Water

806 KiB

Open AccessReview

Review and Research Needs of Bioretention Used for the Treatment of Urban Stormwater

by Jia Liu, David J. Sample, Cameron Bell and Yuntao Guan

Water 2014, 6(4), 1069-1099; https://doi.org/10.3390/w6041069 - 24 Apr 2014

Cited by 223 | Viewed by 29075

The continued development of urban areas in recent decades has caused multiple issues affecting the sustainability of urban drainage systems. The increase of impervious surface areas in urban regions alters watershed hydrology and water quality. Typical impacts to downstream hydrologic regimes include higher [...] Read more.

The continued development of urban areas in recent decades has caused multiple issues affecting the sustainability of urban drainage systems. The increase of impervious surface areas in urban regions alters watershed hydrology and water quality. Typical impacts to downstream hydrologic regimes include higher peak flows and runoff volumes, shorter lag times, and reduced infiltration and base flow. Urban runoff increases the transport of pollutants and nutrients and thus degrades water bodies downstream from urban areas. One of the most frequently used practices to mitigate these impacts is bioretention. Despite its widespread use, research on bioretention systems remains active, particularly in terms of mix design and nitrogen treatment. Recent research focusing on bioretention is reviewed herein. The use of mesocosms provides the ability to isolate particular treatment processes and replicate variability. Computational models have been adapted and applied to simulate bioretention, offering potential improvements to their operation, maintenance, and design. Maintenance practices are important for sustained operation and have also been reviewed. Predicting maintenance is essential to assessing lifecycle costs. Within these research areas, gaps are explored, and recommendations made for future work. Full article

(This article belongs to the Special Issue Sustainable Drainage Systems)

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2963 KiB

Open AccessArticle

Integrated Groundwater Resources Management Using the DPSIR Approach in a GIS Environment Context: A Case Study from the Gallikos River Basin, North Greece

by Christos Mattas, Konstantinos S. Voudouris and Andreas Panagopoulos

Water 2014, 6(4), 1043-1068; https://doi.org/10.3390/w6041043 - 24 Apr 2014

Cited by 26 | Viewed by 12601

Abstract

The Gallikos River basin is located in the northern part of Greece, and the coastal section is part of a deltaic system. The basin has been influenced by anthropogenic activities during the last decades, leading to continuous water resource degradation. The holistic approach [...] Read more.

The Gallikos River basin is located in the northern part of Greece, and the coastal section is part of a deltaic system. The basin has been influenced by anthropogenic activities during the last decades, leading to continuous water resource degradation. The holistic approach of the Driver-Pressure-State-Impact-Response (DPSIR) framework was applied in order to investigate the main causes and origins of pressures and to optimize the measures for sustainable management of water resources. The major driving forces that affect the Gallikos River basin are urbanization, intensive agriculture, industry and the regional development strategy. The main pressures on water resources are the overexploitation of aquifers, water quality degradation, and decrease of river discharge. Recommended responses were based on the Water Framework Directive (WFD) 2000/60/EC, and sum up to rationalization of water resources, land use management and appropriate utilization of waste, especially so effluent. The application of the DPSIR analysis in this paper links the socioeconomic drivers to the water resource pressures, the responses based on the WFD and the national legislation and is as a useful tool for land-use planning and decision making in the area of water protection. Full article

(This article belongs to the Special Issue Water Policy, Productivity and Economic Efficiency)

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395 KiB

Open AccessArticle

Sorption of Emerging Organic Wastewater Contaminants to Four Soils

by Sarah Roberts, Christopher Higgins and John McCray

Water 2014, 6(4), 1028-1042; https://doi.org/10.3390/w6041028 - 24 Apr 2014

Cited by 19 | Viewed by 7619

Abstract

Conventional onsite wastewater treatment system design relies on a septic tank and soil treatment unit (STU) for treatment of wastewater and integration of the final effluent into the environment. Organic water contaminants (OWCs), chemicals found in pharmaceutical drugs, detergents, surfactants, and other personal [...] Read more.

