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Nutrients, total dissolved solids (TDS), and trace elements affect the suitability of water for human and natural needs. Here, trends in such water-quality constituents are analyzed for 1999–2022 for eight nested monitoring sites in the 24,000 km2 Fountain Creek watershed in Colorado, USA, by using the weighted regressions on time, discharge, and season (WRTDS) methodology. Fountain Creek shares characteristics with other western U.S. watersheds: (1) an expanding but more water-efficient population, (2) a heavy reliance on imported water, (3) a semiarid climate trending towards warmer and drier conditions, and (4) shifts of water from agricultural to municipal uses. The WRTDS analysis found both upward and downward trends in the concentrations of nutrients that reflected possible shifts in effluent management, instream uptake, and water conservation by a watershed population that grew by about 40%. Selenium, other trace elements, and TDS can pose water-quality challenges downstream and their concentrations were found to have a downwards trend. Those trends could be driven by either a warming and drying of the local climate or decreased agricultural irrigation, as both would reduce recharge and subsequent mobilization from natural geologic sources via groundwater discharge. The patterns illustrate how changes in climate and water use may have affected water quality in Fountain Creek and demonstrate the patterns to look for in other western watersheds. [ABSTRACT FROM AUTHOR]

Connectivity is critical for stream fish persistence, and fish passage structures are a useful conservation tool to reconnect fragmented systems. The design of fish passage structures is a tradeoff between the area available for construction, slope, and costs associated with the structure. The Longrie–Fecteau fish passage structure was designed to be modular, adjustable to barrier-specific needs, and to have a low slope (2%) to pass small-bodied fishes. We evaluated fish passage through this structure in Fountain Creek, Colorado, USA, via a PIT tag mark–recapture study. We documented four native Great Plains fish species successfully ascending the passage structure, with most passage occurring at night. We estimated a 3% probability of a released fish entering the structure, then 89% and 99% passage to the midpoint and exit of the 123 m structure, respectively. Low entrance efficiency was due to low recapture probability of small-bodied study organisms in a relatively large system, and the low percentage of space of the entryway on this barrier (<3% of the length of the barrier). Fish that entered the structure ascended quickly, with median time for successful ascent of 19 min, and minimum time of 6 min. The Longrie–Fecteau fish passage structure is a conservation tool that may broaden the adoption of fish passage structures for small-bodied fishes due to its modularity and low slope. [ABSTRACT FROM AUTHOR]

For the past few decades, remote sensing has been a valuable tool for deriving global information on snow water equivalent (SWE), where products derived from space-borne passive microwave radiometers are favoured as they respond to snow depth, an important component of SWE. GlobSnow, a novel SWE product, has increased the accuracy of global-scale SWE estimates by combining remotely sensed radiometric data with other physiographic characteristics, such as snow depth, as quantified by climatic stations. However, research has demonstrated that passive microwaves algorithms tend to underestimate SWE for deep snowpack. Approaches were proposed to correct for such underestimation; however, they are computer intensive and complex to implement at the watershed scale. In this study, SWEmax information from the near real time 5-km GlobSnow product, provided by Copernicus and the European Space Agency (ESA) and GlobSnow product at 25 km resolution were corrected using a simple bias correction approach for watershed scale applications. This method, referred to as the Watershed Scale Correction (WSC) approach, estimates the bias based on the direct runoff that occurs during the spring melt season. Direct runoff is estimated on the one hand from SWEmax information as main input. Infiltration is also considered in computing direct runoff. An independent estimation of direct runoff from gauged stations is also performed. Discrepancy between these estimates allows for estimating the bias correction factor. This approach is advantageous as it exploits data that commonly exists i.e., flow at gauged stations and remotely sensed/reanalysis data such as snow cover and precipitation. The WSC approach was applied to watersheds located in Eastern Canada. It was found that the average bias moved from 33.5% with existing GlobSnow product to 18% with the corrected product, using the recommended recursive filter coefficient β of 0.925 for baseflow separation. Results show the usefulness of integrating direct runoff for bias correction of existing GlobSnow product at the watershed scale. In addition, potential benefits are offered using the recursive filter approach for baseflow separation of watersheds with limited in situ SWE measurements, to further reduce overall uncertainties and bias. The WSC approach should be appealing for poorly monitored watersheds where SWE measurements are critical for hydropower production and where snowmelt can pose serious flood-related damages. [ABSTRACT FROM AUTHOR]

