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Frontiers in Water
Number of Followers: 1  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2624-9375
Published by Frontiers Media Homepage  [96 journals]
  • Promise and paradox: A critical sociohydrological perspective on
           small-scale managed aquifer recharge

    • Authors: Britt Basel, Jaime Hoogesteger, Petra Hellegers
      Abstract: Small-scale managed aquifer recharge (MAR) has significant potential as a bottom-up, community-based adaptation solution for increasing local groundwater availability and reducing the experience of drought for small-holder agriculturalists and rural populations. Using a suite of low-tech and low-cost techniques, small-scale MAR increases the infiltration of surface water runoff to replenish groundwater and deliver a suite of societal and ecosystem benefits. While the technique is hydrologically promising, populations may not act, implementation may not be permitted, interventions may not be effective for the population in question, or unexpected consequences (paradoxes) may result. For small-scale MAR to effectively reduce the experience of drought, it is imperative to unravel how such interventions play out within the complexity of the sociohydrological system in which they are implemented. Building on previous conceptualizations of the sociohydrological system, we apply the lens of political ecology to conceptualize the interplay between biophysical, climate, and social systems. Additionally, we explore considerations, feedbacks, and potential paradoxes in the uptake, implementation, and effectiveness of small-scale MAR interventions. We show that within the parameters of climate trends, small-scale MAR may serve to increase the functionality of ecosystems and reduce the impact of climate extremes, while protecting livelihoods and supporting society. In a positive feedback loop, small-scale MAR may both reduce the likelihood of experiencing drought while simultaneously increasing the ability and likelihood of the population to cope with or further avoid drought. Paradoxes and negative feedback processes, however, must be avoided. Specific factors, and how such factors interplay, will be different in each context where small-scale MAR is implemented. Conceptualizing the sociohydrological system in which small-scale MAR is implemented, including explicitly accounting for climate trends and using a power-sensitive approach, allows us to avoid overestimating or oversimplifying small-scale MAR as a solution, while supporting practical and effective implementation.
      PubDate: 2022-11-25T00:00:00Z
  • Structuring the water quality policy problem: Using Q methodology to
           explore discourses in the Brantas River basin

    • Authors: R. Schuyler Houser, Kharis Erasta Reza Pramana, Maurits Willem Ertsen
      Abstract: Recognizing the interrelatedness of water use and conceptual value of IWRM, progressive water resource management systems are moving beyond hierarchical arrangements toward more integrated networks. Increasing calls for participation recognize the value of broadened perspectives that provide both technical expertise as well as social, cultural, and administrative knowledge. Moreover, the call for evidence-based policy of '00s has been tempered by recognition of the political nature of data and science. As such, water decision-makers striving to coproduce and employ shared knowledge must grapple with integrating inputs from diverse participant groups to characterize policy problems and identify effective and feasible solutions. Participatory mandates, coordination bodies, and collaborative networks have emerged to facilitate such integration, and their effective cooperation and alignment relies upon some degree of shared purpose, rather than command and control. But guidance is limited with respect to how to accomplish such integrative aims, including how to support discussions across sectors and silos of practice in order to foster better understanding regarding the problems a policy network collectively aims to address. Motivated by observations within the discourse on water quality in the Brantas River basin in Indonesia, this research explores alternative concepts and problem structures regarding river health via Q methodology. Q methodology, an approach that uses factor analysis to explore human subjectivity, is applied to explore conceptualizations of water quality and the structures of the “water quality problem” in the Brantas. The results show that different groups of perspectives emerge regarding the concept itself, as well as characterization of the current condition of the Brantas. Surprisingly, these variant perspectives do not follow oft-cited government-business-civil society divisions. Moreover, the emergent perspectives demonstrate which aspects of the policy problem are consistent and which are contested, suggesting several starting points for early collaboration and several areas that require further research and facilitated deliberation. The results also offer participants in the collaborative network greater appreciation of the various perspectives and definitions in use, within and across organizations, when discussing water quality.
      PubDate: 2022-11-25T00:00:00Z
  • Verification of PCSWMM's LID processes and their scalability over time and

