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Freshwater unionid mussels are among the most imperiled fauna in North America, and their decline has been partially attributed to sediment from anthropogenic activities. However, there remains a debate regarding the role played by sediment in mussel declines due to a lack of field and laboratory evidence. If sediment is responsible for mussel declines, then a lack of information will likely impede efforts to mitigate species declines and protect remaining habitat. However, if the impacts of sediment are overstated, time and resources may be wasted on a threat that has little bearing on mussel declines or habitat loss. Given this knowledge gap, the purpose of this paper is to review the literature focused on the potential impact of suspended sediment and sedimentation on freshwater mussels. We focused our search on suspended sediment, expressed either as suspended sediment concentration (SSC) or total suspended solids (TSS), and sediment deposition and scour. We found increases in suspended solids could impact mussels by decreasing food availability, physically interfering with filter feeding and respiration, and impeding various aspects of the mussel–host relationship. We also found mussel–sediment thresholds, wherein certain concentrations of sediment caused significant declines in population performance, which could serve as reference points for ecological research and management. Specifically, we found clearance rates (a measure of feeding) were negatively impacted by TSS concentrations >8 mg/L, and respiratory stress occurred at ∼600 mg/L. Declines in fertilization success and glochidial (i.e., mussel larvae) development were observed at TSS values of 15 mg/L, and reproductive failure occurred at 20 mg/L. Impacts on host fish attachment and glochidial encystment occurred at TSS concentrations of 1250–5000 mg/L. Impacts on fish varied depending on the biological endpoint but typically occurred at TSS values ranging from 20 to 5000 mg/L. We also found mussels were sensitive to smothering and mortality occurred at depths as low as 0.6–2.5 cm of substrate. Finally, we found relative shear stress (RSS) values >1, which is a measure of substrate stability in response to scour and entrainment, resulted in significant declines in mussel biodiversity. [ABSTRACT FROM AUTHOR]

This study presents a data-driven system analysis approach intended to improve greywater reuse at the household/community level using a case study of ¨Granular Activated Carbon-Membrane Integrated-Multigrade Effluent¨(GAC-MI-ME) treatment system. It consists of a matrix of advanced filtration units and provides multi-grade water reuse options. Using experimental data with varying greywater strengths, artificial neural networks were applied to develop effluent prediction models for water quality parameters including turbidity, total dissolved solids, five-day biochemical oxidation demand, oxidation redox potential and pH. The results show that the GAC-MI-ME can improve water quality with terminal removal efficiency of 99% and above for turbidity and BOD. At the same time, the model simulations can effectively predict effluent quality, which can be applied as decision-making tools in selecting and the treatment trains of GAC-MI-ME. The concept may help broaden the greywater reuse by ensuring it meets the requirements of diverse water reuse regulations. [ABSTRACT FROM AUTHOR]

This study aims at improving greywater reuse potential. An advanced physical filtration system named as GAC-MI-ME was developed to attain multi-grade effluents for versatile reuse of greywater. It consists of a matrix of treatment trains including coarse filtration, microfiltration, activated carbon, ultrafiltration, ultraviolet, and reverse osmosis. A preliminary set of experiments were conducted to characterize the greywater originating from shower, washbasin, and laundry. The samples were subsequently treated through GAC-MI-ME system. It was observed that the activated carbon along with microfiltration and coarse filtration played vital roles as pre-filtration for ultrafiltration and reverse osmosis. The contaminant load distributions of GAC-MI-ME system were observed with an average of 90.4% turbidity and 53.2% of biochemical oxidation demand (BOD5) as the pre-filtration, whereas the effluents at ultrafiltration and reverse osmosis showed unrestricted water reuse possibilities. The GAC-MI-ME system can be envisioned as advancement to the conventionally applied greywater treatments. [ABSTRACT FROM AUTHOR]

