently larger than atmospheric-lake exchanges. A consistent pattern of shallow ground-water inflow and deep leakage was also evident throughout the study period. The mean time of travel from ground-water that discharges at Lake Five-O (time from recharge at the water table to discharge at the lake) was estimated to be within a range of 3 to 6 years. Flow-path evaluations indicated that the intermediate confining unit probably has a negligible influence on the geochemistry of ground-water inflow to Lake Five-O. The hydrologic budgets and flow-path evaluations provide critical information for developing geochemical budgets for Lake Five-O and for improving the understanding of the relative importance of various processes that regulate the acid-neutralizing capacity of softwater seepage lakes in Florida.

Florida↗
USGS2019

Hydrologic study at Farm Creek Marsh, Dorchester County, Maryland, from April 2015 to April 2016

In 2015, the U.S. Geological Survey began a 1-year hydrologic study to investigate the extent and cause of inundation at Farm Creek Marsh, in Dorchester County, Maryland. In combination with a tide and precipitation gage, a representative section of the marsh was instrumented with surface-water monitors and shallow groundwater piezometers to capture the spatial and temporal extent of inundation. In addition, water-quality data (major ions and nutrients) were collected to help discern the cause of inundation. Results indicate that during the year-long study, all sites were periodically inundated, ranging from a total of 108 days to the entire study period of 353 days. The depth of inundation was typically between 0 and 0.2 feet (ft) (above land surface), with the exception of large storm events. Less than 0.5 ft of elevation was the difference between a site being inundated during the entire study period of 353 days and a site being inundated for 36 consecutive days out of 108 total days of inundation during the study period. Water-quality data showed a large difference in pH between marsh surface water (6.1 to 6.9 standard pH units) and shallow groundwater (3.0 to 3.6 standard pH units), with differences also observed in concentrations of silica, iron, manganese, and potassium. Collectively, the combination of water-quality, hydrologic, and soils data indicate that inundation is caused by tide and storm events rather than groundwater discharge.

Maryland↗
USGS2014

Area- and depth- weighted averages of selected SSURGO variables for the conterminous United States and District of Columbia

This digital data release consists of seven data files of soil attributes for the United States and the District of Columbia. The files are derived from National Resources Conservations Service’s (NRCS) Soil Survey Geographic database (SSURGO). The data files can be linked to the raster datasets of soil mapping unit identifiers (MUKEY) available through the NRCS’s Gridded Soil Survey Geographic (gSSURGO) database ( http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/geo/?cid=nrcs142p2_053628 ). The associated files, named DRAINAGECLASS, HYDRATING, HYDGRP, HYDRICCONDITION, LAYER, TEXT, and WTDEP are area- and depth-weighted average values for selected soil characteristics from the SSURGO database for the conterminous United States and the District of Columbia. The SSURGO tables were acquired from the NRCS on March 5, 2014. The soil characteristics in the DRAINAGE table are drainage class (DRNCLASS), which identifies the natural drainage conditions of the soil and refers to the frequency and duration of wet periods. The soil characteristics in the HYDRATING table are hydric rating (HYDRATE), a yes/no field that indicates whether or not a map unit component is classified as a "hydric soil". The soil characteristics in the HYDGRP table are the percentages for each hydrologic group per MUKEY. The soil characteristics in the HYDRICCONDITION table are hydric condition (HYDCON), which describes the natural condition of the soil component. The soil characteristics in the LAYER table are available water capacity (AVG_AWC), bulk density (AVG_BD), saturated hydraulic conductivity (AVG_KSAT), vertical saturated hydraulic conductivity (AVG_KV), soil erodibility factor (AVG_KFACT), porosity (AVG_POR), field capacity (AVG_FC), the soil fraction passing a number 4 sieve (AVG_NO4), the soil fraction passing a number 10 sieve (AVG_NO10), the soil fraction passing a number 200 sieve (AVG_NO200), and organic matter (AVG_OM). The soil characteristics in the TEXT table are percent sand, silt, and clay (AVG_SAND, AVG_SILT, and AVG_CLAY). The soil characteristics in the WTDEP table are the annual minimum water table depth (WTDEP_MIN), available water storage in the 0-25 cm soil horizon (AWS025), the minimum water table depth for the months April, May and June (WTDEPAMJ), the available water storage in the first 25 centimeters of the soil horizon (AWS25), the dominant drainage class (DRCLSD), the wettest drainage class (DRCLSWET), and the hydric classification (HYDCLASS), which is an indication of the proportion of the map unit, expressed as a class, that is "hydric", based on the hydric classification of a given MUKEY. (See Entity_Description for more detail). The tables were created with a set of arc macro language (aml) and awk (awk was created at Bell Labsin the 1970s and its name is derived from the first letters of the last names of its authors – Alfred Aho, Peter Weinberger, and Brian Kernighan) scripts. Send an email to mewieczo@usgs.gov to obtain copies of the computer code (See Process_Description.) The methods used are outlined in NRCS's "SSURGO Data Packaging and Use" (NRCS, 2011). The tables can be related or joined to the gSSURGO rasters of MUKEYs by the item 'MUKEY.' Joining or relating the tables to a MUKEY grid allows the creation of grids of area- and depth-weighted soil characteristics. A 90-meter raster of MUKEYs is provided which can be used to produce rasters of soil attributes. More detailed resolution rasters are available through NRCS via the link above.

