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USGS2005

Occurrence and distribution of volatile organic compounds and pesticides in ground water in relation to hydrogeologic characteristics and land use in the Santa Ana basin, southern California

This report presents an evaluation of the occurrence and distribution of VOCs and pesticides in the Santa Ana ground-water basins in relation to two types of explanatory factors: hydrogeologic characteristics and land use. The Santa Ana Basin is subdivided into the San Jacinto, the Inland, and the Coastal ground-water basins. Most wells sampled were deep and used for public supply. Data from regional studies were used to evaluate the occurrence and distribution of pesticides and volatile organic compounds (VOCs) in relation to hydrogeologic characteristics and land uses that could potentially explain variations between basins. Additional data from special studies (flow path and aquifer susceptibility) were used to evaluate potential factors affecting water quality for individual basins. The hydrogeologic characteristics evaluated in this report were hydrogeologic setting, ground-water age, depth to the top of the well screen (top of well perforations), and proximity to engineered recharge facilities. Urban land use, agricultural land use, and population density were characterized within a 500-meter radius of sampled wells and at the basin scale. Aquifers in the San Jacinto Basin are generally unconfined, and major land-use categories are urban (33 percent), agricultural (37 percent), and undeveloped (25 percent). Recharge is primarily from the overlying landscape, but engineered recharge is locally important in the Hemet area. VOCs and pesticides were detected more frequently in younger ground water (less than 50 years old) than in older ground water, and more frequently in shallower wells than deeper wells; the numbers of VOCs and pesticides detected also were significantly higher in the younger ground water and in the shallower wells. In the Hemet area of the San Jacinto Basin, VOCs and pesticides were detected more frequently in wells proximal to engineered recharge facilities than in distal wells. These patterns illustrate the importance of proximity to sources of recharge in relation to the occurrence and distribution of VOCs and pesticides in ground water. Aquifers in the Inland Basin also are generally unconfined, and the major land-use category is urban (58 percent), with lesser amounts of agricultural (13 percent) and undeveloped (28 percent) land. Recharge is from engineered facilities that utilize local runoff and imported water and from vertical infiltration. VOCs and pesticides were detected more frequently in younger ground water than in older ground water, and more frequently in shallower wells than deeper wells. The number of VOCs detected per well also was significantly higher in the younger ground water and in the shallower wells. Several solvent plumes extending between 5 and 10 kilometers illustrate the large distances that contaminants travel in basins with intensive use of ground water. Aquifers in the Coastal Basin, in contrast to the other basins, are generally confined. Land use in the basin is largely urban (80 percent), with lesser amounts of agricultural (7 percent) and undeveloped (12 percent) land. Recharge is primarily from engineered facilities that utilize water diverted from the Santa Ana River and imported water. Consequently, VOCs and pesticides were detected more frequently in wells proximal to engineered recharge facilities than in distal wells. These compounds were also detected more frequently in the unconfined area than in the confined area of the basin. In the confined area, the numbers of VOCs and pesticides detected per well were not significantly different in wells with shallower and deeper screens. This distribution reflects the dominance of lateral flow and insulation from overlying land use in the confined aquifers of the Coastal Basin. In the unconfined area of the Coastal Basin, the numbers of VOCs and pesticides detected per well were significantly higher in shallower wells than in deeper wells. VOC and pesticide detections were not statist

Scientific Investigations Report↗

USGS1999

Geohydrology and numerical simulation of the ground-water flow system of Kona, Island of Hawaii

Prior to the early 1990's, ground-water in the Kona area, which is in the western part of the island of Hawaii, was withdrawn from wells located within about 3 mi from the coast where water levels were less than 10 feet above sea level. In 1990, exploratory drilling in the uplands east of the existing coastal wells first revealed the presence of high water levels (greater than 40 feet above sea level) in the Kona area. Measured water levels from 16 wells indicate that high water levels exist in a zone parallel to and inland of the Kona coast, between Kalaoa and Honaunau. Available hydrologic and geophysical evidence is generally consistent with the concept that the high ground-water levels are associated with a buried dike complex. A two-dimensional (areal), steady-state, freshwater-saltwater, sharp-interface ground-water flow model was developed for the Kona area of the island of Hawaii, to enhance the understanding of (1) the distribution of aquifer hydraulic properties, (2) the conceptual framework of the ground-water flow system, and (3) the regional effects of ground-water withdrawals on water levels and coastal discharge. The model uses the finite-difference code SHARP. To estimate the hydraulic characteristics, average recharge, withdrawals, and water-level conditions for the period 1991-93 were simulated. The following horizontal hydraulic-conductivity values were estimated: (1) 7,500 feet per day for the dike-free volcanic rocks of Hualalai and Mauna Loa, (2) 0.1 feet per day for the buried dike complex of Hualalai, (3) 10 feet per day for the northern marginal dike zone (north of Kalaoa), and (4) 0.5 feet per day for the southern marginal dike zone between Palani Junction and Holualoa. The coastal leakance was estimated to be 0.05 feet per day per foot. Measured water levels indicate that ground water generally flows from inland areas to the coast. Model results are in general agreement with the limited set of measured water levels in the Kona area. Model results indicate, however, that water levels do not strictly increase in an inland direction and that a ground-water divide exists within the buried dike complex. Data are not available, however, to verify model results in the area near and inland of the model-calculated ground-water divide. Three simulations to determine the effects of proposed withdrawals from the high water-level area on coastal discharge and water levels, relative to model-calculated, steady-state coastal discharge and water levels for 1997 withdrawal rates, show that the effects are widespread. During 1997, the total withdrawal of ground water from the high water-level area between Palani Junction and Holualoa was about 1 million gallons per day. Model results indicate that it may not be possible to withdraw 25.6 million gallons per day of freshwater from this area between Palani Junction and Holualoa, but that it may be possible to withdraw between 5 to 8 million gallons per day from the same area. For a proposed withdrawal rate of 5.0 million gallons per day uniformly distributed to 12 sites between Palani Junction and Holualoa, the model-calculated drawdown of 0.01 foot or more extends about 9 miles north-northwest and about 7 miles south of the proposed well sites. In all scenarios, freshwater coastal discharge is reduced by an amount equal to the additional freshwater withdrawal. Additional data needed to improve the understanding of the ground-water flow system in the Kona area include: (1) a wider spatial distribution and longer temporal distribution of water levels, (2) improved information about the subsurface geology, (3) independent estimates of hydraulic conductivity, (4) improved recharge estimates, and (5) information about the vertical distribution of salinity in ground water.