    • Authors: Zhonghao Zhang, Caterina Valeo
      Abstract: IntroductionThis paper explores the scalability of PCSWMM's Low Impact Development (LID) modeling tools within the urban stormwater computer model.MethodsThe scalability is assessed for a variety of spatial and temporal scales and for event (50-year return storm) and continuous inputs (daily rainfall for an 11 month period), and with a focus on bioretention cells. The model is calibrated for a moderate to large scale, semi-urban watershed on Vancouver Island, British Columbia, Canada. Sensitivity analysis and specialized metrics are used to verify internal model processes at a variety of scales.ResultsWith regard to spatial scaling, changes in flow path length and slope derived from Digital Elevation Models were the most impactful spatial information when modeling flood event and the model's surface layer was the dominant contributor to peak flowrate and volume mitigation by the bioretention cell. However, when modeling the continuous rainfall inputs, storage layer related parameters dominated model outputs. Aside from the soil layer's depth, soil layer parameters such as hydraulic conductivity, showed negligible influence on response to time series rainfall. Parameters that are kept static by the model such as vegetation cover, hydraulic conductivity and storage void ratio (but are naturally dynamic), were tested for their impact on response if allowed to change seasonally or with excessive loading. Runoff coefficients were greatly impacted by storage layer parameter dynamics with very little impact from vegetation. For event simulations, the berm height in the surface layer was the dominant player in reducing peak flow as well as total volume. An analysis to help illustrate sensitivity across spatial scales is proposed.DiscussionThe Spatial Dynamic Sensitivity Analysis shows that parameter sensitivity changes dynamically as LID implementation percentage changes. In particular, the clogging factor, which is a parameter associated with the storage layer, was highly influential for time series rainfall analysis. The LID model concepts in PCSWM seem appropriate for events because the surface layer dominates the response for very large storms. For smaller storms, continuous time series, and larger spatial scales, the model could be revised to better represent soil layer dynamics and vegetation cover, which were both currently inconsequential to the model's output.
      PubDate: 2022-11-25T00:00:00Z
  • Water and climate: Global environmental sustainability and the current
           state in a developing country, Nicaragua

    • Authors: Katherine Vammen, Elizabet Peña
      Abstract: Environmental sustainability means taking steps to secure adequate management of natural resources in all human productive and livelihood activities. These steps involve a strategy of rational sustainable exploitation and the introduction of effective conservation measures which means integral management on all levels, national, regional and global. The specific situation of Nicaragua, as a prime example of a country in development with a vast richness in natural resources is analyzed. To name a few, in total renewable water resources the country has the 14th highest total yearly internal renewable water resources per capita (24,161/capita/year) in the Americas and as a tropical country has a large variety of biodiversity and ecosystems such as tropical dry and humid forests and 910 km of coastal area in the Caribbean and Pacific coast. These natural resources and more could bring potential to promote its own development. In spite of this, the country is on an unsustainable path as many parts of the world but with even greater challenges due to limited economic sustainability, high vulnerability to climate change and the lack of institutional capacity to establish better management. Unsustainable practices ranging from over-exploitation of resources to drastic land use changes have created environmental problems which consequently affect human wellbeing and health. Additionally, ecosystems and the quality of resources are under pressure which lead to a reduction in quality of water, forests and biodiversity. For example, the dry tropical forests have been reduced in 90% from 2000 to 2011 in the Pacific and Central areas and humid tropical forests are constantly being invaded and converted to agricultural and pasture lands. Water quality has been affected from contamination from agriculture, industries and the natural volcanic geology (arsenic) in groundwater as well as eutrophication and increased sedimentation from the watersheds of both lakes and rivers. Climate change is exacerbating these problems and causing new ones. After illustrating the present state of resources in Nicaragua, strategic suggestions of needed components to introduce an integral and improved management of the water resources have been laid out as a proposal for the future that include improvement in institutional capacity and governance to promote better management.
      PubDate: 2022-11-24T00:00:00Z
  • Lessons learned from water-scarce cities: Proposed policies toward an
           integrated urban water management in Egypt

