USGS Science⌕ Search

SEARCH · USGS Science

Results for “Natural Resource Modeling”

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 1,495 records · Page 83Linked to original sources
USGS2001

Analysis of ambient conditions and simulation of hydrodynamics, constituent transport, and water-quality characteristics in Lake Maumelle, Arkansas, 1991-92

Lake Maumelle is the major drinking-water source for the Little Rock metropolitan area in central Arkansas. Urban and agricultural development has increased in the Lake Maumelle Basin and information is needed related to constituent transport and water quality response to changes in constituent loading or hydrologic regime. This report characterizes ambient conditions in Lake Maumelle and its major tributary, Maumelle River; describes the calibration and verification of a numerical model of hydrodynamics and water quality; and provides several simulations that describe constituent transport and water quality response to changes in constituent loading and hydrologic regime. Ambient hydrologic and water-quality conditions demonstrate the relatively undisturbed nature of Lake Maumelle and the Maumelle River. Nitrogen and phosphorus concentrations were low, one to two orders of magnitude lower than estimates of national background nutrient concentrations. Phosphorus and chlorophyll a concentrations in Lake Maumelle demonstrate its oligotrophic/mesotrophic condition. However, concentrations of chlorophyll a appeared to increase since 1990 within the upper and middle reaches of the reservoir. A two-dimensional, laterally averaged hydrodynamic and water-quality model developed and calibrated for Lake Maumelle simulates water level, currents, heat transport and temperature distribution, conservative material transport, and the transport and transformation of 11 chemical constituents. Simulations included the movement and dispersion of spills or releases in the reservoir during stratified and unstratified conditions, release of the fish nursery pond off the southern shore of Lake Maumelle, and algal responses to changes in external loading. The model was calibrated using 1991 data and verified using 1992 data. Simulated temperature and dissolved oxygen concentrations related well when compared to measured values. Simulated nutrient and algal biomass also related reasonably well when compared to measured values. A simulated spill of conservative material at the upper end of Lake Maumelle during a major storm event took less than 102 hours to disperse the entire length of the reservoir. Simulation of a nursery pond release into a tributary to Lake Maumelle demonstrated how the released water plunges within the receiving embayment and enters the main stem of the reservoir at mid depths. Simulations of algal response to increases of nitrogen and phosphorus loads demonstrate the phosphorus limiting condition in Lake Maumelle. Results from this study will provide water-resource management with information to better understand how changes in hydrology and water quality in the basin affects water quality in the reservoir. With this information, managers will be able to more effectively manage their drinking-water source supply.

Arkansas↗
USGS2009

Inventories and mobilization of unsaturated zone sulfate, fluoride, and chloride related to land use change in semiarid regions, southwestern United States and Australia

Unsaturated zone salt reservoirs are potentially mobilized by increased groundwater recharge as semiarid lands are cultivated. This study explores the amounts of pore water sulfate and fluoride relative to chloride in unsaturated zone profiles, evaluates their sources, estimates mobilization due to past land use change, and assesses the impacts on groundwater quality. Inventories of water‐extractable chloride, sulfate, and fluoride were determined from borehole samples of soils and sediments collected beneath natural ecosystems ( N = 4), nonirrigated (“rain‐fed”) croplands ( N = 18), and irrigated croplands ( N = 6) in the southwestern United States and in the Murray Basin, Australia. Natural ecosystems contain generally large sulfate inventories (7800–120,000 kg/ha) and lower fluoride inventories (630–3900 kg/ha) relative to chloride inventories (6600–41,000 kg/ha). Order‐of‐magnitude higher chloride concentrations in precipitation and generally longer accumulation times result in much larger chloride inventories in the Murray Basin than in the southwestern United States. Atmospheric deposition during the current dry interglacial climatic regime accounts for most of the measured sulfate in both U.S. and Australian regions. Fluoride inventories are greater than can be accounted for by atmospheric deposition in most cases, suggesting that fluoride may accumulate across glacial/interglacial climatic cycles. Chemical modeling indicates that fluorite controls fluoride mobility and suggests that water‐extractable fluoride may include some fluoride from mineral dissolution. Increased groundwater drainage/recharge following land use change readily mobilized chloride. Sulfate displacement fronts matched or lagged chloride fronts by up to 4 m. In contrast, fluoride mobilization was minimal in all regions. Understanding linkages between salt inventories, increased recharge, and groundwater quality is important for quantifying impacts of anthropogenic activities on groundwater quality and is required for remediating salinity problems.

Water Resources Research↗
USGS1985

Interlaboratory comparability, bias, and precision for four laboratories measuring constituents in precipitation, November 1982-August 1983

Four laboratories were evaluated in their analysis of identical natural and simulated precipitation water samples. Interlaboratory comparability was evaluated using analysis of variance coupled with Duncan 's multiple range test, and linear-regression models describing the relations between individual laboratory analytical results for natural precipitation samples. Results of the statistical analyses indicate that certain pairs of laboratories produce different results when analyzing identical samples. Analyte bias for each laboratory was examined using analysis of variance coupled with Duncan 's multiple range test on data produced by the laboratories from the analysis of identical simulated precipitation samples. Bias for a given analyte produced by a single laboratory has been indicated when the laboratory mean for that analyte is shown to be significantly different from the mean for the most-probable analyte concentrations in the simulated precipitation samples. Ion-chromatographic methods for the determination of chloride, nitrate, and sulfate have been compared with the colorimetric methods that were also in use during the study period. Comparisons were made using analysis of variance coupled with Duncan 's multiple range test for means produced by the two methods. Analyte precision for each laboratory has been estimated by calculating a pooled variance for each analyte. Analyte estimated precisions have been compared using F-tests and differences in analyte precisions for laboratory pairs have been reported. (USGS)