2-Methylisoborneol (2-MIB) is the primary cause of the earthy and musty odor produced by cyanobacteria, which deteriorates the quality of fishery products and tap water. Despite the need for controlling outbreaks, few studies have been conducted on 2-MIB in brackish lakes, where capture fisheries are active. This study examined the association between water quality and the outbreak of 2-MIB in a brackish lake using statistical analysis of long-term monitoring data and developed forecasting models for 2-MIB outbreaks. We investigated Lake Ogawara, which is a brackish lake with a cool-temperate climate in Japan, where 2-MIB outbreaks frequently occur between August and December. Logistic regression analyses were performed using the outbreak or non-outbreak of 2-MIB (2-MIB(+ / −)) as the dependent variable and water quality parameters as the independent variables. The results suggested that the density of 2-MIB-producing cyanobacteria was higher when (1) dissolved inorganic nitrogen concentrations were low under the relaxation of phosphorus limitation and/or (2) salinity or micronutrient concentrations were high. In addition, we successfully developed forecasting models with a high predictive power that determined 2-MIB(+ / −) in August–December using only two water quality parameters: dissolved inorganic phosphate and pH in April and total nitrogen/total phosphorous and salinity in May. [ABSTRACT FROM AUTHOR]

Reservoirs are the key infrastructure of water resources management. A controlling variable of reservoir operation is evaporation, which in semi‐arid and arid regions may consume a large fraction of reservoir storage annually. This paper assesses the role of evaporation and the choice of evaporation methods on reservoir operation. The operation of the reservoir is calculated with the standard operation policy (SOP). Several efficiency criteria are employed to rank the evaporation‐calculation methods with the technique for the order of preference by similarity to ideal solution (TOPSIS). The method presented in this paper is illustrated by applying its application to Karkheh reservoir, the largest in Iran. [ABSTRACT FROM AUTHOR]

A novel quantitative assessment of late Holocene precipitation in the Levant is presented, including mean and variance of annual precipitation and their trends. A stochastic framework was utilized and allowed, possibly for the first time, linking high-quality, reconstructed rises/declines in Dead Sea levels with precipitation trends in its watershed. We determined the change in mean annual precipitation for 12 specific intervals over the past 4500 yr, concluding that: (1) the twentieth century was substantially wetter than most of the late Holocene; (2) a representative reference value of mean annual precipitation is 75% of the present-day parameter; (3) during the late Holocene, mean annual precipitation ranged between −17 and +66% of the reference value (−37 to +25% of present-day conditions); (4) the driest intervals were 1500–1200 BC and AD 755–890, and the wettest intervals were 2500–2460 BC, 130–40 BC, AD 350–490, and AD 1770–1940; (5) lake-level rises and declines probably occurred in response to trends in precipitation means and are less likely to occur when precipitation mean is constant; (6) average trends in mean annual precipitation during intervals of ≥200 yr did not exceed 15 mm per decade. The precipitation trends probably reflect shifts in eastern Mediterranean cyclone tracks. [ABSTRACT FROM AUTHOR]

Estimating groundwater recharge is crucial to ensuring the proper management of aquifers. In this study, net regional recharge and spatial potential recharge are estimated at four watersheds within the Charlevoix-Haute-Côte-Nord (CHCN) regions, Quebec Province, Canada. Four methods are applied based on available data. The first two approaches are regional water budget methods. These two methods differ in their estimation of vertical inflow (VI), which is estimated from two hydrological models: GR4J and HYDROTEL. The third method estimates potential recharge spatially over the study area. Finally, the streamflow data are analysed using the Eckhardt baseflow separation method to obtain an estimation of recharge, assuming that discharge is equal to recharge. According to the results of all investigated methods, the mean annual recharge for the CHCN region is approximately 183 mm, which is 18% of the total annual precipitation (P). The discussion section highlights uncertainties due to the assumptions of each method and the reliability of the data. [ABSTRACT FROM AUTHOR]