Data Series↗
USGS2003

Chlorine-36 in groundwater of the United States: Empirical data

Natural production of the radionuclide chlorine - 36 ( 36 Cl) has provided a valuable tracer for groundwater studies. The nuclear industry, especially the testing of thermonuclear weapons, has also produced large amounts of 36 Cl that can be detected in many samples of groundwater . In order to be most useful in hydrologic studies, the natural production prior to 1952 should be distinguished from more recent artificial sources. The object of this study was to reconstruct the probable preanthropogenic levels of 36 Cl in groundwater in the United States . Although significant local variations exist, they are superimposed on a broad regional pattern of 36 Cl/Cl ratios in the United States . Owing to the influence of atmospherically transported ocean salt, natural ratios of 36 Cl/total Cl are lowest near the coast and increase to a maximum in the central Rocky Mountains of the United States .

Hydrogeology Journal↗
USGS1994

Nonpoint and Point Sources of Nitrogen in Major Watersheds of the United States

Estimates of nonpoint and point sources of nitrogen were made for 107 watersheds located in the U.S. Geological Survey's National Water-Quality Assessment Program study units throughout the conterminous United States. The proportions of nitrogen originating from fertilizer, manure, atmospheric deposition, sewage, and industrial sources were found to vary with climate, hydrologic conditions, land use, population, and physiography. Fertilizer sources of nitrogen are proportionally greater in agricultural areas of the West and the Midwest than in other parts of the Nation. Animal manure contributes large proportions of nitrogen in the South and parts of the Northeast. Atmospheric deposition of nitrogen is generally greatest in areas of greatest precipitation, such as the Northeast. Point sources (sewage and industrial) generally are predominant in watersheds near cities, where they may account for large proportions of the nitrogen in streams. The transport of nitrogen in streams increases as amounts of precipitation and runoff increase and is greatest in the Northeastern United States. Because no single nonpoint nitrogen source is dominant everywhere, approaches to control nitrogen must vary throughout the Nation. Watershed-based approaches to understanding nonpoint and point sources of contamination, as used by the National Water-Quality Assessment Program, will aid water-quality and environmental managers to devise methods to reduce nitrogen pollution.

Water-Resources Investigations Report↗
USGS2023

Integrated science strategy for assessing and monitoring water availability and migratory birds for terminal lakes across the Great Basin, United States

