ORCID Profile
0000-0001-8386-4354
Current Organisation
University of Western Australia
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Geochemistry | Isotope Geochemistry | Ecosystem Function | Ecology | Marine and Estuarine Ecology (incl. Marine Ichthyology) | Surfacewater Hydrology | Environmental Engineering Modelling | Inorganic Geochemistry | Wastewater Treatment Processes | Fish physiology and genetics | Geochronology And Isotope Geochemistry | Surfacewater Hydrology | Environmental Chemistry (incl. Atmospheric Chemistry) | Environmental Management | Environmental Monitoring | Conservation And Biodiversity | Freshwater Ecology | Water Resources Engineering | Environmental Science and Management | Ecological Applications | Environmental Technologies | Environmental Engineering | Civil Engineering | Hydrology | Ecohydrology | Environmental Chemistry (Incl. Atmospheric Chemistry) | Animal Physiology—Systems | Ecological impacts of climate change and ecological adaptation | Environmental Sciences Not Elsewhere Classified |
ANZSRC Socio-Economic Objective (SEO)
Physical and Chemical Conditions of Water in Coastal and Estuarine Environments | Physical and Chemical Conditions of Water in Fresh, Ground and Surface Water Environments (excl. Urban and Industrial Use) | Ecosystem Assessment and Management of Coastal and Estuarine Environments | Ecosystem Assessment and Management of Fresh, Ground and Surface Water Environments | Estuarine and lagoon areas | Rehabilitation of degraded coastal and estuarine areas | Urban Water Evaluation (incl. Water Quality) | Global climate change adaptation measures | Sustainability Indicators | Rural Water Evaluation (incl. Water Quality) | Ecosystem Adaptation to Climate Change | Coastal and Estuarine Land Management | Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Living resources (flora and fauna) | Physical and chemical conditions | Mountain and High Country Land and Water Management | Coastal and Estuarine Water Management | Ecosystem Assessment and Management of Marine Environments
Related Links
Publications
Sediment diagenesis models: Review of approaches, challenges and opportunities
Publisher: Elsevier BV
Date: 11-2014
A Spatially Integrated Dissolved Inorganic Carbon (SiDIC) Model for Aquatic Ecosystems Considering Submerged Vegetation
Publisher: American Geophysical Union (AGU)
Date: 02-2023
DOI: 10.1029/2022JG007032
Abstract: Net ecosystem production (NEP) by submerged aquatic vegetation plays a substantial role in capturing atmospheric carbon dioxide into aquatic ecosystems. In lakes and estuaries, the net uptake of carbon dioxide by submerged aquatic vegetation is mediated by stratification of the water column which suppresses the vertical flux of carbon dioxide between the upper and lower layers. The presence of submerged aquatic vegetation can also affect the strength of stratification such that the interactions between vegetation, stratification, and NEP can moderate the carbon dioxide emissions. Since stratification can occur in lakes and estuaries, there is need for a new numerical approach able to consider the effect of submerged aquatic vegetation on stratification, NEP, and carbon dioxide. This study aims to develop a model to investigate how stratification, mediated by vegetation density and flexibility, affects the partial pressure of carbon dioxide ( p CO 2 ) and dissolved inorganic carbon (DIC). After initial parameterization of coefficients based on experimental work, horizontal and vertical variations in DIC were successfully modeled by a spatially (horizontally) integrated DIC (SiDIC) model, which was validated with field observations from an estuarine and freshwater lake case study. The SiDIC model was able to reproduce the p CO 2 changes between daytime and nighttime throughout the water column. Sensitivity tests showed that the fluctuation of p CO 2 was controlled by the suppression of stratification due to the density of submerged aquatic vegetation. The results highlight the importance of resolving vegetation‐induced stratification when modeling the carbon budget within freshwater lakes and coastal environments.
