Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Study Plan”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20Linked to original sources
USGS2009

III.-The Work of Prof. Henry Carvill Lewis in Glacial Geology

The recent notice of the life and work of Prof. Henry Carvill Lewis, whose lamented death occurred in Manchester, July 21st, 1888, in his thirty-fifth year, well indicates the wide range of his scientific labours. He published valuable results of investigations in astronomy, mineralogy and petrology, and especially in glacial geology, the last being based on his exploration of the drift and its terminal moraines in the United States, and later in Ireland, Wales and England. The present article reviews his contributions to our knowledge of these drift formations and of the history of the Ice Age, bringing into comparison and correlation the glacial records of America and Europe. Comprehensive as were Professor Lewis' observations and studies in this field, he was planning yet more thorough and extensive exploration of the drift in Britain, Germany and Scandinavia, when he was taken from us.

Geological Magazine↗
USGS2022

Quantifying and visualizing 32 years of agricultural land use change in Kabul, Afghanistan

Agriculture is a key element of Afghanistan’s economy and plays an essential role supporting the expanding population and urban development of Kabul, the country’s capital. Over the past decades the urban landscape has changed substantially and agricultural land use has shifted in its extent, location, and density. Identifying trends in the amount of agricultural area, as an indication of food production, is important for city planning and humanitarian efforts. While many studies have investigated Afghanistan's agriculture, most are conducted at scales that preclude their use for local-scale decision-making. This study quantifies agricultural extent across 32 years from 1988 to 2020 at local scale using simple and repeatable Landsat multispectral image analysis. The volume of data in time-series analysis complicatesvisualization of key findings and long-term trends. This study also explored visualization methods such as zonal mapping, animations, and the isolation of key themes in a 2D static map.

Kabul↗
USGS2017

Synthesis centers as critical research infrastructure

Demand for the opportunity to participate in a synthesis-center activity has increased in the years since the US National Science Foundation (NSF)–funded National Center for Ecological Analysis and Synthesis (NCEAS) opened its doors in 1995 and as more scientists across a diversity of scientific disciplines have become aware of what synthesis centers provide. The NSF has funded four synthesis centers, and more than a dozen new synthesis centers have been established around the world, some following the NSF model and others following different models suited to their national funding environment ( http://synthesis-consortium.org ). Scientific synthesis integrates diverse data and knowledge to increase the scope and applicability of results and yield novel insights or explanations within and across disciplines (Pickett et al. 2007 , Carpenter et al. 2009 ). The demand for synthesis comes from the pressing societal need to address grand challenges related to global change and other issues that cut across multiple societal sectors and disciplines and from recognition that substantial added scientific value can be achieved through the synthesis-based analysis of existing data. Demand also comes from groups of scientists who see exciting opportunities to generate new knowledge from interdisciplinary and transdisciplinary collaboration, often capitalizing on the increasingly large volume and variety of available data (Kelling et al. 2009 , Bishop et al. 2014 , Specht et al. 2015b ). The ever-changing nature of societal challenges and the availability of data with which to address them suggest there will be an expanding need for synthesis. However, we are now entering a phase in which government support for some existing synthesis centers has ended or will be ending soon, forcing those centers to close or develop new operational models, approaches, and funding streams. We argue here that synthesis centers play such a unique role in science that continued long-term public investment to maximize benefits to science and society is justified. In particular, we argue that synthesis centers represent community infrastructure more akin to research vessels than to term-funded centers of science and technology (e.g., NSF Science and Technology Centers). Through our experience running synthesis centers and, in some cases, developing postfederal funding models, we offer our perspective on the purpose and value of synthesis centers. We present case studies of different outcomes of transition plans and argue for a fundamental shift in the conception of synthesis science and the strategic funding of these centers by government funding agencies.