Lead is a priority pollutant, and lead metal is widely found in the environment as a waterproofing structural component in roofing, fence post covers, venting and flashing, as well as in industrial and urban waste. However, little is known of microbial interactions with metallic lead. The objective of this research was to investigate fungal roles in transformations of lead in a surface biofilm community growing on lead sheeting. The lead surface was found to support a diverse fungal community with several members, such as A ureobasidum pullulans, P homa macrostoma, P enicillium sp. and B otryotinia fuckeliana, probably originating from adjacent phylloplane communities. Many fungal isolates showed tolerance to lead compounds in growth inhibition assays and were able to mediate production of lead-containing secondary minerals in the presence of metallic lead. These exhibited widely differing morphologies to the lead-containing secondary minerals produced under abiotic conditions. The presence of pyromorphite ( Pb5( PO4) 3Cl) (approximately 50 wt%) was detected in the lead sheet biofilm, and we speculate that animal (bird) faeces could be a significant source of phosphorus in this location. Pyromorphite formation represents biomineralization of mobile lead species into a very stable form, and this research provides the first demonstration of its occurrence in the natural environment. [ABSTRACT FROM AUTHOR]

The baseflow separation method based on a digital filter is a simple method for separating the baseflow from streamflow. Appropriate estimation of filter parameters is required to use the digital filter method for analysis. We carried out sensitivity analysis on four digital filter methods: Lyne–Hollick (LH), Chapman, Chapman and Maxwell (CM), and exponentially weighted moving average (EWMA). Furthermore, appropriate filter parameters were suggested for each method in this study. By applying them to 25 stage stations in the Nakdong River in the Republic of Korea, the four methods were evaluated. The results of the evaluation showed that the Chapman and CM methods had problems separating the baseflow during the dry seasons. The EWMA and LH methods were able to achieve reliable baseflow separation of the outcomes by selecting appropriate the filter parameters. Thus, the EWMA and LH methods can be used easily and reasonably among the digital filter methods that have one filter parameter. [ABSTRACT FROM AUTHOR]

The volume and sustainability of streamflow from headwaters to downstream reaches commonly depend on contributions from ground water. Streams that begin in extensive aquifers generally have a stable point of origin and substantial discharge in their headwaters. In contrast, streams that begin as discharge from rocks or sediments having low permeability have a point of origin that moves up and down the channel seasonally, have small incipient discharge, and commonly go dry. Nearly all streams need to have some contribution from ground water in order to provide reliable habitat for aquatic organisms. Natural processes and human activities can have a substantial effect on the flow of streams between their headwaters and downstream reaches. Streams lose water to ground water when and where their head is higher than the contiguous water table. Although very common in arid regions, loss of stream water to ground water also is relatively common in humid regions. Evaporation, as well as transpiration from riparian vegetation, causing ground-water levels to decline also can cause loss of stream water. Human withdrawal of ground water commonly causes streamfiow to decline, and in some regions has caused streams to cease flowing. [ABSTRACT FROM AUTHOR]

Streamwater chemistry was measured at 100-m intervals in all streams of the Hubbard Brook Valley, NH during ‘spring’ (May–July) and during ‘fall’ (October–December) 2001. Overall, streamwater chemistry was very similar during these two periods, but fall median concentrations were consistently higher than spring values, except for ANC, pH, NO3 − and PO4 3−, which had lower values in fall. Median concentrations for NH4 + were approximately the same in spring and fall. Stream chemistry varied throughout the Hubbard Brook Valley by elevation, channel length, drainage area and type of drainage, but most of the variability in stream chemistry was subtle and relatively small. Overall, there were relatively large (two- to 10-fold) changes in chemistry with longitudinal distance of wetted channel, elevation and/or size of drainage area in some streams and for some elements (e.g., H+, Al n+, DOC), but other chemical concentrations changed relatively little (e.g., Cl−, dissolved Si). The main Hubbard Brook, a fifth-order stream at the mouth of the Valley, was remarkably constant in chemistry throughout its length, except where human disturbance near the mouth changed the chemistry. Differences in vegetation, geologic substrates and wetland areas were related to changes in pattern of streamwater chemistry throughout the Valley. [ABSTRACT FROM AUTHOR]

