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At least 901 records · Page 50Linked to original sources
USGS2020

Mapping the thermal landscape of the Upper Mississippi River

Temperature has a fundamental influence on physical, chemical and biological processing in aquatic ecosystems. River temperatures respond to a diverse array of drivers including air temperature, streamflow, and thermal inputs, but the physical template has been shown to play a significant role in structuring spatial and temporal variation in water temperature. How these factors interact to affect water temperature in complex floodplain river habitats such as those present in the Upper Mississippi River System (UMRS) is not well-studied. We used a combination of airborne thermal imagery and continuous temperature loggers deployed across aquatic area types to evaluate spatial and temporal patterns in water temperature in Navigation Pool 8 during the summer and fall of 2017. The mid-wave infrared thermal camera available for this study is not commonly used for thermal imagery acquisition over water, so we discuss accommodations that were made to account for potential interferences and describe considerations for future users interested in using the technology. We quantified thermal metrics from imagery and continuous loggers (e.g., mean, coefficient of variation, range) and compared those to hydrogeomorphic variability across aquatic areas using a Geographic Information System (GIS) dataset. Our findings showed that both temporal and spatial temperature patterns were linked to variation in depth and connectivity of aquatic areas across the pool. Despite some of the technical challenges associated with acquiring this imagery, the method shows promise for characterizing spatial variation in surface temperatures in the UMRS associated with complex physical features such as habitat rehabilitation and enhancement projects.

Iowa, Illinois, Minnesota, Wisconsin↗
USGS2020

Scale-specific metrics for adaptive generalization and geomorphic classification of stream features

The Richardson plot has been used to illustrate fractal dimension of naturally occurring landscape features that are sensitive to changes in scale or resolution, such as coastlines and river channels. The Richardson method estimates the length of a path by traversing (i.e., “walking”) the path with a specific stride length. Fractal dimension is determined as the slope of the Richardson plot, which shows path length over a range of stride lengths graphed on log-log axes. This paper describes a variant of the Richardson plot referred to as the Scale-Specific Sinuosity (S 3 ) plot. S 3 is defined as negative one times the slope of the Richardson plot for a given stride length. A plot of S 3 against stride length offers a frequency distribution whose area under the curve reflects total sinuosity, and whose points mark the amount of sinuosity contributed to the total sinuosity at each stride length. Mathematical relations of S 3 with fractal dimension and sinuosity for linear features are described. The S 3 metric is demonstrated and discussed for several linear stream features distributed over the conterminous United States. The S 3 metric can help guide the preservation of stream feature sinuosity during cartographic generalization and may assist automated geomorphic classification of river systems.

Conference Paper↗
USGS2020

Assessing the state of water resource knowledge and tools for future planning in the lower Rio Grande-Rio Bravo Basin

The Rio Grande/Rio Bravo Basin (hereinafter referred to as the Rio Grande) is a transboundary basin, with the Rio Grande forming the border between the United States and Mexico for approximately 2,034 km. The waters of the Rio Grande serve as a critical drinking source for 13 million people, connecting numerous population centers representing diverse backgrounds and cultures along its length. Cross-border ecosystems and communities make water management strategies particularly challenging. With different regulations and societal interests in the two countries, developing effective water-management strategies is challenging and requires the coordination of diverse interested parties representing different government agencies, institutions, and stakeholder groups with varying and sometimes conflicting objectives. To better evaluate the human and environmental water needs (environmental flows) of this constrained river system, an improved understanding of past and present water management objectives, policies, allocation practices, and water use is needed.

Lower Rio Grande-Río Bravo Basin↗
USGS2021

Coastal observations of alligator snapping turtles in the Florida Panhandle

The genus Macrochelys (alligator snapping turtles) inhabits river systems that empty into the Gulf of Mexico from Florida to Texas and contains the largest freshwater turtles in North America (Pritchard 2006). This paper details observations of Macrochelys on the coast and barrier islands in Franklin and Gulf counties, Florida, that contribute to our knowledge of their movements in brackish or saltwater ecosystems and occurrence on islands. Thomas et al. (2014) described turtles from this geographical area as a new species, Apalachicola alligator snapping turtle ( M. apalachicolae ), but Folt and Guyer (2015) disputed this designation, and many authorities still consider them to be alligator snapping turtles ( M. temminckii ; e.g., Crother 2017, Turtle Taxonomy Working Group 2017).

