The 1997 United Nations Convention on the Law of Non-navigational Uses of International Watercourses: what contribution to the development of the Water Charter for the Volta Basin?

In 2007, the six riparian countries of the Volta Basin adopted the Convention on the Status of the Volta River and the Establishment of Volta Basin Authority (Volta Basin Convention). This legal framework is strongly inspired by the United Nations Convention on the Law of Non-navigational Uses of International Watercourses (UNWC). However, the Volta Basin Convention merely states the major international river management principles without specifying either the terms or the procedures for their implementation. This article examines the potential contribution of the UNWC provisions to the development of a water charter.     

On the process of fine sediment infiltration into static gravel bed: A CFD–DEM modelling perspective

The gravel bed clogging, caused by infiltration and accumulation of fine sediment, degrades the river ecology. A proper understanding of the infiltration process, and underlying mechanism and causes, are necessary to take preventive measures. The process of fine sediment infiltration into static gravel bed is studied by distinguishing between bridging and percolation behaviours, as they affect the river ecology and physical processes occurring in the river system differently. However, several contradicting observations, concerning their occurrences, are reported. We employed the unresolved CFD–DEM method to simulate and investigate the infiltration process. The theoretical size ratios, corresponding to different geometrical configurations for a binary mixture of mono-disperse spherical particles, representing bridging and percolation processes, are considered and simulated with and without flowing water effects. The effects of several turbulence models on the infiltration process are also studied. We found that fine sediment infiltration in fluvial deposits is mainly gravity-dominated, supporting Cui's hypothesis that fine sediment infiltration through intra-gravel flow is similar to fine sediment infiltration driven by gravity. In contrast to consensus in the field, our results demonstrate that the occurrences of different infiltration processes (bridging and percolation) seem to be independent of gravel bed thickness, rather depend only on the relative grain size distribution of fine sediment and gravel. However, a precise definition of a ‘thick enough’ gravel bed is necessary to distinguish between bridging and percolation behaviours. Here, we hypothesize a suitable gravel bed thickness, which might be regarded as a ‘thick enough’ gravel bed.     

India’s water management debate: is the ‘civil society’ making it everlasting?

Abstract

This article discusses the bias of the growing constituency of civil society activists in India against conventional water management solutions implemented by the government, and the ‘alternatives’ they champion, which force the government to enter into an endless debate with these groups. The article goes into the fundamental reasons for this bias, and identifies four types of civil society activist: ‘professional’, ‘ideologue’, ‘romantic’ and ‘doomsday prophet’. The article also argues that water bureaucracies in India should adopt evidence-based policy making, subjecting the ‘alternatives’ to the same degree of scrutiny as the conventional ones, to end the policy dilemma, while enhancing the overall quality of design, execution and management of projects for better outcomes.     

Monitoring the health of large rivers with macroinvertebrates: Do dominant taxa help or hinder the assessment?

Macroinvertebrate communities in the Mississippi River are often dominated by a few taxa (e.g. oligochaetes in the fine sediments and hydropsychid caddisflies on rocks) that exploit the natural abundance of fine organic particles. These taxa are moderately to highly tolerant of pollution, and the combination of high abundance and high pollution tolerance could result in the river being assessed as highly polluted. We examined how the presence or absence of dominant oligochaetes or hydropsychid caddisflies affected biometric values and responses used to monitor environmental stress in large rivers. Responsiveness was assessed across five simulated impairments created by removing different subsets of sensitive taxa from the original data for macroinvertebrates in the Upper Mississippi River near Cape Girardeau, MO. For many metrics, removal of the dominant taxa changed values, and increased the difference between existing conditions and simulated impairments. For macroinvertebrate data from fine‐sediment habitat, 8–9 of 12 metrics responded to the two most severe impairments simulated with or without dominant oligochaetes, but none changed for less severe impairments. For rock habitat, more metrics responded to moderate or severe impairments simulated when dominant hydropsychids were excluded. Few metrics performed better with dominant taxa. Overall, removal of dominant macroinvertebrate taxa improved both the accuracy and interpretability of several metrics commonly used to monitor effects of water pollution on large‐river faunas dominated by a few taxa. Removing them also makes observed responses more comparable to those frequently quantified for wadeable streams and rivers. Copyright © 2009 John Wiley & Sons, Ltd.     

