Water Environmental Flow Research Articles

Paleontology: Ediacaran ecology drove ocean ventilation

Fluid dynamics modeling of an Ediacaran ecosystem illustrates an important positive feedback loop between early multicellular organisms and environmental water flow. Early communities thus helped to chemically shape new environments where oxygen-dependent organisms could thrive.

Simulation of Seabed Erosion Produced by an Inclined Jet

Water jets are widely used in seabed scouring and desilting applications. In the present work, dedicated tests have been conducted using a jet scour model test platform and sand beds containing grains with different sizes. The FLOW-3D simulation software has also been used to tackle the problem form a numerical point of view. The boundary conditions of the simulation have been optimized to reduce the gap between the numerical results and the outcomes of the experimental tests. Scour area calculation has been based on a RNG k-ε Turbulence model. Moreover, the FAVOR (Fractional Area Volume Obstacle Representation) technology has been selected for grid division to make the simulation results more accurate. Jet scours with inclination angles of 10–20° have been simulated. It has been found that jet scouring is greatly affected by the environmental water flow, that is, water flow can weaken the scouring capacity of the jets.

Advances in Environmental Hydraulics

Environmental Hydraulics (EH) is the scientific study of environmental water flows and their related transport and transformation processes affecting the environmental quality of natural water systems, such as rivers, lakes, and aquifers, on our planet Earth [...]

Environmental Hydraulics in the New Millennium: Historical Evolution and Recent Research Trends

Environmental Hydraulics (EH) is the scientific study of environmental water flows and their related transport and transformation processes in natural water systems. This review provides some remarks about the historical development of EH throughout three different paradigms or ages, namely, the Public Health Age, the Water Quality Age, and finally the Integrated Environmental Hydraulics Age. We further evaluate how EH research has changed in the last 20 years through a bibliometric analysis of the proceedings of the International Symposium on Environmental Hydraulics (ISEH) and Environmental Fluid Mechanics (EFMC) journal articles conducted using Citespace and Leximancer. Authors and affiliations are analyzed to identify patterns of collaboration, followed by an analysis of the temporal evolution of the EFMC impact index as well as its highly-cited articles. Finally, the major EH topics are identified with a comparison between the topics extracted from the two different sources. As the EH field is becoming rapidly global, some topics were confirmed to have attracted more interest in EH such as Flow Condition, Numerical Modelling, Experimental Measurements. It is hoped that our findings could provide a reference for students, academics, and policy-makers related to EH.

Costa Rica’s Water Paradox: Linking Rainforests and Droughts through the Water-Energy-Food-Environment Nexus in Guanacaste Province

Costa Rica is known as a verdant, tropical paradise with rich rainforests, abundant wildlife, striking mountains and volcanoes, and picturesque beaches. However, the perceived abundance of Costa Rica’s water resources is only true for part of the country. The same geography and climate that bring abundant precipitation to most of southern Costa Rica and its Caribbean coast also leave the northern Pacific province of Guanacaste with substantially less rainfall and even periods of severe drought. This case study focuses on Guanacaste province, which is a major tourist destination as well as one of the country’s most productive agricultural regions. Water from the lush Caribbean slopes of the Lake Arenal region is transported across the continental divide through extensive infrastructure projects. Passing through the semi-arid regions of Guanacaste, hydroelectric power generation, extensive irrigated agriculture, and tourism development use most of the water, supporting a rapidly growing regional economy but leaving increasingly less water for environmental flows. This case study introduces students to “nexus thinking” to explore the multiple and overlapping water, energy, and food (WEF) demands and ecological challenges present in Guanacaste province. Each sector and its interconnections with other sectors are examined in turn through introductory lectures, and enriched by WEF systems thinking activities and class discussions. At the conclusion of this case study curriculum, students will be able to identify and characterize points of intersection, i.e., the nexus, of WEF supply and demand, and trade-offs that exist between WEF resources and biodiversity conservation.