Florida Field Naturalist↗
USGS1917

Life zone investigations in Wyoming

Wyoming is among the foremost of our States in its wealth of natural scenery, culminating in the grandeur of Yellowstone National Park, one of the wonders of the world. In addition to this distinction it posseses vast open plains and lofty mountains whence flow the headwaters of mighty river systems emptying far away to the west into the Pacific Ocean, to the southeast into the Gulf of Mexico, and to the southwest into the Gulf of California. The various slope exposures of its mountain ranges, the fertility of its intervening valleys or basins, and the aridity of its desert spaces present a study of geographic and vertical distribution of wild life that is in many particulars unique. The study of geographic and vertical distribution of life with the governing factors and attendant problems is valuable as a matter of scientific research and in the attainment of practical knowledge. The Biological Survey has been making detailed investigations of the transcontinental life belts, or zones, of North America for some years, and this work has been carried on with special reference to their practical value. It has become increasingly evident that life zones furnish a fairly accurate index to average climatic conditions and, therefore, are useful as marking the limits of agricultural possibilities, so far as these are dependent upon climate. The knowledge thus gained has been published and made available as the investigations have progressed and the life zones have been mapped. 1

North American Fauna↗
USGS2016

Groundwater-flow model for the Wood River Valley aquifer system, south-central Idaho

A three-dimensional numerical model of groundwater flow was developed for the Wood River Valley (WRV) aquifer system, Idaho, to evaluate groundwater and surface-water availability at the regional scale. This mountain valley is located in Blaine County and has a drainage area of about 2,300 square kilometers (888 square miles). The model described in this report can serve as a tool for water-rights administration and water-resource management and planning. The model was completed with support from the Idaho Department of Water Resources, and is part of an ongoing U.S. Geological Survey effort to characterize the groundwater resources of the WRV. A highly reproducible approach was taken for constructing the WRV groundwater-flow model. The collection of datasets, source code, and processing instructions used to construct and analyze the model was distributed as an R statistical-computing and graphics package. Flow in the WRV aquifer was simulated using the MODFLOW-USG groundwater flow model. The transient flow model simulates groundwater flow between 1995 and 2010. The model uses a 100-meter (328-feet) uniform grid spacing with 54,922 active model cells distributed over three model layers. A confining unit in the south-central part of the Bellevue fan necessitated the use of a multi-layer model. Specified-flow boundaries were used to simulate the groundwater inflows from each of the major tributary basins (also known as tributary basin underflow) and the areal recharge of precipitation and applied irrigation. Head‑dependent flow boundaries were used to simulate the stream-aquifer flow exchange in river reaches and the groundwater discharge at the outlet boundaries of Stanton Crossing and Silver Creek. The model was calibrated by adjusting aquifer hydraulic properties to match simulated and measured water levels and stream-aquifer flow exchange, using the parameter-estimation program PEST. The model reasonably simulated the measured water-table elevation, orientation, and gradients. Stream-aquifer flow exchange along river reaches also was reasonably simulated by the model. Inflow into the WRV aquifer system originates from three sources (from largest to smallest): Streamflow loss from the Big Wood River and Silver Creek, Areal recharge of precipitation and applied irrigation, and Tributary basin underflow. Outflow from the WRV aquifer system originates from five sources (from largest to smallest): Aquifer discharge into the Big Wood River and Silver Creek, Production-well pumping, Discharge across the water table into the vadose zone, Subsurface outflow beneath Silver Creek near Picabo, and Subsurface outflow beneath the Big Wood River near Stanton Crossing. Temporal changes in aquifer storage are most affected by areal recharge and groundwater pumping, and also contribute to changes in streamflow gains.