Water-Resources Investigations Report↗
USGS1990

Geohydrology and simulation of ground-water flow in the carbonate rocks of the Valley Creek basin, eastern Chester County, Pennsylvania

Sixty-eight percent of the 22.6-square-mile Valley Creek basin is underlain by Cambrian and Ordovician limestone and dolomite. Ground water flows through a network of interconnected secondary openings; primary porosity is virtually nonexistent. Some of these openings have been enlarged by solution. Secondary porosity and permeability exhibit great spatial variability, and the yield and specific capacity of wells are highly variable. The number of water-bearing zones decreases with depth. Fifty percent of water-bearing zones are encountered within 100 feet of the land surface, and 81 percent are within 200 feet. Most ground-water flow in the Valley Creek basin is local and discharges to nearby streams. Ground-water discharge comprised an average of 76 percent of the flow of Valley Creek during 1983--87, including both natural ground- water discharge and quarry pumpage discharged to Valley Creek. Discharge from the Cedar Hollow quarry comprised 21 to 26 percent of the base flow of Valley Creek; the average was 23 percent. The average natural base flow of Valley Creek would be 8 percent lower if the quarry were not operating. Regional ground-water flow is to the northeast to the Schuylkill River. On the western side of the Valley Creek basin, the ground-water divide is 1/2 mile west of the surface-water divide. An estimated 0.75 million gallons per day of ground water flows from the adjacent West Valley Creek basn eastward into the Valley Creek basin. A ground-water divide is not present on the eastern side of the basin; the water table slopes gently eastward toward the Schuylkill River. On the northeaster side, an estimated 1.76 million gallons per day of ground water flows northeastward out of the basin to the Schuylkill River beneath the surface-water divide. On the southeaster side, an estimated 0.85 million gallons per day of ground water flows beneath the surface-water divide into the basin. Annual water budgets and an average water budget were calculated for 1983-87 for the 20.8-square-mile area bove the streamflow-gaging station. Annual precipitation for 1983-87 ranged from 40.61 to 56.55 inches and averaged 47.25 inches; annual streamflow ranged from 15.55 to 28.57 inches and averaged 22.31 inches; annual evapotranspiration ranged from 18.21 to 24.83 inches and averaged 22.90 inches; and annual recharge ranged from 15.89 to 26.84 inches and averaged 21.04 inches. The Valley Creek basin was modeled as a two-dimensional water-table aquifer. Recharge to, ground-water flow through, and discharge from the rocks of Chester valley were simulated. In order to include the natural hydrologic boundaries of the ground-water-flwo system, the 66.4-square-mile area between the Brandywine Creek and the Schuylkill River was modeled. The model was calibrated under stead-state conditions using avareage recharge and evapotranspiration rates. Aquifer hydraulic conductivity was estimated from specific-capacity and quifer-test data. The average (1983-87) annual water budget for hte Valley Creek basin was simualted. The effect of increased ground-water development on base flow and underflow was simulated by locating a hypothetical well field produceing 4 million gallons per day in different parts of the basin. Pumpage from a well field near surface-water divides would induce as much as an additional 1.41 inches per year of underflow from an adjacent surface-water basin. Pumpage from a well field near the center of the basin would affect base flow more than underflow. Increased seepage of ground water into quarries as a result of their expansion was simulated as increased withdrawal by pumping. A 100-percent increase in the pumping rate of the Cedar Hollow quarry, from 3.93 to 7.86 million gallons per day, owuld reduce the natural base flow of Valley Creek by 18 percent. However, the quarry pumpage would be discharged to Valley Creek, thereby increasing the base flow at the gaging station by