Executive Summary In 2022, the U.S. Geological Survey (USGS) established the Saline Lake Ecosystems Integrated Water Availability Assessment (IWAAs) to monitor and assess the hydrology of terminal lakes in the Great Basin and the migratory birds and other wildlife dependent on those habitats. Scientists from across the USGS (with specialties in water quantity, water quality, limnology, avian biology, data science, landscape ecology, and science communication) formed the Saline Lake Ecosystems IWAAs Team. The team has developed this regional strategic science plan to guide data collection and assessment activities at terminal lakes in the Great Basin. The U.S. Congress requested the USGS to establish the Saline Lake Ecosystems IWAAs in response to historically low water levels at terminal lakes and associated wetlands across the Great Basin. Not all Great Basin terminal lakes have high salinity; however, all terminal lakes occur in endorheic, closed, basins with no surface-water outflow. Low lake levels across the Great Basin are the result of increased water use for agriculture and municipalities, drought conditions, and a warming climate. Great Basin terminal lake water extents have decreased by as much as 90 percent over the last 150 years, and terminal lake wetlands have decreased in area by as much as 47 percent since 1984. Lake elevations and wetland areas are primarily supported by freshwater inputs from snowmelt feeding upgradient rivers, streams, and springs. These freshwater inputs have been severely reduced because of continued and increased surface-water diversions and surface-water capture through groundwater pumping for agriculture, mining, and public supply as well as unprecedented drought conditions and warming temperatures related to climate change. Water quality, specifically salinity, is highly variable for terminal lakes of the Great Basin, and this variability is a result of the balance between freshwater inflow and evaporation. Variability of salinity at each of the terminal lakes can be affected by lake morphology, hydrogeologic features of the basin, annual variability in weather patterns, and changes in upgradient water use. Hypersaline terminal lakes provide abundant food resources such as brine shrimp and brine flies that support nesting and migrating birds. The density and composition of invertebrates are closely tied to lake salinity. Increased salinity can exceed the tolerance of invertebrates, severely limiting their biomass. In contrast, decreased salinity can lead to altered invertebrate community composition, reducing the abundance of optimal avian prey resources. Great Basin terminal lake ecosystems, including open-water and adjacent aquatic and terrestrial environments, provide resources necessary to sustain many animal populations throughout the year. Although a variety of taxa use terminal lakes, these ecosystems are of acute importance for the millions of migratory waterbirds (for example, shorebirds, wading birds, and waterfowl) dependent on the network of terminal lakes and their associated wetlands. Migratory birds transiting the Pacific and Central Flyways use Great Basin terminal lake ecosystems throughout the year to feed, nest, and transit between wintering and breeding ranges. As such, successful conservation of birds and their habitats requires coordinated management of water and habitats across the Great Basin network of terminal lakes and wetlands. The linkages between water availability and ecosystem vulnerability of terminal lakes in the Great Basin are not well understood. The vulnerability of terminal lakes is related to the factors driving change and adaptive capacity of the lake ecosystem. Saline lake ecosystems are vulnerable when changes in water quantity affect ecosystem function. Water quantity affects salinity, which affects food webs and habitat; these linkages can be investigated with water-quality and food web monitoring. Water quantity also affects inundated habitat, which can be quantified through remote sensing. It is necessary to quantify hydroclimatic and water use controls on water availability to terminal lakes to assess the response of the ecosystems. Remotely sensed data can provide a broad-scale and long-term synoptic view of terminal lake hydrologic characteristics, but ground observations are required to interpret changes in water quality and ecological functions. Some terminal lake basins have ongoing monitoring and modeling efforts within the Great Basin (for example, Great Salt Lake, Carson River Basin), yet most monitoring locations are hydrologically upgradient and too far away from lake inflows to provide an accurate assessment of hydrological trends for the lake ecosystems. Other terminal lakes have no long-term hydrological monitoring in their respective watersheds (for example, Lake Abert). Ecological data collection in the Great Basin is also insufficient to understand how many birds exist on the landscape, how birds use the mosaic of terminal-lake habitats as an interconnected system, and how Great Basin terminal lakes are linked to the larger continental system of the Pacific and Central Flyways. Across agencies and organizations, tracking bird movement, abundance, and diversity is inconsistent, with some lakes having once- or twice-a-year bird survey efforts and a few locations having more intensive ecological data-gathering efforts (for example, Great Salt Lake, Lake Abert). Bridging hydrological and ecological information gaps will improve understanding of the trends in water supply and water quality, habitat availability and usage, and impacts on vulnerable waterbird species, all of which would be used by managers in coordinated conservation of this unique network of terminal-lake habitats. The terminal lakes of the Great Basin are part of the Basin and Range physiographic province that extends from the Colorado Plateau on the east to the Sierra Nevada on the west, and from the Snake River Plain on the north to the Garlock fault and the Mojave block on the south. The Great Basin is larger than 650,000 square kilometers and encompasses most of the State of Nevada but also extends to western Utah, eastern California, southeastern Idaho, southwestern Wyoming, and southeastern Oregon. The climate is arid to semiarid with a hydrologic regime that is snowmelt dominated, providing as much as 75 percent of total annual runoff for the region. Terminal lakes of the Great Basin occupy the lowest areas of closed (endorheic) drainage basins, such that lake levels and water quality respond rapidly to surface-water inflow. Terminal lakes provide local and regional economic value to the States in the Great Basin, including mineral extraction, aquaculture, public works, and recreational uses. As an example, assessments of Great Salt Lake’s ecological health and economic impact find hemispheric importance for the former and regional importance for the latter. Great Salt Lake creates about 7,000 jobs and $2 billion of economic output per year, most of which would be lost with further declines in lake level. The objectives of this Science Strategy are threefold: (1) to identify how changing water availability affects the quality, diversity, and abundance of habitats supporting continental waterbird populations; (2) to highlight the scientific monitoring and assessment needs of Great Basin terminal lakes; and (3) to support coordinated management and conservation actions to benefit those ecosystems, migratory birds, and other wildlife. There are long-term hydrological, ecological, and societal challenges associated with terminal lakes ecosystems in the Great Basin. This Science Strategy benefits partners by providing a conceptual model, nested at different spatial extents, that identifies key scientific information needs to inform coordinated implementation of management and conservation plans within and among hydrologic basins to address these complex challenges.