Hawaii↗

USGS2022

The not-so-dead of winter: Underwater light climate and primary productivity under snow and ice cover in inland lakes

As global surface temperatures continue to rise as a result of anthropogenic climate change, effects in temperate lakes are likely to be more pronounced than in other ecosystems. Decreases in snow and ice cover extent and duration, as well as extended periods of summer stratification have been observed in temperate lake systems throughout the Anthropocene. However, the effects of changing snow and ice cover upon lacustrine communities remain largely uninvestigated. Here, we examined underwater light climate and associated primary productivity patterns under snow-covered and clear lake ice in 6 inland lakes in Minnesota, USA, spanning gradients of water column optical properties (blue, green, brown) associated with trophic status and organic material content. In all lakes, snow cover influenced not only the intensity, but also the spectral signature of light penetrating into the water column. Specifically, the wavelength of maximum penetration was shifted towards longer wavelengths under snow cover in green (eutrophic) lakes, while it was shifted towards shorter wavelengths in blue and brown lakes. Volumetric primary productivity was often higher than anticipated (e.g. ∼1200 mg · m -3 · d -1 ; L. Minnetonka, snow-covered ice). Carbon assimilation rates were lower under snow-covered ice throughout the water column in all lake types, except immediately under cleared ice in eutrophic lakes, where it is likely that phytoplankton were photo-inhibited due to penetration of intense, short-wavelength light. These findings suggest that changing patterns of snow and ice cover under ongoing climate change scenarios can affect patterns of phytoplankton primary productivity in sensitive aquatic ecosystems.

Minnesota↗

USGS2001

Analytical versus numerical estimates of water-level declines caused by pumping, and a case study of the Iao Aquifer, Maui, Hawaii

Comparisons were made between model-calculated water levels from a one-dimensional analytical model referred to as RAM (Robust Analytical Model) and those from numerical ground-water flow models using a sharp-interface model code. RAM incorporates the horizontal-flow assumption and the Ghyben-Herzberg relation to represent flow in a one-dimensional unconfined aquifer that contains a body of freshwater floating on denser saltwater. RAM does not account for the presence of a low-permeability coastal confining unit (caprock), which impedes the discharge of fresh ground water from the aquifer to the ocean, nor for the spatial distribution of ground-water withdrawals from wells, which is significant because water-level declines are greatest in the vicinity of withdrawal wells. Numerical ground-water flow models can readily account for discharge through a coastal confining unit and for the spatial distribution of ground-water withdrawals from wells. For a given aquifer hydraulic-conductivity value, recharge rate, and withdrawal rate, model-calculated steady-state water-level declines from RAM can be significantly less than those from numerical ground-water flow models. The differences between model-calculated water-level declines from RAM and those from numerical models are partly dependent on the hydraulic properties of the aquifer system and the spatial distribution of ground-water withdrawals from wells. RAM invariably predicts the greatest water-level declines at the inland extent of the aquifer where the freshwater body is thickest and the potential for saltwater intrusion is lowest. For cases in which a low-permeability confining unit overlies the aquifer near the coast, however, water-level declines calculated from numerical models may exceed those from RAM even at the inland extent of the aquifer. Since 1990, RAM has been used by the State of Hawaii Commission on Water Resource Management for establishing sustainable-yield values for the State?s aquifers. Data from the Iao aquifer, which lies on the northeastern flank of the West Maui Volcano and which is confined near the coast by caprock, are now available to evaluate the predictive capability of RAM for this system. In 1995 and 1996, withdrawal from the Iao aquifer reached the 20 million gallon per day sustainable-yield value derived using RAM. However, even before 1996, water levels in the aquifer had declined significantly below those predicted by RAM, and continued to decline in 1997. To halt the decline of water levels and to preclude the intrusion of salt-water into the four major well fields in the aquifer, it was necessary to reduce withdrawal from the aquifer system below the sustainable-yield value derived using RAM. In the Iao aquifer, the decline of measured water levels below those predicted by RAM is consistent with the results of the numerical model analysis. Relative to model-calculated water-level declines from numerical ground-water flow models, (1) RAM underestimates water-level declines in areas where a low-permeability confining unit exists, and (2) RAM underestimates water-level declines in the vicinity of withdrawal wells.

