<p>The River Murray is Australia’s largest and most important river.&... more <p>The River Murray is Australia’s largest and most important river.  It carries water for irrigation and city supply from the mountains in the east, semi-arid west.  The river crosses a series of low-angle alluvial fans (distributive fluvial systems) in its 1500 km path.  The Barmah Choke is a narrow section of the River Murray’s channel, formed by a Holocene river avulsion, that restricts flow capacity from the upper to lower Murray River.  The flow capacity of the Choke has declined nearly 20% since the 1980s, which imposes a constraint on regulated flows supplied down-valley, and is constraining economic development downstream.  Whilst there could be multiple geomorphic factors explaining the decline, we demonstrate that the most likely cause is a sheet of coarse sand shallowing the river, much of which originated from historical gold mining and catchment erosion in late 1800s.  The sheet of sand is reducing depth diversity, filling pools up to 5m deep, and degrading the ecological and cultural values of the river.  The whole length of the river through the Barmah Forest has shallowed over the last 30 years, aggrading by 1.9 m at the upstream end and 0.70 m in the most downstream section of the Choke (about 10% decrease in area).  The total volume of sand stored between Yarrawonga and Barmah is over 20 million m<sup>3</sup>, and the average total annual sand load transported into the 82km long Choke ranges between 130,000 m<sup>3 </sup>in a normal flow year to 500,000 m<sup>3</sup> in a flood year (which translates into 2 – 9 cm of aggradation per year).  Surprisingly, overall, long-duration regulated irrigation flows have <em>decreased</em> the rate of sand transport through the Choke.  Decreasing downstream flow capacity across the Barmah Fan is a natural characteristic of this type of distributive fluvial system, but the sand sheet is accelerating the rate of decline.  Without intervention, conveyance through the Choke will inevitably continue to decline until the river avulses into a new channel.  A range of solutions are explored, but all are extremely expensive. </p>
This paper examines the challenges that a region of China is facing as it seeks to integrate a ce... more This paper examines the challenges that a region of China is facing as it seeks to integrate a centrally planned, hierarchically determined water transfer project into its own water supply systems. Water from China's South-North Water Transfer Project (SNWTP) has been available in Shandong since 2013. How has this province been managing the integration of SNWTP water into its water supply plans, and what challenges is it facing in the process? This paper demonstrates that Shandong's planners consistently overestimated future …
Riverbanks can be a dominant sources of sediment in catchments. Several attempts have been made t... more Riverbanks can be a dominant sources of sediment in catchments. Several attempts have been made to predict rates of bank retreat from channel, catchment, and flow characteristics. Many of these are meander models that are not appropriate for whole of catchment analyses. The SedNet model ) is a general model of catchment scale erosion, including a streambank component and was used to provide continental estimates of erosion as part of the Australian National Land and Water Resources Audit. Several limitations have been recognised in the streambank erosion component of SedNet. This project is aimed at developing a more accurate model for predicting sediment yield from bank erosion at the catchment scale. In this paper we report a framework for a generic bank erosion model that accounts for fluvial entrainment and mass failure processes. The rate of bank erosion along a stream link is considered a function of stream power, bank height, and bank strength. The model will be developed based on information contained in widely available data sets. For Victoria, these data sets include the statewide assessment of physical stream conditions (SOS), the Index of Stream Condition (ISC), and stream gauging records, while the Atlas of Australian soils and Ausrivas databases provide national coverage. Bank height is one of the model components and is used as an example of the derivation of inputs from widely available data sets for six basins using the SOS database. In most basins there is a statistically significant relationship between easily derivable surrogates of channel forming characteristics and an average bank height, although these were different for different basins. The model predicts to some extent using the example of the Goulburn River basin (20,000 km 2 ). Examining the model using the actual parameters of some of the surrogates may better capture the variability in stream bank height. When all of the variables in the model have been compiled, the output of the model will be tested by comparing the results with published information e.g. sediment yields, and lateral migration rates of bank erosion
Pool-Rime Sequences (PRSs) enhance the habitat value of many natural streams. Environmental flows... more Pool-Rime Sequences (PRSs) enhance the habitat value of many natural streams. Environmental flows are one management tool that may be used to reinforce such bar morphologies and this study investigated the range of flows that may potentially reinforce the PRS morphology and maintain it over time. A physical model based on a PRS in north-eastern Victoria was used to isolate two processes contributing to PRSs; alternate bar instability and constriction scour. Alternate bars were found to occur at lower width to depth ratios than in previous studies. This suggests that alternate bar instability is a more important process in the development and maintenance of PRSs, even in upland gravel and cobble bed streams. Variation in channel width between rimes and pools was found to explain the majority of depth variation in the prototype PRS. It is suggested that alternate bar instability resonates with width variation. This may help to explain the periodic wavelength of pool-rime sequences wou...