California, Idaho, Nevada, Oregon, Utah, Wyoming↗
USGS2017

Hydrogeologic framework and hydrologic conditions of the Piney Point aquifer in Virginia

The Piney Point aquifer in Virginia is newly described and delineated as being composed of six geologic units, in a study conducted by the U.S. Geological Survey in cooperation with the Virginia Department of Environmental Quality (VA DEQ). The eastward-dipping geologic units include, in stratigraphically ascending order, the sand of the Nanjemoy Formation Woodstock Member, interbedded limestone and sand of the Piney Point Formation, silty and clayey sand of the Gosport Formation equivalent sediments, silty sand of the Oligocene-age sediments, silty fine-grained sand of the Old Church Formation, and silty sand of the Calvert Formation, Newport News unit and basal Plum Point Member. Identification of geologic units is based on typical sediment lithologies of geologic formations. Fine-grained sediments that compose confining units positioned immediately above and below the Piney Point aquifer are also described. The Piney Point aquifer is one of several confined aquifers within the Virginia Coastal Plain and includes a highly porous and solution-channeled indurated limestone within the Piney Point Formation from which withdrawals are made. The limestone is relatively continuous laterally across central parts of the Northern Neck, Middle Peninsula, and York-James Peninsula. Other geologic units are of variable extent. The configurations of most of the geologic units are further affected by newly identified faults that are aligned radially from the Chesapeake Bay impact crater and create constrictions or barriers to groundwater flow. Some geologic units are also truncated beneath the lower Rappahannock River by a resurge channel associated with the impact crater. Groundwater withdrawals from the Piney Point aquifer increased from approximately 1 million gallons per day (Mgal/d) during 1900 to 7.35 Mgal/d during 2004. As a result, a water-level cone of depression in James City and northern York Counties was estimated to be as low as 70 feet (ft) below the National Geodetic Vertical Datum of 1929 (NGVD 29) by 2005. Withdrawals decreased to 5.01 Mgal/d by 2009 as withdrawals were shifted toward other sources, and by 2015 water levels had recovered to approximately 50 ft below NGVD 29. The mean estimated transmissivity of the Piney Point aquifer in York and James City Counties is 16,300 feet squared per day (ft 2 /d), but farther north it is only 925 ft 2 /d. The mean well specific capacity in York and James City Counties is 11.4 gallons per minute per foot (gal/min/ft). Farther north in Virginia, mean specific capacity is only 2.26 gal/min/ft, and in Maryland it is 0.99 gal/min/ft. The northward decrease in specific capacity probably reflects the northward decrease in transmissivity, which results from poor development of the solution-channeled limestone. An aquifer test in northern York County induced vertical leakage to the solution-channeled limestone from overlying silty sand and a change in response of the aquifer to pumping from a single layer to two layers. Transmissivity of the limestone of approximately 19,800 ft 2 /d was distinguished from the silty sand of approximately 2,500 ft 2 /d. Most of the water in the Piney Point aquifer is slightly alkaline with moderate concentrations primarily of sodium and bicarbonate that are slightly undersaturated with respect to calcite. Iron concentrations are generally less than 0.3 milligrams per liter (mg/L). Mixing of freshwater with seawater has elevated chloride concentrations to the southeast to as much as 7,120 mg/L. Information on the Piney Point aquifer can benefit water-resource management in siting production wells, predicting likely well yield, and anticipating water-level response to withdrawals. Models that vertically discretize individual geologic units can potentially be used to evaluate groundwater flow in greater detail by representing lateral flow and vertical leakage among the geologic units. Because groundwater withdrawals are made primarily from the limestone and sand of the Piney Point Formation, the VA DEQ has considered regarding the limestone and sand singly as a regulated aquifer apart from the other geologic units. Under current policy in Virginia, if only the limestone and sand were regarded as a regulated aquifer, a greater amount of drawdown would be allowed than is allowed for the Piney Point aquifer consisting of six geologic units. Some production wells intercept multiple geologic units, and the units can undergo water-level decline and vertical leakage induced by pumping from the limestone and sand. Whether the other geologic units are to be regarded as regulated aquifers is an additional consideration for the VA DEQ.

Virginia↗
USGS1985

Effects of climate, vegetation, and soils on consumptive water use and ground-water recharge to the Central Midwest Regional aquifer system, mid-continent United States

The Central Midwest aquifer system, in parts of Arkansas, Colorado, Kansas, Missouri, Nebraska, New Mexico, South Dakota, and Texas, is a region of great hydrologic diversity. This study examines the relationships between climate, vegetation, and soil that affect consumptive water use and recharge to the groundwater system. Computations of potential recharge and consumptive water use were restricted to those areas where the aquifers under consideration were the immediate underlying system. The principal method of analysis utilized a soil moisture computer model. This model requires four types of input: (1) hydrologic properties of the soils, (2) vegetation types, (3) monthly precipitation, and (4) computed monthly potential evapotranspiration (PET) values. The climatic factors that affect consumptive water use and recharge were extensively mapped for the study area. Nearly all the pertinent climatic elements confirmed the extreme diversity of the region. PET and those factors affecting it--solar radiation, temperature, and humidity--showed large regional differences; mean annual PET ranged from 36 to 70 inches in the study area. The seasonal climatic patterns indicate significant regional differences in those factors affecting seasonal consumptive water use and recharge. In the southern and western parts of the study area, consumptive water use occurred nearly the entire year; whereas, in northern parts it occurred primarily during the warm season (April through September). Results of the soil-moisture program, which added the effects of vegetation and the hydrologic characteristics of the soil to computed PET values, confirmed the significant regional differences in consumptive water use or actual evapotranspiration (AET) and potential groundwater recharge. Under two different vegetative conditions--the 1978 conditions and pre-agricultural conditions consisting of only grassland and woodland--overall differences in recharge were minimal. Mean annual recharge under both conditions averaged slightly more than 4.5 inches for the entire study area, but ranged from less than 0.10 inches in eastern Colorado to slightly more than 15 inches in Arkansas.