The last few years has seen a surge in research activities directed towards investigating properties and dynamics of young marine, limnic and fluvial sediments. It is by now a well established fact that the sequence of sediments ranging from concentrated benthic suspension over fluid mud to un-consolidated material summarized as liquid sediments (LS), act as carriers for a wide range of pollutants discharged or migrated into waterways. Knowledge of the transport and fate of LS allows determining the transport and fate of adsorbed constituents (e.g., heavy metals, pesticides, PCBs, PAHs). To assess the environmental impact of LS, efforts have to be made to better understand the processes in relation to hydrodynamics and the chemical and physical properties of the layers. Since physical laws limit the resolution and detection power of conventional seismo-acoustic systems in respect of LS, alternative measurement, data analysis and processing approaches have to be found. Adapted acoustic procedures initially developed for shallow water marine environments to extreme shallow water regimes using matched field inversion techniques can reveal geoacoustic parameters including density, compressional wave speed and attenuation as a function of depth and time. The paper outlines the effects of sediment mobility upon the environment followed by a short overview of techniques commonly used to investigate sediments and other freshwater/marine events. The problems faced and limitations of existing systems are briefly outlined. Results obtained with recently developed and refined geoacoustic inversion methods are presented highlighting their potential for long-term study of physical properties and dynamics of LS. [ABSTRACT FROM AUTHOR]

Climate change can directly or indirectly influence groundwater resources. The mechanisms of this influence are complex and not easily quantified. Understanding the effect of climate change on groundwater systems can help governments adopt suitable strategies for water resources. The baseflow concept can be used to relate climate conditions to groundwater systems for assessing the climate change impact on groundwater resources. This study applies the stable baseflow concept to the estimation of the groundwater recharge in ten groundwater regions in Taiwan, under historical and climate scenario conditions. The recharge rates at the main river gauge stations in the groundwater regions were assessed using historical data. Regression equations between rainfall and groundwater recharge quantities were developed for the ten groundwater regions. The assessment results can be used for recharge evaluation in Taiwan. The climate change estimation results show that climate change would increase groundwater recharge by 32.6% or decrease it by 28.9% on average under the climate scenarios, with respect to the baseline quantity in Taiwan. The impact of climate change on groundwater systems may be positive. This study proposes a method for assessing the impact of climate change on groundwater systems. The assessment results provide important information for strategy development in groundwater resources management. [ABSTRACT FROM AUTHOR]

Baseflow plays a crucial role in maintaining the stability of streamflows, especially in watersheds. To reveal the evolution of baseflow in watersheds in southern China, this study investigated the variation in baseflow across the small watershed of Pengchongjian in Jiangxi Province. A digital filter method was applied to separate baseflow from local daily streamflow records for 1983–2014 using different values of filtering parameter (β) and filtering times (T). The separation results were validated by the baseflow index (BFI) method to determine the optimal parameters. When β = 0.90 and T = 2, the baseflow separation results conformed to the actual field situation in the watershed. The average monthly baseflow increased at first and then decreased, being unevenly distribution within a year, whereas average monthly BFI followed the opposite trend. On the seasonal scale, baseflow was ranked as spring > summer > winter > autumn, and the BFI as winter > spring > autumn > summer. Both the annual baseflow and BFI decreased at a rate of 2.30 mm/year and 0.0005/year, respectively. When considered on the annual scale, the BFI was lower in the wet years and higher in the dry years compared with normal years, averaging 0.22 in the watershed for the 1983–2014 period. This study obtained key optimal parameters for baseflow separation and revealed baseflow variation in the Pengchongjian watershed. These results provide a useful reference for studying the patterns of baseflow evolution in watersheds in southern China. [ABSTRACT FROM AUTHOR]

ABSTRACT. Prairie Creek Reservoir, located in an agricultural watershed in east-central Indiana, serves as a secondary drinking water supply through water releases to the White River and offers various recreational [...]