The case of the nonionic alkylphenol ethoxylates in the Mediterranean Sea region: is there a problem?

The concentration profiles of the potential endocrine disrupting nonionic alkylphenol ethoxylate (APEO) surfactants in Israel's rivers, groundwaters and coastal water of the eastern Mediterranean Sea, were found to be within the range of 12.5-74.6, trace - 20.2 and 4.2-25.0 microg/L respectively. Determination of the APEO's homologic distribution revealed "skewing" towards the more toxic shorter-chain ethoxylates. Egg production of zebrafish, Danio rerio, exposed to these actually found the environmental concentrations range of the APEOs decreased, after 20 days, to 89.6+/-2.1, 84.7+/-3.9 and 76.9+/-2.2% of the baseline levels, compared with control, in concentrations of 10, 25 and 75 microg/L respectively. These results suggest that, (a) there is a potential health problem, particularly in countries in which the "hard"/environmentally persistent APEOs are still in use; and (b) the related health-risk is seasonally-dependent, particularly in semi-arid regions where the fluctuations in the water quantities in surface- and groundwater are substantial.     

How influential is the role of oligotrophication on the integrity of fish assemblages in the littoral zone?

Food web theory predicts that one of the consequences of oligotrophication is the decline in fisheries following the establishment of nutrient-deficient conditions and low biogenic production. However, emerging evidence suggests that more complex trophic interactions, induced by plankton composition, dietary diversification, temporal and spatial heterogeneity, variations in fish age and size structure can lead to ecosystem responses that deviate from theoretical predictions; especially in the shallow littoral zone. In this study, two end-to-end modelling strategies are used to characterize potential food web structural shifts and overall ecosystem productivity in response to oligotrophication. Our modelling strategy draws upon empirical and theoretical evidence from the Bay of Quinte, a semi-enclosed embayment in northeastern Lake Ontario that has been subjected to phosphorus (P) abatement strategies in the 1970s. We first show that the role of food abundance has been a primary factor shaping fish production, but the fish community gradually responded to the reduced availability of pelagic staples of their diet by displaying greater reliance upon alternative sources, including benthic and other autochthonous (or even allochthonous) food items. Our analysis further suggests that degree of diet overlap between competing trophic guilds can significantly modulate realized biomass levels. The composition of the autotrophic community is another major confounding factor that can induce significant variations from the predicted food web productivity patterns in response to oligotrophication. Overall, our analysis suggests that the proposed reduction of the ambient total phosphorus levels may not necessarily trigger a significant decline in fish biomass in the Bay of Quinte.     

BTX abatement using Chilean natural zeolite: the role of Br?nsted acid sites

In wastewater treatment facilities, air quality is not only affected by conventional unpleasant odour compounds; toxic volatile organic compounds (VOCs) are also found. In this study, the adsorptive capacity of Chilean natural zeolite toward VOC removal was evaluated. Moreover, the influence of zeolite chemical surface properties on VOC elimination was also investigated. Three modified zeolite samples were prepared from a natural Chilean zeolite (53% clinoptilolite, 40% mordenite and 7% quartz). Natural and modified zeolite samples were characterised by nitrogen adsorption at 77 K, elemental analyses and X-ray fluorescence (XRF). Chemical modifications of natural zeolite showed the important role of Br?nsted acid sites on the abatement of VOCs. The presence of humidity has a negative effect on zeolite adsorption capacity. Natural zeolites could be an interesting option for benzene, toluene and xylene vapour emission abatement.     

