Constraints on the recovery of invertebrate assemblages in a regulated snowmelt river during a tributary-sourced environmental flow regime

2011 ◽  
Vol 62 (12) ◽  
pp. 1407 ◽  
Author(s):  
Andrew J. Brooks ◽  
Matthew Russell ◽  
Robyn Bevitt ◽  
Matthew Dasey
Keyword(s):  
Flow Regime ◽  
Environmental Flows ◽  
River Regulation ◽  
Environmental Flow ◽  
Regulated Rivers ◽  
Macroinvertebrate Assemblages ◽  
Fine Sediments ◽  
Tributary Stream ◽  
Invertebrate Assemblages ◽  
And Control

The impacts of river regulation on aquatic biota have been extensively studied, but long-term assessments of the restoration of biota by environmental flows and the principal mechanisms of recovery have rarely occurred. We assessed whether the provision of an environmental flow regime (EFR) via the decommissioning of an aqueduct on a tributary stream altered downstream macroinvertebrate assemblages in the highly regulated Snowy River, Australia. Macroinvertebrate assemblages of the Snowy River, reference and control sites remained distinct despite the provision of environmental flows. Invertebrate assemblages detrimentally affected by regulation probably remained impaired due to either constraints on colonisation from the tributary stream (dispersal constraints) or unsuitable local environmental conditions in the Snowy River caused by flow regulation (e.g. high levels of fine sediments, elevated temperature regime) suppressing new colonists or recovery of extant populations. Our study showed that restoration may be ineffective if EFRs are too small to ameliorate local environmental factors constraining the recovery of affected biota. Other barriers to recovery, such as dispersal constraints, also need to be overcome. Successful restoration of regulated rivers using environmental flows requires an understanding of the mechanisms and pathways of recovery, together with identification and amelioration of any potential barriers to recovery.

scholarly journals Accounting for environmental flow requirements in global water assessments

2014 ◽  
Vol 18 (12) ◽  
pp. 5041-5059 ◽  
Author(s):  
A. V. Pastor ◽  
F. Ludwig ◽  
H. Biemans ◽  
H. Hoff ◽  
P. Kabat
Keyword(s):  
Flow Regime ◽  
Environmental Flows ◽  
Environmental Flow ◽  
Ecological Condition ◽  
Freshwater Ecosystems ◽  
Low Flow ◽  
Human Needs ◽  
High Flows ◽  
The Mean ◽  
Global Vegetation

Abstract. As the water requirement for food production and other human needs grows, quantification of environmental flow requirements (EFRs) is necessary to assess the amount of water needed to sustain freshwater ecosystems. EFRs are the result of the quantification of water necessary to sustain the riverine ecosystem, which is calculated from the mean of an environmental flow (EF) method. In this study, five EF methods for calculating EFRs were compared with 11 case studies of locally assessed EFRs. We used three existing methods (Smakhtin, Tennant, and Tessmann) and two newly developed methods (the variable monthly flow method (VMF) and the Q90_Q50 method). All methods were compared globally and validated at local scales while mimicking the natural flow regime. The VMF and the Tessmann methods use algorithms to classify the flow regime into high, intermediate, and low-flow months and they take into account intra-annual variability by allocating EFRs with a percentage of mean monthly flow (MMF). The Q90_Q50 method allocates annual flow quantiles (Q90 and Q50) depending on the flow season. The results showed that, on average, 37% of annual discharge was required to sustain environmental flow requirement. More water is needed for environmental flows during low-flow periods (46–71% of average low-flows) compared to high-flow periods (17–45% of average high-flows). Environmental flow requirements estimates from the Tennant, Q90_Q50, and Smakhtin methods were higher than the locally calculated EFRs for river systems with relatively stable flows and were lower than the locally calculated EFRs for rivers with variable flows. The VMF and Tessmann methods showed the highest correlation with the locally calculated EFRs (R2=0.91). The main difference between the Tessmann and VMF methods is that the Tessmann method allocates all water to EFRs in low-flow periods while the VMF method allocates 60% of the flow in low-flow periods. Thus, other water sectors such as irrigation can withdraw up to 40% of the flow during the low-flow season and freshwater ecosystems can still be kept in reasonable ecological condition. The global applicability of the five methods was tested using the global vegetation and the Lund-Potsdam-Jena managed land (LPJmL) hydrological model. The calculated global annual EFRs for fair ecological conditions represent between 25 and 46% of mean annual flow (MAF). Variable flow regimes, such as the Nile, have lower EFRs (ranging from 12 to 48% of MAF) than stable tropical regimes such as the Amazon (which has EFRs ranging from 30 to 67% of MAF).