Conventional onsite wastewater treatment system design relies on a septic tank and soil treatment unit (STU) for treatment of wastewater and integration of the final effluent into the environment. Organic water contaminants (OWCs), chemicals found in pharmaceutical drugs, detergents, surfactants, and other personal care and cleaning products, have been observed in septic tank effluent and the environment. Sorption of OWC mass to soil is a key mechanism in the removal and retardation of many of these chemicals in effluent as it travels through an STU. The primary purpose of this study was to investigate the relationship between the fraction of organic carbon of soil and the equilibrium sorption partitioning coefficient of a selected group of relevant and diverse OWCs. A secondary goal is to evaluate current methods of modeling the sorption of selected OWCs in soil. Five point Freundlich isotherms were constructed from equilibrium sorption batch tests for target OWCs with four different soils. For soils with organic carbon fraction between 0.021 and 0.054, K_d values were calculated between 60 and 185 for 4-nonylphenol, 75 to 260 for triclosan, 115 to 270 for bisphenol-A, 3 to 255 for 17β-estradiol, 40 to 55 for 17α-ethynylestradiol, and 28 to 70 for estrone. An empirically derived, direct relationship between f_oc and K_d may be a useful approach to estimating sorption for a soil based on organic carbon content. Full article

(This article belongs to the Special Issue Advances in On-Site Wastewater Treatment and Technologies to Characterize the Fate and Transport of Wastewater Constituents)

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1692 KiB

Open AccessArticle

Quantifying Reaeration Rates in Alpine Streams Using Deliberate Gas Tracer Experiments

by Andrew Benson, Matthew Zane, Timothy E. Becker, Ate Visser, Stephanie H. Uriostegui, Elizabeth DeRubeis, Jean E. Moran, Bradley K. Esser and Jordan F. Clark

Water 2014, 6(4), 1013-1027; https://doi.org/10.3390/w6041013 - 22 Apr 2014

Cited by 30 | Viewed by 8743

Abstract

Gas exchange across the air-water interface is a critical process that maintains adequate dissolved oxygen (DO) in the water column to support life. Oxygen reaeration rates can be accurately measured using deliberate gas tracers, like sulfur hexafluoride (SF₆) or xenon (Xe). [...] Read more.

Gas exchange across the air-water interface is a critical process that maintains adequate dissolved oxygen (DO) in the water column to support life. Oxygen reaeration rates can be accurately measured using deliberate gas tracers, like sulfur hexafluoride (SF₆) or xenon (Xe). Two continuous release experiments were conducted in different creeks in the Sierra Nevada of California: Sagehen Creek in September, 2009, using SF₆ and Martis Creek in August, 2012, using both SF₆ and Xe. Measuring gas loss along the creek, which was approximated with the one-dimensional advection-dispersion equation, allows for the estimation of the SF₆or Xe reaeration coefficient (K_SF6_,K_Xe), which is converted to DO reaeration (K_DO or K₂) using Schmidt numbers. Mean K_SF6 for upper and lower Sagehen and Martis Creeks were, respectively, 34 day⁻¹, 37 day⁻¹ and 33 day⁻¹, with corresponding K_DOs of 61 day⁻¹, 66 day⁻¹ and 47 day⁻¹. In Martis Creek, K_Xe was slightly higher (21%) than K_SF6, but the calculated K_DO from SF₆ agreed with the calculated K_DO from Xe within about 15%; this difference may be due to bubble-enhanced gas transfer. Established empirical equations of K_DO using stream characteristics did a poor job predicting K_DOfor both creeks. Full article

(This article belongs to the Special Issue Environmental Tracers)

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1758 KiB

Open AccessArticle

A Modified Gash Model for Estimating Rainfall Interception Loss of Forest Using Remote Sensing Observations at Regional Scale

by Yaokui Cui and Li Jia

Water 2014, 6(4), 993-1012; https://doi.org/10.3390/w6040993 - 22 Apr 2014

Cited by 45 | Viewed by 9451

Abstract

Rainfall interception loss of forest is an important component of water balance in a forested ecosystem. The Gash analytical model has been widely used to estimate the forest interception loss at field scale. In this study, we proposed a simple model to estimate [...] Read more.