BioScience↗
USGS2025

Management strategy evaluation to assess trade-offs associated with invasive Blue Catfish fisheries and predation impacts

Objective Many species are intentionally introduced beyond their native range to provide benefits to humans (e.g., food, recreation, or biocontrol). However, introduced species can become invasive and can harm native species, prompting resource managers to explore options to simultaneously conserve native biota and enhance fishing opportunities. Management of Chesapeake Bay Blue Catfish Ictalurus furcatus is complicated because the species supports a renowned trophy fishery and commercial and recreational harvest but also negatively affects native species. Consequently, there is uncertainty and disagreement on how to balance trade-offs associated with varying stakeholder interests. Methods We used a management strategy evaluation to project Blue Catfish population dynamics into the future under different fishery policies to understand whether fishery yield, trophy fishing opportunities, and predation on the economically and ecologically important blue crab Callinectes sapidus could be optimized in the James River, a Chesapeake Bay subestuary. Results Simulated population trajectories indicated that objectives related to maintaining fisheries and conserving prey populations were in conflict. Policies that increased the yield and abundance of trophy-size Blue Catfish (≥100 cm total length) generally increased predation on the blue crab, which supports a valuable fishery. Intense harvest of smaller length-classes and protection of larger Blue Catfish yielded outcomes in which trophy fish abundance increased and blue crab predation declined compared to baseline conditions. However, these outcomes were generally associated with lower Blue Catfish yields after 25 years. There were zero scenarios in which the fishery yield increased and blue crab predation decreased after 25 years. Policies limiting the harvest of small Blue Catfish resulted in large population abundances, suggesting that reducing the abundance of small fish could be important for reducing impacts on native species. Conclusions This study supports the importance of management planning to develop objectives and performance measures based on an improved understanding of trade-offs associated with harvest management for a nonnative fish with economic value.

Virginia↗
USGS2017

Decision support frameworks and tools for conservation

The practice of conservation occurs within complex socioecological systems fraught with challenges that require transparent, defensible, and often socially engaged project planning and management. Planning and decision support frameworks are designed to help conservation practitioners increase planning rigor, project accountability, stakeholder participation, transparency in decisions, and learning. We describe and contrast five common frameworks within the context of six fundamental questions (why, who, what, where, when, how) at each of three planning stages of adaptive management (project scoping, operational planning, learning). We demonstrate that decision support frameworks provide varied and extensive tools for conservation planning and management. However, using any framework in isolation risks diminishing potential benefits since no one framework covers the full spectrum of potential conservation planning and decision challenges. We describe two case studies that have effectively deployed tools from across conservation frameworks to improve conservation actions and outcomes. Attention to the critical questions for conservation project planning should allow practitioners to operate within any framework and adapt tools to suit their specific management context. We call on conservation researchers and practitioners to regularly use decision support tools as standard practice for framing both practice and research.

Conservation Letters↗
USGS2024

Deep resistivity geophysics of the San Juan–Silverton caldera complex, San Juan County, Colorado (USA)

Magnetotelluric (MT) and audiomagnetotelluric (AMT) data are used to better understand the subsurface geology and mineral resources in the San Juan–Silverton caldera complex located near Silverton, Colorado, western United States, as part of the extensive southern Rocky Mountains volcanic field that covers much of southwestern Colorado and northern New Mexico. Seven MT and AMT profiles of varying lengths image resistivity structure to depths of ~5 km. The AMT inversion models characterize geophysical responses of near-surface lithologies, structures, and mineralized systems and also help corroborate airborne electromagnetic data at shallow levels. The MT inversion models extend our depth of investigation from near the surface to great depths (~5 km) and help to form hypotheses about roots of the hydrothermal plumbing that fed shallower mineralized systems. Subsurface high resistivities occur beneath intermediate-composition lava flows and Proterozoic units. Subsurface moderate- to low-resistivity values may reflect hydrothermal plumbing that served as flow paths for mineralizing fluids and metallic ore formation. The model interpreta­tions presented in this study could be utilized in remediation planning or mineral resource applications. The methods used could be applied to other watersheds with similar volcanic environments containing acid-generating historical mines or hydrothermally altered and mineralized source rocks.