Pennsylvania↗
USGS1982

Water resources inventory of Connecticut Part 10: Lower Connecticut River basin

The lower Connecticut River basin study area in south-central Connecticut includes 639 square miles and is drained principally by the Connecticut River and by seven smaller streams that flow directly to Long Island Sound between the West River on the west and the Connecticut River on the east. The population in 1979 was estimated to be 210,380. Much of the industrial development and population centers are in the Mattabesset River basin in the northwestern part, and the largest water use is also in the Mattabesset River basin. Precipitation averages 47 inches per year and provides an abundant supply of water. About 20 inches returns to the atmosphere as evapotranspiration, and the remainder either flows directly to streams or percolates to the water table, eventually discharging to Long Island Sound. Small quantities of water are exported from the basin by the New Haven and Meridan Water Departments, and small quantities are imported by the New Britain Water Department and Metropolitan Direct Commission. Precipitation during 1931-60 resulted in an average annual runoff of 302 billion gallons. In inflow from the Connecticut River is added to the average annual runoff, the 4,370 billion gallon s per year is potentially available for water ue. The domestic, institutional, commercial, and industrial (other than cooling water) water use for 1970 was 7 billion gallons, which is only 3 percent of the total water used, whereas 97 percent of the total is cooling water for power plants. Approximately 60 percent of the 7 billion gallons is treated before being discharged back to the streams. The total amount of fresh water used during 1970 was estimated to be 256,000 million gallons (Mgal), of which 247,000 Mgal was used for cooling water at stream electric-generating plants. The quantity for domestic, commercial, industrial, and agricultural used was 9,000 Mgal, which was approximately 120 gallons a day per person. Public water systems providing 70 percent of these requirement and all the systems supplying water met the drinking water standards of the Connecticut General Assembly (1975). Till is widespread and generally provides only small amounts of water. Wells in till normally yield only a few hundred gallons of water daily and may be inadequate during dry periods. The thickness of of till ranges from 0 to 15 feet; a median thickness of 26 feet is estimated from information provided in drillers' logs of 467 wells penetrating underlying bedrock. The till is generally used only as an emergency or secondary source of water. Bedrock aquifers underlie the entire area and include sedimentary and crystalline (igneous and metamorphic) rock types. These aquifers supply small and usually reliable quantities of water to wells and are the chief source of water for many rural homes and farms., About 90 percent of the wells tapping bedrock yield at least 2 gal/min. The median yields from wells tapping aquifers in sedimentary, igneous, and metamorphic rocks are 11, 8, and 6.5 gal/min, respectively. The quantity of water potentially available from stratified drift was estimated on the basis of hydraulic characteristics of the aquifers, mathematical modeling of the aquifer system, and evaluation of natural and induced recharge. Long-term yields estimated or ten areas underlain by significant thickness of stratified drift range from 0.4 to 4.4 million gallons per day (Mgal/d). A change in well spacing or numbering could increase the long-term yields, but detailed modeling verification studies are needed to confirm optimal well locations. The chemical and physical (turbidity, color, taste, and sediment load) quality of water is good. The water if generally low in dissolved solids and is classified as soft to hard. Surface water is less mineralized than ground water, especially during high flow, when it is primarily derived from surface runoff rather than groundwater runoff. A median dissolved-solids concentration of 42 milligrams per liter (mg/L) and median hardness of 18 mg/L were determined from water samples collected from 26 streams during the high-flow period. During the low-flow period, median dissolved-solids concentration of 61 mg/L and median hardness of 27 mg/L were determined from sample from the same streams. The quality of water in stratified-drift and crystalline-rock aquifers is generally better than that in the sedimentary-rock aquifers. Water from 32 wells tapping stratified drift had median dissolved-solids concentrations of 116 mg/L; and 33 wells tapping stratified drift and 42 tapping crystalline rock had median hardness of 73 mg/L and 68 mg/L, respectively. Water from 32 wells tapping sedimentary rock had median dissolved concentrations of 231 and 156 mg/L, respectively. Sedimentary rock generally yields the hardest water. Iron and manganese occur objectionable concentrations in places, particularly in water from streams draining swamps and in water from aquifers either rich in iron and manganese-nearing minerals or where the reducing environment for solution of these minerals is favorable. Concentrations of iron in excess of 0.3 mg/L were found in 35 percent of the high streamflow samples, and in 45 percent of the ground-water samples. Most of the high iron and manganese concentration in streams and aquifers are found east of the Connecticut River. Human activities and tidal influence along the coast have modified the quality of water in much f the study area. The greatest influence from human activities has been in the northwestern part, in the Mattabesset River basin. There, the quality of water has been affected by domestic and animal wastes, which cause high dissolved-solids concentrations, high nitrate and phosphate loads and high bacterial counts. In the entire area, high nitrate in groundwater occur only locally, and its presence in an individual water supply is chiefly a function of its proximity to sources of contamination, of well construction, and of thickness of overburden. Thirty public-supply wells did have water that had high sodium concentrations or objectionable iron and manganese concentrations, but these are not considered health hazards in the concentrations found in the water samples. Streams, wetlands, and some aquifers along the sough boundary of the basin contain salty water because of tidal movement or extensive ground-water withdrawals. High sediment concentrations also occur as a result of tidal influence in this area.

Connecticut↗
USGS2016

The impacts of human recreation on brown bears (Ursus arctos): A review and new management tool

Increased popularity of recreational activities in natural areas has led to the need to better understand their impacts on wildlife. The majority of research conducted to date has focused on behavioral effects from individual recreations, thus there is a limited understanding of the potential for population-level or cumulative effects. Brown bears (Ursus arctos) are the focus of a growing wildlife viewing industry and are found in habitats frequented by recreationists. Managers face difficult decisions in balancing recreational opportunities with habitat protection for wildlife. Here, we integrate results from empirical studies with expert knowledge to better understand the potential population-level effects of recreational activities on brown bears. We conducted a literature review and Delphi survey of brown bear experts to better understand the frequencies and types of recreations occurring in bear habitats and their potential effects, and to identify management solutions and research needs. We then developed a Bayesian network model that allows managers to estimate the potential effects of recreational management decisions in bear habitats. A higher proportion of individual brown bears in coastal habitats were exposed to recreation, including photography and bear-viewing than bears in interior habitats where camping and hiking were more common. Our results suggest that the primary mechanism by which recreation may impact brown bears is through temporal and spatial displacement with associated increases in energetic costs and declines in nutritional intake. Killings in defense of life and property were found to be minimally associated with recreation in Alaska, but are important considerations in population management. Regulating recreation to occur predictably in space and time and limiting recreation in habitats with concentrated food resources reduces impacts on food intake and may thereby, reduce impacts on reproduction and survival. Our results suggest that decisions managers make about regulating recreational activities in time and space have important consequences for bear populations. The Bayesian network model developed here provides a new tool for managers to balance demands of multiple recreational activities while supporting healthy bear populations.