Arkansas, Colorado, Kansas, Missouri, Nebraska, Ne↗
USGS1953

Hydrology of Lake Erie and tributaries

The drainage area of the Great Lakes is equal to nearly one-tenth of the entire area of the United States; 58 percent of this area lies within the United States. The information in Table 3 affords a ready comparison of the land and water areas involved in the United States and Canada in the Great Lakes system. It will be noted that the total water surface is almost one-third of the entire drainage area and more than five-eighths of this water area is on the United States side of the international boundry. Throughout the history of the North American continent, the Great Lakes and the St. Lawrence River have formed a navigable water system of tremendous social and economic importance, extending from the interior of the continent to the Atlantic Ocean.

Lake Erie↗
USGS2000

Hydrology and water and sediment quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

The James Campbell National Wildlife Refuge occupies two lowland marsh and pond complexes on the northern coastal plain of Oahu: the mostly natural ponds and wetlands of the Punamano Unit and the constructed ponds of the Kii Unit. The U.S. Fish and Wildlife Service manages the Refuge primarily to protect and enhance habitat for four endangered species of Hawaiian waterbirds. Kii Unit is fed by artesian wells and rainfall, whereas Punamano Unit is fed naturally by rainfall, runoff, and ground-water seepage. Streams drain from the uplands into lowland ditches that pass through Kii Unit on their way to the ocean. A high-capacity pump transfers water from the inner ditch terminus at Kii to the ocean outlet channel. Stormwaters also exit the inner ditch system over flood-relief swales near the outlet pump and through a culvert with a one-way valve. A hydrologic investigation was done from November 1996 through February 1998 to identify and quantify principal inflows and outflows of water to and from the Refuge, identify hydraulic factors affecting flooding, document ground-water/surface-water interactions, determine the adequacy of the current freshwater supply, and determine water and sediment quality. These goals were accomplished by installing and operating a network of stream-gaging stations, meteorology stations, and shallow ground-water piezometers, by computing water budgets for the two Refuge units, and by sampling and analyzing water and pond-bottom sediments for major ions, trace metals, and organic compounds. Streamflow during the study was dominated by winter stormflows, followed by a gradual recession of flow into summer 1997, as water that had been stored in alluvial fans drained to lowland ditches. Outflow at the ditch terminus in 1997 was 125 million gallons greater than measured inflow to the coastal plain, mainly reflecting gains from ground water along the ditches between outlying gages and the ditch terminus. Of the measured 1997 outflow, 98 percent was through the Kii outlet pump, with the outlet culvert valve only opening for brief periods during storms. Large volumes of stormflow overflowed the flood-relief swales unmeasured. The largest storm of the study, in November 1996, was estimated to have a flood frequency of about 3 to 4 years. Streamflow exceeded culvert capacity and overtopped Kamehameha Highway at Kalaeokahipa Stream and Hospital ditch. Slight overbank flooding in Kii ditch resulted strictly from high discharge. Minor overbank flooding farther out on the coastal plain probably was caused mainly by the small hydraulic gradients available to convey stormflows along the lowland ditches. Stormwaters flooded Kii ponds and flowed back upstream along Punamano ditch into Punamano marsh, introducing suspended sediment and possibly other contaminants to the Refuge. Two smaller storms in January 1997 resulted in smaller flows and no overbank flooding. The Kii outlet pump ran continuously for 7 days during the November 1996 storm and for 1 to 2 days during the January 1997 storms. During all three storms, the outlet culvert valve opened and the inner ditches overtopped the flood-relief swales, allowing free outflow of water from the inner ditch. Backwater effects hindered drainage during the January 1997 storms at Hospital ditch at Kamehameha Highway, and at Punamano ditch at Nudist Camp Road (where the backflow into Punamano marsh in November 1996 constituted an extreme backwater effect). A probable marine backwater effect was imposed at the ocean outlet ditch during the November 1996 storm through a combination of high spring tides and wave setup from large surf. Whether this backwater effect propagated upstream in the ditches to affect inland sites could not be determined conclusively. A sand plug may have built up in the ocean outlet channel before the November 1996 storm, but if so, it probably washed out prior to, or early in the storm, and was not present at the time of peak stage at inland sites. A season-long buildup of the sand plug in late 1997 was inferred from rising water levels in the outlet ditch. Seawater flows up the outlet channel or over the sand berm and into the outer ditch system on most high tides, and particularly during spring high tides. Ponds and ditches of the Refuge and surrounding lowlands have mud- and clay-lined bottoms that form an effective confining unit and inhibit interaction with an underlying shallow limestone aquifer. At Kii Unit, pond levels are higher than adjacent ditch levels and underlying ground-water levels, establishing lateral and downward head gradients that could foster seepage losses from the ponds. Regional ground-water discharge from the Koolau aquifer to the coastal-plain sediments is mostly diffuse, but is concentrated where ridges of Koolau Basalt plunge beneath coastal-plain sediments near Punamano Unit and at the head of Hospital ditch. Kii ditch gains brackish ground water downstream of Kamehameha Highway. Wastewater disposal from the sewage treatment plant adjoining Kii Unit poses little or no threat to Refuge habitat. Disposal is at six injection wells located 0.45 mi away at Kahuku, and the wells inject into confined limestone aquifers that do not extend to Kii Unit. The natural freshwater supply to Punamano Unit is adequate for maintaining the wildlife habitat, judging from stable pond levels and low salinities there. A monthly water budget for Punamano showed an apparent annual deficit in measurable flows in 1997, requiring unmeasured ground-water gains equalling 51 inches of water. The freshwater supply to Kii Unit is inadequate according to Refuge managers, because there is not enough water to manipulate levels adequately in the ponds during most of the year, and particularly during the driest months. This is confirmed by monthly deficits in the water budget for the Kii ponds during summer months. However, the Kii budget showed an annual surplus in measurable flows for 1997 equalling 24 inches of water. Unmeasured losses are required to explain the apparent annual surplus, such as discharge to the ditches through pond water-control structures and downward and/or lateral ground-water seepage. The apparent surplus at Kii is strictly hydrologic and is not a surplus in a management sense; it cannot be stored or used to supply the Refuge, but instead reflects losses from the system that render this amount of water unavailable for use. The budget year, 1997, was drier than normal (24 percent below long-term mean rainfall) and so the measured potential evaporation for 1997 was probably higher than the long-term mean. Few metals or organic compounds of potential concern were detected in pond and ditch waters and in pond-bottom sediments. Detected pesticides were at trace levels or just above minimum reporting limits. Exceptions that exceeded quality guidelines for freshwater sediment were copper and zinc in sediment from Kii ponds C and D, and copper in sediment from Punamano north pond. Therefore, urban and agricultural runoff probably have contributed little in the way of harmful metals or organic compounds to the Refuge, although the potential for such contribution remains from periodic flooding of the ponds by ditch stormflows. Salinity was low throughout most Refuge waters, qualifying as fresh to slightly brackish and suitable for the environmental needs of Refuge fauna. Higher salinities have been observed in ditches during past periods of sugarcane cultivation and saltwater aquaculture, however. Resumption of saltwater aquaculture could raise ditch salinities if saltwater effluents are disposed directly into the ditches, as they were in the past.