Rainfall interception loss of forest is an important component of water balance in a forested ecosystem. The Gash analytical model has been widely used to estimate the forest interception loss at field scale. In this study, we proposed a simple model to estimate rainfall interception loss of heterogeneous forest at regional scale with several reasonable assumptions using remote sensing observations. The model is a modified Gash analytical model using easily measured parameters of forest structure from satellite data and extends the original Gash model from point-scale to the regional scale. Preliminary results, using remote sensing data from Moderate Resolution Imaging Spectroradiometer (MODIS) products, field measured rainfall data, and meteorological data of the Automatic Weather Station (AWS) over a picea crassifolia forest in the upper reaches of the Heihe River Basin in northwestern China, showed reasonable accuracy in estimating rainfall interception loss at both the Dayekou experimental site (R² = 0.91, RMSE = 0.34 mm∙d ⁻¹) and the Pailugou experimental site (R² = 0.82, RMSE = 0.6 mm∙d ⁻¹), compared with ground measurements based on per unit area of forest. The interception loss map of the study area was shown to be strongly heterogeneous. The modified model has robust physics and is insensitive to the input parameters, according to the sensitivity analysis using numerical simulations. The modified model appears to be stable and easy to be applied for operational estimation of interception loss over large areas. Full article

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605 KiB

Open AccessReview

A Review of Sustainable Urban Drainage Systems Considering the Climate Change and Urbanization Impacts

by Qianqian Zhou

Water 2014, 6(4), 976-992; https://doi.org/10.3390/w6040976 - 22 Apr 2014

Cited by 319 | Viewed by 73262

Abstract

Climate change and urbanization are converging to challenge city drainage infrastructure due to their adverse impacts on precipitation extremes and the environment of urban areas. Sustainable drainage systems have gained growing public interest in recent years, as a result of its positive effects [...] Read more.

Climate change and urbanization are converging to challenge city drainage infrastructure due to their adverse impacts on precipitation extremes and the environment of urban areas. Sustainable drainage systems have gained growing public interest in recent years, as a result of its positive effects on water quality and quantity issues and additional recreational amenities perceived in the urban landscape. This paper reviews recent progress in sustainable drainage development based on literature across different disciplinary fields. After presenting the key elements and criteria of sustainable drainage design, various devices and examples of sustainable drainage systems are introduced. The state-of-the-art model approaches and decision-aid tools for assessing the sustainable alternatives are discussed and compared. The paper further explores some limitations and difficulties in the application of the innovative solutions and suggests an integrated and trans-disciplinary approach for sustainable drainage design. Full article

(This article belongs to the Special Issue Sustainable Drainage Systems)

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601 KiB

Open AccessArticle

The Prediction Methods for Potential Suspended Solids Clogging Types during Managed Aquifer Recharge

by Xinqiang Du, Yunqing Fang, Zijia Wang, Jiawei Hou and Xueyan Ye

Water 2014, 6(4), 961-975; https://doi.org/10.3390/w6040961 - 22 Apr 2014

Cited by 28 | Viewed by 7648

Abstract

The implementation and development of managed aquifer recharge (MAR) have been limited by the clogging attributed to physical, chemical, and biological reactions. In application field of MAR, physical clogging is usually the dominant type. Although numerous studies on the physical clogging mechanism during [...] Read more.

The implementation and development of managed aquifer recharge (MAR) have been limited by the clogging attributed to physical, chemical, and biological reactions. In application field of MAR, physical clogging is usually the dominant type. Although numerous studies on the physical clogging mechanism during MAR are available, studies on the more detailed suspended clogging types and its prediction methods still remain few. In this study, a series of column experiments were inducted to show the process of suspended solids clogging process. The suspended solids clogging was divided into three types of surface clogging, inner clogging and mixed clogging based on the different clogging characteristics. Surface clogging indicates that the suspended solids are intercepted by the medium surface when suspended solids grain diameter is larger than pore diameter of infiltration medium. Inner clogging indicates that the suspended solids particles could transport through the infiltration medium. Mixed clogging refers to the comprehensive performance of surface clogging and inner clogging. Each suspended solids clogging type has the different clogging position, different changing laws of hydraulic conductivity and different deposition profile of suspended solids. Based on the experiment data, the ratio of effective medium pore diameter (D_p) and median grain size of suspended solids (d₅₀) was proposed as the judgment index for suspended solids clogging types. Surface clogging occurred while D_p/d₅₀ was less than 5.5, inner clogging occurred while D_p/d₅₀ was greater than 180, and mixed clogging occurred while D_p/d₅₀ was between 5.5 and 180. In order to improve the judgment accuracy and applicability, Bayesian method, which considered more ratios of medium pore diameter (D_p) and different level of grain diameter of suspended solids (d_i), were developed to predict the potential suspended solids types. Full article