PLoS ONE↗
USGS2018

Drain tiles and groundwater resources: Understanding the relations

Executive Summary Drainage for agricultural production over the past 150 years has been an integral component of human-driven change to Minnesota’s rural landscapes. Benefits of drainage Historically, poorly drained soils across much of the State would often remain saturated or flooded after spring snowmelt, preventing timely farm operations such as tilling and planting crops (Arneman, 1963). Installation of agricultural drainage, both surface ditches and subsurface drainage, accelerated transport of water off farm fields and imparted producers higher crop yields (Beauchamp, 1987; Stoner and others, 1993). Agricultural drainage offered many other benefits such as preventing crop drown out, aerating the soil profile for improved plant growth, limiting surface runoff and soil erosion, and allowing farmers better access to croplands (Fausey and others, 1987). Without agricultural drainage on much of Minnesota’s croplands, it would have been difficult to realize high enough crop yields to remain economically viable. Environmental concerns While drainage of Minnesota croplands provided the benefits mentioned above, several environmental concerns result. These include wetland loss, degradation of downstream water quality, and reduced [potential for] recharge. Early agricultural drainage efforts (pre-20th century) led to the disappearance of much of Minnesota’s natural wetlands. Increased focus on preventing or mitigating wetland loss over the last 50 years has helped curtail further losses, even as agricultural drainage proceeds. Prior to establishment of Minnesota statehood, wetlands accounted for more than 10 million acres in Minnesota, including prairie wetlands, peatlands, and forest wetlands that comprised approximately 19 percent of the total land area (Palmer, 1915; King, 1980). In 2018, only half of Minnesota’s pre-settlement wetlands remain, mostly in parts of the State that have not experienced widespread drainage, such as northern Minnesota. Water-quality monitoring has shown that agricultural drainage, in particular the practice of subsurface drainage, provides a direct flow path for nutrient (nitrogen and soluble phosphorus) losses to surface water resources. The negative consequences of agricultural drainage on surface water quality are well documented (for example, Dinnes and others, 2002; Kladivko and others, 2004; Richards and others, 2008; Rozemeijer and others, 2010; Schottler and others, 2013). Agricultural basins with a high percentage of agricultural drainage have been implicated as part of the cause of the Gulf of Mexico hypoxia zone due to excessive nitrogen export (Goolsby and Battaglin, 2001; Randall and Mulla, 2001). The connection of hydrological effects of agricultural subsurface drainage on groundwater recharge and aquifers, on the other hand, has not been well-established. Agricultural subsurface drainage intercepts infiltrating water below croplands and directly discharges the water to nearby surface waters. However, the size of the water balance shift from drained water that would have evapotranspired or run off the land to drained water that would recharge underlying aquifers has been poorly characterized (Schuh, 2008). Drain Tiles and Groundwater Given the poor accounting of subsurface drainage effects on groundwater resources, the Minnesota Ground Water Association (MGWA) deemed it imperative that we document these effects so that groundwater resources in agricultural regions with substantial drainage can be effectively managed. This white paper documents the relations of drain tiles and groundwater resources and discusses the historical significance of agricultural drainage practices, the recognized positive benefits and potential negative consequences of agricultural drainage practices, and the gaps in understanding of the connections between agricultural drainage and groundwater resources. The major messages emerged from the findings of this white paper are: Complex history. Minnesota has a long history of agricultural drainage, spanning over 150 years. Agricultural drainage, and the eventual widespread usage of subsurface drainage, can be separated into at least four distinct periods of time: (a) early drainage to get water off the land, pre-20th century; (b) the boom and bust era (1900-1945); (c) postwar resurgence of subsurface drainage and early conservation efforts (1945-1960); and, (d) emergence of the environmental movement (1960 to present). The State’s regulatory framework that both allowed for drainage and controlled its usage during these periods is complicated and has been governed by a patchwork of both State and Federal statutes. Drainage Provinces. This white paper advances the concept of tile drainage provinces to aid in the discussion of regional differences in subsurface drainage and its overall effect on groundwater resources. Built upon the concept of groundwater provinces (Minnesota Department of Natural Resources, 2001), three distinct tile drainage provinces were conceptualized: (1) the Southeastern Province; (2) the SouthCentral Province; and, (3) the Western Province. The distinct geology and the soils that developed in these regions have implications for each region’s subsurface drainage density and the potential implications for groundwater. Knowledge gaps. Several critical knowledge gaps are identified in this paper, creating opportunities for further research to improve our understanding for better managed water resources: Extent of drainage is unknown. Direct estimates of the extent of subsurface drainage do not exist in Minnesota. However, several indirect methods have been utilized to estimate subsurface drainage, from the field-scale to countylevel through the use of geographic information system (GIS) analysis and aerial photography. Based on a 2012 U.S. Geological Survey estimate of subsurface drainage extent (Nakagaki and Wieczorek, 2016), about 21% of the land area in Minnesota has some density of subsurface drainage. Effect of drainage on underlying aquifers is unknown. A basic understanding of unconfined and confined aquifers and their recharge is necessary to connect any hydrological effects from agricultural drainage to groundwater. The basic goal of subsurface drainage to efficiently drain saturated soils clearly alters the water balance in croplands. However, its overall effect on groundwater resources has been poorly characterized, and is in large part determined by the geology below drained areas and the arrangement of underlying aquifers. Water balance shifts. An improved understanding of historical water balance shifts from pre- to post-drainage periods is necessary to understand long-term implications on net groundwater recharge. Also, more direct field-scale studies and indirect modeling studies are needed to characterize water budgets for fields with subsurface drainage.