Hawaii↗

USGS2017

The contribution of lakes to global inland fisheries harvest

Freshwater ecosystems provide numerous services for communities worldwide, including irrigation, hydropower, and municipal water; however, the services provided by inland fisheries – nourishment, employment, and recreational opportunities – are often comparatively undervalued. We provide an independent estimate of global lake harvest to improve biological and socioeconomic assessments of inland fisheries. On the basis of satellite-derived estimates of chlorophyll concentration from 80,012 globally distributed lakes, lake-specific fishing effort based on human population, and output from a Bayesian hierarchical model, we estimated that the global lake fishery harvest in the year 2011 was 8.4 million tons (mt). Our calculations excluded harvests from highly productive rivers, wetlands, and very small lakes; therefore, the true cumulative global fishery harvest from all freshwater sources likely exceeded 11 mt as reported by the Food and Agriculture Organization of the United Nations (FAO). This putative underestimate by the FAO could diminish the perceived importance of inland fisheries and perpetuate decisions that adversely affect these fisheries and millions of people.

Frontiers in Ecology and the Environment↗

USGS1996

Assessment of saltwater intrusion in southern coastal Broward County, Florida

Of the counties in southeastern Florida, Broward County has experienced some of the most severe effects of saltwater intrusion into the surficial Biscayne aquifer because, before 1950, most public water-supply well fields in the county were constructed near the principal early population centers located less than 5 miles from the Atlantic Ocean. The construction of major regional drainage canals in the early 20th century caused a lowering of the water table and a gradual inland movement of the saltwater front toward the well fields. The U.S. Geological Survey began field investigations of saltwater intrusion in the Biscayne aquifer of southeastern Broward County in 1939. As part of the present study, the positions of the saltwater front in 1945, 1969, and 1993 were estimated using chloride concentrations of water samples collected between 1939 and 1994 from various monitoring and exploratory wells. The data indicate that, between 1945 and 1993, the saltwater front has moved as much as 0.5 mile inland in parts of the study area. The position and movement of the saltwater front were simulated numerically to help determine which of the various hydrologic factors and water-management features characterizing the coastal subsurface environment and its alteration by man are of significance in increasing or decreasing the degree of saltwater intrusion. Two representational methods were applied by the selection and use of appropriate model codes. The SHARP code simulates the position of the saltwater front as a sharp interface, which implies that no transition zone (a zone in which a gradational change between freshwater and saltwater occurs) separates freshwater and saltwater. The Subsurface Waste Injection Program (SWIP) code simulates a two-fluid, variable-density system using a convective-diffusion approach that includes a representation of the transition zone that occurs between the freshwater and saltwater bodies. The models were applied to: (1) approximately replicate predevelopment and current positions of the interface in the study area; and (2) study the relative importance of various factors affecting the interface position. The model analyses assumed a conceptual model of uniform easterly flow in the aquifer toward points of offshore discharge to tidewater. Measurements of water-table altitude and the depth to the interface in the study area exhibit an interrelation that differes substantially from the classical Ghyben-Herzberg relation. However, both model codes simulated water-table altitudes and interface positions that were generally consistent with the Ghyben-Herzberg relation but differed substantially from observed data. The simulate interface positions were inland of the known positions, and simulate water-table altitudes were higher than measured ones. The SHARP and SWIP simulations were in general agreement with each other when a low value of longitudinal dispersivity was specified in the SWIP simulation and also for higher values of longitudinal dispersivity when modified dispersion algorithms were used in SWIP that greatly reduced the simulated degree of vertical dispersion. Sensitivity analyses performed using the SHARP code indicated simulation results to be relatively insensitive to a substantial change in the specified slope of the base of the aquifer and moderately sensitive to a 150-percent change in net atmospheric recharge to the aquifer (rainfall minus evapotranspiration). Representing well-field pumping by the City of hallandale had only a minor, localized influence on the simulated regional interface position. Using various cross-sectional grid designs in applications of the SWIP code, near convergence of all lines of equal concentrations in the transition zone was achieved within a simulation time of 10 years. The simulated equilibrium interface location was sensitive to substantial spatial variations in the specified hydraulic conductivity values, but was relatively insensitive to seasonal varying

Florida↗

USGS2014

Some relations between ground‐water hydrology and oceanography

In many areas along the sea-coasts of the world the water-supply for human use is derived largely, and in some areas wholly, from underground sources. Because of the proximity to the ocean in these areas, in some respects the geologic and hydrologic conditions that govern the occurrence and movement of ground-water are quite different from those in inland areas, and to properly interpret them the ground-water hydrologist must avail himself of facts developed by the oceanographer. These conditions are encountered in a marginal zone that in different localities may extend only a few feet or many miles inland from the coast, and presumably for greater or less distances out beneath the ocean. These special conditions have been recognized and extensively studied for many years, for example, in the lowland-area of Holland that lies between the Zuider Zee and the North Sea, and on Long Island, New York. Within recent years more or less attention has been given to these conditions in many of the coastal states of the United States, and in the Hawaiian Islands and Cuba. It is the purpose of this statement to indicate some of the problems of groundwater hydrology that are related to oceanography.