MIKE SHE is a physically based, integrated water resources model that simulates both surface and subsurface water dynamics. These dynamics include interception, evapotranspiration, overland flow, channel flow, unsaturated flow, and saturated zone flow. The model can also simulate limited surface water quality processes using the advection dispersion equation and groundwater quality with a random-walk tracking method. This article is intended to describe the components of MIKE SHE and its calibration, validation, and applications. Given the deterministic, physically based characteristics of MIKE SHE and the large number of processes it simulates simultaneously, the number of parameters to calibrate can be large. A combination of user experience with the model, knowledge of the problem being solved, and an automatic calibration feature help in selecting the most sensitive parameters to calibrate. A case study describing the use of the MIKE SHE model, coupled with the hydraulic MIKE 11 model, to solve water flow in agricultural reservoirs in south Florida is presented. The problem required the use of the MIKE SHE model due to the high groundwater and overland flow interactions as well as the complex flow patterns inside the reservoir. The horizontal and vertical saturated hydraulic conductivities and the leakage coefficient were identified as the calibration parameters. The model was calibrated and evaluated for two reservoirs using two different time periods. Results showed matching between measured and simulated data for both reservoirs for the calibration and validation periods. The coupled MIKE SHE/MIKE 11 model has the capabilities to simulate complex hydrological processes and their interactions, which few other watershed models can match, and is suitable for current problems, such as the effects of climate change and land use change. [ABSTRACT FROM AUTHOR]

The effects of organic amendments on vegetable crop production, phosphorus (P), and trace element (Zn, Cu, Mn, B, Cd, Pb, Ni) concentrations in groundwater were investigated on calcareous and sandy soils in south Florida. Treatments consisted of applying yard trash and food compost, biosolids compost, a co-compost of municipal solid waste and biosolids, and inorganic fertilizer. A randomized complete block design with four replications was used at both study sites. Total Kjeldahl phosphorus (TKP) and soluble reactive phosphorus (SRP) were periodically measured in grab samples collected for two years for both soils from wells above and below the spodic horizon at Ft. Pierce and from one depth at Homestead. Treatments were similar (P > 0.05) except on two sampling dates from the deep wells in the sandy soil at Ft. Pierce, one for SRP and one for TKP. Phosphorus concentrations for all treatments averaged < 1.2 mg SRP L-1 at Ft. Pierce and 0.04 mg SRP L-1 for the calcareous soil at Homestead. From solely a P consideration, organic P sources could be used to offset all or a portion of P required to satisfy vegetable crop nutrient requirements. This statement is consistent with crop yields at Ft. Pierce where yields from the three organic sources were equal to or exceeded inorganic fertilization yields. Micronutrient and trace element concentration responses to organic treatments were more pronounced at Ft. Pierce, perhaps due to soil chemical conditions including lower soil pH. The cocompost should be used cautiously to avoid contamination problems, especially when application rates are based on N fertilization as in this study. Due to the calcareous soil at Homestead, trace element concentrations in the groundwater were considerably lower than Ft. Pierce concentrations. However, the cocompost source was elevated for lead (Pb) (P < 0.05) compared with all other treatments, although higher concentrations were observed only on one sampling date. Results from this study indicated that, combined with the environmental benefits of recycling waste, the use of these organic amendments is a viable alternative to inorganic P fertilizers in the sandy and calcareous soils of peninsular Florida. The compost treatments were comparable to inorganic fertilizer with regard to P concentrations in the groundwater white producing similar or higher vegetable crop yields. [ABSTRACT FROM AUTHOR]

Experiments were conducted on calcareous and sandy soils to investigate the effects of organic amendments for vegetable production on groundwater nitrogen (N) concentration in south Florida. The treatments consisted of applying yard and food residuals compost, biosolids compost, a cocompost of the municipal solid waste and biosolids, and inorganic fertilizer. Nitrate nitrogen (NO3-N), ammonium nitrogen (NH4-N), and total N concentrations were collected for a period of two years for both soils. Statistical analysis results revealed that for the three species tested, there were no significant differences among treatments. NO3-N concentrations for all treatments remained less than the maximum contamination level (10 mg/L). NO3-N transport to groundwater was higher in calcareous soil (mean=5.3 mg/L) than in sandy soil (mean=0.6 mg/L). NH4-N concentrations ranged from 0 to 13.6 mg/L throughout the experiment. Calcareous soil had lower NH4-N concentrations (mean=0.1 mg/L) than sandy soils (mean=0.7 mg/L). Total N ranged from 0.4 to 21.7 mg/L for all treatments for both soils reflecting high adsorption of dissolved organic N in both soils. Overall, results indicated that all the compost treatments were comparable to inorganic fertilizer with regard to N leaching and N concentrations in the groundwater while producing similar or higher yields. [ABSTRACT FROM AUTHOR]

