Rivers and Wetlands Unit

Goulburn, Australia

Rivers and Wetlands Unit

Goulburn, Australia
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Rogers K.,University of Wollongong | Saintilan N.,Rivers and Wetlands Unit | Colloff M.J.,CSIRO | Wen L.,Rivers and Wetlands Unit
Environmental Monitoring and Assessment | Year: 2013

We propose a framework in which thresholds of potential concern (TPCs) and limits of acceptable change (LACs) are used in concert in the assessment of wetland condition and vulnerability and apply the framework in a case study. The lower Murrumbidgee River floodplain (the 'Lowbidgee') is one of the most ecologically important wetlands in Australia and the focus of intense management intervention by State and Federal government agencies. We used a targeted management stakeholder workshop to identify key values that contribute to the ecological significance of the Lowbidgee floodplain, and identified LACs that, if crossed, would signify the loss of significance. We then used conceptual models linking the condition of these values (wetland vegetation communities, waterbirds, fish species and the endangered southern bell frog) to measurable threat indicators, for which we defined a management goal and a TPC. We applied this framework to data collected across 70 wetland storages', or eco-hydrological units, at the peak of a prolonged drought (2008) and following extensive re-flooding (2010). At the suggestion of water and wetland mangers, we neither aggregated nor integrated indices but reported separately in a series of chloropleth maps. The resulting assessment clearly identified the effect of rewetting in restoring indicators within TPC in most cases, for most storages. The scale of assessment was useful in informing the targeted and timely management intervention and provided a context for retaining and utilising monitoring information in an adaptive management context. © 2013 Springer Science+Business Media Dordrecht.


Rogers K.,University of Wollongong | Saintilan N.,Rivers and Wetlands Unit | Copeland C.,Conservation Action Unit
Ecological Modelling | Year: 2013

Empirical data derived from a network of surface elevation tables established on the Hunter River, Australia, in 2000 was used to model sediment accretion within estuarine wetlands using factorial analysis of variance. As surface elevation change did not differ significantly from accretion over the 10 year study period in the mangrove and saltmarsh (p=0.4104), the accretion model was regarded as a reliable estimate of elevation change. Using the current rate of sea-level rise (3.65mmy-1), a rate deemed to be relatively moderate, a landscape elevation model was developed by applying the accretion model to a LiDAR-derived digital elevation model at annual increments to 2050. Based on current rates of sea-level rise and the intertidal elevation that currently supports mangrove and saltmarsh, the landscape elevation model projected a 16% increase in the area within the elevation range suitable to support mangrove and saltmarsh. This contrasts 'bathtub modelling', which projected a 6% decline in wetland extent. Bathtub modelling fails to account for the ability of mangrove and saltmarsh to accommodate sea-level rise through processes of accretion, shrink-swell of sediments and the accumulation of organic material. Results from the landscape elevation model suggest that planning for sea-level rise should be directed towards facilitating wetland adaptation by promoting tidal exchange to mangrove and saltmarsh and providing land for wetland migration. © 2012 Elsevier B.V.


Rogers K.,University of Wollongong | Ralph T.J.,Macquarie University | Saintilan N.,Rivers and Wetlands Unit
Wetlands | Year: 2012

The complex task of determining the inundation requirements of large floodplain wetlands is often simplified through the use of representative, umbrella or flagship species. This subset of species is targeted based on the assumption that their collective inundation requirements serve as a surrogate for the broader suite of species found within the wetland. We tested the application of representative species commonly used in wetland and water management planning in the Murray-Darling Basin. In a review of the water requirements of 155 plants and animals, we collated information on preferred inundation timing, duration, depth, rate of rise and fall, and inter-flood period for 115 species. We then used cluster analysis to determine the extent to which ten commonly used representative species corresponded in inundation requirements to the broader suite of species. We found that the habitat surrogates of river red gum, black box, spike rush, coolibah, water couch, lignum and marsh clubrush represented only one third of species at a 60% level of similarity in inundation requirements, due mainly to the lower inundation return period and duration required by the habitat surrogates. The addition of faunal representative species facilitated the inclusion of a broader range of requirements, though primarily amongst related taxa. We recommend the inclusion of several additional indicator species to more adequately cover the inundation requirements of large wetland ecosystems. © Society of Wetland Scientists 2012.