Eos, Transactions, American Geophysical Union↗

USGS2015

Bistability of mangrove forests and competition with freshwater plants

Halophytic communities such as mangrove forests and buttonwood hammocks tend to border freshwater plant communities as sharp ecotones. Most studies attribute this purely to underlying physical templates, such as groundwater salinity gradients caused by tidal flux and topography. However, a few recent studies hypothesize that self-reinforcing feedback between vegetation and vadose zone salinity are also involved and create a bistable situation in which either halophytic dominated habitat or freshwater plant communities may dominate as alternative stable states. Here, we revisit the bistability hypothesis and demonstrate the mechanisms that result in bistability. We demonstrate with remote sensing imagery the sharp boundaries between freshwater hardwood hammock communities in southern Florida and halophytic communities such as buttonwood hammocks and mangroves. We further document from the literature how transpiration of mangroves and freshwater plants respond differently to vadose zone salinity, thus altering the salinity through feedback. Using mathematical models, we show how the self-reinforcing feedback, together with physical template, controls the ecotones between halophytic and freshwater communities. Regions of bistability along environmental gradients of salinity have the potential for large-scale vegetation shifts following pulse disturbances such as hurricane tidal surges in Florida, or tsunamis in other regions. The size of the region of bistability can be large for low-lying coastal habitat due to the saline water table, which extends inland due to salinity intrusion. We suggest coupling ecological and hydrologic processes as a framework for future studies.

Florida↗

USGS2022

Bathymetry retrieval from CubeSat image sequences with short time lags

The rapid expansion of CubeSat constellations could revolutionize the way inland and nearshore coastal waters are monitored from space. This potential stems from the ability of CubeSats to provide daily imagery with global coverage at meter-scale spatial resolution. In this study, we explore the unique opportunity to improve the retrieval of bathymetry offered by CubeSats, specifically those of the PlanetScope constellation. The orbital design of the PlanetScope constellation enables the acquisition of image sequences with short time lags (from seconds to hours). This characteristic allows multiple images to be captured during a short period of steady bathymetric conditions, especially in dynamic environments like rivers. We hypothesize that taking the ensemble mean of a CubeSat image sequence can enhance bathymetry retrieval compared to standard single-image analysis. Along with the existing optimal band ratio analysis (OBRA) algorithm, we also use a new neural network-based depth retrieval (NNDR) technique to infer bathymetry from both individual and time-averaged images. The two methodologies are evaluated using field data from five different river reaches with depths up to 15 m and both top-of-atmosphere (TOA) radiance and bottom-of-atmosphere (BOA) surface reflectance PlanetScope data products. Despite low spectral resolution and concerns about the radiometric quality of CubeSat imagery, accuracy assessment based on in-situ comparisons indicates the potential (0.52 < R 2 < 0.7 for the NNDR method) of PlanetScope imagery to retrieve depths up to ∼ 10 m in clear water conditions. The proposed image averaging consistently improves bathymetry retrieval over single image analysis. The NNDR technique was found to outperform OBRA, illustrating the importance of leveraging all spectral bands through machine learning approaches. TOA data provided more robust bathymetry results than BOA data for the OBRA technique, but the NNDR technique was minimally impacted by the type of data product.

International Journal of Applied Earth Observation↗

USGS1997

Organic geochemical study of sequences overlying coal seams; example from the Mansfield Formation (Lower Pennsylvanian), Indiana

Roof successions above two coal seams from the Mansfield Formation (Lower Pennsylvanian) in the Indiana portion of the Illinois Basin have been studied with regard to sedimentary structures, organic petrology and organic geochemistry. The succession above the Blue Creek Member of the Mansfield Formation is typical of the lithologies covering low-sulphur coals (< 1%) in the area studied, whereas the succession above the unnamed Mansfield coal is typical of high-sulphur coals (>2.%). The transgressive-regressive packages above both seams reflect the periodic inundation of coastal mires by tidal flats and creeks as inferred from bioturbation and sedimentary structures such as tidal rhythmites and clay-draped ripple bedforms. Geochemistry and petrology of organic facies above the Blue Creek coal suggest that tidal flats formed inland in fresh-water environments. These overlying fresh water sediments prevented saline waters from invading the peat, contributing to low-sulphur content in the coal. Above the unnamed coal, trace fossils and geochemical and petrological characteristics of organic facies suggest more unrestricted seaward depositional environment. The absence of saline or typically marine biomarkers above this coal is interpreted as evidence of very short periods of marine transgression, as there was not enough time for establishment of the precursor organisms for marine biomarkers. However, sufficient time passed to raise SO 4 2− concentration in pore waters, resulting in the formation of authigenic pyrite and sulphur incorparation into organic matter.

International Journal of Coal Geology↗

USGS2015

Human activities and climate variability drive fast-paced change across the world's estuarine-coastal ecosystems

Time series of environmental measurements are essential for detecting, measuring and understanding changes in the Earth system and its biological communities. Observational series have accumulated over the past 2–5 decades from measurements across the world's estuaries, bays, lagoons, inland seas and shelf waters influenced by runoff. We synthesize information contained in these time series to develop a global view of changes occurring in marine systems influenced by connectivity to land. Our review is organized around four themes: (i) human activities as drivers of change; (ii) variability of the climate system as a driver of change; (iii) successes, disappointments and challenges of managing change at the sea-land interface; and (iv) discoveries made from observations over time. Multidecadal time series reveal that many of the world's estuarine–coastal ecosystems are in a continuing state of change, and the pace of change is faster than we could have imagined a decade ago. Some have been transformed into novel ecosystems with habitats, biogeochemistry and biological communities outside the natural range of variability. Change takes many forms including linear and nonlinear trends, abrupt state changes and oscillations. The challenge of managing change is daunting in the coastal zone where diverse human pressures are concentrated and intersect with different responses to climate variability over land and over ocean basins. The pace of change in estuarine–coastal ecosystems will likely accelerate as the human population and economies continue to grow and as global climate change accelerates. Wise stewardship of the resources upon which we depend is critically dependent upon a continuing flow of information from observations to measure, understand and anticipate future changes along the world's coastlines.