Colorado↗
USGS1885

Notes on the stratigraphy of California

A complete examination of the Coast Ranges of California can hardly be undertaken by the Geological Survey for some years to come, consistently with the plans at present formed. The detailed study of certain small areas in these ranges, however, raised a number of questions as to the age and stratigraphical relations of the various series of beds, which it seemed necessary to answer as well as circumstances permitted. Having reached certain conclusions, for the most part on structural grounds, it became indispensable for me to obtain the co-operation of an expert paleontologist. At my solicitation, and with the approval of the director, Dr. C. A. White consented to visit the field with me. He passed several months of the summer of 1884 in studying my collections and the occurrence of fossils in place with reference to the points at issue. His results appear in Bulletin No. 15, that and this being complementary to one another. I had the great satisfaction of finding that Dr. White was led from a purely paleontological position to conclusions entirely accordant with those at which I had already arrived on structural grounds. His long experience as a general geologist also made his agreement with me as to the structural indications a welcome confirmation of my opinions. These studies, in conjunction with many observations made by earlier workers on the Pacific Coast, particularly those of the State Geological Survey of California, under Prof. J. D. Whitney, have led to some seemingly well established general conclusions of interest. The more purely geological results will be presented in the following pages, in the imperfect form in which alone it will be possible to give them until an immense amount of additional work shall have been done.

California↗
USGS1995

National Water-Quality Assessment Program; summary of pesticide data collected on East Fork Double Bayou, near Anahuac, Texas, March to September 1994

The Trinity River Basin study-unit assessment began in October 1991, with 2 years dedicated to planning, analyzing existing information, and designing data-collection networks, surveys, and studies. Then, a 3-year intensive data-collection program was initiated. The assessment followed guidelines provided by the National Water-Quality Assessment (NAWQA) Program National Synthesis team and considered suggestions made by the study unit's liaison committee. One of the issues selected for study concerned the quality of runoff in the coastal prairie. The study includes collecting streamflow, water-quality and watershed data on three streams, each representing watersheds in different parts of the coastal prairie. This fact sheet presents a summary of the pesticide data collected on East Fork Double Bayou from March to September 1994.

Texas↗
USGS1995

National Water-Quality Assessment Program; summary of pesticide data collected on West Prong Old River near Dayton, Texas, March to September 1994

The Trinity River Basin study-unit assessment began in October 1991, with 2 years dedicated to planning, analyzing existing information, and designing data-collection networks, surveys, and studies. Then, a 3-year intensive data-collection program was initiated. The assessment followed guidelines provided by the National Water-Quality Assessment (NAWQA) Program National Synthesis team and considered suggestions made by the study unit's liaison committee. One of the issues selected for study concerned the quality of runoff in the coastal prairie. The study includes collecting streamflow, water-quality, and watershed data on three streams, each representing watersheds in different parts of the coastal prairie. This fact sheet presents a summary of the pesticide data collected on West Prong Old River from March to September 1994.

Texas↗
USGS2012

Mapping plant species ranges in the Hawaiian Islands: developing a methodology and associated GIS layers

This report documents a methodology for projecting the geographic ranges of plant species in the Hawaiian Islands. The methodology consists primarily of the creation of several geographic information system (GIS) data layers depicting attributes related to the geographic ranges of plant species. The most important spatial-data layer generated here is an objectively defined classification of climate as it pertains to the distribution of plant species. By examining previous zonal-vegetation classifications in light of spatially detailed climate data, broad zones of climate relevant to contemporary concepts of vegetation in the Hawaiian Islands can be explicitly defined. Other spatial-data layers presented here include the following: substrate age, as large areas of the island of Hawai'i, in particular, are covered by very young lava flows inimical to the growth of many plant species; biogeographic regions of the larger islands that are composites of multiple volcanoes, as many of their species are restricted to a given topographically isolated mountain or a specified group of them; and human impact, which can reduce the range of many species relative to where they formerly were found. Other factors influencing the geographic ranges of species that are discussed here but not developed further, owing to limitations in rendering them spatially, include topography, soils, and disturbance. A method is described for analyzing these layers in a GIS, in conjunction with a database of species distributions, to project the ranges of plant species, which include both the potential range prior to human disturbance and the projected present range. Examples of range maps for several species are given as case studies that demonstrate different spatial characteristics of range. Several potential applications of species-range maps are discussed, including facilitating field surveys, informing restoration efforts, studying range size and rarity, studying biodiversity, managing invasive species, and planning of conservation efforts.