Idaho↗
USGS1980

Mathematical model of the Tesuque aquifer system underlying Pojoaque River basin and vicinity, New Mexico

A three-dimensional digital model of ground-water flow was constructed to represent the dipping anisotropic beds of the Tesuque aquifer system underlying the Pojoaque River basin and vicinity, New Mexico. Simulations of steady-state conditions and historical ground-water withdrawals were consistent with observed data. The model was used to simulate the response of the aquifer system to an irrigation development plan in the Pojoaque River basin. Storage is the main source of water as 34.05 cubic feet per second (86 percent of the withdrawal rate) was simulated to be withdrawn from storage after 50 years of withdrawals for irrigation development; the maximum simulated water-level decline was 334 feet; and net simulated streamflow capture from the Rio Grande, Santa Cruz, Pojoaque, and Santa Fe Rivers was 5.63 cubic feet per second (14 percent of the withdrawal rate). The sensitivity of the model was tested by varying aquifer characteristics to the limits of the plausible range. Change in hydraulic head in Pojoaque River basin is most sensitive to hydraulic conductivity. In all simulations, after 50 years of withdrawals, the maximum simulated decline in hydraulic head ranged between 210 and 474 feet, storage in the aquifer system was the source of 80 to 90 percent of the water withdrawn from wells, and streamflow capture from the Rio Grande and its tributaries plus irrigation diversions from the tributaries of the Pojoaque River simulated a decrease in the flow of the Rio Grande of between 17.13 and 21.11 cubic feet per second.

New Mexico↗
USGS2007

Detailed measured sections, cross sections, and paleogeographic reconstructions of the upper cretaceous and lower tertiary nonmarine interval, Wind River Basin, Wyoming: Chapter 10 in Petroleum systems and geologic assessment of oil and gas resources in the Wind River Basin Province, Wyoming

Detailed measured sections and regional stratigraphic cross sections are used to reconstruct facies maps and interpret paleogeographic settings for the interval from the base of Upper Cretaceous Mesaverde Formation to top of lower member of the Paleocene Fort Union Formation in the Wind River Basin, Wyoming. The Mesaverde Formation spans the time during which the Upper Cretaceous seaway retreated eastward out of central Wyoming in Campanian time and the initial stages of the Lewis transgression in earliest Maastrichtian time. This retreat stalled for a considerable period of time during deposition of the lower part of the Mesaverde, creating a thick buildup of marginal marine sandstones and coaly coastal plain deposits across the western part of the basin. The Lewis sea transgressed into the northeast part of Wind River Basin, beginning in early Maastrichtian time during deposition of the Teapot Sandstone Member of the Mesaverde Formation. The Meeteetse Formation, which overlies the Teapot, was deposited in a poorly-drained coastal plain setting southwest of the Lewis seaway. The Lewis seaway, at maximum transgression, covered much of the northeast half of the Wind River Basin area but was clearly deflected around the present site of the Wind River Range, southwest of the basin, providing the first direct evidence of Laramide uplift on that range. Uplift of the Wind River Range continued during deposition of the overlying Maastrichtian Lance Formation. The Granite Mountains south of the basin also became a positive feature during this time. A rapidly subsiding trough during the Maastrichtian time formed near the presentday trough of the Wind River Basin in which more than 6,000 feet of Lance was deposited. The development of this trough appears to have begun before the adjacent Owl Creek Mountains to the north started to rise; however, a muddy facies in the upper part of Lance in the deep subsurface, just to the south, might be interpreted to indicate that the Cretaceous Cody Shale was being eroded off a rising Owl Creek Mountains in latest Cretaceous time. The Paleocene Fort Union Formation unconformably overlies older units but with only slight angular discordance around much of the margins of the Wind River Basin. Pre-Fort Union erosion was most pronounced toward the Wind River Range to the southwest, where the Fort Union ultimately overlies strata as old as the upper part of the Cretaceous Cody Shale. The unconformity appears to die out toward the basin center. Coal-forming mires developed throughout the western part of the basin near the beginning of the Paleocene. River systems entering the basin from the Wind River Range to the southwest and the Granite Mountains to the south produced areas of sandy fluvial deposition along mountain fronts. A major river system appears to have entered the basin from about the same spot along the Wind River Range throughout much of the Paleocene, probably because it became incised and could not migrate laterally. The muddy floodplain facies that developed along the deep basin trough during latest Cretaceous time, expanded during the early part of the Paleocene. Coal-forming mires that characterize part of the lower Fort Union Formation reached maximum extent near the beginning of the late Paleocene and just prior to the initial transgression of Lake Waltman. From the time of initial flooding, Lake Waltman expanded rapidly, drowning the coal-forming mires in the central part of the basin and spreading to near basin margins. Outcrop studies along the south margin of the basin document that once maximum transgression was reached, the lake was rapidly pushed basinward and replaced by fluvial environments.

