Do Alluvial Sand Dunes Create Energetic Refugia for Benthic Fishes? An Experimental Test with the Endangered Pallid Sturgeon

River modifications have altered critical habitats for fishes at a variety of spatial scales and caused global declines of many fluvial species. At small spatial scales (<1 m²), alluvial sand dunes, a ubiquitous habitat in highly modified rivers, are thought to provide energetic relief for benthic fishes in energetically costly riverine landscapes created by water flow. However, use of alluvial dune habitat is not well understood, and it is unclear whether dunes provide refuge that effectively reduces energetic costs. We designed a scale‐relevant experiment to examine the energetic responses associated with sand dune habitat in rivers. We tested whether the US federally endangered pallid sturgeon (Scaphirhynchus albus ), a benthic fish commonly associated with sand dunes, experienced reduced energetic costs with different configurations of simulated sand dune habitat. We quantified mass specific oxygen consumption (M O₂; mg O₂ kg^?1 h^?1) using intermittent flow‐through respirometry for age‐0 sturgeon (140–170 mm) in front of a sand dune, behind a sand dune and in the absence of a sand dune at two velocities (25 and 50 cm s^?1) commonly observed in field studies of sturgeon habitat use. Sturgeon displayed distinct station holding behaviours for each habitat configuration. Dune location did not affect energy expenditure, but sturgeon M O₂ was on average 16–20% higher in the absence of a sand dune depending on dune configuration. M O₂ was on average 14% higher at 50 cm s^?1 compared with 25 cm s^?1. Our results provide a potential mechanism for over two decades of research on why sturgeon and other benthic fishes exhibit selection for sand dune habitat in large rivers. Fishes that select main channel habitats may depend on energetic relief provided by sand dunes, especially when other forms of structure are not available. For this reason, alluvial sand dune habitat may be important to the persistence of benthic fishes in high flow environments. Copyright © 2017 John Wiley & Sons, Ltd.     

Virtual Water in Global Food and Water Policy Making: Is There a Need for Rethinking?

The argument that economies that face acute water scarcity problems can and should meet their water demand for food through cereal imports from water-rich countries; and that virtual water trade can be used to achieve water securities has become dominant in global water discussions. Analysis of country level data on renewable freshwater availability and net virtual water trade of 146 nations across the world shows that a country's virtual water trade is not determined by its water situation. Some countries have the advantage of high “economic efficiency” in food production and have surplus water, but resort to food import, whereas some water scarce countries achieve high virtual water trade balances. Further analysis with a set of 131 countries showed that virtual water trade increased with increase in gross cropped area. This is because of two reasons: First, when access to arable land increases, the ability to utilize available blue water for irrigation increases. Second, increasing access to arable land improves the access to water held in the soil profile as “free good”, a factor not taken into account in assessing water availability. Hence, many of the humid, water-rich countries will not be in a position to produce surplus food and feed the water scarce nations; and virtual water often flows out of water-poor, land rich countries to land-poor water-rich countries. This means that “distribution of scarcity” and “global water use efficiency”, are goals that are difficult to achieve through virtual water trade in a practical sense. For a water-poor, but land rich country, virtual water import offer little scope as a sound water management strategy as what is often achieved through virtual water trade is improved “global land use efficiency”. The important policy inferences emerging from the analyses are two: First, assessing the food security challenges posed to nations in future purely from a water resource perspective provides a distorted view of the food security scenario. National policies on food security should take into account “access to arable land” apart from water availability. Second, analysis of water challenges posed by nations purely from the point of view of renewable water availability and aggregate demands will be dangerous. Access to water in the soil profile, which is determined by access to arable land, would be an important determinant of effective water availability.     

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.     

Is water scarcity a constraint to feeding Asia's growing population?