It is self evident that the majority of stream length in Australia flows through rural rather tha... more It is self evident that the majority of stream length in Australia flows through rural rather than urban areas. The result is that stream condition is seen to be a rural issue. In fact, the condition of rural streams in Australia is determined, to a large degree, by food choices made by people in cities. Using Melbourne as a case-study, we show that for every litre of water consumed directly in the average Melbourne household, nine more litres are consumed indirectly through the water used to produce food. This is called 'embodied’ or ‘virtual’ water'. Thus, product choices made by city people ultimately drive how much water is removed from rural streams. We suggest four ways that consumers can dramatically reduce their indirect water consumption: waste less food; select comparable products that use less water; substitute types of food that use more water for types that use less; and become a vegetarian. It is also clear that changing food choices will not automatically lead...
Important disclaimer CSIRO advises that the information contained in this publication comprises g... more Important disclaimer CSIRO advises that the information contained in this publication comprises general statements based on scientific research. The reader is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must therefore be made on that information without seeking prior expert professional, scientific and technical advice. To the extent permitted by law, CSIRO (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it.
ABSTRACT Key Points • Rapid urban sprawl in major cities and centres throughout Australia with co... more ABSTRACT Key Points • Rapid urban sprawl in major cities and centres throughout Australia with conventional stormwater drainage may have unaccounted impacts and costs for downstream waterways. • Alternative stormwater management in greenfield developments, such as stormwater harvesting and biofiltration, can generate local benefits, cost savings and avoided costs to downstream waterways • Downstream waterway benefits include reduced fluvial flooding, increased amenity opportunities along waterways, protection of biodiversity, and healthier receiving estuaries and bays. • The business case for greenfield urban developments should consider the benefits of alternatives at both the local scale and for downstream waterways Abstract The development of new suburbs dramatically increases stormwater volumes into streams, much of which is of poor quality. In recent years, stormwater harvesting has increasingly been considered a significant source for water supply augmentation, but also as a means to improve human comfort and general amenity through cooling provided by irrigated urban vegetation at the development and surrounding landscape. To these recognised 'local' benefits of stormwater management, we add the avoided costs to downstream waterways. It is well known that conventional urban stormwater systems in headwaters degrade the biodiversity of streams and rivers, exacerbate downstream flooding, damage infrastructure through erosion, and impact on the condition of estuaries and bays. This damage can be so extensive as to be effectively irreversible. At present, the cost of repairing this damage is borne by the broader community rather than developers . We argue that there is a compelling business case for alternative stormwater management in new suburbs, if the avoided costs downstream of the development are coupled with the multiple local scale benefits (within the development).
Geomorphic complexity is an important measure of stream health, because highly structured habitat... more Geomorphic complexity is an important measure of stream health, because highly structured habitats tend to contain more species than simply structured ones. Humans disturb fluvial systems, reducing the natural geomorphic complexity of streams. Considerable research has been carried out describing the impacts of disturbance on stream geomorphology, yet few studies have investigated the subsequent recovery of streams. An ability to determine the time scales of recovery will be extremely useful for prioritising stream rehabilitation projects. Streams that have been disturbed by large pulses of sand (sand slugs) or gravel provide good case studies of the recovery process. Sand slugs reduce the geomorphic complexity of streams as fine sediment fills in undercuts, backwater zones, edgewater habitats and pools and riffles. In this paper we hypothesise that ‘the amount of recovery in the stream is a function of the time since the slug passed, and the range of flows experienced in that time’...