    • Authors: Zeina ElZein, Amal Abdou, Ina Säumel
      Abstract: Water scarcity is one of the main challenges facing countries in arid or semi-arid zones. As an example, Egypt needs to deal with both insufficient quantity and quality of water for residents. Here, we propose actions and policies to promote an integrated water management approach to respond to water challenges in Egypt. Based on a literature review, we have selected a set of criteria concerning the environmental, economic, social, governmental, and physical dimensions of urban water management. We studied approaches from Peru, Namibia, and South Australia as these countries have similar climatic conditions and water issues and have made substantial advances toward sustainable water management. Key criteria are state or municipal ownership of water and related infrastructure, agreement on master plans for sustainable water management, improvement of water sanitation and overall infrastructure, and reduction of water demand. Participatory, and educational campaigns put water issues at the center of public debates. We evaluated which elements of water management approaches can be adapted and used in Egypt, which faces limited freshwater resources, and which faces a highly increasing population. Proposed actions included directing water fees to ecosystem projects, treatment of wastewater to be potable, participatory approaches that engage the community in water management, educational campaigns that lead to change of public perception and knowledge dissemination. We interviewed key stakeholders in the water sector in Egypt to validate our proposed approaches. The stakeholders supported knowledge dissemination, suggested using water fees in implementing environmental projects and criticized converting wastewater into drinking water. Finally, we drafted specific recommendations at the organizational and urban levels of water management. We recommended establishing a General Organization for Water Management to oversee water-related organizations and ministries. We also recommended prioritizing the economic conditions to support alleviation of water subsidy, increasing public awareness, and creating a public database for water knowledge. In addition, we recommended decentralized water management and water sensitive urban design. The value of these approaches is their applicability, with minor adaptations, to countries with similar or close climatic and socio-economic conditions to Egypt, such as the MENA region.
      PubDate: 2022-11-17T00:00:00Z
  • Ontological and epistemological commitments in interdisciplinary water
           research: Uncertainty as an entry point for reflexion

    • Authors: Tobias Krueger, Rossella Alba
      Abstract: Against the background of a renewed interest in interdisciplinary water research, we begin this paper by diagnosing a need for deeper engagement at the epistemological and ontological level. We then analyse the ontological and epistemological commitments of three modeling examples: an academic human-flood model, a nutrient transfer decision support model and a policy facing water security model. These examples demonstrate how research practices are not neutral but intervene in the world by distributing agency unequally, providing naturalized and de-politicized explanations of the past and pre-configuring certain futures while foreclosing others. Lastly, we position hydrology's uncertainty tradition and its problematisation of choices in the research process as an entry point for reflexion on the contingencies of and ethical responsibility for research practices. This uncertainty tradition provides more common ground for collaboration between hydrologists and critical water researchers than previously acknowledged, while such collaboration would still thrive on confrontation. We conclude with a call for greater humility in water research, especially when using models, and practical suggestions for how researchers could uncover ontological and epistemological commitments and live up to the ethical responsibility they entail.
      PubDate: 2022-11-17T00:00:00Z
  • A review on irrigation parameterizations in Earth system models

    • Authors: Arianna Valmassoi, Jan D. Keller
      Abstract: Irrigation is the process of artificially providing water to agricultural lands in order to provide crops with the necessary water supply to ensure or foster the growth of the plants. However, its implications reach beyond the agro-economic aspect as irrigation affects the soil-land-atmosphere interactions and thus influences the water and energy cycles in the Earth system. Past studies have shown how through these interactions, an increase in soil moisture due to irrigation also affects the atmospheric state and its dynamics. Thus, the lack of representation of irrigation in numerical Earth system models—be it for reanalysis, weather forecasting or climate prediction—can lead to significant errors and biases in various parameters of the system including but not limited to surface temperature and precipitation. In this study, we aim to summarize and discuss currently available irrigation parameterizations across different numerical models. This provides a reference framework to understand the impact of irrigation on the various components of Earth system models. Specifically, we discuss the impact of these parameterizations in the context of their spatio-temporal scale representation and point out the benefits and limitations of the various approaches. In fact, most of the parameterizations use irrigation as a direct modification of soil moisture with just a few implementations add irrigation as a form of surface water. While the former method might be suitable for coarse spatio-temporal scales, the latter better resembles the range of employed irrigation techniques. From the analysis, we find that not only the method or the spatio-temporal scales but the actual amount of water used is of great importance to the response of the Earth system model.
      PubDate: 2022-11-16T00:00:00Z
  • Upstream-downstream asymmetries of drought impacts in major river basins
           of the European Alps