Rogers K.,University of Wollongong | Saintilan N.,Rivers and Wetlands Unit | Copeland C.,Conservation Action Unit
Ecological Modelling | Year: 2012

Empirical data derived from a network of surface elevation tables established on the Hunter River, Australia, in 2000 was used to model sediment accretion within estuarine wetlands using factorial analysis of variance. As surface elevation change did not differ significantly from accretion over the 10 year study period in the mangrove and saltmarsh (p=0.4104), the accretion model was regarded as a reliable estimate of elevation change. Using the current rate of sea-level rise (3.65mmy -1), a rate deemed to be relatively moderate, a landscape elevation model was developed by applying the accretion model to a LiDAR-derived digital elevation model at annual increments to 2050. Based on current rates of sea-level rise and the intertidal elevation that currently supports mangrove and saltmarsh, the landscape elevation model projected a 16% increase in the area within the elevation range suitable to support mangrove and saltmarsh. This contrasts 'bathtub modelling', which projected a 6% decline in wetland extent. Bathtub modelling fails to account for the ability of mangrove and saltmarsh to accommodate sea-level rise through processes of accretion, shrink-swell of sediments and the accumulation of organic material. Results from the landscape elevation model suggest that planning for sea-level rise should be directed towards facilitating wetland adaptation by promoting tidal exchange to mangrove and saltmarsh and providing land for wetland migration. © 2012 Elsevier B.V.


Rogers K.,University of Wollongong | Saintilan N.,Rivers and Wetlands Unit | Copeland C.,Australian Department of Primary Industries and Fisheries
Estuaries and Coasts | Year: 2014

We analyse the potential impacts of sea-level rise on the management of saline coastal wetlands in the Hunter River estuary, NSW, Australia. We model two management options: leaving all floodgates open, facilitating retreat of mangrove and saltmarsh into low-lying coastal lands; and leaving floodgates closed. For both management options we modelled the potential extent of saline coastal wetland to 2100 under a low sea-level rise scenario (based on 5 % minima of SRES B1 emissions scenario) and a high sea-level rise scenario (based on 95 % maxima of SRES A1FI emissions scenario). In both instances we quantified the carbon burial benefits associated with those actions. Using a dynamic elevation model, which factored in the accretion and vertical elevation responses of mangrove and saltmarsh to rising sea levels, we projected the distribution of saline coastal wetlands, and estimated the volume of sediment and carbon burial across the estuary under each scenario. We found that the management of floodgates is the primary determinant of potential saline coastal wetland extent to 2100, with only 33 % of the potential wetland area remaining under the high sea-level rise scenario, with floodgates closed, and with a 127 % expansion of potential wetland extent with floodgates open and levees breached. Carbon burial was an additional benefit of accommodating landward retreat of wetlands, with an additional 280,000 tonnes of carbon buried under the high sea-level rise scenario with floodgates open (775,075 tonnes with floodgates open and 490,280 tonnes with floodgates closed). Nearly all of the Hunter Wetlands National Park, a Ramsar wetland, will be lost under the high sea-level rise scenario, while there is potential for expansion of the wetland area by 35 % under the low sea-level rise scenario, regardless of floodgate management. We recommend that National Parks, Reserves, Ramsar sites and other static conservation mechanisms employed to protect significant coastal wetlands must begin to employ dynamic buffers to accommodate sea-level rise change impacts, which will likely require land purchase or other agreements with private landholders. The costs of facilitating adaptation may be offset by carbon sequestration gains. © 2013 Coastal and Estuarine Research Federation.


Saintilan N.,Rivers and Wetlands Unit
Wetlands | Year: 2012

The paper introduces a Special Feature ofWetlands concerned with the ecology and management of the Murray Darling Basin, Australia. The Murray and Darling River systems in SE Australia combine to form the largest draining basin on the continent and the most economically important. The river system supports 16 wetlands listed as internationally important under the Ramsar convention, and sustains nationally significant populations of waterbirds, and endemic flora and fauna. Many of these values have been threatened by the development of water resources, particularly in the southern tributaries, and the diversion of water for irrigated agriculture. The restoration of ecological health within the Murray Darling is contingent on the optimal use of water reserved for environmental use. This objective can only be achieved through the development and application of quantitative, testable models linking environmental water regimes to ecological outcomes. This Special Feature of Wetlands explores the use of evidence in support of environmental water management, with papers considering the standards of evidence, the testing of assumptions relating to indicator species, the formulation of empirically-based flow-response models and the incorporation of these relationships in decision support tools. The further testing and development of quantitative predictive models is advocated as a key objective of environmental flow monitoring. © Society of Wetland Scientists 2012.