Environmental water flow can boost foraging success of the juvenile rapa whelk Rapana venosa (Muricidae) in aquaculture tanks with still or flowing water: Indication of chemosensory foraging

Artificial breeding of Rapana venosa has been attempted in China, but the high mortality rate of rapa whelk juveniles (10–40 mm) seriously restricts the breeding success of this species in artificial cultivation and the overall aquaculture industry, and thus the scale of industrialization is far from being realized. One main factor was found to contribute to this high mortality rate: the low predation efficiency of juveniles. We studied the foraging behavior of various sized R. venosa juveniles in still, flowing, and circulating water, with the juveniles being positioned either upstream or downstream from the prey in the flowing water experiments. Our findings demonstrated that the distance between juveniles and prey in still water significantly restricted the ability of juveniles to locate food, but water flow significantly enhanced this ability. In addition, the small-sized juveniles were found to be more active predators than the larger sized juveniles. Our findings demonstrated that circulating water flow is important to improve the survival and growth rate of juveniles in R. venosa cultures. Our results broaden the understanding of chemical orientation in gastropods and can be used to develop or improve commercial breeding strategies for R. venosa.

Opportunities to improve the future of South Australia’s terrestrial biodiversity

It is unequivocal that the poor condition of South Australia’s terrestrial biodiversity is continuing to decline overall – much like elsewhere in Australia. This decline is mainly due to the legacy of vegetation clearing and habitat modification since European colonisation, the destructive influence of invasive species (especially predators like cats and foxes) on its native fauna and flora, and impotent or broken legislation to prevent further damage. The struggle to maintain our remaining biodiversity, and our intentions to restore once-healthy ecosystems, are rendered even more difficult by the added influence of rapid climate disruption. Despite the pessimistic outlook, South Australians have successfully employed several effective conservation mechanisms, including increasing the coverage of our network of protected areas, doing ecological restoration projects, reducing the densities of feral animals across landscapes, encouraging private landholders to protect their biodiversity assets, releasing environmental water flows to rivers and wetlands, and bringing more people in touch with nature. While these strategies are certainly stepping in the right direction, our policies and conservation targets have been hampered by arbitrary baselines, a lack of cohesion among projects and associated legislation, unrepresentative protected areas, and inappropriate spatial and time scales of intervention. While the challenges are many, there are several tractable and affordable actions that can be taken immediately to improve the prospect of the State’s biodiversity into the near future. These include coordinating existing and promoting broader-scale ecological restoration projects, establishing strategic and evidence-based control of invasive species, planning more representative protected-area networks that are managed effectively for conservation outcomes, fixing broken environmental legislation, avoiding or severely limiting biodiversity-offset incentives, expanding conservation covenants on private land, coordinating a state-wide monitoring network and protocol that tells the South Australian community how effective we are with our policies and actions, expanding existing conservation investment and tapping into different funding schemes, and coordinating better communication and interaction among government and non-governmental environment agencies. Having a more transparent and defensible link between specific conservation actions and targeted outcomes will also likely improve confidence that conservation investments are well-spent. With just a little more effort, coordination, funding, and foresight, South Australia has the opportunity to become a pillar of biodiversity conservation.

Good Water Governance for the Sustainable Development of the Arid and Semi-arid Areas of Northwest China

Water resources are of great importance for the sustainable development of the Arid and Semi-arid Areas of Northwest China. The theory of good water governance could provide inspirations for properly dealing with the water challenges of these areas. The integrated water resources management, the environmental water flow protection and the public participation are three major requirements of the good water governance. There are three major challenges for promoting the good water governance. The first is related to the clarification of the responsibilities of the water governance. The second is about balancing the diversified water needs. The third is about the optimal approach for improving the public participation. Three policy choices are proposed for promoting the good water governance. The integration of the water governance system, which emphasizes the four principles and the role of the basin management, could be a significant way of clarifying the responsibilities. Improving the water use efficiency could help the water supply for the ecological environment. The capacity building should be enhanced for facilitating the public participation.

Buying water for the environment: A hydro-economic analysis of Salton Sea inflows

As societies confront greater levels of water scarcity, conflict follows. Water transfers are increasing with irrigation water regularly considered in such discussions given it often comprises the bulk of water rights within a particular region, especially in water scarce environments. Here we analyze the impacts of three widely considered and implemented strategies to purchase water from irrigated agriculture—land fallowing, improvements in irrigation efficiency, and direct leasing. Our empirical application involves water transfers from Colorado River water rights holders to the Salton Sea, a critical ecological resource that has been in decline for many decades, with environmental damages estimated in the tens of billions of dollars. We develop a regional hydro-economic model that accounts for essential field-level agro-hydrologic processes related to crop production, irrigation, and salinity to evaluate the cost-effectiveness of these three programs. Results indicate that both fallow and direct water lease programs are capable of generating significant environmental water flows with relatively small decreases in agricultural production and no appreciable decrease in grower profits. Because these policies focus on a single input (applied water) rather than overall inflows to the Sea, the direct lease program—which is the most cost-effective approach for generating water conservation— may result in less inflows into the Sea than a land fallowing program.