Nitrate estimation in the denitrifying post-filtration unit of a municipal wastewater treatment plant: the Viikinm?ki case

In this work we present and discuss the design of an array of soft-sensors to estimate the nitrate concentration in the denitrifying post-filtration unit at the Viikinm?ki wastewater treatment plant in Helsinki (Finland). The developed sensors aim at supporting the existing hardware analyzers by providing a reliable back-up system in case of malfunction of the instruments. In the attempt to design easy to implement and interpretable sensors, computationally light linear models have been considered. However, due to the intrinsic nonlinearity of the process, also nonlinear but still computationally affordable models have been considered for comparison. The experimental results demonstrate the potential of the developed soft-sensors and the possibility for an on-line implementation in the plant's control system as alternative monitoring devices.     

The Accuracy and Reliability of Traditional Surface Flow Type Mapping: Is it Time for a New Method of Characterizing Physical River Habitat?

Surface flow types (SFTs) are advocated as ecologically relevant hydraulic units, often mapped visually from the bankside to characterize rapidly the physical habitat of rivers. SFT mapping is simple, non‐invasive and cost‐efficient. However, it is also qualitative, subjective and plagued by difficulties in recording accurately the spatial extent of SFT units. Quantitative validation of the underlying physical habitat parameters is often lacking and does not consistently differentiate between SFTs. Here, we investigate explicitly the accuracy, reliability and statistical separability of traditionally mapped SFTs as indicators of physical habitat, using independent, hydraulic and topographic data collected during three surveys of a c. 50 m reach of the River Arrow, Warwickshire, England. We also explore the potential of a novel remote sensing approach, comprising a small unmanned aerial system (sUAS) and structure‐from‐motion photogrammetry (SfM), as an alternative method of physical habitat characterization. Our key findings indicate that SFT mapping accuracy is highly variable, with overall mapping accuracy not exceeding 74%. Results from analysis of similarity tests found that strong differences did not exist between all SFT pairs. This leads us to question the suitability of SFTs for characterizing physical habitat for river science and management applications. In contrast, the sUAS–SfM approach provided high resolution, spatially continuous, spatially explicit, quantitative measurements of water depth and point cloud roughness at the microscale (spatial scales ≤1 m). Such data are acquired rapidly, inexpensively and provide new opportunities for examining the heterogeneity of physical habitat over a range of spatial and temporal scales. Whilst continued refinement of the sUAS–SfM approach is required, we propose that this method offers an opportunity to move away from broad, mesoscale classifications of physical habitat (spatial scales 10–100 m) and towards continuous, quantitative measurements of the continuum of hydraulic and geomorphic conditions, which actually exists at the microscale. Copyright © 2016 John Wiley & Sons, Ltd.     

Assessing Assessment: Can the Expected Effects of the St. Marys River Sea Lamprey Control Strategy Be Detected?

In 1997 the Great Lakes Fishery Commission approved a 5-year (1998 to 2002) control strategy to reduce sea lamprey (Petromyzon marinus) production in the St. Marys River, the primary source of parasitic sea lampreys in northern Lake Huron. An assessment plan was developed to measure the success of the control strategy and decide on subsequent control efforts. The expected effects of the St. Marys River control strategy are described, the assessments in place to measure these effects are outlined, and the ability of these assessments to detect the expected effects are quantified. Several expected changes were predicted to be detectable: abundance of parasitic-phase sea lampreys and annual mortality of lake trout (Salvelinus namaycush) by 2001, abundance of spawning-phase sea lampreys by 2002, and relative return rates of lake trout and sea lamprey wounding rates on lake trout by 2005. Designing an effective assessment program to quantify the consequences of fishery management actions is a critical, but often overlooked ingredient of sound fisheries management.     

Correction to: How Does the Coupling of Real‑World Policies with Optimization Models Expand the Practicality of Solutions in Reservoir Operation Problems?

Water Resources Management -     

Lake Trout Spawning on Artificial Reefs and the Effect of Zebra Mussels: Fatal Attraction?