Riparian revegetation is often used as method to reduce sediment delivery to receiving waters. We... more Riparian revegetation is often used as method to reduce sediment delivery to receiving waters. We investigated the role of revegetation in controlling suspended sediment delivery to a small stream in South East Queensland by continuously monitoring suspended sediment as turbidity at a treatment stream and adjacent unforested control and forested reference streams for 3 years. We found that the unforested stream yielded 14.5-87.8 t/km/a compared to the forested stream yielding 3-78 t/km/a and the treatment stream yielding 12.3-212.2 t/km/a. The treatment stream initially had a similar suspended sediment yield to the control stream. The revegetation activities in the treatment stream resulted in an increase in suspended sediment yield (to approximately double that of the control stream). The revegetation process required the removal of existing invasive pasture grass ground cover and woody weeds. We suspect that this disturbance of the riparian zone and the period taken for the plante...
The riparian zone of Australia's river networks has become a focal point for environmental re... more The riparian zone of Australia's river networks has become a focal point for environmental rehabilitation efforts in the last decade. Revegetation of the stream corridor is occurring both through active replanting and natural recovery facilitated by fencing off the stream to exclude stock. These measures are motivated by the tide of evidence showing that the reinstatement of riparian communities improves the health of both aquatic and terrestrial ecosystems, and positively contributes to physical attributes such as water quality and bank stability. However, additional vegetation within the channel increases the resistance to flow, thereby reducing the volume of water the channel can carry before flooding commences. The argument levelled against riparian restoration is that it will increase the incidence of flooding causing increased economic loss primarily to rural landholders, the same people who are being asked to restore the waterway in the first place. There is an added comp...
Researchers have proposed several thresholds to predict the transition from unstable to stable st... more Researchers have proposed several thresholds to predict the transition from unstable to stable states in incised channels. One of the most frequently applied is the 35Wm -2 threshold of specific stream power. However this threshold has not formally been tested in environments distinct from its origin. An approach integrating GIS and hydrologic relationships was developed to calculate specific stream power and shear stress at over 1000 sites in Fairfax County, Virginia, USA. Analysis indicated that specific stream power did not discriminate between stable and unstable sites, even when the dominant substrate material was incorporated into the analysis. Substrate type provided a greater influence statistically on channel stability than values of specific stream power, but substrate type alone did not discriminate between stable and unstable sites. Although the research methods failed to provide any practical evidence to support the notion of a stability threshold of specific stream pow...
Planting native vegetation on stream banks is the most common stream restoration activity in Aust... more Planting native vegetation on stream banks is the most common stream restoration activity in Australia, because it is relatively low cost, and is widely believed to provide multiple benefits for the stream. However, there are few scientific studies that can be applied in the Australian context on how riparian vegetation affects stream channel form. The purpose of this paper is to present the current scientific evidence on the association between vegetation and stream channel width, and supplement existing information with data from Victorian streams. This data indicates that different types of vegetation are associated with stream channels of different widths. Measurements of Victorian streams suggest that there is little difference between the width of streams lined with native trees and those lined with pasture grasses. However, where exotic willows invade the stream bed (usually in small streams) channels tend to be wider than those lined with native vegetation. In contrast, wher...
Environmental policy is often implemented using market instruments. In some cases, including carb... more Environmental policy is often implemented using market instruments. In some cases, including carbon taxing, the links between financial products and the environmental objectives, are transparent. In other cases, including water markets, the links are less transparent. In Australia’s Murray–Darling Basin (MDB), financial water products are known as ‘entitlements’, and are similar to traditional financial products, such as shares. The Australian water market includes ‘Low Security’ entitlements, which are similar to ‘sub-prime’ mortgage bonds because they are unlikely to yield an amount equal to their financial worth. Nearly half the water purchased under the Murray–Darling Basin Plan for environmental purposes is ‘Low Security’. We suggest that the current portfolio of water held by the Australian Government for environmental purposes reflects the mortgage market in the lead-up to the global financial crisis. Banks assumed that the future value of the mortgage market would reflect pa...