Minnesota↗
USGS2000

Variability of bed mobility in natural, gravel‐bed channels and adjustments to sediment load at local and reach scales

Local variations in boundary shear stress acting on bed‐surface particles control patterns of bed load transport and channel evolution during varying stream discharges. At the reach scale a channel adjusts to imposed water and sediment supply through mutual interactions among channel form, local grain size, and local flow dynamics that govern bed mobility. In order to explore these adjustments, we used a numerical flow model to examine relations between model‐predicted local boundary shear stress (т j ( and measured surface particle size ( D 50 ) at bank‐full discharge in six gravel‐bed, alternate‐bar channels with widely differing annual sediment yields. Values of т j and D 50 were poorly correlated such that small areas conveyed large proportions of the total bed load, especially in sediment‐poor channels with low mobility. Sediment‐rich channels had greater areas of full mobility; sediment‐poor channels had greater areas of partial mobility; and both types had significant areas that were essentially immobile. Two reach‐mean mobility parameters (Shields stress and Q *) correlated reasonably well with sediment supply. Values which can be practicably obtained from carefully measured mean hydraulic variables and particle size would provide first‐order assessments of bed mobility that would broadly distinguish the channels in this study according to their sediment yield and bed mobility.

Water Resources Research↗
USGS2010

Effects of low-impact-development (LID) practices on streamflow, runoff quantity, and runoff quality in the Ipswich River Basin, Massachusetts: A summary of field and modeling studies

Low-impact-development (LID) approaches are intended to create, retain, or restore natural hydrologic and water-quality conditions that may be affected by human alterations. Wide-scale implementation of LID techniques may offer the possibility of improving conditions in river basins, such as the Ipswich River Basin in Massachusetts, that have run dry during the summer because of groundwater withdrawals and drought. From 2005 to 2008, the U.S. Geological Survey, in a cooperative funding agreement with the Massachusetts Department of Conservation and Recreation, monitored small-scale installations of LID enhancements designed to diminish the effects of storm runoff on the quantity and quality of surface water and groundwater. Funding for the studies also was contributed by the U.S. Environmental Protection Agency’s Targeted Watersheds Grant Program through a financial assistance agreement with Massachusetts Department of Conservation and Recreation. The monitoring studies examined the effects of replacing an impervious parking-lot surface with a porous surface on groundwater quality, installing rain gardens and porous pavement in a neighborhood of 3 acres on the quantity and quality of stormwater runoff, and installing a 3,000-ft2 (square-foot) green roof on the quantity and quality of rainfall-generated roof runoff. In addition to these small-scale installations, the U.S. Geological Survey’s Ipswich River Basin model was used to simulate the basin-wide effects on streamflow of several changes: broad-scale implementation of LID techniques, reduced water-supply withdrawals, and water-conservation measures. Water-supply and conservation scenarios for application in model simulations were developed with the assistance of two technical advisory committees that included representatives of State agencies responsible for water resources, the U.S. Environmental Protection Agency, the U.S. Geological Survey, water suppliers, and non-governmental organizations. From June 2005 to June 2007, groundwater quality was monitored at the Silver Lake town beach parking lot in Wilmington, Massachusetts, prior to and following the replacement of the conventional, impervious-asphalt surface with a porous surface consisting primarily of porous asphalt and porous pavers designed to enhance rainfall infiltration into the groundwater and to minimize runoff to Silver Lake. Concentrations of phosphorus, nitrogen, cadmium, chromium, copper, lead, nickel, zinc, and total petroleum hydrocarbons in groundwater were monitored. Enhancing infiltration of precipitation did not result in discernible increases in concentrations of these potential groundwater contaminants. Concentrations of dissolved oxygen increased slightly in groundwater profiles following the removal of the impervious asphalt parking-lot surface. In Wilmington, Massachusetts, in a 3-acre neighborhood, stormwater runoff volume and quality were monitored to determine the ability of selected LID enhancements (rain gardens and porous paving stones) to reduce flows and loads of the selected constituents to Silver Lake. Water-quality samples were analyzed for nutrients, metals, total petroleum hydrocarbons, and total-coliform and E. coli bacteria. A decrease in runoff quantity was observed for storms of 0.25 inch or less of precipitation. Water-quality-monitoring results were inconclusive; there were no statistically significant differences in concentrations or loads when the pre- and post-installation-period samples were compared. In a third field study, the characteristics of runoff from a vegetated "green" roof and a conventional, rubber-membrane roof were compared. The two primary factors affecting the green roof’s water-storage capacity were the amount of precipitation and antecedent dry period. Although concentrations of many of the chemicals in roof runoff were higher from the green roof than from the conventional roof, the ability of the green roof to retain water generally resulted in decreased differences between the total amounts (loads) of the chemicals that ran off the roofs. Land-use and water-management changes associated with LID implementation were investigated at multiple spatial scales, using the U.S. Geological Survey’s Ipswich River Basin model, to evaluate the effects of updated water-supply withdrawals for the towns of Reading and Wilmington (representing new baseline conditions for all simulations), potential land-use changes at buildout (potential future development), widespread implementation of retrofitting LID techniques, basin-scale water withdrawal reductions based on water-conservation pilot programs conducted by the Massachusetts Department of Conservation and Recreation, and land-use change and LID applications at a local scale. The new baseline simulation indicated that reduced water-supply withdrawals for the towns of Reading and Wilmington led to substantially higher medium and low flows in most of the reaches upstream from the South Middleton streamgage in the upper Ipswich River basin. Overall, simulations pointed to the importance of spatial scale in determining the effects of land-use change and LID practices on streamflow. Potential land-use changes at buildout had modest effects on streamflow in most subbasins (percent differences of less than 20 percent) because relatively little land in the basin was available for development. Results of the simulations conducted to evaluate widespread effective-impervious-area reductions upstream from the South Middleton streamgage indicated that the percentages of urban land use and associated effective impervious area were too small for even a 50-percent reduction of effective impervious area to appreciably affect streamflow in most subbasins. In contrast, the results of the hypothetical local-scale simulations indicated that for smaller streams, with high percentages of urban land use and associated effective impervious area, land-use change, development patterns, and LID practices may have substantial effects on streamflow. Modeling studies concurred with the results of fieldwork in the assessment that LID enhancements would likely have the greatest effect on decreasing stormwater runoff when broadly applied to highly impervious urban areas.