Growing population and wealth, as measured by per capita GDP, are predicted to put water resources and food production in Asia under increasing pressure over the next few decades. Critical factors include the increasing demand for animal proteins in diets and the growing need for energy. Climate change impacts may further reduce available water resources because of greater evaporation losses in some areas and storms and floods in others. If we are to overcome these significant constraints on food production, we must turn to strategies that are focused around sustainable intensification of agriculture. These include modernization of old irrigation schemes to increase water productivity, innovative concepts that capture and store flood runoff for use in agriculture, much more recycling and reuse of urban wastewater, and other efficiency-improvement techniques. However, these will not happen in a policy vacuum, and it is argued that reforms are needed in water policy, water training and water management institutions across Asia.     

Introduction: Water for Food and Ecosystems: How to Cut which Pie?

Two decades of awareness-raising and dialogues have clearly spelled out the water-related challenges the world is facing. Still, not enough concrete improvements have been realized on key issues, such as the coverage of potable water and sanitation services, and an adequate balance between water for food and ecosystems. Addressing these problems remains a continuous challenge that can only be confronted with an integrated approach, comprising knowledge generation, permanent communication between very different stakeholders, adequate capacity-building and continuous learning, and innovative technology development. With a view to the Fourth World Water Forum in Mexico, this contribution reviews such issues, drawing lessons from experience in a program on Water for Food and Ecosystems (funded by Netherlands Partners for Water initiative) and related on-going work in this area carried out by Wageningen University and Research Centre working closely with partner institutions inside and outside the Netherlands. The debate is structured around three key dimensions (i) balancing human and natural values of water, (ii) multiple stakeholder involvement, (iii) technological innovation. Visualized in the Triangle of Sustainability, the study recognizes the advances made in integrating political processes such as multi-stakeholder negotiation in water resource management as a way of achieving a better balance between the values of water, but warn against neglecting the potential for technical advances that can help increasing the size of the ‘cake’ as a whole.     

Why Is Water Pricing Ineffective for Deficit Irrigation Schemes? A Case Study in Southern Spain

This paper explores the impact on water demand of the adoption of deficit and precision irrigation as a farmer’s attempt to respond to water scarcity by maximising water productivity. The case study is characterised by the intensive use of deficit irrigation techniques in olive groves, which account for 50% of all irrigated land in southern Spain. These technologies have an important influence on the structure of the water demand. This study reveals that following the adoption of such technologies, water demand does not respond to moderate changes in water price, unless price increases become so great that they reach a threshold price representing a disproportionate and unaffordable social impact. This fact has significant consequences for water policy as water pricing becomes an ineffective instrument for managing water demand in a context characterised by resource scarcity and farmers’ adoption of deficit irrigation techniques.     

HEC—5Q Model Applied to a Lake System in Illinois for Water Quality Evaluations

Abstract

The United States Army Corps of Engineers HEC-5Q model was applied to Lake Spring-field and two proposed lakes (Hunter Lake and Lick Creek Reservoir) to be built for supplementing Lake Springfield's water. Lake Springfield is the water supply reservoir for the city of Springfield, Illinois. Water from the lake is also used for cooling the city's power plant complex. The model was calibrated and verified on Lake Springfield using monitored data in 1986 and 1988. Eight water quality constituents were simulated. Calibration, verification, and predictions were made only for temperature, dissolved oxygen, nitrate-nitrogen, and phosphate-phosphorus. The calibrated and verified model was used to predict water surface elevations and constituent concentrations in the three lakes, individually and in combination, with meteorological and estimated flow data for a twenty-month period in 1953–1954, the most severe drought of record. The model provided a useful tool in the water quality evaluations of the three lakes.     

Is a sequencing batch biofilter granular reactor suitable for textile wastewater treatment?