ASTA — A method for multi-criteria evaluation of water supply technologies to Assess the most SusTainable Alternative for Copenhagen

Utilities in larger cities have to make complex decisions planning future investments in urban water infrastructure. Changes are driven by physical water stress or political targets for environmental water flows e.g. through the implementation of the European water framework directive. To include these environmental, economic and social sustainability dimensions we introduce a novel multi-criteria assessment method for evaluation of water supply technologies. The method is presented and demonstrated for four alternatives for water supply based on groundwater, rain- & stormwater or seawater developed for augmenting Copenhagen's current groundwater based water supply. To identify the most sustainable technology, we applied rank order distribution weights to a multi-criteria decision analysis to combine the impact assessments of environment, economy and society. The three dimensions were assessed using 1) life-cycle assessment, 2) cost calculations taking operation and maintenance into account and 3) the multi-criteria decision analysis method Analytical hierarchy process. Specialists conducted the life-cycle assessment and cost calculations and the multi-criteria decision analyses were based on a stakeholder workshop gathering stakeholders relevant for the specific case. The workshop reached consensus on three sets of ranked criteria. Each set represented stakeholder perspectives with first priority given to one of the three sustainability dimensions or categories. The workshop reached consensus and when the highest weight was assigned to the environmental dimension of sustainability then the alternative of ‘Rain- & stormwater harvesting’ was the most sustainable water supply technology; when the highest weight was assigned to the economy or society dimensions then an alternative with ‘Groundwater abstraction extended with compensating actions’ was considered the most sustainable water supply technology. Across all three sets of ranked weights, the establishment of new well fields is considered the least sustainable alternative.

HESS Opinions: A planetary boundary on freshwater use is misleading

Abstract. In 2009, a group of prominent Earth scientists introduced the planetary boundaries (PB) framework: they suggested nine global control variables, and defined corresponding thresholds which, if crossed, could generate unacceptable environmental change. The concept builds on systems theory, and views Earth as a complex adaptive system in which anthropogenic disturbances may trigger non-linear, abrupt, and irreversible changes at the global scale, and push the Earth system outside the stable environmental state of the Holocene. While the idea has been remarkably successful in both science and policy circles, it has also raised fundamental concerns, as the majority of suggested processes and their corresponding planetary boundaries do not operate at the global scale, and thus apparently lack the potential to trigger abrupt planetary changes. This paper picks up the debate with specific regard to the planetary boundary on global freshwater use. While the bio-physical impacts of excessive water consumption are typically confined to the river basin scale, the PB proponents argue that water-induced environmental disasters could build up to planetary-scale feedbacks and system failures. So far, however, no evidence has been presented to corroborate that hypothesis. Furthermore, no coherent approach has been presented to what extent a planetary threshold value could reflect the risk of regional environmental disaster. To be sure, the PB framework was revised in 2015, extending the planetary freshwater boundary with a set of basin-level boundaries inferred from environmental water flow assumptions. Yet, no new evidence was presented, either with respect to the ability of those basin-level boundaries to reflect the risk of regional regime shifts or with respect to a potential mechanism linking river basins to the planetary scale. So while the idea of a planetary boundary on freshwater use appears intriguing, the line of arguments presented so far remains speculative and implicatory. As long as Earth system science does not present compelling evidence, the exercise of assigning actual numbers to such a boundary is arbitrary, premature, and misleading. Taken as a basis for water-related policy and management decisions, though, the idea transforms from misleading to dangerous, as it implies that we can globally offset water-related environmental impacts. A planetary boundary on freshwater use should thus be disapproved and actively refuted by the hydrological and water resources community.

Living in flowing water increases resistance to ultraviolet B radiation.