Massachusetts↗
USGS2025

Over, under, and through: Hydrologic connectivity and the future of coastal landscape salinization

Seawater intrusion (SWI) affects coastal landscapes worldwide. Here we describe the hydrologic pathways through which SWI occurs - over land via storm surge or tidal flooding, under land via groundwater transport, and through watersheds via natural and artificial surface water channels—and how human modifications to those pathways alter patterns of SWI. We present an approach to advance understanding of spatiotemporal patterns of salinization that integrates these hydrologic pathways, their interactions, and how humans modify them. We use examples across the East Coast of the United States that exemplify mechanisms of salinization that have been reported around the planet to illustrate how hydrologic connectivity and human modifications alter patterns of SWI. Finally, we suggest a path for advancing SWI science that includes (a) deploying standardized and well-distributed sensor networks at local to global scales that intentionally track SWI fronts, (b) employing remote sensing and geospatial imaging techniques targeted at integrating above and belowground patterns of SWI, and (c) continuing to develop data analysis and model-data fusion techniques to measure the extent, understand the effects, and predict the future of coastal salinization.

Water Resources Research↗
USGS1997

Methods for predicting peak discharge of floods caused by failure of natural and constructed earthen dams

Floods from failures of natural and constructed dams constitute a widespread hazard to people and property. Expeditious means of assessing flood hazards are necessary, particularly in the case of natural dams, which may form suddenly and unexpectedly. We revise statistical relations (derived from data for past constructed and natural dam failures) between peak discharge ( Q p ) and water volume released ( V 0 ) or drop in lake level ( d ) but assert that such relations, even when cast into a dimensionless form, are of limited utility because they fail to portray the effect of breach-formation rate. We then analyze a simple, physically based model of dam-breach formation to show that the hydrograph at the breach depends primarily on a dimensionless parameter η= kV 0 / g l/2 d 7/2 , where k is the mean erosion rate of the breach and g is acceleration due to gravity. The functional relationship between Q p and η takes asymptotically distinct forms depending on whether η ≪ 1 (relatively slow breach formation or small lake volume) or η ≫ 1 (relatively fast breach formation or large lake volume). Theoretical predictions agree well with data from dam failures for which k , and thus η, can be estimated. The theory thus provides a rapid means of predicting the plausible range of values of peak discharge at the breach in an earthen dam as long as the impounded water volume and the water depth at the dam face can be estimated.

Water Resources Research↗
USGS2016

The international river interface cooperative: Public domain flow and morphodynamics software for education and applications

This paper describes a new, public-domain interface for modeling flow, sediment transport and morphodynamics in rivers and other geophysical flows. The interface is named after the International River Interface Cooperative (iRIC), the group that constructed the interface and many of the current solvers included in iRIC. The interface is entirely free to any user and currently houses thirteen models ranging from simple one-dimensional models through three-dimensional large-eddy simulation models. Solvers are only loosely coupled to the interface so it is straightforward to modify existing solvers or to introduce other solvers into the system. Six of the most widely-used solvers are described in detail including example calculations to serve as an aid for users choosing what approach might be most appropriate for their own applications. The example calculations range from practical computations of bed evolution in natural rivers to highly detailed predictions of the development of small-scale bedforms on an initially flat bed. The remaining solvers are also briefly described. Although the focus of most solvers is coupled flow and morphodynamics, several of the solvers are also specifically aimed at providing flood inundation predictions over large spatial domains. Potential users can download the application, solvers, manuals, and educational materials including detailed tutorials at www.-i-ric.org . The iRIC development group encourages scientists and engineers to use the tool and to consider adding their own methods to the iRIC suite of tools.