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513 KiB

Open AccessArticle

Reliability and Cost Analysis of a Rainwater Harvesting System in Peri-Urban Regions of Greater Sydney, Australia

by Evan Hajani and Ataur Rahman

Water 2014, 6(4), 945-960; https://doi.org/10.3390/w6040945 - 14 Apr 2014

Cited by 82 | Viewed by 12386

Abstract

In large cities, rainwater tanks are used to save mains water, but in peri-urban and rural areas, rainwater tanks are used as a sole water supply for many households, as these regions often do not have any other means of water supply. This [...] Read more.

In large cities, rainwater tanks are used to save mains water, but in peri-urban and rural areas, rainwater tanks are used as a sole water supply for many households, as these regions often do not have any other means of water supply. This paper investigates the performance of a rainwater harvesting system (RWHS) in peri-urban regions of Greater Sydney, Australia. Considering the daily rainfall data over the entire period of record at ten different locations, it has been found that a 5 kL tank can meet 96% to 99% of the demand for toilet and laundry use depending on the location in Greater Sydney regions. However, in the driest year, a 5 kL tank can meet 69% to 99% of toilet and laundry demand depending on the location. Based on the results of life cycle cost analysis, it has been found that a 5 kL tank has the highest benefit–cost ratio (ranging from 0.86 to 0.97) among the eight possible tank sizes examined in this study. Interestingly, for a 5 kL tank, with a combined use (i.e., toilet, laundry and irrigation), the current water price in Sydney needs to be increased by 3% to 16% to achieve a benefit–cost ratio exceeding one. A set of regression equations are developed which can be used to estimate reliability using the average annual rainfall data at any arbitrary location in the peri-urban regions of Greater Sydney. The method presented in this paper can also be applied to other Australian states and other countries to estimate water savings and reliability of a RWHS using daily rainfall data. Full article

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230 KiB

Open AccessArticle

An Input-Output Assessment of Water Productivity in the Castile and León Region (Spain)

by Carlos Dionisio Pérez Blanco and Thomas Thaler

Water 2014, 6(4), 929-944; https://doi.org/10.3390/w6040929 - 14 Apr 2014

Cited by 27 | Viewed by 9815

Abstract

The failure in the past to acknowledge the limits of water supply and to decouple economic development from water demand has resulted in a water dependent growth model currently threatened by increasing scarcity and droughts. Consequently, there is now an urgent need to [...] Read more.

The failure in the past to acknowledge the limits of water supply and to decouple economic development from water demand has resulted in a water dependent growth model currently threatened by increasing scarcity and droughts. Consequently, there is now an urgent need to use sparse water resources in a more sustainable and efficient way. This demands a comprehensive understanding of water productivity and the linkages among economic sectors to illustrate the tradeoffs in water reallocations from productive sectors to priority uses (household and urban uses). This paper develops a methodology based on the Hypothetical Extraction Method to estimate inter-temporal direct and indirect water productivity. The method is applied to the Spanish region of Castile and León. Results confirm the existence of a relevant water productivity gap between the agriculture (the largest water consumer) and that of the other sectors, which are nonetheless largely dependent on the agricultural output (and thus, on agricultural water demand). Results also show that Gross Domestic Product (GDP) growth, say about 1%, results in an increase of indirect water productivity in the manufacturing blocks (0.49% and 0.38%), energy and water (0.39%) and service blocks (0.41%), providing evidence of the existence of a Verdoorn’s Law for water. Full article

(This article belongs to the Special Issue Water Policy, Productivity and Economic Efficiency)

2123 KiB

Open AccessArticle

Application of Set Pair Analysis-Based Similarity Forecast Model and Wavelet Denoising for Runoff Forecasting

by Chien-Ming Chou

Water 2014, 6(4), 912-928; https://doi.org/10.3390/w6040912 - 11 Apr 2014

Cited by 12 | Viewed by 6586

Abstract

This study presents the application of a set pair analysis-based similarity forecast (SPA-SF) model and wavelet denoising to forecast annual runoff. The SPA-SF model was built from identical, discrepant and contrary viewpoints. The similarity between estimated and historical data can be obtained. The [...] Read more.