Hawai'i↗
USGS2015

Summarizing components of U.S. Department of the Interior vulnerability assessments to focus climate adaptation planning

A secretarial order identified climate adaptation as a critical performance objective for future management of U.S. Department of the Interior (DOI) lands and resources in response to global change. Vulnerability assessments can inform climate adaptation planning by providing insight into what natural resources are most at risk and why. Three components of vulnerability—exposure, sensitivity, and adaptive capacity—were defined by the Intergovernmental Panel on Climate Change (IPCC) as necessary for identifying climate adaptation strategies and actions. In 2011, the DOI requested all internal bureaus report ongoing or completed vulnerability assessments about a defined range of assessment targets or climate-related threats. Assessment targets were defined as freshwater resources, landscapes and wildlife habitat, native and cultural resources, and ocean health. Climate-related threats were defined as invasive species, wildfire risk, sea-level rise, and melting ice and permafrost. Four hundred and three projects were reported, but the original DOI survey did not specify that information be provided on exposure, sensitivity, and adaptive capacity collectively as part of the request, and it was unclear which projects adhered to the framework recommended by the IPCC. Therefore, the U.S. Geological Survey National Climate Change and Wildlife Science Center conducted a supplemental survey to determine how frequently each of the three vulnerability components was assessed. Information was categorized for 124 of the 403 reported projects (30.8 percent) based on the three vulnerability components, and it was discovered that exposure was the most common component assessed (87.9 percent), followed by sensitivity (68.5 percent) and adaptive capacity (33.1 percent). The majority of projects did not fully assess vulnerability; projects focused on landscapes/wildlife habitats and sea-level rise were among the minority that simultaneously addressed all three vulnerability components. To maintain consistency with the IPCC definition of vulnerability, DOI may want to focus initial climate adaptation planning only on the outcomes of studies that comprehensively address vulnerability as inclusive of exposure, sensitivity, and adaptive capacity. Although the present study results are preliminary and used an unstructured survey design, they illustrate the importance of a comprehensive and consistent vulnerability definition and of using information on vulnerability components in DOI surveys to ensure relevant data are used to identify adaptation options.

Open-File Report↗
USGS1980

Outer Continental Shelf oil and gas activities in the mid-Atlantic and their onshore impacts: A summary report, November 1979: Update 1, June 30, 1980

The Master Water Data Index (MWDI) of the U.S. Geological Survey's National Water Data Exchange (NAWDEX) is a computerized data base which contains information about water data collected at specific sites. The data base identifies the organization collecting the data, the site location, the major types of data collected, the period of collection, and the frequency of measurement of major parameters for each type of data. This manual contains instructions for the encoding and keypunching of information for entry into the MWDI. Updates are published approximately every 6 months to provide new and revised information. A new Summary Report will be published only if a significant event occurs in the Region. This update covers new drilling operations in the Lease Sale 40 and 49 areas, information on the status of the upcoming Lease Sale 59, and an update on studies relevant to OCS-related planning activities. The organization of the update parallels that of the first Mid-Atlantic Summary Report. A copy of the Summary Report (USGS Open-File Report 80-17) can be obtained from the OCSIP. The address is listed on the reverse side of the title page.

Open-File Report↗
USGS1991

National Water-Quality Assessment Program - Western Lake Michigan Drainage Basin

In 1991 , the U.S. Geological Survey (USGS) began to implement a full -scale National Water-Quality Assessment (NA WQA) program. The long-term goal of the NA WQA program are to desc ribe the tatus and trends in the quality of a large, representative part of the Nation's urface- and ground-water resources and to provide a sound , scientific understanding of the primary natural and human factor affecting the quality of these resources. In meeting these goal , the program will produce a wealth of water-quality information that will be useful to policy makers and managers at the nationa l, State , and local levels. A major design feature of the NA WQA program will enable water-quality information at di ffe rent areal scales to be integrated . A major component of the program is study-unit investigations, which comprise the princ ipal bui lding blocks of the program on which national-level asses ment activities a re based . The 60 study-unit in vestigations that make up the program are hydrologic systems that include parts of most major river bas ins and a qui fer systems. These study units cover areas of I ,200 to more than 65 ,000 square mi les and incorporate about 60 to 70 percent of the Nation's water use and popul ation e rved by public water supply. In 1991 , the Western Lake Michigan drainage basin was among the fir st 20 NA WQA study unit selected for study under the full -scale implementation plan.