Hawaii↗
USGS1979

Water resources of the Swinomish Indian Reservation, Washington

The Swinomish Indian Reservation occupies 17 mi 2 on Fidalgo Island, northwestern Washington. Six square miles are underlain by mudflats or low-lying alluvial deposits, and are not part of the study area. An appraisal of the water resources of the reservation was made because the Swinomish Tribal Community expects rapid economic and population growth in the near future. Average inflow to the hydrologic system of the reservation is 24 ft 3 /s (cubic feet per second). Outflow consists of evapotranspiration (15 ft 3 /s), subsurface outflow (5 ft 3 /s), and surface-water outflow (4 ft 3 /s). Recharge to the ground-water reservoir is 8 ft 3 /s. Most of the study area is a remnant of a glacial drift plain underlain by three types of unconsolidated deposits. The uppermost unit consists primarily of till, the intermediate unit is predominantly sand and gravel, and the lowermost unit is nearly all clay and silt. The total storage capacity is about 6.3 billion cubic feet of water. During 1976 human interaction with the hydrologic system was negligible, with an average rate of water use of 0.19 ft 3 /s. Seventy percent of this was pumped from the ground-water reservoir and the rest was imported. Water levels in six wells extending below mean sea level were found to fluctuate as much as 2.8 feet in response to tidal fluctuations, representing maximum tidal efficiencies of 42 percent. Below sea level is a freshwater-saltwater zone of diffusion at least 150 feet thick. Dissolved-solids concentrations are estimatd to be 10-20 mg/L (milligrams per liter) in precipitation, increase to 15-35 mg/L due to evapotranspiration, reach 45 mg/L in direct runoff, and increase to about 160 mg/L in shallow ground water and about 245 mg/L in deep ground water. In the zone of saltwater diffusion concentrations up to 1,570 mg/L were measured. Human interaction with the hydrologic system has had little apparent effect on water quality. Ground-water quality is generally within the acceptable limits of the Federal Safe Drinking Water Act. The maximum contaminant levels for turbidity, arsenic, and coliform bacteria have been exceeded in a few samples. Recommended limits have been exceeded for iron, manganese, chloride, dissolved solids, pH, and color. Most of the large concentrations of these constituents were in water from the zone of saltwater diffusion. The ground-water reservoir can be developed to a greater degree. If 20 percent of the 8 ft 3 /s of ground-water recharge can be intercepted, a net rate of ground-water withdrawal of 1.6 ft 3 /s can be attained. Aquiculture development is possible on the two largest streams in the reservation in the form of incubation stations handling 600,000 eggs each.