Wen L.,Rivers and Wetlands Unit | Rogers K.,Rivers and Wetlands Unit | Ling J.,Rivers and Wetlands Unit | Saintilan N.,Rivers and Wetlands Unit
Journal of Hydrology | Year: 2011

This study demonstrated that the Standardised Flow Index (SFI) was a simple and useful tool to research, monitor and manage hydrologic drought in a highly regulated river system, the Murrumbidgee River in southeast Australia. To validate the applicability of the theory underlining the widely used Standardised Precipitation Index (SPI) to river discharge data, we investigated the probability distribution of the time series of monthly river discharge month by month using long-term (over 100. years) river flow records. Our results showed that the Gamma probability distribution function was adequate to describe and model the skewed river flow data. The generalised additive models (GAM) with Locally Estimated Scattersplot Smoothing (LOESS) additive terms were applied to the computed SFI and SPI sequences to investigate the impacts of river regulation and water diversion on the duration and magnitude of hydrologic droughts in Lower Murrumbidgee River from 1890. The results revealed that upstream regulations had successfully reduced the drought severity at Wagga Wagga, a weir located downstream of the two major dams but immediately upstream of the major irrigation areas. However, the hydrological benefits of river regulation gradually disappeared as the river travels downstream and more and more water abstracted. At Balranald, the end valley weir, hydrologic drought was progressively aggravated during the modelling period, and the impacts were greater during drier periods. The results of the study highlighted the importance of balancing the needs between upstream and downstream water users in river management. © 2011 Elsevier B.V.


Saintilan N.,Rivers and Wetlands Unit | Wen L.,Rivers and Wetlands Unit
Estuarine, Coastal and Shelf Science | Year: 2012

The regulation of freshwater flow into estuaries has been identified as a potential threat to estuarine ecosystem structure and function, and the productivity of fisheries in particular. Correlative studies are one means by which associations between freshwater inputs and commercial landings have been identified. The study compared monthly landings of five species of finfish and two species of crustacean with monthly and 6-month running means of river discharge, climatic variables (temperature and rainfall) and the area of vegetated habitat (saltmarsh, mangrove and seagrass) for 11 temperate estuaries on the NSW coast. The monthly climatic and discharge record covered a 10-year period (1997-2007). High river discharge and rainfall were associated with higher catches of flathead (Platycephalus spp.) and Mullet (Mugil spp.), a result consistent with subtropical estuaries to the north. We found no relationships between landings and river discharge for any of the other species, which included school prawns (Metapenaeus macleayi). Temporal variability at a monthly time-step was more consistently associated with variation in temperature, reflecting seasonal variation in activity, and possibly fishing effort. Landings of several species showed strong habitat relationships, with greater seagrass area consistently associated with higher catches of blue swimmer crab (Portunis pelagicus), and intertidal wetlands (mangrove and saltmarsh) with mud crab (Scylla serrata), school prawns, flathead, and mullet (Mugil spp.), a result consistent with habitat-scale surveys. The results draw into question the efficacy of dam releases as stimulants of fisheries productivity in the region, although the effects of flow on juvenile populations and catadromous species were not studied. © 2012 Elsevier Ltd.


PubMed | Rivers and Wetlands Unit
Type: Journal Article | Journal: Environmental monitoring and assessment | Year: 2011

The monitoring of resource condition is receiving renewed attention across several levels of government in Australia. This interest is linked to substantial investment in environmental remediation and aquatic ecosystem restoration in particular. In this context, it is timely to consider principles which ought to guide the development and implementation of monitoring programmes for wetland ecosystems. A framework is established which places monitoring in the context of the strategic adaptive management of wetlands. This framework requires there has to be clear goals for the extent and condition of the resource, with these goals being defined within thresholds of acceptable variability. Qualitative and, where possible, quantitative conceptual models linking management interventions to management goals should be the basis of indicator selection and assessment. The intensity of sampling ought to be informed by pilot surveys of statistical power in relation to the thresholds of acceptable variability identified within the management plan.


Saintilan N.,Rivers and Wetlands Unit
Environmental Monitoring and Assessment | Year: 2012

The monitoring of resource condition is receiving renewed attention across several levels of government in Australia. This interest is linked to substantial investment in environmental remediation and aquatic ecosystem restoration in particular. In this context, it is timely to consider principles which ought to guide the development and implementation of monitoring programmes for wetland ecosystems. A framework is established which places monitoring in the context of the strategic adaptive management of wetlands. This framework requires there has to be clear goals for the extent and condition of the resource, with these goals being defined within thresholds of acceptable variability. Qualitative and, where possible, quantitative conceptual models linking management interventions to management goals should be the basis of indicator selection and assessment. The intensity of sampling ought to be informed by pilot surveys of statistical power in relation to the thresholds of acceptable variability identified within the management plan. © 2011 Springer Science+Business Media B.V.

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