A two-dimensional finite element based overland flow model was developed and used to study the accuracy and stability of three numerical schemes and watershed parameter aggregation error. The conventional consistent finite element scheme results in oscillations for certain time step ranges. The lumped and the upwind finite element schemes are tested as alternatives to the consistent scheme. The upwind scheme did not improve on the stability or the accuracy of the solution, while the lumped scheme provided stable and accurate solutions for time steps twice the size of time steps needed for the consistent scheme. A new accuracy based dynamic time step estimate for the two-dimensional overland flow kinematic wave solution is developed for the lumped scheme. The newly developed dynamic time step estimates are functions of the mesh size, and time of concentration of the watershed hydrograph. Due to lack of analytical solutions, the time step was developed by comparing numerical solutions of various levels of discretization to a reference solution using a very fine mesh and a very small time step. The time step criteria were tested on a different set of problems and proved to be adequate for accurate and stable solutions. A sensitivity analysis for the watershed slope, Manning’s roughness coefficient and excess rainfall rate was conducted in order to test the effect of parameter aggregation on the stability and accuracy of the solution. The results of this analysis show that aggregation of the slope data resulted in the highest error. The roughness coefficient had a smaller effect on the solution while the rainfall intensity did not show any significant effect on the flow rate solution for the range of rainfall intensity used. This work pioneers the challenge of providing guidelines for accurate and stable numerical solutions of the two-dimensional kinematic wave equations for overland flow. [Copyright &y& Elsevier]

Solving the kinematic wave equations for overland flow using the conventional consistent Galerkin finite element scheme is known to result in numerical oscillations due to the non-symmetric first spatial derivative terms in the kinematic wave equations. In this paper the lumped and the upwind finite element schemes are evaluated as alternatives to the consistent Galerkin finite element scheme. Stability analysis of the upwind scheme shows that the damping effect, that could reduce the oscillations, is small for the high Courant numbers encountered in overland flow problems. The upwind scheme, using upwind factors of 0.1 and 1.0, did not provide any improvement to the stability of the lumped and the consistent schemes. The lumped scheme considerably reduces oscillations without significant reduction in the overall solution accuracy. No analytical guidelines for time-step criteria that will insure stability and accuracy were provided by the stability analysis performed for the three schemes. Problem specific accuracy-based dynamic time-step criteria was developed and evaluated for the lumped scheme. These time-steps were found to be on average, double the size of the dynamic time-steps for the consistent scheme. [Copyright &y& Elsevier]

Rapid urbanization, aging infrastructure, and climate change impacts have put a strain on existing stormwater drainage systems. One commonly acknowledged solution to relieve such stress is Green Stormwater Infrastructure (GSI). Interest in GSI technology has been growing. However, the level of implementation in many areas around the world lags behind the interest level. This study aims to critically review the body of literature from the last decade to determine the main barriers to wide adoption and the offered solutions to overcome them. Based on a review of 92 peer‐reviewed journal articles published between 2012 and 2022, we classify barriers and solutions into six categories: socio‐cultural, financial, institutional and governance, legislative and regulatory, technical, and biophysical. Based on observations and conclusions from the reviewed articles, we recommend the following pillars and considerations for more GSI adoption: increasing awareness and outreach programs; enhancing knowledge and data co‐production and dissemination; acknowledging interdependency and context‐specificity of many of the challenges and solutions; prioritizing integrated and participatory watershed planning; overcoming institutional path‐dependencies; prioritizing innovative solutions; giving specific consideration to maintenance protocols; considering the role of public entities; and actively engaging with communities. This article is categorized under:Engineering Water > Planning WaterWater and Life > Conservation, Management, and Awareness [ABSTRACT FROM AUTHOR]