Australian waterbirds - time and space travellers in dynamic desert landscapes

2010 ◽  
Vol 61 (8) ◽  
pp. 875 ◽  
Author(s):  
R. T. Kingsford ◽  
D. A. Roshier ◽  
J. L. Porter
Keyword(s):  
Resource Availability ◽  
Environmental Flows ◽  
Anthropogenic Impacts ◽  
Aquatic Organisms ◽  
River Regulation ◽  
Population Declines ◽  
Time And Space ◽  
Regulated Rivers ◽  
Spatial And Temporal Scales ◽  
Resource Patches

Australia’s waterbirds are mostly nomadic, capitalising on highly variable aquatic resources in the arid interior (70% of the continent) for feeding and breeding. Waterbirds, unlike most aquatic organisms, can move between catchments, exploiting habitat wherever it occurs. In Australia, patterns of resource availability for waterbirds are mostly pulsed with peaks of productivity, coinciding with flooding and differing in time and space, affecting individuals, species and functional groups of waterbirds. Australian waterbirds are no different from waterbirds elsewhere, with their behaviour reflecting broad-scale resource availability. They respond to changing patterns of resource distribution, with rapid movements at spatial and temporal scales commensurate with the dynamics of the resource. The most serious conservation threat to waterbirds is a bottleneck in resource availability, leading to population declines, increasingly forced by anthropogenic impacts. River regulation and other threats (e.g. draining) reduce the availability of wetland habitat and decrease the probability of viable resource patches. It is axiomatic that waterbirds need water and such population bottlenecks may occur when the availability of water across the continent is limited. The rehabilitation of regulated rivers with environmental flows and protection of naturally flowing rivers in the arid region are essential for long-term sustainability of Australia’s waterbird populations.

Provision of environmental flows promotes spawning of a nationally threatened diadromous fish

2017 ◽  
Vol 68 (1) ◽  
pp. 159 ◽  
Author(s):  
W. M. Koster ◽  
F. Amtstaetter ◽  
D. R. Dawson ◽  
P. Reich ◽  
J. R. Morrongiello
Keyword(s):  
Environmental Flows ◽  
Environmental Flow ◽  
Individual Species ◽  
Spawning Activity ◽  
Regulated Rivers ◽  
Potential Conflict ◽  
Effective Delivery ◽  
Environmental Requirements ◽  
Australian Grayling ◽  
Species Ecology

Detailed understanding of flow-ecology requirements for aquatic biota underpins the use of environmental flows as an effective restoration tool in regulated rivers. However, flow recommendations are often overly simplistic and insufficient to provide the necessary environmental requirements for these biota. This is often due to failure to gain and integrate information on individual species ecology and, by using coarse generalisations, about flow-ecology responses. To inform more effective delivery of environmental flows, we investigated spawning responses of the threatened Australian grayling (Prototroctes maraena) to environmental flows over 2 years in three coastal rivers. Spawning activity was highest during within-channel flow pulses, especially during periods of environmental flow delivery. Peak spawning occurred in late autumn and was positively related to flow duration. This result has important implications for environmental flows management in regions where water is scarce and there is potential conflict among multiple users because, for Australian grayling, it is not necessarily the volume of water released that is important, but how the flow is delivered. Our study demonstrated the importance of quantifying flow-ecology relationships via targeted monitoring and research so as to develop appropriate flow regimes, and should encourage managers to examine more critically the logic behind generalised environmental flow objectives.