Wyoming↗
USGS2007

Estimates of ground-water recharge to the Yakima River Basin aquifer system, Washington, for predevelopment and current land-use and land-cover conditions

Two models were used to estimate ground-water recharge to the Yakima River Basin aquifer system, Washington for predevelopment (estimate of natural conditions) and current (a multi-year, 1995-2004, composite) land-use and land-cover conditions. The models were the Precipitation-Runoff Modeling System (PRMS) and the Deep Percolation Model (DPM) that are contained in the U.S. Geological Survey's Modular Modeling System. Daily values of recharge were estimated for water years 1950-98 using previously developed PRMS-watershed models for four mainly forested upland areas, and for water years 1950-2003 using DPM applied to 17 semiarid to arid areas in the basin. The mean annual recharge under predevelopment conditions was estimated to be about 11.9 in. or 5,450 ft 3 /s (about 3.9 million acre-ft) for the 6,207 mi 2 in the modeled area. In the modeled areas, recharge ranged from 0.08 in. (1.2 ft 3 /s) to 34 in. (2,825 ft 3 /s). About 97 percent of the recharge occurred in the 3,667 mi 2 area included in the upland-area models, but much of this quantity is not available to recharge the bedrock hydrogeologic units. Only about 1.0 in., or 187 ft 3 /s (about 0.14 million acre-ft), was estimated to occur in the 2,540 mi 2 area included in the semiarid to arid lowland modeled areas. The mean annual recharge to the aquifer system under current conditions was estimated to be about 15.6 in., or 7,149 ft 3 /s (about 5.2 million acre-ft). The increase in recharge is due to the application of irrigation water to croplands. The annual quantity of irrigation was more than five times the annual precipitation for some of the modeled areas. Mean annual actual evapotranspiration was estimated to have increased from predevelopment conditions by more than 1,700 ft 3 /s (about 1.2 million acre-ft) due to irrigation.

Washington↗
USGS2007

Burial history, thermal maturity, and oil and gas generation history of petroleum systems in the Wind River Basin Province, central Wyoming: Chapter 6 in Petroleum systems and geologic assessment of oil and gas resources in the Wind River Basin Province, Wyoming

Burial history, thermal maturity, and timing of oil and gas generation were modeled for eight key source rock units at nine well locations throughout the Wind River Basin Province. Petroleum source rocks include the Permian Phosphoria Formation, the Cretaceous Mowry Shale, Cody Shale, and Mesaverde, Meeteetse, and Lance Formations, and the Tertiary (Paleocene) Fort Union Formation, including the Waltman Shale Member. Within the province boundary, the Phosphoria is thin and only locally rich in organic carbon. Phosphoria oil produced from reservoirs in the province is thought to have migrated from the Wyoming and Idaho thrust belt. Locations (wells) selected for burial history reconstructions include three in the deepest parts of the province (Adams OAB-17, Bighorn 1-5, and Coastal Owl Creek); three at intermediate depths (Hells Half Acre, Shell 33X-10, and West Poison Spider); and three at relatively shallow locations (Young Ranch, Amoco Unit 100, and Conoco-Coal Bank). The thermal maturity of source rocks is greatest in the deep northern and central parts of the province and decreases to the south and east toward the basin margins. The results of the modeling indicate that, in the deepest areas, (1) peak petroleum generation from Cretaceous rocks occurred from Late Cretaceous through middle Eocene time, and (2) onset of oil generation from the Waltman Shale Member occurred from late Eocene to early Miocene time. Based on modeling results, gas generation from the cracking of Phosphoria oil reservoired in the Park City Formation reached a peak in the late Paleocene/early Eocene (58 to 55 Ma) only in the deepest parts of the province. The Mowry Shale and Cody Shale (in the eastern half of the basin) contain a mix of Type-II and Type-III kerogens. Oil generation from predominantly Type-II source rocks of these units in the deepest parts of the province reached peak rates during the latest Cretaceous to early Eocene (65 to 55 Ma). Only in these areas of the basin did these units reach peak gas generation from the cracking of oil, which occurred in the early to middle Eocene (55 to 42 Ma). Gas-prone source rocks of the Mowry and Cody Shales (predominantly Type-III kerogen), and the Mesaverde, Meeteetse, Lance, and Fort Union Formations (Type –III kerogen) reached peak gas generation in the latest Cretaceous to late Eocene (67 to 38 Ma) in the deepest parts of the province. Gas generation from the Mesaverde source rocks started at all of the modeled locations but reached peak generation at only the deepest locations and at the Hells Half Acre location in the middle Paleocene to early Eocene (59 to 48 Ma). Also at the deepest locations, peak gas generation occurred from the late Paleocene to the early Eocene (57 to 49 Ma) for the Meeteetse Formation, and during the Eocene for the Lance Formation (55 to 48 Ma) and the Fort Union Formation (44 to 38 Ma). The Waltman Shale Member of the Fort Union Formation contains Type-II kerogen. The base of the Waltman reached a level of thermal maturity to generate oil only at the deep-basin locations (Adams OAB-17 and Bighorn 1-5 locations) in the middle Eocene to early Miocene (36 to 20 Ma).