Advances in Water Resources↗
USGS2023

The severity of the 2014–2015 snow drought in the Oregon Cascades in a multicentury context

The western United States (US) is a hotspot for snow drought. The Oregon Cascade Range is highly sensitive to warming and as a result has experienced the largest mountain snowpack losses in the western US since the mid-20th century, including a record-breaking snow drought in 2014–2015 that culminated in a state of emergency. While Oregon Cascade snowpacks serve as the state's primary water supply, short instrumental records limit water managers' ability to fully constrain long-term natural snowpack variability prior to the influence of ongoing and projected anthropogenic climate change. Here, we use annually-resolved tree-ring records to develop the first multi-century reconstruction of Oregon Cascade April 1st Snow Water Equivalent (SWE). The model explains 58% of observed snowpack variability and extends back to 1688 AD, nearly quintupling the length of the existing snowpack record. Our reconstruction suggests that only one other multiyear event in the last three centuries was as severe as the 2014–2015 snow drought. The 2015 event alone was more severe than nearly any other year in over three centuries. Extreme low-to-high snowpack “whiplash” transitions are a consistent feature throughout the reconstructed record. Multi-decadal intervals of persistent below-the-mean peak SWE are prominent features of pre-instrumental snowpack variability, but are generally absent from the instrumental period and likely not fully accounted for in modern water management. In the face of projected snow drought intensification and warming, our findings motivate adaptive management strategies that address declining snowpack and increasingly variable precipitation regimes.

Oregon↗
USGS2007

Porphyry copper deposit tract definition - A global analysis comparing geologic map scales

Geologic maps are a fundamental data source used to define mineral-resource potential tracts for the first step of a mineral resource assessment. Further, it is generally believed that the scale of the geologic map is a critical consideration. Previously published research has demonstrated that the U.S. Geological Survey porphyry tracts identified for the United States, which are based on 1:500,000-scale geology and larger scale data and published at 1:1,000,000 scale, can be approximated using a more generalized 1:2,500,000-scale geologic map. Comparison of the USGS porphyry tracts for the United States with weights-of-evidence models made using a 1:10,000,000-scale geologic map, which was made for petroleum applications, and a 1:35,000,000-scale geologic map, which was created as context for the distribution of porphyry deposits, demonstrates that, again, the USGS US porphyry tracts identified are similar to tracts defined on features from these small scale maps. In fact, the results using the 1:35,000,000-scale map show a slightly higher correlation with the USGS US tract definition, probably because the conceptual context for this small-scale map is more appropriate for porphyry tract definition than either of the other maps. This finding demonstrates that geologic maps are conceptual maps. The map information shown in each map is selected and generalized for the map to display the concepts deemed important for the map maker's purpose. Some geologic maps of small scale prove to be useful for regional mineral-resource tract definition, despite the decrease in spatial accuracy with decreasing scale. The utility of a particular geologic map for a particular application is critically dependent on the alignment of the intention of the map maker with the application. ?? International Association for Mathematical Geology 2007.

Natural Resources Research↗
USGS1976

Model analysis of effects on water levels at Indiana Dunes National Lakeshore caused by construction dewatering

Two computer models were developed to investigate possible hydrologic effects within the Indiana Dunes National Lakeshore caused by planned dewatering at the adjacent Bailly Nuclear Generator construction site. The dewatering, which is scheduled to last for about 18 months, would cause ground-water levels to be drawn down 20 to 30 feet (6 to 9 metres) to an elevation of 4 ft (1.2 m) below Lake Michigan datum under the approximately 7-acre (2.8-square hectometre) construction site, which is about 800 ft (245 m) west of the Lakeshore property. The results of this study have been used by the National Park Service to help evaluate the environmental impact of the dewatering, particularly the effects on the ecosystem of the lakeshore. The aquifer underlying the area is about 50 ft (15 m) thick and is composed of fine sand with layers of medium sand and gravel. All natural ponds in the area are separated from the aquifer by a low-permeability layer of silty organic muck and clay that ranges from about 1 to 4 ft (0.3 to 1.2 m) in thickness. This pond-bottom material acts only to retard the flow of water either to or from the aquifer beneath the ponds, depending upon the relative head in the pond and the aquifer. Elsewhere, the aquifer is under water-table conditions. The model analysis indicates that the planned dewatering would cause a drawdown of about 4 ft (1.2 m) under the westernmost pond of the Lakeshore and that this drawdown would cause the pond to go almost dry--less than 0.5 ft (0.15 m) of water remaining in about 1 percent of the pond--under average conditions during the 18-month dewatering period. When water levels are below average, as during late July and early August 1974, the pond would go dry in about 5 1/2 months. However, the pond may not have to go completely dry to damage the ecosystem. If the National Park Service's independent study determines the minimum pond level at which ecosystem damage would be minimized, the models developed in this study could be used to predict the hydrologic conditions necessary to maintain that level.