This study presents the application of a set pair analysis-based similarity forecast (SPA-SF) model and wavelet denoising to forecast annual runoff. The SPA-SF model was built from identical, discrepant and contrary viewpoints. The similarity between estimated and historical data can be obtained. The weighted average of the annual runoff values characterized by the highest connection coefficients was regarded as the predicted value of the estimated annual runoff. In addition, runoff time series were decomposed using wavelet transforms to acquire approximate and detailed runoff signals at various resolution levels. At each resolution level, threshold quantifications were performed by setting the values of a detailed signal below a fixed threshold to zero. The denoised runoff time series data were obtained from the approximation at the final resolution level and processed detailed signals using threshold quantification at all resolution levels of runoff by wavelet reconstruction. Instead of using the original annual runoff, the denoised annual runoff was applied to compute the similarity between estimated and historical data for model calibration. The original data were used for model calibration and validation; the denoised runoff data were used as input data to calibrate the model (obtaining different connection coefficients) that is then applied for validation purposes by using as benchmark the same original data. To verify the accuracy of the proposed method, the annual runoff data of six stations in Eastern Taiwan were analyzed. Based on a root mean square error (RMSE) criterion, the analytical results demonstrated that, for all six stations, the proposed method using denoised annual runoff outperformed the traditional SPA-SF model, using original annual runoff, because noise was effectively removed from the detailed data, using a constant threshold, thus enhancing the accuracy of the annual runoff forecasting for the SPA-SF model. Full article

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1320 KiB

Open AccessArticle

Aquatic Plant Dynamics in Lowland River Networks: Connectivity, Management and Climate Change

by Benoît O.L. Demars, Gerhard Wiegleb, David M. Harper, Udo Bröring, Holger Brux and Wolfgang Herr

Water 2014, 6(4), 868-911; https://doi.org/10.3390/w6040868 - 9 Apr 2014

Cited by 17 | Viewed by 9151

Abstract

The spatial structure and evolution of river networks offer tremendous opportunities to study the processes underlying metacommunity patterns in the wild. Here we explore several fundamental aspects of aquatic plant biogeography. How stable is plant composition over time? How similar is it along [...] Read more.

The spatial structure and evolution of river networks offer tremendous opportunities to study the processes underlying metacommunity patterns in the wild. Here we explore several fundamental aspects of aquatic plant biogeography. How stable is plant composition over time? How similar is it along rivers? How fast is the species turnover? How does that and spatial structure affect our species richness estimates across scales? How do climate change, river management practices and connectivity affect species composition and community structure? We answer these questions by testing twelve hypotheses and combining two spatial surveys across entire networks, a long term temporal survey (21 consecutive years), a trait database, and a selection of environmental variables. From our river reach scale survey in lowland rivers, hydrophytes and marginal plants (helophytes) showed contrasting patterns in species abundance, richness and autocorrelation both in time and space. Since patterns in marginal plants reflect at least partly a sampling artefact (edge effect), the rest of the study focused on hydrophytes. Seasonal variability over two years and positive temporal autocorrelation at short time lags confirmed the relatively high regeneration abilities of aquatic plants in lowland rivers. Yet, from 1978 to 1998, plant composition changed quite dramatically and diversity decreased substantially. The annual species turnover was relatively high (20%–40%) and cumulated species richness was on average 23% and 34% higher over three and five years respectively, than annual survey. The long term changes were correlated to changes in climate (decreasing winter ice scouring, increasing summer low flows) and management (riparian shading). Over 21 years, there was a general erosion of species attributes over time attributed to a decrease in winter ice scouring, increase in shading and summer low flows, as well as a remaining effect of time which may be due to an erosion of the regional species pool. Temporal and spatial autocorrelation analyses indicated that long term hydrophyte biomonitoring, for the Water Framework Directive in lowland rivers, may be carried out at 4–6 years intervals for every 10 km of rivers. From multi-scale and abundance-range size analyses evidence of spatial isolation and longitudinal connectivity was detected, with no evidence of stronger longitudinal connectivity (fish and water current propagules dispersal) than spatial isolation (bird, wind and human dispersal) contrary to previous studies. The evidence for longitudinal connectivity was rather weak, perhaps resulting from the effect of small weirs. Further studies will need to integrate other aquatic habitats along rivers (regional species pool) and larger scales to increase the number of species and integrate phylogeny to build a more eco-evolutionary approach. More mechanistic approaches will be necessary to make predictions against our changing climate and management practices. Full article