The textile industry releases highly polluted and complex wastewaters, which are difficult to treat and require numerous treatment steps. Innovative technologies for on-site treatment at each factory would permit cost reduction. For this reason, we ran a laboratory-scale study to assess the suitability of a sequencing batch biofilter granular reactor (SBBGR) for textile wastewater treatment, testing four different types of wastewater. Results demonstrate that wastewater characteristics greatly affect the reactor efficiency. Hence, a pre-study is advisable to define the best operational conditions and the maximum treatment capability for the wastewater under analysis. Nevertheless, SBBGR is a valuable biological treatment, effective in the reduction of pollutant load with stable performances despite the variability in wastewater composition. Tests with ozone integration have demonstrated that it is possible to dose small quantities of ozone to obtain an effluent suitable for direct discharge. However, a dynamic ozone dosage should be used to optimize the process as the correct ozone dose strongly depends on the wastewater composition.     

When are Partnerships a Viable Tool for Development? Institutions and Partnerships for Water and Sanitation Service in Latin America

Partnerships are increasingly becoming unpopular in Latin America, they have narrowly been analysed in the context of the international political agenda and criticized for bringing benefits only to the private sector and not to the public sector and society at large. Nevertheless, there are successful experiences for providing water and sanitation at local level. The questions are: Are local level successful experiences the product of a partnership? Was it necessary to build partnerships to add value to the community presence and informal actors? What are the advantages of partnerships at local and national scale? The case studies presented demonstrate that actors need to have an incentive to work together and to build trust. The context in which they operate is also relevant, and in Latin America it is needed a strong national legal institutional framework if partnerships or any agreement should be an alternative to public delivery of water and sanitation. This paper analyses the context in which water and sanitation is delivered in peri-urban areas based on case studies, identified actions for effective provision and on discussion of the institutional framework options and partnership implementation at local and national level. This paper does not advocate partnerships per se; nor are these seen as the problem.     

Is There a Residual and Hidden Potential for Small and Micro Hydropower in Europe? A Screening-Level Regional Assessment

Small hydropower plants (installed power below 10 MW) are generally considered less impacting than larger plants, and this has stimulated their rapid spread, with a developing potential that is not exhausted yet. However, since they can cause environmental impacts, especially in case of cascade installations, there is the need to operate them in a more sustainable way, e.g. considering ecosystem needs and by developing low-impacting technologies. In this paper, an assessment was conducted to estimate how the environmental flow and the plant spatial density affect the small hydropower potential (considering run-of-river schemes, diversion type, DROR) in the European Union. The potential of DROR is 79 TWh/y under the strictest environmental constraints considered, and 1,710 TWh/y under the laxest constraints. The potential of low-impacting micro technologies (< 100 kW) was also assessed, showing that the economic potential of hydrokinetic turbines in rivers is 1.2 TWh/y, that of water wheels in old mills is 1.6 TWh/y, and the hydropower potential of water and wastewater networks is 3.1 TWh/y, at an average investment cost of 5,000 €/kW.

     

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.     

Post‐Spawning Survival and Downstream Passage of Landlocked Atlantic Salmon (Salmo salar) in a Regulated River: Is There Potential for Repeat Spawning?

Repeat salmonid spawners may make large contributions to total recruitment and long term population stability. Despite their potential importance, relatively little is known about this phase of the life history for anadromous populations, and nothing has been reported for landlocked populations. Here, we studied post‐spawning behaviour and survival of landlocked Atlantic salmon in relation to downstream dam passage in the River Klarälven, Sweden. Eight hydropower stations separate the feeding grounds in Lake Vänern from the spawning grounds in the River Klarälven, and no measures to facilitate downstream migration are present in the river. Forty‐nine percent of the salmon survived spawning and initiated downstream migration. Females and small fish had higher post‐spawning survival than males and large fish. The post‐spawners migrated downstream in autumn and spring and remained relatively inactive in the river during winter. Downstream migration speed in the free flowing part of the river was highly variable with a median of 9.30 km/day. Most fish passed the first hydropower station via upward‐opening spill gates after a median residence time in the forebay of 25 min. However, no tagged fish survived passage of all eight hydropower stations to reach Lake Vänern. This result underscores the need for remedial measures to increase the survival of downstream migrating kelts. Copyright © 2015 John Wiley & Sons, Ltd.