Global Change Biology↗

USGS2016

Drivers of barotropic and baroclinic exchange through an estuarine navigation channel in the Mississippi River Delta Plain

Estuarine navigation channels have long been recognized as conduits for saltwater intrusion into coastal wetlands. Salt flux decomposition and time series measurements of velocity and salinity were used to examine salt flux components and drivers of baroclinic and barotropic exchange in the Houma Navigation Channel, an estuarine channel located in the Mississippi River delta plain that receives substantial freshwater inputs from the Mississippi-Atchafalaya River system at its inland extent. Two modes of vertical current structure were identified from the time series data. The first mode, accounting for 90% of the total flow field variability, strongly resembled a barotropic current structure and was coherent with alongshelf wind stress over the coastal Gulf of Mexico. The second mode was indicative of gravitational circulation and was linked to variability in tidal stirring and the horizontal salinity gradient along the channel’s length. Tidal oscillatory salt flux was more important than gravitational circulation in transporting salt upestuary, except over equatorial phases of the fortnightly tidal cycle during times when river inflows were minimal. During all tidal cycles sampled, the advective flux, driven by a combination of freshwater discharge and wind-driven changes in storage, was the dominant transport term, and net flux of salt was always out of the estuary. These findings indicate that although human-made channels can effectively facilitate inland intrusion of saline water, this intrusion can be minimized or even reversed when they are subject to significant freshwater inputs.

Louisiana↗

USGS1984

Ground-water monitoring at Santa Barbara, California: Phase 2 — Effects of pumping on water levels and on water quality in the Santa Barbara ground-water basin

From July 1978 to January 1980, water levels in the southern part of the Santa Barbara ground-water basin declined more than 100 feet. These water-level declines resulted from increases in municipal pumping since July 1978. The increase in municipal pumping was part of a basin-testing program designed to determine the usable quantity of ground water in storage. The pumping, centered in the city less than 1 mile from the coast, has caused water-level declines to altitudes below sea level in the main water-bearing zones. As a result, the ground-water basin would be subject to saltwater intrusion if the study-period pumpage were maintained or increased. Data indicate that saltwater intrusion has degraded the quality of the water yielded from six coastal wells. During the study period, the six coastal wells all yielded water with chloride concentrations in excess of 250 milligrams per liter, and four of the wells yielded water with chloride concentrations in excess of 1,000 milligrams per liter. Previous investigators believed that saltwater intrusion was limited to the shallow part of the aquifer, directly adjacent to the coast. The possibility of saltwater intrusion into the deeper water-bearing deposits in the aquifer was thought to be remote because an offshore fault truncates these deeper deposits so that they lie against consolidated rocks on the seaward side of the fault. Results of this study indicate, however, that ocean water has intruded the deeper water-bearing deposits, and to a much greater extent than in the shallow part of the aquifer. Apparently the offshore fault is not an effective barrier to saltwater intrusion. No physical barriers are known to exist between the coast and the municipal well field. Therefore, if the pumping rate maintained during the basin-testing program were continued, the degraded water along the coast could move inland and contaminate the municipal supply wells. The time required for the degraded water to move from the coast to the nearest supply well is estimated, using Darcy's equation, to be about 20 years. Management alternatives for controlling saltwater intrusion in the Santa Barbara area include (1) decreasing municipal pumping, (2) increasing the quantity of water available for recharge by releasing surplus water from surface reservoirs to Mission Creek, (3) artificially recharging the basin using injection wells, and (4) locating municipal supply wells farther from the coast and spacing them farther apart in order to minimize drawdown. Continued monitoring of water levels and water quality would enable assessment of the effectiveness of the control measures employed.

California↗

USGS1999

Ground-water resources in Kaloko-Honokohau National Historical Park, Island of Hawaii, and numerical simulation of the effects of ground-water withdrawals