Lake trout stocked in the Great Lakes appear to spawn primarily on shallow reefs (< 16 m deep), particularly on breakwaters or water intake lines. Shallow water substrates are being rapidly colonized by zebra mussels, potentially resulting in degraded substrate and interstitial water quality. The attraction of spawning lake trout to new substrate and the effect of zebra mussels on spawning success was examined. Lake trout eggs and fry were collected on clean cobble and cobble fouled with zebra mussels at the Port of Indiana in southern Lake Michigan, and on each of three recently constructed submerged reefs. Egg deposition was similar among all sites except on new, unfouled cobble, where deposition was 11 to 29 times higher, depending on the collection device used. The ratio of empty egg chorions to intact eggs was similar among all sites except the fouled substrate, where the ratio was 129× higher (P < 0.001). Fry catches were similar on fouled and unfouled substrate, but 6.5 × higher on one of the new reefs (P < 0.01). In laboratory incubators, egg hatching rates were similar in cobble with and without zebra mussels. Lake trout were attracted to spawn on newly constructed artificial reefs, but the presence of zebra mussels appeared to reduce egg deposition and increase damage to eggs. Artificial reefs may successfully increase the amount of spawning substrate available for lake trout, but if they are constructed in shallow water they may not be productive areas for egg incubation and fry hatch due to the presence of zebra mussels, shallow-water egg and fry predators, and storm surge.     

Patterns of long-term dynamics of aquatic communities and water quality parameters in the Great Lakes: Are they synchronized?

Long time series data can provide insights into dynamics of large lakes. We use the USEPA-GLNPO biological monitoring dataset (phytoplankton, benthos, zooplankton and water quality), collected from 1996 through 2016, to identify whether there is evidence of concordant linear or non-linear trends in community composition, density/biomass/biovolume and major environmental parameters. We show changes in biotic assemblages and water quality variables, particularly in Lakes Michigan and Huron. These include changes in phytoplankton biovolume and zooplankton biomass, increasing invasive Dreissena abundance and decreasing densities of other benthos. Biotic changes are accompanied by pronounced changes in water quality and nutrient ratios. Species change-points, identified using threshold indicator taxon analysis, are often less abrupt, but there are clear shifts in a large proportion of species in each assemblage. The concordance of breakpoints among assemblages or lack thereof provides valuable insight into potential drivers of ecosystem change.     

Is it Worth the Money? The Functionality of Engineered Shallow Stream Banks as Habitat for Juvenile Fishes in Heavily Modified Water Bodies

Heavily modified water bodies (HMWB) are characterized by monotonous and straightened channel morphologies with high degrees of bank enforcement. They often lack shallow bank habitats, which are considered important for critical life stages of fishes. In this study, three principle options to engineer shallow stream zones were assessed concerning the value of the created habitats for larval, juvenile and adult stages of fishes in 30 sites from three HMWB. The construction scheme of the juvenile habitats comprised different degrees of embankment ranging from rip‐rap structures with steep bank angles to almost nature‐like construction schemes with very flat river‐banks and sparing usage of structural enrichment such as boulders and dead wood. In general, the differences between the three habitat types were more pronounced in density of different life stages than in the presence or absence of species or certain life stages. A steep bank angle and a high degree of engineering such as placement of rip‐rap embankment, boulders or dead wood structure in the habitats were hardly accepted by early larval and juvenile stages of rheophilic fishes. In contrast, the construction scheme of a nature‐like habitat with a flat bank angle (<10%), low water depth (mean = 24 cm) and a sparing usage of coarse woody debris (CWD) and boulders had the highest success. Other investigated habitat types did not provide additional benefit, neither in terms of supporting additional species and life stages, nor in high individual numbers and should thus only be implemented when land for restoration is scarce and nature‐like habitats cannot be realized. Copyright © 2016 John Wiley & Sons, Ltd.     

Bioaccumulation of Inorganic Elements in Dreissena polymorpha from the Ebro River,Spain: Could Zebra Mussels Be Used as a Bioindicator of the Impact of Human Activities?