Washington↗
USGS2010

Saltcedar and Russian olive interactions with wildlife: Chapter 4

Riparian areas of flood plains typically provide a mosaic of productive habitats (Stanford and others, 2005; Latterell and others, 2006) capable of supporting many wildlife species, particularly in the arid and semiarid Western United States. The establishment of nonnative invasive plants can alter riparian habitat by inhibiting native plant recruitment and by increasing the risk of wildfire (Howe and Knopf, 1991; Busch and Smith, 1995). However, the effects of nonnative plants are not necessarily always negative. Many wildlife species will use the exotic plants to some extent, especially when mixed with native vegetation (van Riper and others, 2008), but overall, species of wildlife exhibit a negative or neutral response to exotic habitat. In many areas of the Western United States where riparian systems have been degraded via anthropogenic activities (for example, flood control or groundwater pumping), native vegetation may have difficulty persisting and nonnative vegetation may provide the only available habitat for some species of wildlife (Katz and Shafroth, 2003; Stromberg and others, 2007). Therefore, where possible, the ultimate goal of ecological restoration activities should be the reestablishment of native riparian plant communities and a return to more natural hydrological regimes. Nonnative saltcedar (Tamarix spp.) and Russian olive (Elaeagnus angustifolia) are the second and fifth most abundant plants in riparian areas in the Western United States (see chap. 2, this volume; Friedman and others, 2005). Methods for controlling nonnative vegetation can alter riparian areas, often in unpredictable ways, and have the potential to impact a variety of habitat types used by wildlife (Bateman, Chung-MacCoubrey, Finch, and others, 2008). Therefore, understanding how wildlife utilize saltcedar and Russian olive and the effects of control activities on wildlife are important for resource managers who must balance management decisions such as nonnative plant control with protecting critical wildlife habitat. In this chapter, we present a synthesis of published literature on the use of saltcedar and Russian olive by wildlife and discuss how wildlife respond or are likely to respond to control measures for saltcedar and Russian olive and subsequent restoration efforts. We discuss responses of several groups of wildlife, including arthropods, birds, mammals, herpetofauna, and fish.

Book chapter↗
USGS1989

Paleohydrology of the Anadarko Basin, central United States

Geohydrologic systems in the Anadarko basin in the central United States are controlled by topography, climate, geologic structures, and aquifer hydraulic properties, all of which are the result of past geologic and hydrologic processes, including tectonics and diagenesis. From Late Cambrian through Middle Ordovician time, a generally transgressive but cyclic sea covered the area. The first deposits were permPable sand, followed by calcareous mud. During periods of sea transgression, burial diagenesis decreased porosity and permeability. During periods of sea recession, uplift diagenesis increased porosity and permeability, especially in exposed rocks. During most of Silurian and Devonian time, the sea receded; increased porosity and permeability resulted from uplift diagenesis. However, at the end of the Devonian and during the Early Mississippian, very slightly permeable clay, which now is a regional confining unit, was deposited in a mostly euxinic sea. Later during Mississippian time, calcareous muds, which became limestone, were deposited in and adjacent to the Anadarko basin and underwent burial diagenesis. During Pennsylvanian time, rapid sedimentation accompanied rapid subsidence in the Anadarko basin. A geopressure zone probably resulted when sediments with little permeability trapped depositional water in Lower Pennsylvanian sands. Burial diagenesis included compaction and thermal alteration of deeply buried organic material, which released carbon dioxide, water, and hydrocarbons. By Middle Pennsylvanian time, the sea had submerged most of the central United States, including the Ozarks, as tectonic activity reached its maximum. During Late Pennsylvanian and Early Permian time, the Ouachita uplift had been formed and was higher than the Ozarks. Uplift was accompanied by a regional upward tilt toward the Ouachita-Ozarks area; the sea receded westward, depositing large quantities of calcareous mud and clay, and precipitating evaporitic material in the restricted-circulation environment. By the end of Permian time, > 20,000 ft of Pennsylvanian and Permian sediments had been deposited in the Anadarko basin. These thick sediments caused rapid and extreme burial diagenesis, including alteration of organic material. During Permian time in the Ozarks area, development of the Ozark Plateaus aquifer system commenced in the permeable Cambrian-Mississippian rocks near the St. Francois Mountains as the Pennsylvanian confining material was removed. Since Permian time, uplift diagenesis has been more active than burial diagenesis in the Anadarko basin. Synopsis of paleohydrologic interpretation indicates that Cambrian-Mississippian rocks in the Anadarko basin should be relatively impermeable, except for local secondary permeability, because rocks in the basin have undergone little uplift diagenesis.