Michigan, Wisconsin↗
USGS1999

Geochemical investigations and interim recommendations for priority abandoned mine sites, BLM lands, upper Animas River watershed, San Juan County, Colorado

Field observations, sampling of mine dumps and mine drainage waters, and laboratory studies of dump materials have been made at mining areas deemed to be on public lands administered by the U. S. Bureau of Land Management (BLM) in the Upper Animas River watershed. Results of chemical analyses of dump materials, leachates of those materials, and surface waters draining mines or dumps provide indications of where acid is generated or consumed, and metal concentrations below mines or dumps. Information on sites previously identified as needing reclamation is reviewed and available geochemical information is used to rank 26 sites into four classes of priority for reclamation. Although there are more than a thousand mining sites (productive mines and prospects) on BLM lands in the Upper Animas River watershed study area, the majority are very small (less than about 70 cubic yards of dump material), are more than 2 miles from a major stream, or so inaccessible as to prohibit reclamation. In the summers of 1997 and 1998 approximately 200 sites were observed and more than 100 of these that appeared to have the potential to geochemically impact the watershed were examined more carefully and sampled. Building upon the prior work of the BLM and associated agencies, this work attempted to identify the most significant sources of mine-related contamination and to rank those sites as to priority for reclamation. These most significant mining areas have been examined within a geologic framework and were evaluated by multiple criteria, including tendency to generate acid and release toxic metals, observed damage to vegetation, potential to release metals based on leach tests, and likelihood of transport into streams of the watershed. No single measurable parameter, such as metal concentration, can be used to rank the sites. Rather, subjective estimates are required to evaluate combinations or interactions among several parameters. The most subjective estimate, while ranking feasibility of reclamation, is the relative amounts of naturally occurring metals and acidity and mine-related contamination at each mining area. Mitigation of natural contributions at mines or unmined areas is beyond the scope of my studies, but should be considered when planning reclamation. Available information for the 26 priority sites is adequate for ranking, but at some sites additional information on groundwater conditions is needed for a more complete site evaluation.

Open-File Report↗
USGS2010

Geohydrology of the stratified-drift aquifer system in the lower Sixmile Creek and Willseyville Creek trough, Tompkins County, New York