This is the first substantial field measurement of riverbank erosion around fallen logs in rivers... more This is the first substantial field measurement of riverbank erosion around fallen logs in rivers. Whilst numerous studies have established that living trees can stabilize river banks, and that fallen trees can cause scour of the river bed, knowledge of bank erosion effects from logs is largely restricted to qualitative observations. Recent flume studies suggest that a single log can increase near-bank velocity (and thus erosion) and this increase is related to the blockage ratio of the log and the distance between the log and bank. However, hydraulic interactions between logs can reduce this increase or even decrease the near-bank velocity. These theories, developed in a straight flume, have not been tested in the field. We measured erosion rates (relative to controls) on riverbanks adjacent to 35 large logs for two years, and velocity distributions around 11 logs during a near-bankfull flow in anabranching channels of the River Murray, SE Australia. This channel has This article is protected by copyright. All rights reserved. This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as
Integrated Environmental Assessment and Management
Agriculture is one of the major drivers of ecological degradation in river basins. Excluding stoc... more Agriculture is one of the major drivers of ecological degradation in river basins. Excluding stock (cows and sheep) from grazing riverbanks, and accessing rivers, is one of the most common river restoration activities. To be effective, stock exclusion must be maintained indefinitely. In Australia, and elsewhere, stock exclusion projects are most commonly implemented by establishing voluntary agreements between landholders and government agencies. This study examined: the extent to which landholders in three catchment management authority (CMA) regions in south east Australia maintain stock exclusion from waterways, whether vegetation on riverbanks recovered, and the effectiveness of assessment methods. It was found that nearly half of landholders continue to graze stock on the riverbank. There has been some success with improving the condition of riparian vegetation. Sites with full stock exclusion contain the pre-European abundance of juvenile trees, and, sites with continued grazing contain significantly lower abundance of juvenile trees. Establishing the effectiveness of management was made more difficult by the inconsistent methods used by the different CMAs. Stock exclusion projects implemented using voluntary agreements have the potential to succeed if overseeing is improved between government agencies and CMAs, and between CMAs and landholders. Projects will be easier to assess if regional authorities use consistent methods of assessment. Voluntary agreements are only Page 1 of 35 Integrated Environmental Assessment and Management 2 suitable for environmental management if projects are monitored, maintained, and assessed appropriately.
<p>The River Murray is Australia’s largest and most important river.&... more <p>The River Murray is Australia’s largest and most important river.  It carries water for irrigation and city supply from the mountains in the east, semi-arid west.  The river crosses a series of low-angle alluvial fans (distributive fluvial systems) in its 1500 km path.  The Barmah Choke is a narrow section of the River Murray’s channel, formed by a Holocene river avulsion, that restricts flow capacity from the upper to lower Murray River.  The flow capacity of the Choke has declined nearly 20% since the 1980s, which imposes a constraint on regulated flows supplied down-valley, and is constraining economic development downstream.  Whilst there could be multiple geomorphic factors explaining the decline, we demonstrate that the most likely cause is a sheet of coarse sand shallowing the river, much of which originated from historical gold mining and catchment erosion in late 1800s.  The sheet of sand is reducing depth diversity, filling pools up to 5m deep, and degrading the ecological and cultural values of the river.  The whole length of the river through the Barmah Forest has shallowed over the last 30 years, aggrading by 1.9 m at the upstream end and 0.70 m in the most downstream section of the Choke (about 10% decrease in area).  The total volume of sand stored between Yarrawonga and Barmah is over 20 million m<sup>3</sup>, and the average total annual sand load transported into the 82km long Choke ranges between 130,000 m<sup>3 </sup>in a normal flow year to 500,000 m<sup>3</sup> in a flood year (which translates into 2 – 9 cm of aggradation per year).  Surprisingly, overall, long-duration regulated irrigation flows have <em>decreased</em> the rate of sand transport through the Choke.  Decreasing downstream flow capacity across the Barmah Fan is a natural characteristic of this type of distributive fluvial system, but the sand sheet is accelerating the rate of decline.  Without intervention, conveyance through the Choke will inevitably continue to decline until the river avulses into a new channel.  A range of solutions are explored, but all are extremely expensive. </p>
This paper examines the challenges that a region of China is facing as it seeks to integrate a ce... more This paper examines the challenges that a region of China is facing as it seeks to integrate a centrally planned, hierarchically determined water transfer project into its own water supply systems. Water from China's South-North Water Transfer Project (SNWTP) has been available in Shandong since 2013. How has this province been managing the integration of SNWTP water into its water supply plans, and what challenges is it facing in the process? This paper demonstrates that Shandong's planners consistently overestimated future …