Ultraviolet B radiation (UV-B) is an important environmental driver that can affect locomotor performance negatively by inducing production of reactive oxygen species (ROS). Prolonged regular exercise increases antioxidant activities, which may alleviate the negative effects of UV-B-induced ROS. Animals naturally performing exercise, such as humans performing regular exercise or fish living in flowing water, may therefore be more resilient to the negative effects of UV-B. We tested this hypothesis in a fully factorial experiment, where we exposed mosquitofish (Gambusia holbrooki) to UV-B and control (no UV-B) conditions in flowing and still water. We show that fish exposed to UV-B and kept in flowing water had increased sustained swimming performance (Ucrit), increased antioxidant defences (catalase activity and glutathione concentrations) and reduced cellular damage (lipid peroxidation and protein carbonyl concentrations) compared with fish in still water. There was no effect of UV-B or water flow on resting or maximal rates of oxygen consumption. Our results show that environmental water flow can alleviate the negative effects of UV-B-induced ROS by increasing defence mechanisms. The resultant reduction in ROS-induced damage may contribute to maintain locomotor performance. Hence, the benefits of regular exercise are 'transferred' to improve resilience to the negative impacts of UV-B. Ecologically, the mechanistic link between responses to different habitat characteristics can determine the success of animals. These dynamics have important ecological connotations when river or stream flow changes as a result of weather patterns, climate or human modifications.

Biotic and abiotic determinants of appendage length evolution in a cave amphipod

AbstractSubterranean animals are known for their highly evolved phenotypes. They are eyeless, depigmented and possess elongated appendages compared to their surface relatives. Increased antenna and leg length of cave species has traditionally been explained as a consequence of selection for non‐visual senses and increased food‐finding ability in an environment low in energy. Variation in appendage length between cave species is usually thought to result from differences in time since the colonization of the subterranean habitat. In this study, we analyzed appendage length variation in the Dinaric amphipod speciesNiphargus croaticus. Relative length of appendages varied substantially among populations. Using multilocus phylogenetic analysis, we showed that the species is nested within highly specializedN. steuerispecies complex and rejected the time hypothesis. Next, we explored the effects and strength of two environmental factors, water flow and presence of a competing species,N. subtypicus. Populations in caves with flowing water had shorter appendages than populations in cave lakes. Presence of the competing sister species did lead to longer appendages in stagnant water, but had no effect in flowing water. Abiotic factors had a stronger effect than biotic factors, but their relative strength differed among appendage pairs. High variation in appendage length between adjacent population shows that the morphology of cave arthropods is changing quickly and therefore cannot be used to predict species age. Rather than being a general adaptation to cave life, long appendages seem to be associated with the absence of water flow as well as character displacement when in sympatry with ecologically similar competing species.

Water Markets, Environmental Flows, and Adaptation to Climate Change

The possibility of climate change and the effects it will have on global and regional hydrology opens up serious questions about how the affected sectors of the economy and the water-dependent environmental assets can best adapt to the new, harsher climatic conditions. One of the possible approaches toward securing environmental water flows is to hold water rights on behalf of the public, and manage those rights for environmental purposes. This type of policy has been in effect in the Murray-Darling Basin, Australia, where the Commonwealth Environmental Water Holder (CEWH) now has some 20% of all water rights in the basin. Thus far, the use of these water rights has been almost exclusively for environmental purposes, besides the calls for some of the allocations on these water rights to be sold to irrigators. This paper examines whether a change in policy that will allow a more flexible trading behavior of the CEWH so that it can be an active participant in the market for water allocations can help with adaptation to climate change from environmental management perspective, as well as from the perspective of irrigated agriculture industry. This objective is pursued by analyzing the effects of likely hydrological variations under climate change. Key parameters that are taken into account are expected water availability, and the variability in water availability. The discourse is framed within the concept of optimal allocation of water resources so as to maximize overall social benefit from water use. The results indicate that active participation of the CEWH in the water market leads to superior outcomes in terms of both greater overall social benefit, and greater quantity of water being available for environmental purposes under climate change. The key policy implication is that trading rules for CEWH should be relaxed, especially under the projected climate change scenarios.