Wyoming↗
USGS2015

Hydrogeology, groundwater levels, and generalized potentiometric-surface map of the Green River Basin lower Tertiary aquifer system, 2010–14, in the northern Green River structural basin

In cooperation with the Bureau of Land Management, groundwater levels in wells located in the northern Green River Basin in Wyoming, an area of ongoing energy development, were measured by the U.S. Geological Survey from 2010 to 2014. The wells were completed in the uppermost aquifers of the Green River Basin lower Tertiary aquifer system, which is a complex regional aquifer system that provides water to most wells in the area. Except for near perennial streams, groundwater-level altitudes in most aquifers generally decreased with increasing depth, indicating a general downward potential for groundwater movement in the study area. Drilled depth of the wells was observed as a useful indicator of depth to groundwater such that deeper wells typically had a greater depth to groundwater. Comparison of a subset of wells included in this study that had historical groundwater levels that were measured during the 1960s and 1970s and again between 2012 and 2014 indicated that, overall, most of the wells showed a net decline in groundwater levels. The groundwater-level measurements were used to construct a generalized potentiometric-surface map of the Green River Basin lower Tertiary aquifer system. Groundwater-level altitudes measured in nonflowing and flowing wells used to construct the potentiometric-surface map ranged from 6,451 to 7,307 feet (excluding four unmeasured flowing wells used for contour construction purposes). The potentiometric-surface map indicates that groundwater in the study area generally moves from north to south, but this pattern of flow is altered locally by groundwater divides, groundwater discharge to the Green River, and possibly to a tributary river (Big Sandy River) and two reservoirs (Fontenelle and Big Sandy Reservoirs).

Wyoming↗
USGS2015

The quality of our Nation's waters: Water quality in the Mississippi embayment-Texas coastal uplands aquifer system and Mississippi River Valley alluvial aquifer, south-central United States, 1994-2008

About 8 million people rely on groundwater from the Mississippi embayment—Texas coastal uplands aquifer system for drinking water. The Mississippi River Valley alluvial aquifer also provides drinking water for domestic use in rural areas but is of primary importance to the region as a source of water for irrigation. Irrigation withdrawals from this aquifer are among the largest in the Nation and play a key role in the economy of the area, where annual crop sales total more than $7 billion. The reliance of the region on both aquifers for drinking water and irrigation highlights the importance of long-term management to sustain the availability and quality of these resources.

Alabama, Arkansas, Kentucky, Louisiana, Mississipp↗
USGS2005

Drought allocations using the Systems Impact Assessment Model: Klamath River

Water supply and allocation scenarios for the Klamath River, Ore. and Calif., were evaluated using the Systems Impact Assessment Model (SIAM), a decision support system developed by the U.S. Geological Survey. SIAM is a set of models with a graphical user interface that simulates water supply and delivery in a managed river system, water quality, and fish production. Simulation results are presented for drought conditions, one aspect of Klamath River water operations. The Klamath River Basin has experienced critically dry conditions in 1992, 1994, and 2001. Drought simulations are useful to estimate the impacts of specific legal or institutional flow constraints. In addition, simulations help to identify potential adverse water quality consequences including evaluating the potential for reducing adverse temperature impacts on anadromous fish. In all drought simulations, water supply was insufficient to fully meet upstream and downstream targets for endangered species.