Riverbanks can be a dominant sources of sediment in catchments. Several attempts have been made t... more Riverbanks can be a dominant sources of sediment in catchments. Several attempts have been made to predict rates of bank retreat from channel, catchment, and flow characteristics. Many of these are meander models that are not appropriate for whole of catchment analyses. The SedNet model ) is a general model of catchment scale erosion, including a streambank component and was used to provide continental estimates of erosion as part of the Australian National Land and Water Resources Audit. Several limitations have been recognised in the streambank erosion component of SedNet. This project is aimed at developing a more accurate model for predicting sediment yield from bank erosion at the catchment scale. In this paper we report a framework for a generic bank erosion model that accounts for fluvial entrainment and mass failure processes. The rate of bank erosion along a stream link is considered a function of stream power, bank height, and bank strength. The model will be developed based on information contained in widely available data sets. For Victoria, these data sets include the statewide assessment of physical stream conditions (SOS), the Index of Stream Condition (ISC), and stream gauging records, while the Atlas of Australian soils and Ausrivas databases provide national coverage. Bank height is one of the model components and is used as an example of the derivation of inputs from widely available data sets for six basins using the SOS database. In most basins there is a statistically significant relationship between easily derivable surrogates of channel forming characteristics and an average bank height, although these were different for different basins. The model predicts to some extent using the example of the Goulburn River basin (20,000 km 2 ). Examining the model using the actual parameters of some of the surrogates may better capture the variability in stream bank height. When all of the variables in the model have been compiled, the output of the model will be tested by comparing the results with published information e.g. sediment yields, and lateral migration rates of bank erosion
Pool-Rime Sequences (PRSs) enhance the habitat value of many natural streams. Environmental flows... more Pool-Rime Sequences (PRSs) enhance the habitat value of many natural streams. Environmental flows are one management tool that may be used to reinforce such bar morphologies and this study investigated the range of flows that may potentially reinforce the PRS morphology and maintain it over time. A physical model based on a PRS in north-eastern Victoria was used to isolate two processes contributing to PRSs; alternate bar instability and constriction scour. Alternate bars were found to occur at lower width to depth ratios than in previous studies. This suggests that alternate bar instability is a more important process in the development and maintenance of PRSs, even in upland gravel and cobble bed streams. Variation in channel width between rimes and pools was found to explain the majority of depth variation in the prototype PRS. It is suggested that alternate bar instability resonates with width variation. This may help to explain the periodic wavelength of pool-rime sequences wou...
It is self evident that the majority of stream length in Australia flows through rural rather tha... more It is self evident that the majority of stream length in Australia flows through rural rather than urban areas. The result is that stream condition is seen to be a rural issue. In fact, the condition of rural streams in Australia is determined, to a large degree, by food choices made by people in cities. Using Melbourne as a case-study, we show that for every litre of water consumed directly in the average Melbourne household, nine more litres are consumed indirectly through the water used to produce food. This is called 'embodied’ or ‘virtual’ water'. Thus, product choices made by city people ultimately drive how much water is removed from rural streams. We suggest four ways that consumers can dramatically reduce their indirect water consumption: waste less food; select comparable products that use less water; substitute types of food that use more water for types that use less; and become a vegetarian. It is also clear that changing food choices will not automatically lead...
Important disclaimer CSIRO advises that the information contained in this publication comprises g... more Important disclaimer CSIRO advises that the information contained in this publication comprises general statements based on scientific research. The reader is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must therefore be made on that information without seeking prior expert professional, scientific and technical advice. To the extent permitted by law, CSIRO (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it.
ABSTRACT Key Points • Rapid urban sprawl in major cities and centres throughout Australia with co... more ABSTRACT Key Points • Rapid urban sprawl in major cities and centres throughout Australia with conventional stormwater drainage may have unaccounted impacts and costs for downstream waterways. • Alternative stormwater management in greenfield developments, such as stormwater harvesting and biofiltration, can generate local benefits, cost savings and avoided costs to downstream waterways • Downstream waterway benefits include reduced fluvial flooding, increased amenity opportunities along waterways, protection of biodiversity, and healthier receiving estuaries and bays. • The business case for greenfield urban developments should consider the benefits of alternatives at both the local scale and for downstream waterways Abstract The development of new suburbs dramatically increases stormwater volumes into streams, much of which is of poor quality. In recent years, stormwater harvesting has increasingly been considered a significant source for water supply augmentation, but also as a means to improve human comfort and general amenity through cooling provided by irrigated urban vegetation at the development and surrounding landscape. To these recognised 'local' benefits of stormwater management, we add the avoided costs to downstream waterways. It is well known that conventional urban stormwater systems in headwaters degrade the biodiversity of streams and rivers, exacerbate downstream flooding, damage infrastructure through erosion, and impact on the condition of estuaries and bays. This damage can be so extensive as to be effectively irreversible. At present, the cost of repairing this damage is borne by the broader community rather than developers . We argue that there is a compelling business case for alternative stormwater management in new suburbs, if the avoided costs downstream of the development are coupled with the multiple local scale benefits (within the development).