[Display omitted] • A new framework successfully identified flood hotspots in an urban drainage system. • Inlet structure depth was found to be the main parameter that predicts flooding. • GSI can significantly mitigate stormwater inlet floods. • Combining GSI and gray infrastructure provides the most effective mitigation. • Cost of overflow mitigation from GSI is lower than gray infrastructure. Mitigation of localized pluvial flooding is one of the major resiliency goals in urban environments, and Green Stormwater Infrastructure (GSI) has the potential to deliver such an outcome. However, there is a lack of systematic approaches to prioritize investment in different candidate areas. This study provides a framework to identify vulnerable stormwater drainage inlets and their contributing areas, prioritize them, identify dominant factors in their selection, assess the potential of GSI in mitigating their overflows, and compare the impact and its cost to gray infrastructure upgrade alternatives. Using SWMM 5.1.013, decision trees, and a volumetric-based assessment of GSI overflow capture, we applied the framework to the City of Dallas, Texas, for three design storms with three GSI practices— bioretention cells, raingardens, and rainwater harvesting tanks. Results showed that there was a significant increase in the number of overflowing stormwater drainage inlets, referred to as hotspots, and their contributing subwatersheds, referred to as opportunity areas, with more intense storms especially in problematic watersheds. Also, prioritization results provided a series of maps to rank the opportunity areas based on overflow severity, recurrence of the overflows, and GSI availability. Moreover, classification results showed that inlet features, especially the inlet depth, were the dominant factors in the identification of the non-problematic inlets. Finally, the GSI impact assessment showed substantial overflow mitigation even at the "very high" severity levels when GSI is comprehensively deployed across opportunity areas. Despite gray infrastructure upgrades yielding higher reduction levels, their cost per cubic meter was higher than GSI. Therefore, a combination of GSI and gray results in maximum overflow reduction at a lower cost compared to common practices. [ABSTRACT FROM AUTHOR]

• TIA and DCIA positively affect the probability of runoff yield. • DCIA contributes far more than TIA to generating far-above-average runoff depth. • The contributions of TIA and DCIA to far-above-average peak flow are comparable. • The impacts of TIA and DCIA are subject to climate variability. • TIA and DCIA control is effective within a specific range of rainfall depth. Total impervious area (TIA) is one of the most common measures for predicting runoff yield in hydrologic studies and regulating urbanization in land use policy. Directly connected impervious area (DCIA), a subset of TIA, represents the hydraulic connection between development and underground sewer systems. Which indicator to use in runoff prediction has been subject to debate. The effectiveness of TIA and DCIA in the face of climate variability also remains unclear. The present study empirically assessed the impacts of TIA and DCIA on urban runoff in three metropolitan statistical areas (MSAs) in the U.S. state of Texas. The total monthly runoff depths of 92 watersheds and peak flows of 43 watersheds were computed using streamflow monitored by the U.S. Geological Survey from 2010 to 2017. A series of ordinal logit regression models were developed to determine which imperviousness indicator better predicted probable runoff yield. Additionally, an average marginal effect analysis was performed to investigate how TIA and DCIA responded to changing precipitation depths. The results demonstrate that DCIA outperformed TIA in runoff depth prediction, whereas TIA predicted peak flow better than DCIA. However, for far-above-average runoff, the contribution of DCIA to runoff depth was far greater than that of TIA, but no difference was found for peak flow. The effectiveness of TIA and DCIA also varied by total and 24-hour peak depths of monthly precipitation. After reaching their maximum capacity, both TIA and DCIA became less effective in predicting runoff and did not correlate with rainfall depth in extremely wet months. Meanwhile, the control of TIA and DCIA for runoff volume reduction was most effective for monthly rainfall of a 5% to 10% probability of exceedance in all MSAs, whereas that of peak flow reduction was most effective if the 24-hour peak storm in a month had a 2% to 5% probability of exceedance. The findings of this study demonstrate the hydrologic significance of regulating DCIA over TIA for high-risk runoff under certain rainfall depths and return periods. The study expands the current knowledge of urban hydrology for effective stormwater management and mitigation of future flooding risk. [ABSTRACT FROM AUTHOR]