Naturally occurring long-term mean annual recharge to ground water in Nebraska was estimated by a novel water-balance approach. This approach uses geographic information systems (GIS) layers of land cover, elevation of land and ground water surfaces, base recharge, and the recharge potential in combination with monthly climatic data. Long-term mean recharge > 140 mm per year was estimated in eastern Nebraska, having the highest annual precipitation rates within the state, along the Elkhorn, Platte, Missouri, and Big Nemaha River valleys where ground water is very close to the surface. Similarly high recharge values were obtained for the Sand Hills sections of the North and Middle Loup, as well as Cedar River and Beaver Creek valleys due to high infiltration rates of the sandy soil in the area. The westernmost and southwesternmost parts of the state were estimated to typically receive < 30 mm of recharge a year., Introduction In regional-scale water balance and ground water modeling studies, recharge to the ground water is an important but often poorly known variable because it is influenced by a host [...]

Iron Mountain is located in the West Shasta Mining District in California. An investigation of the generation of acid rock drainage and metals loading to Boulder Creek at Iron Mountain was conducted. As part of that investigation, a hydrograph separation technique was used to determine the contribution of ground water to total flow in Boulder Creek. During high-flow storm events in the winter months, peak flow in Boulder Creek can exceed 22.7 [m.sup.3]/sec, and comprises surface runoff, interflow, and ground water discharge. A hydrograph separation technique was used to estimate ground water discharge into Boulder Creek during high-flow conditions. Total ground water discharge to the creek approaches 0.31 [m.sup.3]/sec during the high-flow season. The hydrograph separation technique combined with an extensive field data set provided reasonable estimates of ground water discharge. These estimates are useful for other investigations, such as determining a corresponding metals load from the metal-rich ground water found at Iron Mountain and thus contributing to remedial alternatives., Introduction One of the hydrologic and geochemical investigations at Iron Mountain near Redding, California (Figure 1), is the characterization of ground water and its role as a transport mechanism of [...]

Ground water discharge to the Great Lakes around the Lower Peninsula of Michigan is primarily from recharge in riparian basins and proximal upland areas that are especially important to the northern half of the Lake Michigan shoreline. A steady-state finite-difference model was developed to simulate ground water flow in four regional aquifers in Michigan's Lower Peninsula: the Glaciofluvial, Saginaw, Parma-Bayport, and Marshall aquifers interlayered with the Till/'red beds,' Saginaw, and Michigan confining units, respectively. The model domain was laterally bound by a continuous specified-head boundary, formed from lakes Michigan, Huron, St. Clair, and Erie, with the St. Clair and Detroit River connecting channels. The model was developed to quantify regional ground water flow in the aquifer systems using independently determined recharge estimates. According to the flow model, local stream stages and discharges account for 95% of the overall model water budget; only 50/0 enters the lakes directly from the ground water system. Direct ground water discharge to the Great Lakes' shorelines was calculated at 36 [m.sup.3]/sec, accounting for 5% of the overall model water budget. Lowland areas contribute far less ground water discharge to the Great Lakes than upland areas. The model indicates that Saginaw Bay receives only ~1.13 [m.sup.3]/sec ground water; the southern half of the Lake Michigan shoreline receives only ~2.83 [m.sup.3]/sec. In contrast, the northern half of the Lake Michigan shoreline receives more than 17 [m.sup.3]/sec from upland areas., Introduction The water balances of the Great Lakes are of considerable interest to numerous stakeholders. Airborne and riverine fluxes are more accessible and thus better known than ground water discharges. [...]

Introduction In hydrologic and ecosystem investigations of mountainous or hilly terrain, the study unit is typically a surface water drainage basin, or catchment, outlined by the surrounding topographic divide. In [...]

Keith J. Halford [a] Gregory C. Mayer [b] Abstract Ground water discharge and recharge frequently have been estimated with hydrograph-separation techniques, but the critical assumptions of the techniques have not [...]