    • Authors: Heindriken Dahlmann, Ruth Stephan, Kerstin Stahl
      Abstract: The European Alps, despite being Europe's water towers, are increasingly affected by droughts. In recent decades, when climate warming has intensified, drought impacts have illustrated the regions' vulnerability. Improved knowledge on the spatial distribution of drought impacts from high elevation headwater regions down to plateau and foothill areas is of tremendous importance to understand socio-economic drought dimensions. The region has an exceptional data availability including archived drought impact information. It is therefore a good test bed for the often-assumed general hypothesis that drought impacts occur more often downstream. The aim of this study was to investigate whether upstream-downstream differences in the distribution of drought impacts exist in the four major river basins of the European Alps - Rhine, Rhone, Po and Danube. Two different classifications were developed to divide these basins in up- and downstream areas. We based the first classification on the distances to the main sink, and the second classification on human influence. The EDIIALPS database provided qualitative data to analyze the distribution patterns of reported drought impacts from 2000 to 2020. The results suggest a strong regional variability regarding the temporal and spatial distribution of drought impacts within the individual basins. But they support the general hypothesis: for both classifications the number of drought impacts per area is higher in downstream regions. For the classification based on distances differences are statistically significant for the Rhine and Danube basin. Further, the analysis of the drought indices SPI-6 and SPEI-6 revealed that the drought event does not have a large impact on the upstream-downstream differences. The study provides support for the existence of upstream-downstream asymmetries, but most importantly, the spatial distributions of drought impacts found in the four major river basins of the European Alps highlight the need for a network based analysis with more consistent impact data within river basins. Climate change and enhanced cascading effects likely increase these asymmetries and consequently future drought management strategies should take them into account.
      PubDate: 2022-11-15T00:00:00Z
  • Climate change impacts on sea level rise to flood depth and extent of
           Sarawak River

    • Authors: King Kuok Kuok, Mohd. Elfy Mersal, Po Chan Chiu, Mei Yun Chin, Md. Rezaur Rahman, Muhammad Khusairy Bin Bakri
      Abstract: This study focuses on the impact of climate change on Sarawak River flow due to heavy rainfall and the backflow of sea level. The sea level around Sarawak is expected to rise at 3.6 mm/year. When surface runoff meets seawater backflow, especially during king tides, determining the flood inundation level at low-lying regions along the Sarawak River is critical to prepare appropriate mitigation measures. The hydrodynamic model was developed using Infoworks River Simulation (RS) software. The flow of the Sarawak River is modeled from Git Station to Muara Tebas port. Various data are input into the hydrodynamic model for calibration and validation, including boundary conditions, river networks, ground models, river cross-section, water level, and rainfall data. The simulation was carried out for the years 2050 and 2080. The flood maps were generated to depict flood depth, extent, and submerged areas. In 2020, the backflow of seawater did not overwhelm Kuching City, which is located within the Sarawak River Basin. However, many low-lying locations along Sarawak River are expected to be inundated by 2050, with the flood depth ranging from 1 to 4 m. In 2080, the average increment of flood depth is predicted to be 1 m especially for low-lying areas compared to year 2050. Hence, the relevant authorities must take proactive efforts to manage the growing flood challenges caused by climate change, particularly in low-lying areas.
      PubDate: 2022-11-11T00:00:00Z
  • Water policy, politics, and practice: The case of Kitui County, Kenya

    • Authors: Johanna Koehler, Cliff Nyaga, Rob Hope, Pauline Kiamba, Nancy Gladstone, Mike Thomas, Albert Mumma, Andrew Trevett
      Abstract: The devolution of governance to county level in Kenya provides a window for innovation in water policy and practice, critical to improving water security in rural areas where almost half of households lack basic water services. In rural Kitui County, Kenya, a number of projects supported by different funders have served as policy experiments over the past 10 years. We apply an action-oriented knowledge framework to explore the kinds of knowledge that have been produced in the course of these interventions and reflect on what kinds of knowledge are contributing to institutional change and how they are contributing to sustainability in the rural water sector. Actionable recommendations for the further development of county-level water policy include: First, ensure local ownership of the policy-making process whilst enabling appropriate technical and legal support; second, take long timeframes of institutional change into account in donor programming; third, establish water, sanitation and hygiene forums bringing diverse actors within the sector together to build cohesion, facilitate knowledge exchange, enable collaborative learning, and deliver collective action.
      PubDate: 2022-11-10T00:00:00Z
  • Effects of deforestation on dissolved organic carbon and nitrate in
           catchment stream water revealed by wavelet analysis