Within the Kaloko-Honokohau National Historical Park, which was established in 1978, the ground-water flow system is composed of brackish water overlying saltwater. Ground-water levels measured in the Park range from about 1 to 2 feet above mean sea level, and fluctuate daily by about 0.5 to 1.5 feet in response to ocean tides. The brackish water is formed by mixing of seaward flowing fresh ground water with underlying saltwater from the ocean. The major source of fresh ground water is from subsurface flow originating from inland areas to the east of the Park. Ground-water recharge from the direct infiltration of precipitation within the Park area, which has land-surface altitudes less than 100 feet, is small because of low rainfall and high rates of evaporation. Brackish water flowing through the Park ultimately discharges to the fishponds in the Park or to the ocean. The ground water, fishponds, and anchialine ponds in the Park are hydrologically connected; thus, the water levels in the ponds mark the local position of the water table. Within the Park, ground water near the water table is brackish; measured chloride concentrations of water samples from three exploratory wells in the Park range from 2,610 to 5,910 milligrams per liter. Chromium and copper were detected in water samples from the three wells in the Park and one well upgradient of the Park at concentrations of 1 to 5 micrograms per liter. One semi-volatile organic compound, phenol, was detected in water samples from the three wells in the Park at concentrations between 4 and 10 micrograms per liter. A regional, two-dimensional (areal), freshwater-saltwater, sharp-interface ground-water flow model was used to simulate the effects of regional withdrawals on ground-water flow within the Park. For average 1978 withdrawal rates, the estimated rate of fresh ground-water discharge to the ocean within the Park is about 6.48 million gallons per day, or about 3 million gallons per day per mile of coastline. Although the coastal discharge within the Park is actually brackish water, the model assumes that freshwater and saltwater do not mix and therefore the model-calculated coastal discharge within the Park is in the form of freshwater discharge. Model results indicate that ground-water withdrawals in excess of average 1978 withdrawal rates will reduce the rate of freshwater coastal discharge within the Park. Withdrawals from wells directly upgradient of the Park had the greatest effect on the model-calculated freshwater coastal discharge within the Park, whereas withdrawals from wells south of Papa Bay had little effect on the freshwater discharge within the Park. For an increased ground-water withdrawal rate of 56.8 million gallons per day, relative to average 1978 withdrawal rates in the Kona area, model-calculated freshwater coastal discharge within the Park was reduced by about 47 percent.

Hawaii↗

USGS2015

Water Quality, Cyanobacteria, and Environmental Factors and Their Relations to Microcystin Concentrations for Use in Predictive Models at Ohio Lake Erie and Inland Lake Recreational Sites, 2013-14

Harmful cyanobacterial “algal” blooms (cyanoHABs) and associated toxins, such as microcystin, are a major water-quality issue for Lake Erie and inland lakes in Ohio. Predicting when and where a bloom may occur is important to protect the public that uses and consumes a water resource; however, predictions are complicated and likely site specific because of the many factors affecting toxin production. Monitoring for a variety of environmental and water-quality factors, for concentrations of cyanobacteria by molecular methods, and for algal pigments such as chlorophyll and phycocyanin by using optical sensors may provide data that can be used to predict the occurrence of cyanoHABs. To test these monitoring approaches, water-quality samples were collected at Ohio recreational sites during May–November in 2013 and 2014. In 2013, samples were collected monthly at eight sites at eight lakes to facilitate an initial assessment and select sites for more intensive sampling during 2014. In 2014, samples were collected approximately weekly at five sites at three lakes. Physical water-quality parameters were measured at the time of sampling. Composite samples were preserved and analyzed for dissolved and total nutrients, toxins, phytoplankton abundance and biovolume, and cyanobacterial genes by molecular methods. Molecular assays were done to enumerate (1) general cyanobacteria, (2) general Microcystis and Dolichospermum ( Anabaena ), (3) mcyE genes for Microcystis , Dolichospermum ( Anabaena ), and Planktothrix targeting deoxyribonucleic acid (DNA), and (4) mcyE transcripts for Microcystis , Dolichospermum ( Anabaena ), and Planktothrix targeting ribonucleic acid (RNA).The DNA assays for the mcyE gene provide data on cyanobacteria that have the potential to produce microcystin, whereas the RNA assays provide data on cyanobacteria that are actively transcribing the toxin gene. Environmental data were obtained from available online sources. Quality-control (QC) samples were collected and analyzed for all constituents to characterize bias and variability; however, QC data for molecular assays were examined in more detail than for the other constituents. The QC data for molecular assays suggested that sampling variability and qPCR variability were small in comparison with the combined variability associated with sample filtering, extraction and purification, and the matrix itself. A total of 46 water-quality samples were collected during 2013 at 8 beach sites—Buck Creek, Buckeye Crystal, Deer Creek, Harsha Main, Maumee Bay State Park (MBSP) Inland (negative control site), MBSP Lake Erie, Port Clinton, and Sandusky Bay. Microcystin was detected in 67–100 percent of samples at all sites except for MBSP Inland, where microcystin was detected in only 20 percent of samples. Microcystin concentrations ranged from <0.10 to 48 micrograms per liter (µ/L), with the widest range found at MBSP Lake Erie and the highest concentrations found at Buckeye Crystal. Saxitoxin was detected in five samples, and cylindrospermopsin was not detected in any samples. A total of 65 water-quality samples were collected during 2014 at 5 sites on 3 lakes—Buckeye Fairfield and Onion Island, Harsha Main and Campers, and MBSP Lake Erie beach. Four of the sites were bathing beaches and one site, Onion Island, was an offshore boater swim area. Concentrations of microcystin ranged from <0.10 to 240 µ/L and, as in 2013, the widest range was found at MBSP Lake Erie. At Buckeye Lake, microcystin concentrations were consistently high (greater than 20 µ/L), ranging from 23 to 81 µ/L. At Harsha Main and Campers, microcystin concentrations ranged from <0.10 to 15 µ/L. Saxitoxin was detected in four samples collected at MBSP Lake Erie. Throughout the 2014 season, the cyanobacterial community, as determined by molecular and microscopy methods, and the dominance associated with the highest microcystin concentrations were unique to individual lakes. At Buckeye Lake, Planktothrix dominated the cyanobacterial community throughout the season and Planktothrix DNA and RNA were found in 100 percent of samples; Microcystis mcyE DNA was found in low concentrations. At Harsha Lake, Dolichospermum and Microcystis were a substantial percentage of the community from late May through August, and the highest microcystin concentrations occurred in June and July. At MBSP Lake Erie, Microcystis generally dominated from mid-July through early November, and the highest microcystin concentrations occurred in August. Spearman’s correlation coefficient (rho) was computed to determine the relations between environmental and water-quality factors and microcystin concentrations at four sites—Buckeye Fairfield, Buckeye Onion Island, Harsha Main, and MBSP Lake Erie. Factors were evaluated for use as potential independent variables in two types of predictive models—daily and long-term models. Easily or continuously measured water-quality factors and available environmental data are used for daily predictions that do not require a site visit. Data from factors used in daily predictions and results from samples collected and analyzed in a laboratory are used for long-term predictions (a few days to several weeks). A few statistically significant correlations (p ≤ 0.05) between microcystin concentrations and factors for both daily and long-term predictions were found at Buckeye Onion Island, and many were found at Harsha Main and MBSP Lake Erie. There were only a few statistically significant factors for daily predictions at Buckeye Fairfield, likely because of the lack of variability in microcystin concentrations. Among factors for daily predictions, phycocyanin had the highest Spearman’s correlation to microcystin concentrations (rho = 0.79 to 0.93) at all sites except for Buckeye Fairfield. Turbidity, pH, algae category, and Secchi depth were significantly correlated to microcystin concentrations at Harsha Main and MBSP Lake Erie. Algae categories were observational categories from 0 (none) to 4 (extreme). Several discharge variables (Maumee River at Waterville, river mouth is approximately 3.5 miles from the beach) at MBSP Lake Erie were promising environmental factors for daily predictions. In addition to discrete water-quality measurements recorded at Harsha Main at the time of sampling, many manipulated measurements (factors derived from mathematical manipulation of time-series data) available from a nearby continuous monitor were strongly correlated to microcystin concentrations; the highest correlation was found for the relation between microcystin concentrations and the antecedent 7-day average phycocyanin (rho = 0.98). For long-term predictions, the most highly correlated molecular assays were Planktothrix mcyE DNA at Buckeye Onion Island and Microcystis mcyE DNA at Harsha Main and MBSP Lake Erie. Concentrations of several nutrient constituents were significantly correlated to microcystin concentrations including total nitrogen at Buckeye Onion Island, ammonia and nitrate plus nitrite (both negatively correlated) at Harsha Main and MBSP Lake Erie, and total phosphorus at MBSP Lake Erie. The results of this study showed that water-quality and environmental variables are promising for use in site-specific daily or long-term predictive models. In order to develop more accurate models to predict toxin concentrations at freshwater lake sites, data need to be collected more frequently and for consecutive days in future studies.