scholarly journals Towards a Holistic Environmental Flow Regime in Chile: Providing for Ecosystem Health and Indigenous Rights

2020 ◽  
Vol 9 (3) ◽  
pp. 481-519
Author(s):  
Elizabeth J. Macpherson ◽  
Pia Weber Salazar
Keyword(s):  
Flow Regime ◽  
Environmental Flows ◽  
Water Governance ◽  
Indigenous Rights ◽  
Indigenous Communities ◽  
Environmental Flow ◽  
Ecological Condition ◽  
Political Crisis ◽  
Regulatory Frameworks ◽  
Environmental Interests

AbstractA widespread response to the pressures placed on the ecological condition of rivers is the design and implementation of environmental flow regimes in domestic regulatory frameworks for water. Environmental interests in water are not confined to hydrological functioning but include relationships between water resources and human cultural and economic livelihoods, including those of Indigenous communities. Since the mid-1980s there has been some provision for environmental flows in Chilean law. However, the legal and policy requirements are limited in scope and have been poorly implemented by regulatory institutions. In this article we critically examine the treatment of environmental flows in Chilean legal and policy frameworks. We argue that there is an urgent need for a comprehensive minimum flow regime in Chile to protect the environmental qualities of rivers, which must also reflect and provide for Indigenous water rights and interests. The developing constitutional crisis in Chile, the most significant political crisis since the end of the Pinochet dictatorship (1973–90), highlights the need to revisit the sensitive and unresolved issues of water governance and equity.

A simulation tool for managing environmental flows in regulated rivers

2015 ◽  
Vol 73 ◽  
pp. 117-132 ◽  
Author(s):  
C.M.M. Steinfeld ◽  
R.T. Kingsford ◽  
E.C. Webster ◽  
A. Sharma
Keyword(s):  
Environmental Flows ◽  
Simulation Tool ◽  
Regulated Rivers

scholarly journals Response of the Snowy River Estuary to two environmental flows

2015 ◽  
Vol 127 (2) ◽  
pp. 28
Author(s):  
Errol J. McLean ◽  
Jon B. Hinwood
Keyword(s):  
Fresh Water ◽  
Peak Flow ◽  
Environmental Flows ◽  
River Estuary ◽  
Environmental Flow ◽  
River Channel ◽  
Salinity Gradients ◽  
Tasman Sea ◽  
Eastern Australia ◽  
Major River

The Snowy River is a major river in south-eastern Australia, discharging to the Tasman Sea via a barrier estuary, with its entrance constricted by marine sands. Since the construction of the Snowy Mountains Scheme, river flows have not been sufficient to maintain the river channel. A program of environmental flow releases (EFR) is returning water to the river to restore the fluvial reaches and is now trialling flow regimes that may also benefit the estuarine reaches. This paper documents the response of the estuarine segments of the Snowy River to two EFRs; the release in 2010 was designed to scour the upper reaches of the Snowy River while the larger 2011 release was intended to extend the scouring downstream. For each release, the effects on the entrance morphology, tides and salinity through the flow peak and recovery are described. Each EFR caused minor increases in depth and very minor longshore movement of the entrance channel, although each EFR had been preceded by a larger fresh flow that would have scoured the channels. The small increase in fresh water inflow in the 2010 EFR pushed salinity contours seawards and steepened vertical salinity gradients. The larger inflow in the 2011 EFR purged the upper estuary of saltwater. After the peak flow, salinity recovery was rapid in the principal estuarine channels but took weeks where poorly connected wetlands could store fresh flood waters. Critical flows for scouring the entrance and purging salinity are estimated.

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