In 2002, the U.S. Geological Survey, in cooperation with the Tompkins County Planning Department began a series of studies of the stratified-drift aquifers in Tompkins County to provide geohydrologic data for planners to develop a strategy to manage and protect their water resources. This aquifer study in lower Sixmile Creek and Willseyville Creek trough is the second in a series of aquifer studies in Tompkins County. The study area is within the northern area of the Appalachian Plateau and extends about 9 miles from the boundary between Tompkins County and Tioga County in the south to just south of the City of Ithaca in the north. In lower Sixmile Creek and Willseyville Creek trough, confined sand and gravel aquifers comprise the major water-bearing units while less extensive unconfined units form minor aquifers. About 600 people who live in lower Sixmile Creek and Willseyville Creek trough rely on groundwater from the stratified-drift aquifer system. In addition, water is used by non-permanent residents such as staff at commercial facilities. The estimated total groundwater withdrawn for domestic use is about 45,000 gallons per day (gal/d) or 0.07 cubic foot per second (ft3/s) based on an average water use of 75 gal/d per person for self-supplied water systems in New York. Scouring of bedrock in the preglacial lower Sixmile Creek and Willseyville Creek valleys by glaciers and subglacial meltwaters truncated hillside spurs, formed U-shaped, transverse valley profiles, smoothed valley walls, and deepened the valleys by as much as 300 feet (ft), forming a continuous trough. The unconsolidated deposits in the study area consist mostly of glacial drift, both unstratified drift (till) and stratified drift (laminated lake, deltaic, and glaciofluvial sediments), as well as some post-glacial stratified sediments (lake-bottom sediments that were deposited in reservoirs, peat and muck that were deposited in wetlands, and alluvium deposited by streams). Multiple advances and retreats of the ice in the study area resulted in several sequences of various types of glacial deposits. A large moraine (Valley Heads Moraine) dominates the southern part of the study area, a large delta dominates the central part, and ground moraine (mostly till) dominates the northern part. Glacial sediments in the center of the lower Sixmile Creek and Willseyville Creek trough typically range from 150 to 200 ft but can be greater than 300 ft in some places. Where the sediments are composed of sand and gravel they form aquifers. In most parts of the lower Sixmile Creek and Willseyville Creek trough, there is an upper and a basal confined aquifer. However, underlying the central parts of the Brooktondale delta, there are as many as four confined aquifers, whereas in the northern part of the study area, only one extensive confined aquifer is present. The major sources of recharge to these confined aquifers are (1) direct infiltration of precipitation where confined aquifers crop out at land surface (mostly along the western trough wall in the southern and central parts of the study area and, to a lesser degree, along the eastern trough wall); (2) unchanneled surface and subsurface runoff from adjacent upland areas that seeps into the aquifer along the western trough walls; (3) subsurface flow from underlying till or bedrock at the lateral contacts at trough walls; (4) adjacent fine-grained stratified drift, especially when the aquifer is pumped; and (5) discharge from bedrock at the bottom and sides of the trough. In the central part of the study area, the surficial coarse-grained sediments (sand and gravel) comprise a delta near Brooktondale and form a small unconfined aquifer (0.3 square mile). Although much of the upper part of the delta has been removed by several aggregate mining operations, sufficient amounts of sand and gravel remain in most places to form a thin unconfined aquifer. The major sources of recharge to the unconfined aquifer are (1)

Scientific Investigations Report↗
USGS2012

Algal community characteristics and response to nitrogen and phosphorus concentrations in streams in the Ozark Plateaus, Southern Missouri, 1993-95 and 2006-07

Nutrient and algae data were collected in the 1990s and 2000s by the U.S. Geological Survey for the National Water- Quality Assessment program in the Ozark Highlands, southern Missouri. These data were collected at sites of differing drainage area, land use, nutrient concentrations, and physiography. All samples were collected at sites with a riffle/pool structure and cobble/gravel bed material. A total of 60 samples from 45 sites were available for analyses to determine relations between nutrient concentrations and algal community structure in this region. This information can be used by the Missouri Department of Natural Resources to develop the State's nutrient criteria plan. Water samples collected for this study had total nitrogen concentrations ranging from 0.07 to 4.41 milligram per liter (mg/L) with a median of 0.26 mg/L, and total phosphorus concentrations ranging from 0.003 to 0.78 mg/L with a median of 0.007 mg/L. These nutrient concentrations were transformed into nutrient categories consisting of varying percentiles of data. Algal community data were entered into the U.S. Geological Survey's Algae Data Analysis System for the computation of more than 250 metrics. These metrics were correlated with nutrient categories, and four metrics with the strongest relation with the nutrient data were selected. These metrics were Organic Nitrogen Tolerance, Oxygen Tolerance, Bahls Pollution Class, and the Saprobien index with the 25th and 80th percentile nutrient categories. These data indicate that near the 80th percentile (Total Nitrogen = 0.84 mg/L, Total Phosphorus = 0.035 mg/L) the algae communities significantly changed from nitrogen-fixing species dominance to those species more tolerant of eutrophic conditions.