Book chapter↗
USGS1990

Topographic effects on flow path and surface water chemistry of the Llyn Brianne catchments in Wales

Topographic shape is a watershed attribute thought to influence the flow path followed by water as it traverses a catchment. Flow path, in turn, may affect the chemical composition of surface waters. Topography is quantified in the hydrological model TOPMODEL as the relative frequency distribution of the index ln(atanB), where a is the upslope area per unit contour that drains past a point and tanB is the local surface slope. Spatial distributions of ln(atanB) were calculated for eight catchments in Wales on a 25 m x 25 m grid. Among the catchments, mean observed stream H+ concentration during high flow periods was highly correlated with the mean of the ln(atanB) distribution. The steady-state gain of a transfer function (time series) model relating H+ to discharge was positively correlated with the mean of the ln(atanB) distribution. These results suggest that during high flow periods, both the average stream acidity and the magnitude of fluctuations in H+ are conditioned by the topographic shape of the catchment. By performing a sensitivity analysis on TOPMODEL, we also show that as the mean of the ln(atanB) distribution for a catchment increases, so does its theoretical likelihood to produce significant quantities of surface and near-surface runoff. Our observed results in the Llyn Brianne catchments are consistent with this theoretical expectation in that surface or near-surface runoff is often higher in acidity than are deeper sources of hillslope runoff.

Wales↗
USGS2015

River corridor science: Hydrologic exchange and ecological consequences from bedforms to basins

Previously regarded as the passive drains of watersheds, over the past 50 years, rivers have progressively been recognized as being actively connected with off-channel environments. These connections prolong physical storage and enhance reactive processing to alter water chemistry and downstream transport of materials and energy. Here we propose river corridor science as a concept that integrates downstream transport with lateral and vertical exchange across interfaces. Thus, the river corridor, rather than the wetted river channel itself, is an increasingly common unit of study. Main channel exchange with recirculating marginal waters, hyporheic exchange, bank storage, and overbank flow onto floodplains are all included under a broad continuum of interactions known as “hydrologic exchange flows.” Hydrologists, geomorphologists, geochemists, and aquatic and terrestrial ecologists are cooperating in studies that reveal the dynamic interactions among hydrologic exchange flows and consequences for water quality improvement, modulation of river metabolism, habitat provision for vegetation, fish, and wildlife, and other valued ecosystem services. The need for better integration of science and management is keenly felt, from testing effectiveness of stream restoration and riparian buffers all the way to reevaluating the definition of the waters of the United States to clarify the regulatory authority under the Clean Water Act. A major challenge for scientists is linking the small-scale physical drivers with their larger-scale fluvial and geomorphic context and ecological consequences. Although the fine scales of field and laboratory studies are best suited to identifying the fundamental physical and biological processes, that understanding must be successfully linked to cumulative effects at watershed to regional and continental scales.

Water Resources Research↗
USGS2025

Relating surface water dynamics in wetlands and lakes to spatial variability in hydrologic signatures

The retention of surface water in wetlands and lakes can modify the timing, duration, and magnitude of river discharge. However, efforts to characterize the influence of surface water on discharge regimes have been generally limited to small, wetland-dense watersheds. We developed random forest models to explain spatial variability in six hydrologic signatures, reflecting flashiness, high, and low flow conditions, at 72 gaged watersheds with variable water storage capacity across the conterminous United States. In addition to variables representing meteorology and landscape characteristics, we also tested the inclusion of surface water dynamics, derived from Sentinel-1 and Sentinel-2. Models for all six signatures improved with the addition of catchment characteristics, including surface water dynamics, relative to models with only climate variables. Percent improvement in model adjusted R 2 , mean square error, and Akaike information criterion ranged from 4.00 to 14.33%, 5.00 to 20.30%, and 2.75–8.14, respectively. Automated variable selection can be indicative of the relative importance of certain variables over others. Using a forward selection process, five of the six signature models selected remotely sensed inundation or wetland variables ( p < 0.05). For example, the variable semi-permanent and permanent (SP + P) floodplain inundation (i.e., lakes along rivers) was associated with lower annual flashiness. Further, SP + P non-floodplain waters and geographically isolated wetlands significantly contributed to explaining variability in the low flow signatures. Our findings underscore the capacity of wetlands to stabilize and maintain flows during dry periods. Improved understanding of how surface water dynamics influence hydrologic signatures can inform wetland restoration efforts and facilitate improved resilience to extreme flow conditions.

Wetland Ecology & Management↗