Journal of Water Resources Planning and Management↗
USGS2004

Simulation of ground-water flow in the Cedar River alluvial aquifer flow system, Cedar Rapids, Iowa

The Cedar River alluvial aquifer is the primary source of municipal water in the Cedar Rapids, Iowa, area. Since 1992, the U.S. Geological Survey, in cooperation with the City of Cedar Rapids, has investigated the hydrogeology and water quality of the Cedar River alluvial aquifer. This report describes a detailed analysis of the ground-water flow system in the alluvial aquifer, particularly near well field areas. The ground-water flow system in the Cedar Rapids area consists of two main components, the unconsolidated Quaternary deposits and the underlying carbonate bedrock that has a variable fracture density. Quaternary deposits consist of eolian sand, loess, alluvium, and glacial till. Devonian and Silurian bedrock aquifers overlie the Maquoketa Shale (Formation) of Ordovician age, a regional confining unit. Ground-water and surface-water data were collected during the study to better define the hydrogeology of the Cedar River alluvial aquifer and Devonian and Silurian aquifers. Stream stage and discharge, ground-water levels, and estimates of aquifer hydraulic properties were used to develop a conceptual ground-water flow model and to construct and calibrate a model of the flow system. This model was used to quantify the movement of water between the various components of the aluvial aquifer flow system and provide an improved understanding of the hydrology of the alluvial aquifer. Ground-water flow was simulated for the Cedar River alluvial aquifer and the Devonian and Silurian aquifers using the three-dimensional finite-difference ground-water flow model MODFLOW. The model was discretized into 223 rows and 354 columns of cells. Areal cell sizes range from about 50 feet on a side near the Cedar River and the Cedar Rapids municipal wells to 1,500 feet on a side near the model boundaries and farthest away from the Cedar Rapids municipal well fields. The model is separated into five layers to account for the various hydrogeologic units in the model area. Model results indicate that the primary sources of inflow to the modeled area are infiltration from the Cedar River (53.0 percent) and regional flow in the glacial and bedrock materials (34.1 percent). The primary sources of outflow from the modeled area are discharge to the Cedar River (45.4 percent) and pumpage (44.8 percent). Current steady-state pumping rates have increased the flow of water from the Cedar River to the alluvial aquifer by 43.8 cubic feet per second. Steady-state and transient hypothetical pumpage scenarios were used to show the relation between changes in pumpage and changes in infiltration of water from the Cedar River. Results indicate that more than 99 percent of the water discharging from municipal wells infiltrates from the Cedar River, that the time required for induced river recharge to equilibrate with municipal pumpage may be 150 days or more, and that ground-water availability in the Cedar Rapids area will not be significantly affected by doubling current pumpage as long as there is sufficient flow in the Cedar River to provide recharge.

Iowa↗
USGS1997

Concentrations and transport of atrazine in the Delaware River-Perry Lake system, northeast Kansas, July 1992 through September 1995

About 283,000 pounds of atrazine are applied annually in the 1,100-square-mile Delaware River basin. Of this amount, an annual average of 3,500 pounds runs off into Perry Lake, a public-water supply source and main reservoir in the basin. About 90 percent of the atrazine that runs off to streams occurs between May and July. However, annual average concentrations did not exceed the maximum contaminant level in water from any of 10 stream sites or the outflow of Perry Lake for either the 1993 or 1994 crop years.

Kansas↗
USGS1996

Concentrations and transport of atrazine in the Delaware River-Perry Lake system, northeast Kansas, July 1993 through September 1995