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925 KiB

Open AccessCommunication

An Estimate of Energy Available via Microbial Sulfate Reduction at a Quaternary Aquifer in Northern Japan considered for Low Temperature Thermal Energy Storage

by Seiichiro Ioka and Hirofumi Muraoka

Water 2014, 6(4), 858-867; https://doi.org/10.3390/w6040858 - 9 Apr 2014

Cited by 2 | Viewed by 6200

Abstract

The energy available via microbial sulfate reduction was estimated for a Quaternary aquifer in northern Japan that is a candidate site for low temperature aquifer thermal energy storage. In evaluating whether microbial sulfate reduction proceeded or ceased, it was assumed that electron donor/acceptor [...] Read more.

The energy available via microbial sulfate reduction was estimated for a Quaternary aquifer in northern Japan that is a candidate site for low temperature aquifer thermal energy storage. In evaluating whether microbial sulfate reduction proceeded or ceased, it was assumed that electron donor/acceptor concentrations were unchanged by temperature increase. The estimated energy availability via microbial sulfate reduction at 9 °C with no thermal disturbance was 37, 51, and 53 kJ·(mol SO₄²⁻)⁻¹. The low estimate of 37 kJ·(mol SO₄²⁻)⁻¹ wasattributed to low concentration of SO₄²⁻. Excluding the sampling site with low concentration of electron acceptors, energy availability was estimated 52 and 54 kJ·(mol SO₄²⁻)⁻¹ at 20 °C; 54 and 57 kJ·(mol SO₄²⁻)⁻¹ at 40 °C; and 57 and 59 kJ·(mol SO₄²⁻)⁻¹ at 60 °C. These results indicate that possible energy availability via microbial sulfate reduction at approximately 40–60 °C exceeded the range of available energy (compiled from previous studies) at which sulfate reduction would cease. Thus, microbial sulfate reduction at this site may proceed at approximately 40–60 °C. Full article

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852 KiB

Open AccessArticle

Addressing Flooding and SuDS when Improving Drainage and Sewerage Systems—A Comparative Study of Selected Scandinavian Cities

by Geir Torgersen, Jarle T. Bjerkholt and Oddvar G. Lindholm

Water 2014, 6(4), 839-857; https://doi.org/10.3390/w6040839 - 2 Apr 2014

Cited by 12 | Viewed by 10087

Abstract

Pluvial flooding already challenges the capacity of drainage and sewerage system in urban areas in Scandinavia. For system owners this requires a stricter prioritization when improving the systems. Experts seem to agree that a regime shift from improving old combined sewers by piped [...] Read more.

Pluvial flooding already challenges the capacity of drainage and sewerage system in urban areas in Scandinavia. For system owners this requires a stricter prioritization when improving the systems. Experts seem to agree that a regime shift from improving old combined sewers by piped solutions to more sustainable drainage systems (SuDS), must take place. In this paper results from an investigation amongst the largest cities in Norway, Denmark and Sweden concerning drivers and preferred methods for improving the old system are presented. The results indicate that Norway ranks flood prevention lower than the other Scandinavian countries. During the last decades, Norwegian authorities have had a strong focus on pollution from wastewater treatment plants (WWTP). The attention to drainage and sewerage system regarding flooding, water leaks, infiltration or pollution has been neglected. Renewal or rate of investment in relation to existing drainage and sewerage system is easy to register, and provides a measure of the activity. In order to optimize flood prevention, and may be promoting the use of SuDS, the cities should be required to measure the efficiency, either by monitoring or modeling the impact of stormwater to the system. Lack of such requirements from Norwegian authorities seem to be a plausible explanation to why Norwegian cities are less focused on flood prevention compared to Swedish and Danish cities. Full article