Possible negative feedbacks from ‘gold-plating’ irrigation infrastructure

For an irrigator, investments in on-farm water infrastructure that increase the marginal productivity of water may improve use efficiency. However, increasing on-farm water use efficiency invariably diminishes return flows, compromising the ability to maintain sufficient water flows in streams to support natural environmental values, particularly in dry states of nature. As climate change can increase the probability of dry states, modelling that does not incorporate state-contingent treatments of uncertainty may misrepresent the benefits of public investment on irrigation infrastructure improvements to recover environmental water flows. This paper uses a state-contingent modelling approach to review an extended farm capital investment policy in Australia's Murray–Darling Basin. We examine technical efficiency gain implications for irrigation and environmental water managers under alternative states of inflow variability and the role that increasing climatic uncertainty has on policy objectives. Results suggest that the incentives provided to recover environment water via on-farm capital investments could have two principal negative feedbacks given future uncertainties. First, farm capital investments may encourage inflexible production systems that fail to respond to future water scarcity, exposing that investment to increased risk. Second, technical efficiency gains may reduce return flows, creating perverse policy outcomes aligned with meeting environmental objectives. Highlighting these ulterior policy outcomes provides irrigators and policy makers the capacity to adapt and develop flexible arrangements, robust policy, and management solutions that help negate future uncertainty.

English

Specific conductance and selenium (Se) are two water quality parameters of emerging concern in the Appalachian coalfields. Isolation of high specific conductance and Se producing spoils from environmental water flows using a low permeability barrier is one method of minimizing the leaching of these constituents from coal mine spoils. Ideally, the material used to form the barrier should be readily accessible, have low levels of specific conductance and Se, and be capable of achieving a low permeability with the proper moisture adjustment. Brown and gray weathered sandstones are often readily available at mine sites in the Appalachian coalfields. Spoil samples and water quality samples from the University of Kentucky Bent Mountain Research Complex near Pikeville, Kentucky indicated that these spoil types hold promise in meeting the criteria of being a low specific conductance producing material. However, these sandstones tend to have higher sand contents than those typically used in compacted barriers or liners in landfills. The objective of this study was to assess the potential of using brown and/or gray weathered sandstones to create a low permeability barrier. To meet the objective of the study, a total of four spoil samples (identified as M1-M4) were collected in 2012. Each spoil sample was obtained from a different mine in eastern Kentucky. Samples M1 and M2 consisted of brown sandstone; sample M3 was gray sandstone; and sample M4 was a mixture of brown and gray sandstones. Each spoil sample was screened and analyzed for soil texture. Spoil moisture content-density relationships and spoil saturated hydraulic conductivity-moisture content relationships were developed for each sample using double ring permeameters. Maximum saturated hydraulic conductivity values ranged between a low of 5.9 x 10 -8 cm s -1 to a high of 3.1 x 10 -7 cm s -1 in the laboratory for the <2mm fraction. These saturated hydraulic conductivity values were comparable to soils used to construct liners in landfills, particularly in instances where the percentage of fines in the spoils were about 50% or greater. When in the field, however, it is expected that these saturated hydraulic conductivity values will typically be 1-3 orders of magnitude higher due to rock fragments. These results demonstrate that brown sandstone, with its higher fines content, is likely a more suitable media than gray sandstone for constructing a low permeability barrier to isolate high specific conductance producing and/or Se generating spoils. Based on these laboratory results, field assessments of brown weathered sandstones for this application are recommended.

Australian irrigators' recognition of the need for more environmental water flows and intentions to donate water allocations

Future water policy strategies to address low environmental flows in the River Murray in Australia may include the continued development of programmes for irrigators to donate water. We identify and control for the interdependence between irrigators' recognition of the need for increased flows and their stated intention to donate seasonal allocations over time. The increased uncertainty of seasonal water allocations played one of the largest roles in negatively influencing both recognition and intention. An increase in the opportunity cost of water donation over time was negatively associated with intention. The identification of significant willingness to donate allocations supports the movement towards a more adaptive water policy approach.