A study of the distribution and transport of atrazine in surface water in the 1,117 square-mile Delaware River Basin in northeast Kansas was conducted from July 1992 through September 1995. The purpose of this report is to present information to assess the present (1992-95) con ditions and possible future changes in the distri bution and magnitude of atrazine concentrations, loads, and yields spatially, temporally, and in rela tion to hydrologic conditions and land-use characteristics. A network of 11 stream-monitoring and sam-ple-collection sites was established within the basin. Stream-water samples were collected during a wide range of hydrologic conditions throughout the study. Nearly 5,000 samples were analyzed by enzyme-linked immunosorbent assay (ELISA) for triazine herbicide concentrations. Daily mean triazine herbicide concentrations were calculated for all sampling sites and subsequently used to estimate daily mean atrazine concentrations with a linear-regression relation between ELISA-derived triazine concentrations and atrazine concentrations determined by gas chromatography/mass spectrometry for 141 dual-analyzed surface-water samples. During May, June, and July, time-weighted, daily mean atrazine concentrations in streams in the Delaware River Basin commonly exceeded the value of the 3.0-μg/L (micrograms per liter) annual mean Maximum Contaminant Level (MCL) established by the U.S. Environmental Protection Agency for drinking-water supplies. Time-weighted, daily mean concentrations equal to or greater than 20 μg/L were not uncommon. However, most time-weighted, daily mean concentrations were less than 1.0 μg/L from August through April. The largest time-weighted, monthly mean atrazine concentrations occurred during May, June, and July. Most monthly mean concentrations between August and April were less than 0.50 μg/L. Large differences were documented in monthly mean concentrations within the basin. Sites receiving runoff from the northern and northeastern parts of the Delaware River Basin had the largest monthly and annual mean atrazine concentrations. Time-weighted, annual mean atrazine concen trations did not exceed the MCL in water from any sampling site for either the 1993 or 1994 crop years (April—March); however, concentrations were larger during 1994 than during 1993. Time- weighted, annual mean concentrations in water from among the 11 sampling sites during the 1993 crop year ranged from 0.27 to 1.5 μg/L and from 0.36 to 2.8 μg/L during the 1994 crop year. Fur thermore, concentrations in samples from the out- flow of Perry Lake were larger during the first 6 months of the 1995 crop year than during the previous year. Flow-weighted, annual mean atrazine concentrations were larger than time-weighted, annual mean concentrations in water from all sampling sites upstream of Perry Lake, and samples from several sites had concentrations that were substantially larger than the MCL. This difference explained why time-weighted, annual mean concentrations in the outflow of Perry Lake were larger than corresponding time-weighted concentrations in water from sampling sites upstream of Perry Lake. Flow-weighted, annual mean concentrations in water from among the 11 sampling sites during the 1993 crop year ranged from 1.0 to 4.4 and from 1.0 to 8.9 μg/L during the 1994 crop year. Statistically significant linear-regression equa tions were identified relating the percentage of subbasin in cropland to time- and flow-weighted, average annual mean atrazine concentrations. The relations indicate that time-weighted, average annual mean atrazine concentrations may not exceed the MCL in water from subbasins with at least about 70-percent cropland. However, flow- weighted, average annual mean atrazine concen trations may exceed the MCL when the percent- age of cropland is greater than about 40 percent. Approximately 90 percent of the annual atrazine load is transported from May through July. Atrazine loads and yields were larger during the 1993 crop year than during the 1994 crop year because of much greater runoff in 1993. Yields at sampling sites upstream of Perry Lake ranged from 2.4 to 17 lb/mi2 (pounds per square mile) during the 1993 crop year and from 0.29 to 4.4 lb/mi2 during the 1994 crop year. Loads and yields were largest at sampling sites receiving runoff from the northern and northeastern parts of the Delaware River Basin. A statistically significant linear-regression equation was identified relating percentage of subbasin in cropland to atrazine yields. About 283,000 lb (pounds) of atrazine are applied each year in the Delaware River Basin. Annual atrazine loads (5,200 and 2,000 lb), yields (4.7 and 1.8 lb/mi2), and transport ratios (1.8 and 0.7 percent) were estimated for the entire Delaware River Basin for the 1993 and 1994 crop years, respectively. Differences between the 1993 and 1994 crop years are the result of differences in rainfall amounds and subsequent runoff volumes.