(This article belongs to the Special Issue Sustainable Drainage Systems)

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1090 KiB

Open AccessArticle

Transport of Pathogen Surrogates in Soil Treatment Units: Numerical Modeling

by Ivan Morales, Janet A. Atoyan, José A. Amador and Thomas Boving

Water 2014, 6(4), 818-838; https://doi.org/10.3390/w6040818 - 2 Apr 2014

Cited by 19 | Viewed by 8171

Abstract

Segmented mesocosms (n = 3) packed with sand, sandy loam or clay loam soil were used to determine the effect of soil texture and depth on transport of two septic tank effluent (STE)-borne microbial pathogen surrogates—green fluorescent protein-labeled E. coli (GFPE) and [...] Read more.

Segmented mesocosms (n = 3) packed with sand, sandy loam or clay loam soil were used to determine the effect of soil texture and depth on transport of two septic tank effluent (STE)-borne microbial pathogen surrogates—green fluorescent protein-labeled E. coli (GFPE) and MS-2 coliphage—in soil treatment units. HYDRUS 2D/3D software was used to model the transport of these microbes from the infiltrative surface. Mesocosms were spiked with GFPE and MS-2 coliphage at 10⁵ cfu/mL STE and 10⁵–10⁶ pfu/mL STE, respectively. In all soils, removal rates were >99.99% at 25 cm. The transport simulation compared (1) optimization; and (2) trial-and-error modeling approaches. Only slight differences between the transport parameters were observed between these approaches. Treating both the die-off rates and attachment/detachment rates as variables resulted in an overall better model fit, particularly for the tailing phase of the experiments. Independent of the fitting procedure, attachment rates computed by the model were higher in sandy and sandy loam soils than clay, which was attributed to unsaturated flow conditions at lower water content in the coarser-textured soils. Early breakthrough of the bacteria and virus indicated the presence of preferential flow in the system in the structured clay loam soil, resulting in faster movement of water and microbes through the soil relative to a conservative tracer (bromide). Full article

(This article belongs to the Special Issue Advances in On-Site Wastewater Treatment and Technologies to Characterize the Fate and Transport of Wastewater Constituents)

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148 KiB

Open AccessBook Review

Wetland Ecology Principles and Conservation, Second Edition

by Richard Smardon

Water 2014, 6(4), 813-817; https://doi.org/10.3390/w6040813 - 2 Apr 2014

Cited by 7 | Viewed by 7940

Abstract

This is a book review of Wetland Ecology Principles and Conservation, second edition, by Paul Keddy. This review focuses on the book’s content as it relates to wetland sustainability for both science and management. Besides overall comments, comparisons are made with the first [...] Read more.

This is a book review of Wetland Ecology Principles and Conservation, second edition, by Paul Keddy. This review focuses on the book’s content as it relates to wetland sustainability for both science and management. Besides overall comments, comparisons are made with the first edition of the book and then very specific chapter-by-chapter relationships to wetland sustainability are made to illustrate specific applications toward wetland sustainability. Full article

(This article belongs to the Special Issue Wetlands and Sustainability)

735 KiB

Open AccessArticle

Optimal Reoperation of Multi-Reservoirs for Integrated Watershed Management with Multiple Benefits

by Xinyi Xu, Lingling Bin, Chengzhong Pan, Aizhong Ding and Desheng Chen

Water 2014, 6(4), 796-812; https://doi.org/10.3390/w6040796 - 2 Apr 2014

Cited by 13 | Viewed by 7401

Abstract

Constructing reservoirs can make more efficient use of water resources for human society. However, the negative impacts of these projects on the environment are often ignored. Optimal reoperation of reservoirs, which considers not only in socio-economic values but also environmental benefits, is increasingly [...] Read more.