Dreissena polymorpha is among the top 100 most harmful invasive species in aquatic habitats. European Directive 2013/39/UE establishes Environmental Quality Standards for biota because it has been demonstrated that pollutants bioaccumulate in aquatic organisms. This study evaluated bioaccumulation of inorganic elements in the soft tissues of D. polymorpha in order to assess the usefulness of zebra mussels as a bioindicator of contaminant presence in superficial waters. Concentrations of 66 elements were measured in order to evaluate their relationship with nearby anthropogenic activity and to the values recommended by Environmental Quality Standards for biota. Bivalves were collected from four sample points along the Ebro River Basin (Spain), where diverse human activities are carried out. Zebra mussels accumulate toxins in soft tissue during their life cycle, including Al, Cr, Fe, Hg, Pb, Th, Cd and U. The highest levels of accumulation corresponded to elements associated with human activity in the area, showing the impact of anthropogenic actions on biota. D. polymorpha not only supplies information about current water quality but also acts as a witness of past water quality by bioconcentrating toxic elements present in the environment and providing relevant results about historical water contamination. In conclusion, D. polymorpha is a harmful and dangerous invasive species, but its pervasiveness means that it can be used as a bioindicator to assess current and past presence of elements in water. Copyright © 2017 John Wiley & Sons, Ltd.     

Industrial water supply for the Kursk TÉTs-1 heating and electric power plant with the ecological safety of the River Seim taken into account

The Kursk TéTs-1 heating and electric power plant is discussed as an illustration of preventing thermal contamination of its water supply (River Seim) by circulating water. An effective water supply system is taken to be one for which the overheating of the water at a monitoring site (near the outlet location) does not exceed an approved level for the water use conditions. The required cooling capacity of a spray pond for circulating and flow-through water supplies is determined.     

Difficulties of fishing at Lake Naivasha,Kenya: is community participation in management the solution?

Unlike other lakes in tropical regions, Lake Naivasha exhibits low fish species diversity. The fishery is based on introduced fish species that are not native to the lake. The lake ecosystem is very fragile, as reflected in its fluctuating fish catches. The fishery almost completely collapsed in 2001, due partly to mismanagement and ignorance about needed conservation measures. The Kenyan government, like many governments around the world, recognized the need to involve fishers and other stakeholders, in order to ensure better management of the lake fisheries resources. Also referred to as collaborative management (co-management), this management approach provides the opportunity to share responsibility for managing the fishery resources between the government and the community. A total ban on fishing was imposed in February 2001, lasting for 1 year, to allow lake fish stocks to recover. This study analyses the co-management process for Lake Naivasha, and discusses the role played by the community during the fishing ban, as well as the successes and challenges encountered, and the tribulations and perceptions of the fishers regarding the new management strategy. It also comprises the first documentation of community participation in fisheries management begun for Lake Naivasha in the year 2001.     

Discrepancies in Flood Modelling Approaches in Transboundary River Systems: Legacy of the Past or Well-grounded Choices?

Flood modelling in transnational rivers requires efficient cross-border collaboration among the riparian countries. Currently, each country/region usually uses a different hydraulic modelling approach, which may hinder the modelling of the entire river. For the sake of accurate and consistent river modelling there is a necessity for the establishment of a framework that fosters international collaborations. This study investigates the current hydraulic modelling approach across the whole length of the River Meuse, the main course of which crosses three north-western European countries. The numerical models used by French, Belgian, and Dutch agencies and authorities were interconnected by exchanging boundary conditions at the borders. At the central part of the river, the Belgian hydraulic model assumed steady flow conditions, while the rest of the river was modelled in unsteady mode. Results for various flood scenarios revealed a distinctive pattern of water depths at the Belgian-Dutch border. To clarify whether this is a bias induced by the change in modelling approach at the border (steady vs. unsteady), we remodelled a stretch of the river across the Belgian-Dutch border using a consistent unsteady modelling approach. The steady and unsteady approaches led to similar patterns across the border, hence discarding the hypothesis of a bias resulting from a change in the employed model. Instead, the pattern in water depths was attributed to a change in the topography of the Meuse Valley, where there is a transition from a narrow steep corridor with limited water storing capacity in Ardennes massif to wide floodplains in the Dutch lowlands. The associated flood damping for the 100-year discharge is less than 1% in the Ardennes and exceeds 15% in the Dutch lowlands. It can be inferred that the current differences in regional hydraulic modelling approaches for the River Meuse are generally well-grounded and not just a legacy of the past.