Kansas↗
USGS2001

Surface-geophysical characterization of ground-water systems of the Caloosahatchee River basin, southern Florida

The Caloosahatchee River Basin, located in southwestern Florida, includes about 1,200 square miles of land. The Caloosahatchee River receives water from Lake Okeechobee, runoff from the watershed, and seepage from the underlying ground-water systems; the river loses water through drainage to the Gulf of Mexico and withdrawals for public-water supply and agricultural and natural needs. Water-use demands in the Caloosahatchee River Basin have increased dramatically, and the Caloosahatchee could be further stressed if river water is used to accommodate restoration of the Everglades. Water managers and planners need to know how much water will be used within the river basin and how much water is contributed by Lake Okeechobee, runoff, and ground water. In this study, marine seismic-reflection and ground-penetrating radar techniques were used as a means to evaluate the potential for flow between the river and ground-water systems. Seven test coreholes were drilled to calibrate lithostratigraphic units, their stratal geometries, and estimated hydraulic conductivities to surface-geophysical profiles. A continuous marine seismic-reflection survey was conducted over the entire length of the Caloosahatchee River and extending into San Carlos Bay. Lithostratigraphic units that intersect the river bottom and their characteristic stratal geometries were identified. Results show that subhorizontal reflections assigned to the Tamiami Formation intersect the river bottom between Moore Haven and about 9 miles westward. Oblique and sigmoidal progradational reflections assigned to the upper Peace River Formation probably crop out at the floor of the river in the Ortona area between the western side of Lake Hicpochee and La Belle. These reflections image a regional-scale progradational deltaic depositional system containing quartz sands with low to moderate estimated hydraulic conductivities. In an approximate 6-mile length of the river between La Belle and Franklin Lock, deeper karstic collapse structures are postulated. These structures influence the geometries of parallel reflections that intersect the river channel. Here, reflections assigned to the Buckingham Limestone Member of the Tamiami Formation (a confining unit) and reflections assigned to the clastic zone of the sandstone aquifer likely crop out at the river bottom. Beneath these shallow reflections, relatively higher amplitude parallel reflections of the carbonate zone of the sandstone aquifer are well displayed in the seismic-reflection profiles. In San Carlos Bay, oblique progradational reflections assigned to the upper Peace River Formation are shown beneath the bay. Almost everywhere beneath the river, a diffuse ground-water flow system is in contact with the channel bottom. Ground-penetrating radar profiles of an area about 2 miles north of the depositional axis of the deltaic depositional system in the Ortona area show that progradational clinoforms imaged on seismic reflection profiles in the Caloosahatchee River are present within about 17 feet of the ground surface. Ground-penetrating radar profiles show southward dipping, oblique progradational reflections assigned to the upper Peace River Formation that are terminated at their tops by a toplapping or erosional discontinuity. These clinoformal reflections image clean quartz sand that is probably characterized by moderate hydraulic conductivity. This sand could be mapped using ground-penetrating radar methods.

Water-Resources Investigations Report↗
USGS2021

Conceptual and numerical groundwater flow model of the Cedar River alluvial aquifer system with simulation of drought stress on groundwater availability near Cedar Rapids, Iowa, for 2011 through 2013

Between July 2011 and February 2013, the City of Cedar Rapids observed water level declines in their horizontal collector wells approaching 11 meters. As a result, pumping from these production wells had to be halted, and questions were raised about the reliability of the alluvial aquifer under future drought conditions. The U.S. Geological Survey, in cooperation with the City of Cedar Rapids, completed a study to better understand the effects of drought stress on the Cedar River alluvial aquifer using a numerical groundwater flow model. Previously published groundwater flow models were combined with newly collected airborne, waterborne, down-hole, and land-based geophysical survey data and provided a detailed three-dimensional lithologic model of the Cedar River alluvial aquifer and surrounding area. An improved conceptual model for the groundwater flow system and a lithologic model were used to build and inform a numerical groundwater flow model capable of simulating water levels observed in the City of Cedar Rapids horizontal collector wells during the 2012 drought. Model performance was assessed primarily on the ability of the model to simulate water table elevation at six monitoring wells. Statistical tests were used to assess the numerical model during the calibration period, and results varied from satisfactory to unsatisfactory, likely because of stage changes in the Cedar River and production well withdrawal rates near monitoring wells. Simulated water levels during the 2012 drought indicated a depression near the horizontal collector wells, although simulated elevations at these locations and at monitoring wells were generally overestimated compared to measured values. The numerical groundwater flow model was modified to account for a decrease in seepage rate caused by low flow in the Cedar River and increased production. With seepage rate modification, model results improved; the simulated water table elevations were like those observed in horizontal collector and monitoring wells. Results demonstrated the ability of the model to simulate water levels observed in the horizontal collector wells during the 2012 drought when accounting for a decrease in infiltration from the Cedar River.

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