Geomorphic complexity is an important measure of stream health, because highly structured habitat... more Geomorphic complexity is an important measure of stream health, because highly structured habitats tend to contain more species than simply structured ones. Humans disturb fluvial systems, reducing the natural geomorphic complexity of streams. Considerable research has been carried out describing the impacts of disturbance on stream geomorphology, yet few studies have investigated the subsequent recovery of streams. An ability to determine the time scales of recovery will be extremely useful for prioritising stream rehabilitation projects. Streams that have been disturbed by large pulses of sand (sand slugs) or gravel provide good case studies of the recovery process. Sand slugs reduce the geomorphic complexity of streams as fine sediment fills in undercuts, backwater zones, edgewater habitats and pools and riffles. In this paper we hypothesise that ‘the amount of recovery in the stream is a function of the time since the slug passed, and the range of flows experienced in that time’...
Riparian revegetation is often used as method to reduce sediment delivery to receiving waters. We... more Riparian revegetation is often used as method to reduce sediment delivery to receiving waters. We investigated the role of revegetation in controlling suspended sediment delivery to a small stream in South East Queensland by continuously monitoring suspended sediment as turbidity at a treatment stream and adjacent unforested control and forested reference streams for 3 years. We found that the unforested stream yielded 14.5-87.8 t/km/a compared to the forested stream yielding 3-78 t/km/a and the treatment stream yielding 12.3-212.2 t/km/a. The treatment stream initially had a similar suspended sediment yield to the control stream. The revegetation activities in the treatment stream resulted in an increase in suspended sediment yield (to approximately double that of the control stream). The revegetation process required the removal of existing invasive pasture grass ground cover and woody weeds. We suspect that this disturbance of the riparian zone and the period taken for the plante...
The riparian zone of Australia's river networks has become a focal point for environmental re... more The riparian zone of Australia's river networks has become a focal point for environmental rehabilitation efforts in the last decade. Revegetation of the stream corridor is occurring both through active replanting and natural recovery facilitated by fencing off the stream to exclude stock. These measures are motivated by the tide of evidence showing that the reinstatement of riparian communities improves the health of both aquatic and terrestrial ecosystems, and positively contributes to physical attributes such as water quality and bank stability. However, additional vegetation within the channel increases the resistance to flow, thereby reducing the volume of water the channel can carry before flooding commences. The argument levelled against riparian restoration is that it will increase the incidence of flooding causing increased economic loss primarily to rural landholders, the same people who are being asked to restore the waterway in the first place. There is an added comp...
Researchers have proposed several thresholds to predict the transition from unstable to stable st... more Researchers have proposed several thresholds to predict the transition from unstable to stable states in incised channels. One of the most frequently applied is the 35Wm -2 threshold of specific stream power. However this threshold has not formally been tested in environments distinct from its origin. An approach integrating GIS and hydrologic relationships was developed to calculate specific stream power and shear stress at over 1000 sites in Fairfax County, Virginia, USA. Analysis indicated that specific stream power did not discriminate between stable and unstable sites, even when the dominant substrate material was incorporated into the analysis. Substrate type provided a greater influence statistically on channel stability than values of specific stream power, but substrate type alone did not discriminate between stable and unstable sites. Although the research methods failed to provide any practical evidence to support the notion of a stability threshold of specific stream pow...
Planting native vegetation on stream banks is the most common stream restoration activity in Aust... more Planting native vegetation on stream banks is the most common stream restoration activity in Australia, because it is relatively low cost, and is widely believed to provide multiple benefits for the stream. However, there are few scientific studies that can be applied in the Australian context on how riparian vegetation affects stream channel form. The purpose of this paper is to present the current scientific evidence on the association between vegetation and stream channel width, and supplement existing information with data from Victorian streams. This data indicates that different types of vegetation are associated with stream channels of different widths. Measurements of Victorian streams suggest that there is little difference between the width of streams lined with native trees and those lined with pasture grasses. However, where exotic willows invade the stream bed (usually in small streams) channels tend to be wider than those lined with native vegetation. In contrast, wher...