    • Authors: Kerri-Leigh Robinson, Heye R. Bogena, Qiqi Wang, Erik Cammeraat, Roland Bol
      Abstract: Deforestation can lead to an increase in the availability of nutrients in the soil and, in turn, have an impact on the quality of water in receiving water bodies. This study assesses the impact of deforestation by evaluating the in-stream concentrations of dissolved organic carbon (DOC) and nitrate, their internal relationship, and those with stream discharge in the Wüstebach headwater catchment (Germany). This catchment has monitored stream water and associated environmental parameters for over a decade as part of the TERENO initiative. Additionally, there is a paired undisturbed forested catchment that serves as a reference stream. Our approach included a more advanced correlation analysis, namely wavelet analysis, that assists in determining changes in the correlation and lag time between the variables of interest over different time scales. This study found that after deforestation, there was an immediate increase in in-stream DOC concentrations, followed by an increase in nitrate ~1 year later. Overall, the mean DOC concentration increased, and mean nitrate concentration decreased across the catchment post-deforestation. Elevated stream water nutrient levels peaked around 2 to 3 years after the clear-cutting, and returned to pre-deforestation levels after ~5 years. The deforestation had no influence on the anti-correlation between DOC and nitrate. However, the correlation between both compounds and discharge was likely altered due to the increased soil nutrients availability as a result of deforestation. Wavelet coherence analysis revealed the “underlying” changing strengths and directions of the main correlations between DOC, nitrate and discharge on different time scales resulting from severe forest management interventions (here deforestation). This information provides new valuable impact insights for decision making into such forest management interventions.
      PubDate: 2022-11-10T00:00:00Z
  • Hydrosocial research for better understanding, managing, and modeling
           human-nature interactions

    • Authors: Sandra Ricart, Nicholas Kirk
      PubDate: 2022-11-10T00:00:00Z
  • Examining spatial variation in soil solutes and flowpaths in a semi-arid,
           montane catchment

    • Authors: Reece B. Gregory, Sidney A. Bush, Pamela L. Sullivan, Holly R. Barnard
      Abstract: Biogeochemical properties of soils play a crucial role in soil and stream chemistry throughout a watershed. How water interacts with soils during subsurface flow can have impacts on water quality, thus, it is fundamental to understand where and how certain soil water chemical processes occur within a catchment. In this study, ~200 soil samples were evaluated throughout a small catchment in the Front Range of Colorado, USA to examine spatial and vertical patterns in major soil solutes among different landscape units: riparian areas, alluvial/colluvial fans, and steep hillslopes. Solutes were extracted from the soil samples in the laboratory and analyzed for major cation (Li, K, Mg, Br, and Ca) and anion (F, Cl, NO2, NO3, PO4, and SO4) concentrations using ion chromatography. Concentrations of most solutes were greater in near surface soils (10 cm) than in deeper soils (100 cm) across all landscape units, except for F which increased with depth, suggestive of surface accumulation processes such as dust deposition or enrichment due to biotic cycling. Potassium had the highest variation between depths, ranging from 1.04 mg/l (100 cm) to 3.13 mg/l (10 cm) sampled from riparian landscape units. Nearly every solute was found to be enriched in riparian areas where vegetation was visibly denser, with higher mean concentrations than the hillslopes and fans, except for NO3 which had higher concentrations in the fans. Br, NO2, and PO4 concentrations were often below the detectable limit, and Li and Na were not variable between depths or landscape units. Ratioed stream water concentrations (K:Na, Ca:Mg, and NO3:Cl) vs. discharge relationships compared to the soil solute ratios indicated a hydraulic disconnection between the shallow soils (
      PubDate: 2022-11-09T00:00:00Z
  • Sanitation work: Realizing equity and inclusion in WASH