Environmental and Human Rights to Water in the Murray Darling Basin: The Federal Water Act 2007, the Water Amendment Act 2008 and Lessons from International Water and Trade Law

The Murray Darling Basin, Australia, famously described as Australia’s food bowl, suffered intense drought for the period 2001 to mid 2010. In late 2010 and early 2011 the drought ended, punctuated by severe flooding in the Northern basin and Southern Basin. Following a succession of water trading reforms which delivered limited gains during a period high water scarcity from the mid 1990s to 2004, the Australian Federal government recognized a need to engage in centralized management of the water resources of the Murray Darling Basin in 2007, enacting the Water Act 2007. The new legislation left power to grant water entitlements as property rights in the hands of Basin State governments. The key feature of the new Federal law is a Basin wide plan to be managed by a new Federal government agency, the Murray Darling Basin Authority. The legislation was subsequently refined by the Water Amendment Act 2008, breaking ground by expressly recognizing the human right to water to serve critical human needs in water planning alongside delivering rights in environmental water flows which had been established in the original Federal law. The Water Act 2007 is also unique in setting mandatory requirements to produce socio-economic risk management strategies to address the impacts of sustainable diversion cuts to be made for the delivery of environmental flows under section 22, Items 3 and 5. In these two respects the Water Act 2007 and Water Amendment Act 2008 seek to balance human rights to water in environmental flows, property, drinking water and for broader socio-economic security goals. However room for reform within the Water Act 2007 and the Water Amendment Act 2008 remains. Two seminal principles of international water law which remains in its entirety customary law are missing, namely, the principles of reasonable and equitable utilization and no significant harm. The two legal principles are inherently bound to one another and express recognition of these principles is now clearly necessary for the management of disputes between Basin states. Furthermore both pieces of legislation, having been drafted during a period of extreme drought, now require a second set of amendments making express reference to the linkages between flood mitigation strategies and drought management. This paper reviews the key features of the Water Act 2007 and the Water Amendment Act 2008, with reference to the critical literature, principles of international water law and, trade and environmental law, with a view establishing a need to engage in the development of more detailed legal reforms.

Environmental flows in Bhadra River, Karnataka, India

Environmental water requirements, also referred as ‘environmental flows’, are a compromise between water resources development and the maintenance of a river in ecologically acceptable or agreed condition. Managing environmental water flow is a complex task because the change of quantity of water occurs as the flow moves downstream. In this work, an attempt has been made to evaluate the existing conditions of the water flow in the Bhadra River at Lakkavalli, Shimoga District, Karnataka State, India and the significance of the ecosystem services through environmental flows. The possible impacts from the absence of environmental flows have also been recorded. The study involves an analysis of water flow status of Bhadra River for thirty years and also the field investigations which cover complete livelihood dependent fishermen communities and command area dependent agricultural communities. The upper catchment of the river is covered with good vegetation; the downstream of the river for 40 km has shrunken in its river bed due to the Bhadra dam, the river flow is completely irregular over a period of years. It has altered the natural flow, resulting in massive loss of riparian, aquatic habitat and water quality. Local communities are aware of the importance of environmental flows and have also realized the damages done by themselves through encroachments of flood plains and river bed for agricultural activities. More than 60% of the downstream dwellers have changed their livelihood occupations, and also migration level has increased in the fishermen communities. Communities have been impacted by irregular dry season water level fluctuations, which are characterized by extreme highs and lows, and rapid changes in water levels.

Numerical modelling of flood flows over irregular topography

In solving the hyperbolic equations of environmental shallow water flows, computational difficulty arises when the topography is irregular. In particular, under a conventional operator-splitting framework, a very small time step is often necessary to ensure stability, and this limitation on the time step is dictated by the magnitude of the source terms in relation to the irregular topography and inevitably increases the computational cost. Here a practically efficient finite volume algorithm is presented for solving the hyperbolic equations of shallow water flows. The numerical solution is achieved under an operator-splitting framework, a second-order weighted average flux (WAF) total variation diminishing (TVD) method along with the Harten Lax van Leer (HLL) approximate Riemann solver for the homogeneous equations, and a Runge–Kutta scheme for the ordinary differential equations of source terms. For numerical stability, a self-adaptive time step method is proposed under the Runge–Kutta scheme. Numerical tests for a case of glacier-lake outburst flooding demonstrate that the present model is essentially free from the restriction on time step arising from irregular topography, and therefore computational efficiency is substantially enhanced. The model is benchmarked with an urban flooding event in Glasgow, UK, and the modelling results are in reasonable agreement with those attained by others from the Flood Risk Management Research Consortium, UK.