Environmental policy is often implemented using market instruments. In some cases, including carb... more Environmental policy is often implemented using market instruments. In some cases, including carbon taxing, the links between financial products and the environmental objectives, are transparent. In other cases, including water markets, the links are less transparent. In Australia’s Murray–Darling Basin (MDB), financial water products are known as ‘entitlements’, and are similar to traditional financial products, such as shares. The Australian water market includes ‘Low Security’ entitlements, which are similar to ‘sub-prime’ mortgage bonds because they are unlikely to yield an amount equal to their financial worth. Nearly half the water purchased under the Murray–Darling Basin Plan for environmental purposes is ‘Low Security’. We suggest that the current portfolio of water held by the Australian Government for environmental purposes reflects the mortgage market in the lead-up to the global financial crisis. Banks assumed that the future value of the mortgage market would reflect pa...
This is the first substantial field measurement of riverbank erosion around fallen logs in rivers... more This is the first substantial field measurement of riverbank erosion around fallen logs in rivers. Whilst numerous studies have established that living trees can stabilize river banks, and that fallen trees can cause scour of the river bed, knowledge of bank erosion effects from logs is largely restricted to qualitative observations. Recent flume studies suggest that a single log can increase near-bank velocity (and thus erosion) and this increase is related to the blockage ratio of the log and the distance between the log and bank. However, hydraulic interactions between logs can reduce this increase or even decrease the near-bank velocity. These theories, developed in a straight flume, have not been tested in the field. We measured erosion rates (relative to controls) on riverbanks adjacent to 35 large logs for two years, and velocity distributions around 11 logs during a near-bankfull flow in anabranching channels of the River Murray, SE Australia. This channel has This article is protected by copyright. All rights reserved. This is the author manuscript accepted for publication and has undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as
Integrated Environmental Assessment and Management
Agriculture is one of the major drivers of ecological degradation in river basins. Excluding stoc... more Agriculture is one of the major drivers of ecological degradation in river basins. Excluding stock (cows and sheep) from grazing riverbanks, and accessing rivers, is one of the most common river restoration activities. To be effective, stock exclusion must be maintained indefinitely. In Australia, and elsewhere, stock exclusion projects are most commonly implemented by establishing voluntary agreements between landholders and government agencies. This study examined: the extent to which landholders in three catchment management authority (CMA) regions in south east Australia maintain stock exclusion from waterways, whether vegetation on riverbanks recovered, and the effectiveness of assessment methods. It was found that nearly half of landholders continue to graze stock on the riverbank. There has been some success with improving the condition of riparian vegetation. Sites with full stock exclusion contain the pre-European abundance of juvenile trees, and, sites with continued grazing contain significantly lower abundance of juvenile trees. Establishing the effectiveness of management was made more difficult by the inconsistent methods used by the different CMAs. Stock exclusion projects implemented using voluntary agreements have the potential to succeed if overseeing is improved between government agencies and CMAs, and between CMAs and landholders. Projects will be easier to assess if regional authorities use consistent methods of assessment. Voluntary agreements are only Page 1 of 35 Integrated Environmental Assessment and Management 2 suitable for environmental management if projects are monitored, maintained, and assessed appropriately.
Drones offer a means to survey river channels in high resolution, providing a unique perspective ... more Drones offer a means to survey river channels in high resolution, providing a unique perspective of the riverine network and an enhanced ability to survey in-channel features. Structure from Motion (SfM) is a photogrammetric range imaging technique which was implemented to capture the three-dimensional structure of geomorphic units within headwater ephemeral channels in the Pilbara, Western Australia. The SfM method is becoming more frequently used as a cost-effective surveying method in remote or difficult terrain. The precision of SfM relies on a high-density network of ground control points to validate measurements but can yield results within centimetre or even millimetre accuracy. A series of headwater channels were examined within the semi-arid Pilbara to understand their diversity and associated geomorphic units. SfM surveys combined with traditional RTK methods were carried out to understand and identify the range of geomorphic units; bars, benches and anabranches within small remote river channels. The SfM approach yielded high resolution ground sampling of one point per centimetre and an average vertical accuracy of under 5cm. Dense point clouds were created and then used to characterise the river channels using channel geometry measurements to distinguish ephemeral channel types and associated local variable controls. This technique enabled identification of geomorphic units and their boundary conditions, at a resolution which was not possible using other surveying methods.
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