    • Authors: Amita Bhakta, Sally Cawood, Mariam Zaqout, Barbara Evans
      Abstract: Recognition of the human right to water, sanitation and hygiene (WASH), and equity and inclusion concerns around gender, disability and age have led to crucial change in WASH programmes and policy, responding to commonly hidden issues such as menstrual hygiene, inclusive facilities for people with disabilities, and affordable services for residents of informal settlements. Despite progress toward realizing the rights of end users “to” sanitation, this crucial body of work has overlooked the rights of an unseen, diverse population working “in” these services, including those who handle human waste. There are increasing calls within and beyond WASH for sanitation workers - marginalized by their informal and hazardous roles, and intersections of caste, religion and gender - to realize their rights to safe working conditions and social security. Yet, sanitation work has received little attention from equity and inclusion WASH scholars, despite the pressing need to challenge dominant technical, health-centric framings of sanitation that can overlook workers' lived realities. We argue for an intersectional, interdisciplinary approach to support sanitation workers to realize rights to fair living and working conditions, including inclusive WASH infrastructure at work. We draw on the limited literature available to highlight gaps in, and show the importance of the sub-sector of equity and inclusion to engage further with the lived realities of sanitation workers. Increased collaboration between sanitation workers, activists, and allies working on inclusion, labor rights, fecal sludge and solid waste management is paramount to realize sanitation workers' rights and to truly provide “inclusive” sanitation for all by 2030.
      PubDate: 2022-11-08T00:00:00Z
  • Detecting industrial discharges at an advanced water reuse facility using
           online instrumentation and supervised machine learning binary

    • Authors: Kyle A. Thompson, Amos Branch, Tyler Nading, Thomas Dziura, Germano Salazar-Benites, Chris Wilson, Charles Bott, Andrew Salveson, Eric R. V. Dickenson
      Abstract: Industries occasionally discharge slugs of concentrated pollutants to municipal sewers. These industrial discharges can cause challenges at wastewater treatment plants (WWTPs) and reuse systems. For example, elevated total organic carbon that is refractory through biological wastewater treatment increases the required ozone dose, or even exceeds the capacity of the ozone unit, resulting in a treatment pause or diversion. So, alert systems are necessary for potable reuse. Machine learning has many advantages for alert systems compared to the status quo, fixed thresholds on single variables. In this study, industrial discharges were detected using supervised machine learning and hourly data from sensors within a WWTP and downstream advanced treatment facility for aquifer recharge. Thirty-five different types of machine learning models were screened based on how well they detected an industrial discharge using default tuning parameters. Six models were selected for in-depth evaluation based in their training set accuracy, testing set accuracy, or event sensitivity: Boosted Tree, Cost-Sensitive C5.0, Oblique Random Forest with Support Vector Machines, penalized logistic regression, Random Forest Rule-Based Model, and Support Vector Machines with Radial Basis Function Kernel. After optimizing the tuning parameters and variable selection, Boosted Tree had the highest testing set accuracy, 99.2%. Over the 5-day testing set, it had zero false positives and would have detected the industrial discharge in 1 h. However, setting fixed thresholds based on the maximum normal datapoint within the training set resulted in nearly as good testing set accuracy, 98.3%. Overall, this study was a successful desktop proof-of-concept for a machine learning-based alert system for potable reuse.
      PubDate: 2022-11-04T00:00:00Z
  • Editorial: Critical zone geophysics

    • Authors: Marc Dumont, Sylvain Pasquet, Nicole Fernandez, Jean Marçais, Ludovic Bodet
      PubDate: 2022-11-01T00:00:00Z
  • Future projections of river nutrient export to the global coastal ocean
           show persisting nitrogen and phosphorus distortion

    • Authors: Arthur H. W. Beusen, Alexander F. Bouwman
      Abstract: Nitrogen (N) and phosphorus (P) from anthropogenic sources are needed to produce food for the growing world population. As a result, these nutrients can be found in nearly every water body across the globe. Not only nutrient loading is important but also the molar ratio and its deviation from the “natural” Redfield ratio. Here we show that rivers, which have more than 50% anthropogenic sources and at the same time elevated N:P ratios (> 25) contributed 36% to the total global N export to coastal waters in 2015. The five Shared Socioeconomic Pathways (SSP) were used in combination with the Representative Concentration Pathways climate scenarios to project river nutrient loadings for 2050. Future nutrient export is projected to decline in high-income countries (with N:P ratios exceeding Redfield). In Brazil, India and China, however, a decline of N:P is only the case in a scenario oriented toward sustainable development (SSP1). The human-dominated river N and P export with elevated N:P ratios will increase in all SSPs, except in SSP1 where it stabilizes. Integrated strategies for both N and P considering all relevant trade-offs and societal sectors are urgently needed to reduce the nutrient pressure on surface waters.
      PubDate: 2022-11-01T00:00:00Z
  • Corrigendum: Planning for livelihoods under hydrosocial uncertainty in
           periurban Pune