Examination of the role of the microbial loop in regulating lake nutrient stoichiometry and phytoplankton dynamics
Publisher: Copernicus GmbH
Date: 05-06-2014
Abstract: Abstract. The recycling of organic material through bacteria and microzooplankton to higher trophic levels, known as the "microbial loop", is an important process in aquatic ecosystems. Here the significance of the microbial loop in influencing nutrient supply to phytoplankton has been investigated in Lake Kinneret (Israel) using a coupled hydrodynamic–ecosystem model. The model was designed to simulate the dynamic cycling of carbon, nitrogen and phosphorus through bacteria, phytoplankton and zooplankton functional groups, with each pool having unique C : N : P dynamics. Three microbial loop sub-model configurations were used to isolate mechanisms by which the microbial loop could influence phytoplankton biomass, considering (i) the role of bacterial mineralisation, (ii) the effect of micrograzer excretion, and (iii) bacterial ability to compete for dissolved inorganic nutrients. The nutrient flux pathways between the abiotic pools and biotic groups and the patterns of biomass and nutrient limitation of the different phytoplankton groups were quantified for the different model configurations. Considerable variation in phytoplankton biomass and dissolved organic matter demonstrated the sensitivity of predictions to assumptions about microbial loop operation and the specific mechanisms by which phytoplankton growth was affected. Comparison of the simulations identified that the microbial loop most significantly altered phytoplankton growth by periodically lifying internal phosphorus limitation due to bacterial competition for phosphate to satisfy their own stoichiometric requirements. Importantly, each configuration led to a unique prediction of the overall community composition, and we conclude that the microbial loop plays an important role in nutrient recycling by regulating not only the quantity, but also the stoichiometry of available N and P that is available to primary producers. The results demonstrate how commonly employed simplifying assumptions about model structure can lead to large uncertainty in phytoplankton community predictions and highlight the need for aquatic ecosystem models to carefully resolve the variable stoichiometry dynamics of microbial interactions.
Climate change overtakes coastal engineering as the dominant driver of hydrological change in a large shallow lagoon
Publisher: Copernicus GmbH
Date: 27-11-2020
DOI: 10.5194/HESS-24-5673-2020
Abstract: Abstract. Ecosystems in shallow micro-tidal lagoons are particularly sensitive to hydrologic changes. Lagoons are complex transitional ecosystems between land and sea, and the signals of direct human disturbance can be confounded by variability of the climate system, but from an effective estuary management perspective, the effects of climate versus direct human engineering interventions need to be identified separately. This study developed a 3D finite-volume hydrodynamic model to assess changes in hydrodynamics of the Peel–Harvey Estuary, a large shallow lagoon with restricted connection with ocean this was done by considering how attributes such as water retention time, salinity and stratification have responded to a range of factors, focusing on the drying climate trend and the opening of a large artificial channel over the period from 1970 to 2016, and how they will evolve under current climate projections. The results show that the introduction of the artificial channel has fundamentally modified the flushing and mixing within the lagoon, and the drying climate has changed the hydrology by comparable magnitudes to that of the opening of the artificial channel. The results also highlight the complexity of their interacting impacts. Firstly, the artificial channel successfully improved the estuary flushing by reducing average water ages by 20–110 d, while in contrast the reduced precipitation and catchment inflow had a gradual opposite effect on the water ages during the wet season this has almost counteracted the reduction brought about by the channel. Secondly, the drying climate caused an increase in the salinity of the lagoon by 10–30 PSU (Practical Salinity Unit) whilst the artificial channel increased the salinity during the wet season, it has reduced the likelihood of hypersalinity ( PSU) during the dry season in some areas. The opening of the artificial channel was also shown to increase the seawater fluxes and salinity stratification, while the drying climate acted to reduce the salinity stratification in the main body of the estuary. The impacts also varied spatially in this large lagoon. The southern estuary, which has the least connection with the ocean through the natural channel, is the most sensitive to climate change and the opening of the artificial channel. The projected future drying climate is shown to slightly increase the retention time and salinity in the lagoon and increase the hypersalinity risk in the rivers. The significance of these changes for nutrient retention and estuary ecology are discussed, highlighting the importance of these factors when setting up monitoring programmes, environmental flow strategies and nutrient load reduction targets.
Land-use intensity alters both the source and fate of CO2 within eight sub-tropical estuaries
Publisher: Elsevier BV
Date: 2020
Modeling dissolved inorganic carbon considering submerged aquatic vegetation
Publisher: Elsevier BV
Date: 09-2020
Moving up or going under? Differential livelihood trajectories in coastal communities in Vietnam
Publisher: Elsevier BV
Date: 02-2021
A Modeling Approach for Addressing Sensitivity and Uncertainty of Estuarine Greenhouse Gas (CO2 and CH4) Dynamics
Publisher: American Geophysical Union (AGU)
Date: 06-2022
DOI: 10.1029/2021JG006722
Abstract: Estuaries make an important contribution to the global greenhouse gas budget. Yet modeling predictions of carbon dioxide (CO 2 ) and methane (CH 4 ) emissions from estuaries remain highly uncertain due to both simplified assumptions about the underpinning hydrologic and biologic processes and inadequate data availability to uniquely define parameters related to CO 2 and CH 4 processes. This study presents a modeling framework to quantify the sensitivity and uncertainty of predicted CO 2 and CH 4 concentrations and emissions, which is demonstrated through application to a subtropical urban estuary (Brisbane River, Australia). A 3D hydrodynamic‐biogeochemical model was constructed, and calibrated using the model‐independent Parameter ESTimation software (PEST) with field data sets that captured strong gradients of CO 2 and CH 4 concentrations and emissions along the estuary. The approach refined uncertainty in the estimation of whole‐estuary annual emissions, and enabled us to assess the sensitivity and uncertainty of CO 2 and CH 4 dynamics. Estuarine CO 2 concentrations were most sensitive to uncertainty in riverine inputs, whereas estuarine CH 4 concentrations were most sensitive to sediment production and pelagic oxidation. Over the modeled year, variance in the daily fluctuations in carbon emissions from this case‐study spanned the full range of emission rates reported for estuaries around the world, highlighting that spatially or temporally limited s ling regimes could significantly bias estuarine greenhouse gas emission estimates. The combination of targeted field c aigns with the modeling approach presented in this study can help to improve carbon budgeting in estuaries, reduce uncertainty in emission estimates, and support management strategies to reduce or offset estuary greenhouse gas emissions.