Ohio↗

USGS2016

On the sustainability of inland fisheries: Finding a future for the forgotten

At present, inland fisheries are not often a national or regional governance priority and as a result, inland capture fisheries are undervalued and largely overlooked. As such they are threatened in both developing and developed countries. Indeed, due to lack of reliable data, inland fisheries have never been part of any high profile global fisheries assessment and are notably absent from the Sustainable Development Goals. The general public and policy makers are largely ignorant of the plight of freshwater ecosystems and the fish they support, as well as the ecosystem services generated by inland fisheries. This ignorance is particularly salient given that the current emphasis on the food-water-energy nexus often fails to include the important role that inland fish and fisheries play in food security and supporting livelihoods in low-income food deficit countries. Developing countries in Africa and Asia produce about 11 million tonnes of inland fish annually, 90 % of the global total. The role of inland fisheries goes beyond just kilocalories; fish provide important micronutrients and essentially fatty acids. In some regions, inland recreational fisheries are important, generating much wealth and supporting livelihoods. The following three key recommendations are necessary for action if inland fisheries are to become a part of the food-water-energy discussion: invest in improved valuation and assessment methods, build better methods to effectively govern inland fisheries (requires capacity building and incentives), and develop approaches to managing waters across sectors and scales. Moreover, if inland fisheries are recognized as important to food security, livelihoods, and human well-being, they can be more easily incorporated in regional, national, and global policies and agreements on water issues. Through these approaches, inland fisheries can be better evaluated and be more fully recognized in broader water resource and aquatic ecosystem planning and decision-making frameworks, enhancing their value and sustainability for the future.

Ambio↗

USGS2011

Predicting lake trophic state by relating Secchi-disk transparency measurements to Landsat-satellite imagery for Michigan inland lakes, 2003-05 and 2007-08