Indiana↗
USGS1980

Geohydrology and model analysis for water-supply management in a small area of west-central Kansas

The Ogallala Formation in the intensive-study area, an area of 12 square miles in northeastern Wichita County, west-central Kansas, has had a substantial decrease in saturated thickness since the development of irrigation. The annual water-level decline during 1950-78 ranged from 1.08 to 2.22 feet per year. The hydrologic system was investigated to study methods of conserving the remaining ground water in the intensive-study area. During 1977-78, the average annual ground-water withdrawal was 7,400 acre-feet, and the water-level decline ranged from 0.91 to 5.05 feet. The saturated thickness in 1977 ranged from about 40 to 80 feet, and aquifer storage was about 61,000 acre-feet. Natural recharge is estimated to be 0.28 inch per year. Projections from a digital ground-water flow model were used to indicate the additional water-level decline that might occur from 1978 to 1988 if pumpages in the 480-square-mile model area were one-half, equal to, or double the 1977 pumpage rate. The additional water-level declines in the intensive-study area would range from 5 to 15 feet if pumpages were one-half, 15 to 30 feet if pumpages were equal to, and 25 to 40 feet if pumpages were double the 1977 rate. Projections also were used to indicate the water-level declines if pumpages in the model area were equal to the 1977 rate and if pumpages in the intensive-study area were one-half or double the 1977 rate. Additional water-level declines in the intensive-study area would range from 10 to 20 feet if pumpages were one-half and from 20 to 25 feet if pumpages were doubled. Decreased pumpage in the area could reduce the water-level declines, but continued pumpage in adjacent areas would cause declines to be greater near the edge than near the center. The digital model was more sensitive to changes in pumpage than to changes in hydraulic conductivity, specific yield, and recharge.

Kansas↗
USGS2017

Climate change refugia and habitat connectivity promote species persistence

Background Climate change refugia, areas buffered from climate change relative to their surroundings, are of increasing interest as natural resource managers seek to prioritize climate adaptation actions. However, evidence that refugia buffer the effects of anthropogenic climate change is largely missing. Methods Focusing on the climate-sensitive Belding’s ground squirrel ( Urocitellus beldingi ), we predicted that highly connected Sierra Nevada meadows that had warmed less or shown less precipitation change over the last century would have greater population persistence, as measured by short-term occupancy, fewer extirpations over the twentieth century, and long-term persistence measured through genetic diversity. Results Across California, U. beldingi were more likely to persist over the last century in meadows with high connectivity that were defined as refugial based on a suite of temperature and precipitation factors. In Yosemite National Park, highly connected refugial meadows were more likely to be occupied by U. beldingi . More broadly, populations inhabiting Sierra Nevada meadows with colder mean winter temperatures had higher values of allelic richness at microsatellite loci, consistent with higher population persistence in temperature-buffered sites. Furthermore, both allelic richness and gene flow were higher in meadows that had higher landscape connectivity, indicating the importance of metapopulation processes. Conversely, anthropogenic refugia, sites where populations appeared to persist due to food or water supplementation, had lower connectivity, genetic diversity, and gene flow, and thus might act as ecological traps. This study provides evidence that validates the climate change refugia concept in a contemporary context and illustrates how to integrate field observations and genetic analyses to test the effectiveness of climate change refugia and connectivity. Conclusions Climate change refugia will be important for conserving populations as well as genetic diversity and evolutionary potential. Our study shows that in-depth modeling paired with rigorous fieldwork can identify functioning climate change refugia for conservation.

California↗
USGS2000

Simulation of the shallow hydrologic system in the vicinity of Middle Genesee Lake, Wisconsin, using analytic elements and parameter estimation

Middle Genesee Lake is a ground-water flow-through lake located in a developing area in southeastern Wisconsin. Because the lake is in good connection with the shallow ground-water system, hydrologic stresses to the shallow ground-water system could adversely affect the lake system. In order to assess the effects of potential stresses on the lake, a study was completed by the U.S. Geological Survey, in cooperation with the Middle Genesee Lake Management District. The objective of the study was to identify areas that contribute ground water to the lake and estimate the hydrologic budget of the lake and hydraulic parameters affecting ground-water flow. A two-dimensional, steady-state analytic element model of the lake and surrounding area was developed using the computer code GFLOW. A parameter estimation model, UCODE, was used to optimize the calibration to measured water levels and streamflow. The calibrated model was used to evaluate the effect of three hypothetical stress scenarios on the stage of Middle Genesee Lake; the simulations were linked to UCODE, which formally incorporated parameter uncertainty into 95-percent confidence intervals around the simulated value. The scenarios included: (1) pumping from upgradient irrigation wells, (2) pumping from Lower Genesee Lake to lower lake levels, and (3) reduction in recharge resulting from development. The results of the simulations demonstrated that lake levels could be affected by hydrologic stresses in the shallow hydrologic system, with effects ranging from a 2.7 feet decline in lake stage resulting from pumping in Lower Genesee Lake to a 0.1 feet decline in lake stage from development in part of the upgradient recharge area. The range of lake stage decline increased when parameter uncertainty was included, from a decline of 3.1 feet for pumping from Lower Genesee Lake to no reduction in lake stage for the development in the recharge area. Whereas these simulated effects are within the natural variation in lake stage, they represent a systematic reduction of ground-water flow to the lake. Therefore, these hypothetical stresses are expected to establish a new, lower, baseline lake stage over which the natural variation due to climatic effects are added and subtracted.

Wisconsin↗