Constructing reservoirs can make more efficient use of water resources for human society. However, the negative impacts of these projects on the environment are often ignored. Optimal reoperation of reservoirs, which considers not only in socio-economic values but also environmental benefits, is increasingly important. A model of optimal reoperation of multi-reservoirs for integrated watershed management with multiple benefits was proposed to alleviate the conflict between water use and environmental deterioration. The social, economic, water quality and ecological benefits were respectively taken into account as the scheduling objectives and quantified according to economic models. River minimum ecological flows and reservoir water levels based on flood control were taken as key constraint conditions. Feasible search discrete differential dynamic programming (FS-DDDP) was used to run the model. The proposed model was used in the upstream of the Nanpan River, to quantitatively evaluate the difference between optimal reoperation and routine operation. The results indicated that the reoperation could significantly increase the water quality benefit and have a minor effect on the benefits of power generation and irrigation under different hydrological years. The model can be readily adapted to other multi-reservoir systems for water resources management. Full article

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422 KiB

Open AccessArticle

Do Estimates of Water Productivity Enhance Understanding of Farm-Level Water Management?

by Dennis Wichelns

Water 2014, 6(4), 778-795; https://doi.org/10.3390/w6040778 - 27 Mar 2014

Cited by 34 | Viewed by 11549

Abstract

Estimates of water productivity are appearing with increasing frequency in the literature pertaining to agronomy, water management, and water policy. Some authors report such estimates as one of the outcome variables of experiment station studies, while others calculate water productivities when comparing regional [...] Read more.

Estimates of water productivity are appearing with increasing frequency in the literature pertaining to agronomy, water management, and water policy. Some authors report such estimates as one of the outcome variables of experiment station studies, while others calculate water productivities when comparing regional crop production information. Many authors suggest or imply that higher values of water productivity are needed to ensure that future food production goals are achieved. Yet maximizing water productivity might not be consistent with farm-level goals or with societal objectives regarding water allocation and management. Farmers in both rainfed and irrigated settings must address a complex set of issues pertaining to risk, uncertainty, prices, and opportunity costs, when selecting activities and determining optimal strategies. It is not clear that farmers in either setting will or should choose to maximize water productivity. Upon examining water productivity, both conceptually and empirically, using published versions of crop production functions, I conclude that estimates of water productivity contain too little information to enhance understanding of farm-level water management. Full article

(This article belongs to the Special Issue Water Policy, Productivity and Economic Efficiency)

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1425 KiB

Open AccessArticle

Use of Natural and Applied Tracers to Guide Targeted Remediation Efforts in an Acid Mine Drainage System, Colorado Rockies, USA

by Rory Cowie, Mark W. Williams, Mike Wireman and Robert L. Runkel

Water 2014, 6(4), 745-777; https://doi.org/10.3390/w6040745 - 27 Mar 2014

Cited by 17 | Viewed by 11911

Abstract

Stream water quality in areas of the western United States continues to be degraded by acid mine drainage (AMD), a legacy of hard-rock mining. The Rico-Argentine Mine in southwestern Colorado consists of complex multiple-level mine workings connected to a drainage tunnel discharging AMD [...] Read more.

Stream water quality in areas of the western United States continues to be degraded by acid mine drainage (AMD), a legacy of hard-rock mining. The Rico-Argentine Mine in southwestern Colorado consists of complex multiple-level mine workings connected to a drainage tunnel discharging AMD to passive treatment ponds that discharge to the Dolores River. The mine workings are excavated into the hillslope on either side of a tributary stream with workings passing directly under the stream channel. There is a need to define hydrologic connections between surface water, groundwater, and mine workings to understand the source of both water and contaminants in the drainage tunnel discharge. Source identification will allow targeted remediation strategies to be developed. To identify hydrologic connections we employed a combination of natural and applied tracers including isotopes, ionic tracers, and fluorescent dyes. Stable water isotopes (δ¹⁸O/δD) show a well-mixed hydrological system, while tritium levels in mine waters indicate a fast flow-through system with mean residence times of years not decades or longer. Addition of multiple independent tracers indicated that water is traveling through mine workings with minimal obstructions. The results from a simultaneous salt and dye tracer application demonstrated that both tracer types can be successfully used in acidic mine water conditions. Full article

(This article belongs to the Special Issue Environmental Tracers)

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Water, Volume 6, Issue 4 (April 2014) – 18 articles , Pages 745-1099

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