Inland lakes are an important economic and environmental resource for Michigan. The U.S. Geological Survey and the Michigan Department of Natural Resources and Environment have been cooperatively monitoring the quality of selected lakes in Michigan through the Lake Water Quality Assessment program. Sampling for this program began in 2001; by 2010, 730 of Michigan’s 11,000 inland lakes are expected to have been sampled once. Volunteers coordinated by the Michigan Department of Natural Resources and Environment began sampling lakes in 1974 and continue to sample (in 2010) approximately 250 inland lakes each year through the Michigan Cooperative Lakes Monitoring Program. Despite these sampling efforts, it still is impossible to physically collect measurements for all Michigan inland lakes; however, Landsat-satellite imagery has been used successfully in Minnesota, Wisconsin, Michigan, and elsewhere to predict the trophic state of unsampled inland lakes greater than 20 acres by producing regression equations relating in-place Secchi-disk measurements to Landsat bands. This study tested three alternatives to methods previously used in Michigan to improve results for predicted statewide Trophic State Index (TSI) computed from Secchi-disk transparency (TSI (SDT)). The alternative methods were used on 14 Landsat-satellite scenes with statewide TSI (SDT) for two time periods (2003– 05 and 2007–08). Specifically, the methods were (1) satellitedata processing techniques to remove areas affected by clouds, cloud shadows, haze, shoreline, and dense vegetation for inland lakes greater than 20 acres in Michigan; (2) comparison of the previous method for producing a single open-water predicted TSI (SDT) value (which was based on an area of interest (AOI) and lake-average approach) to an alternative Gethist method for identifying open-water areas in inland lakes (which follows the initial satellite-data processing and targets the darkest pixels, representing the deepest water, before regression equations are created); and (3) checking to see whether the predicted TSI (SDT) values compared well between two regression equations, one previously used in Michigan and an alternative equation from the hydrologic literature. The combination of improved satellite-data processing techniques and the Gethist method to identify open-water areas in inland lakes during 2003–05 and 2007–08 provided a stronger relation and statistical significance between predicted TSI (SDT) and measured TSI than did the AOI lake-average method; differences in results for the two methods were significant at the 99-percent confidence level. With regard to the comparison of the regression equations, there were no statistically significant differences at the 95-percent confidence level between results from the two equations. The previously used equation, in combination with the Gethist method, yielded coefficient of determination (R 2 ) values of 0.71 and 0.77 for the periods 2003–05 and 2007–08, respectively. The alternative equation, in combination with the Gethist method, yielded R 2 values of 0.74 and 0.75 for 2003–05 and 2007–08, respectively. Predicted TSI (SDT) and measured TSI (SDT) values for lakes used in the regression equations compared well, with R 2 values of 0.95 and 0.96 for predicted TSI (SDT) for 2003–05 and 2007–08, respectively. The R 2 values for statewide predicted TSI (SDT) for all inland lakes with available open-water areas for 2003–05 and 2007–08 were 0.91 and 0.93, respectively. Although the two equations predicted similar trophic-state classes, the alternative equation is planned to be used for future prediction of TSI (SDT) values for Michigan inland lakes, to promote consistency in comparing predicted values between States and for potential use in trend analysis.

Michigan↗

USGS1969

Water in the Kahuku area, Oahu, Hawaii

The Kahuku area comprises the north end of the Koolau Range and its bordering coastal plain. This part of the range is less deeply eroded than oth3r parts, and except for long, narrow valleys and cliffs near the shore, it has retained the general shape of the original volcanic dome. A 21/2-mile-wide dike zone of parallel and subparallel dikes along the crest is the remnant of the fissure zone of eruption. Outcrops are mostly permeable lava flows of the Koolau Volcanic Series, which are intruded by dikes inside the dike zone and are free of dikes outside it. The lava flows constitute main aquifers, and water bodies in them are called dike water inside the dike zone and basal water outside it. Dikes, because they are less permeable than the lava flows they intrude, impound ground water, thereby controlling its movement, discharge, and storage. The top of the dike-impounded water is at an altitude of at least 1,000 feet near the south end of the Kahuku area. Dike water is discharged as leakage, the amount of which fluctuates in response to changes in storage, as flow into streams, where they intersect saturated rock, and as underflow to the basal-water body. Basal water occurs on either side of the dike zone, which forms both a structural and hydrologic boundary. It is artesian on the windward side wherever it underlies the coastal plain, and the altitude of water levels ranges from 7 to 22 feet. Leeward of the dike zone, basal water occurs only under water-table conditions because of the near absence of a coastal plain, and the altitude of water levels ranges from less than 1 foot to about 3 feet. The quality of dike water is excellent except near the north end. where it is slightly contaminated by infiltration of irrigation water that contains as much as 1,200 mg/1 (milligrams per liter) chloride. Irrigation water is also a source of contamination of the basal-water body. The major contaminant, however, is sea water, which underlies the basal-water body. In the Kahuku subarea--where pumpage from the basal-water body is greatest--sea-water contamination is a major concern. Natural contamination by encroaching sea water extends more than 2 miles inland in the Waimea-Kawela subarea and generally precludes development of large quantities of basal water. At low altitudes where the perennial flow is small, all streams are intermittent except Kaluanui and Kamananui. Some streams are perennial in their upper reaches because of persistent rainfall, and some are perennial in their middle reaches owing to the discharge of dike water; however, most flows are small in the lower reaches because most of the flow has infiltrated into the ground-water reservoir. For these reasons, streamflow cannot be economically developed and is not a reliable source of water supply. Average rainfall is about 240 mgd (million gallons per day). Of this amount, about 220 mgd is in the mountains. On .the basis of a rainfall input of 220 mgd and estimates of stream runoff and evapotranspiration, ground-water flow is estimated to be 85 mgd, a figure which compares favorably with estimates based on analyses of pumping-test data. Of this amount, an average of 30 mgd is discharged by wells and the remaining 55 mgd is eventually discharged to the sea by underflow or to the atmosphere by evapotranspiration. The most promising areas for developing basal water are in the Hauula and Laie subareas, where draft is low and ground-water flow is high. The Waimea-Kawela subarea is not promising owing 'to low ground-water flow even though draft is low. Least promising for development is in the Kahuku subarea where an overdeveloped condition prevails in which draft for sugarcane irrigation exceeds the ground-water flow. The development of dike water is promising in the Waimea-Kawela subarea where ground-water flow greatly exceeds the draft.

Water Supply Paper↗