    • Authors: Sarah Luft, Sharlene L. Gomes, Shreya Chakraborty, Leon M. Hermans, Carsten Butsch
      PubDate: 2022-10-28T00:00:00Z
  • Extraction, analysis, and occurrence of per- and polyfluoroalkyl
           substances (PFAS) in wastewater and after municipal biosolids land
           application to determine agricultural loading

    • Authors: Justin Caniglia, Daniel D. Snow, Tiffany Messer, Shannon Bartelt-Hunt
      Abstract: Given the ubiquitous detection of per- and polyfluoroalkyl substances (PFAS) within numerous soil and water environmental compartments, there is a need for global understanding of current methodologies for extracting water, solids, polar organic chemical integrative samplers (POCIS), and plant tissue for these substances. This study provides details of several current extraction methods, demonstrates the use of POCIS in monitoring these compounds in a wastewater environment, and provides evidence of detectable levels of certain PFAS compounds within Midwestern municipalities and agroecosystems. Validated extraction procedures help characterize occurrence and release of 18 PFAS in a midwestern wastewater treatment plant (WWTP), surface water, runoff after land application of biosolids to agricultural test plots, infiltration into topsoil, and uptake by grain sorghum. Of the compounds measured, 14 PFAS were detected at least at one sampling site or type. The average total (Σ PFAS) dissolved phase time-weighted average (TWA) concentration in wastewater influent, effluent and in the upstream and downstream effluent mixing zone (EMZ) sites in the receiving stream, respectively, were 27.9, 132, 37.7, and 71.4 ng L−1. Long-chain PFAS dominated most of the aqueous compartments, and perfluoroalkyl acids (PFAAs) occurred in the WWTP and receiving surface waters. Total Σ14 PFAS measured in municipal biosolids applied to soils were 22.9 ng g−1 dw with long-chain PFAS comprising 77.5% of the cumulative PFAS mass. Perfluorooctanesulfonic acid (PFOS) was the most abundant compound detected in biosolids at the highest concentration (9.40 ng g−1 dw). Accumulation in WWTP biosolids was estimated to occur at a rate of 72.8 g day−1 dw based on the difference between influent and effluent time weighted average concentrations. PFAS were detected in both surface soil and runoff after land application of biosolids, but also in control plots consistent with background PFAS contamination. PFAS concentrations in surface runoff decreased over time from plots treated with biosolids. These results provide evidence of the introduction of PFAS to agroecosystems from wastewater effluent and land application of biosolids in the Midwest.
      PubDate: 2022-10-27T00:00:00Z
  • Simulation of diffusive solute transport in heterogeneous porous media
           with dipping anisotropy

    • Authors: Danyang Su, Mingliang Xie, Klaus Ulrich Mayer, Kerry T. B. MacQuarrie
      Abstract: Dipping anisotropy is a common feature in heterogeneous porous media that can substantially affect solute transport. For problems with complex geometry the influence of dipping anisotropy must be analyzed using numerical models, since suitable analytical solutions are not available. The most straightforward approach is to use a Cartesian coordinate system aligned with the material coordinate system. However, this approach is usually not practical, especially in 3D simulation domains with dipping layers and heterogeneous material properties. Furthermore, in the case of diffusion-dominated transport, the effect of anisotropy is often neglected. In this research, a general-purpose, fully 3-D unstructured grid code was developed to simulate diffusion-dominated solute transport in systems with dipping anisotropy, while accounting for complex geometry. The code has been verified against both 2-D and 3-D analytical solutions and has then been applied to two anisotropic diffusion problems, including an in-situ diffusion experiment and a hypothetical deep geologic repository, respectively. The simulation results indicate that consideration of anisotropy is required if the solute distribution in the rock matrix is of importance, in particular for assessing long-term evolution in layered systems. The formulation presented provides a versatile method for assessing diffusion-dominated solute transport in systems with dipping anisotropy subject to complex geometry.
      PubDate: 2022-10-25T00:00:00Z
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