Missouri↗
USGS1997

Digital simulation of ground-water flow in the Warwick Aquifer, Fort Totten Indian Reservation, North Dakota

The demand for water from the Warwick aquifer, which underlies the Fort Totten Indian Reservation in northeastern North Dakota, has been increasing during recent years. Therefore, the Spirit Lake Sioux Nation is interested in resolving questions about the quantity and quality of water in the aquifer and in developing a water-management plan for future water use. A study was conducted to evaluate the surface-water and ground-water resources of the Fort Totten Indian Reservation and, in particular, the ground-water resources in the area of the Warwick aquifer. A major component of the study, addressed by this report, was to define the ground-water flow system of the aquifer. The Warwick aquifer consists of outwash deposits of the Warwick outwash plain that are as much as 30 feet thick and buried-valley deposits beneath the outwash plain that are as much as 200 feet thick. The aquifer is bounded on the north and west by end-moraine deposits and Devils Lake, on the south by the Sheyenne River Valley, and on the east by outwash deposits and ravines. The aquifer is underlain by Pierre Shale or by glacial till, clay, or silt. Ground-water gradients generally are small and rarely are more than 3 or 4 feet per mile. From 1982 to 1993, withdrawals from the Devils Lake well field averaged 1.5 cubic feet per second, and withdrawals from irrigation wells averaged 1.29 cubic feet per second. The combined discharge from springs may be about 3 cubic feet per second. During the early 1990s, the Warwick aquifer probably was in a steady-state condition with regard to storage change in the aquifer. A finite-difference, three-dimensional, ground-water flow model provided a reasonable simulation of ground-water flow in the Warwick aquifer. The aquifer was divided vertically into two layers and horizontally into a grid of 83 by 109 cells, each measuring 656 feet (200 meters) per side. The steady-state simulation was conducted using 1992 pumpage rates and October 1992 water levels. The mean absolute difference between simulated and derived water-level altitudes during final calibration of the model was 1.52 feet. The two transient simulations were conducted for 20 time intervals of 1 year each using both the small and large storage estimates, doubled 1992 pumpage from the Devils Lake well field, 1992 irrigation pumpage, and initial water-level altitudes simulated by the October 1992 steady-state simulation. In the simulation using the small storage estimate and doubled pumpage, model cells in the area of the well field went dry after 13 years. Assumptions made in the design of the model generally are supported by the digital simulation. Except in the area of Warwick Springs and smaller springs, lateral and basal boundaries of the aquifer are impermeable. The flow system is dominated by recharge and evapotranspiration. Recharge rates obtained during the calibration process were lower in topographically high areas than in topographically low areas. Hydraulic conductivity in the area of the Devils Lake well field was larger than that in the rest of the aquifer.

Water-Resources Investigations Report↗
USGS2022

A framework for ensemble modelling of climate change impacts on lakes worldwide: The ISIMIP lake sector.

Empirical evidence demonstrates that lakes and reservoirs are warming across the globe. Consequently, there is an increased need to project future changes in lake thermal structure and resulting changes in lake biogeochemistry in order to plan for the likely impacts. Previous studies of the impacts of climate change on lakes have often relied on a single model forced with limited scenario-driven projections of future climate for a relatively small number of lakes. As a result, our understanding of the effects of climate change on lakes is fragmentary, based on scattered studies using different data sources and modelling protocols, and mainly focused on individual lakes or lake regions. This has precluded identification of the main impacts of climate change on lakes at global and regional scales and has likely contributed to the lack of lake water quality considerations in policy-relevant documents, such as the Assessment Reports of the Intergovernmental Panel on Climate Change (IPCC). Here, we describe a simulation protocol developed by the Lake Sector of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) for simulating climate change impacts on lakes using an ensemble of lake models and climate change scenarios for ISIMIP phases 2 and 3. The protocol prescribes lake simulations driven by climate forcing from gridded observations and different Earth system models under various representative greenhouse gas concentration pathways (RCPs), all consistently bias-corrected on a 0.5 ∘ × 0.5 ∘ global grid. In ISIMIP phase 2, 11 lake models were forced with these data to project the thermal structure of 62 well-studied lakes where data were available for calibration under historical conditions, and using uncalibrated models for 17 500 lakes defined for all global grid cells containing lakes. In ISIMIP phase 3, this approach was expanded to consider more lakes, more models, and more processes. The ISIMIP Lake Sector is the largest international effort to project future water temperature, thermal structure, and ice phenology of lakes at local and global scales and paves the way for future simulations of the impacts of climate change on water quality and biogeochemistry in lakes.

Geoscientific Model Development↗