The development and application of improved solids modelling to enable resilient urban sewer networks
Publisher: Elsevier BV
Date: 06-2019
DOI: 10.1016/J.JENVMAN.2019.03.120
Abstract: Decreasing per capita water consumption in several OECD countries has led to a notable flow reduction into sewer systems. However, sewers still transport similar quantities of solids and pollutants, leading to increased wastewater concentration and, potentially, excess solids deposition. The shift towards decentralised water schemes in cities and widely reported changes in rainfall patterns cast additional uncertainty on future wastewater quality and flows into sewers. Excess solids deposition in sewers can cause increased environmental pollution risks at Combined Sewer Overflows from solids resuspension and reduced sewer hydraulic capacities. This review analyses the magnitude of excess solids deposition due to changing wastewater composition and evaluates current approaches to modelling sewer solids. Gaps in commonly used modelling approaches for deposited bed processes, specifically in bed consolidation and bed particle cohesion processes, and gross solids transport were identified and addressed to enable better solids risk prediction and management.
The role of bioirrigation in sediment phosphorus dynamics and blooms of toxic cyanobacteria in a temperate lagoon
Publisher: Elsevier BV
Date: 12-2016
Invasive macrophytes control the spatial and temporal patterns of temperature and dissolved oxygen in a shallow lake: A proposed feedback mechanism of macrophyte loss
Publisher: Frontiers Media SA
Date: 08-12-2017
Chapter 7 Peel-Harvey Estuary, Western Australia
Publisher: Elsevier
Date: 2019
Tracing environmental and livelihood dynamics in a tropical coastal lagoon through the lens of multiple adaptive cycles
Publisher: Resilience Alliance, Inc.
Date: 2020
Twenty-three unsolved problems in hydrology (UPH) – a community perspective
Publisher: Informa UK Limited
Date: 02-07-2019
A prototype framework for models of socio-hydrology: identification of key feedback loops with application to two Australian case-studies
Publisher: Copernicus GmbH
Date: 14-01-2014
DOI: 10.5194/HESSD-11-629-2014
Abstract: Abstract. It is increasingly acknowledged that, in order to sustainably manage global freshwater resources, it is critical that we better understand the nature of human-hydrology interactions at the broader catchment system-scale. Yet to date, a generic conceptual framework for building models of catchment systems that include adequate representation of socioeconomic systems – and the dynamic feedbacks between human and natural systems – has remained elusive. In an attempt to work towards such a model, this paper outlines a generic framework for a model of socio-hydrology that posits a novel construct, a composite Community Sensitivity state variable, as a key link to elucidate the drivers of behavioural response in a hydrological context. The framework provides for both macro-scale contextual parameters, which allow it to be applied across climate, socioeconomic and political gradients, and catchment-specific conditions, by way of tailored "closure relationships", in order to ensure that site-specific and application-specific contexts of socio-hydrologic problems can be accommodated. To demonstrate how such a framework would be applied, two different socio-hydrological case studies, taken from the Australian experience, are presented and discussed. It is envisioned that the application of this framework across study sites and gradients will aid in developing our understanding of the fundamental interactions and feedbacks in such complex human-hydrology systems, and allow hydrologists to participate in the growing field of social-ecological systems modelling.
SewerSedfoam: A model for free surface flow, sediment transport, and deposited bed morphology in sewers
Publisher: MDPI AG
Date: 17-01-2020
DOI: 10.3390/W12010270
Abstract: This paper aims to bridge the gap in the detailed modelling of flow and sediment process interactions in sewers through the development of a computational fluid dynamics (CFD) model. It draws on previous models developed for surface water sediment transport in the OpenFOAM CFD framework and builds on them to improve their suitability for sewer sediment processes. Three distinct sediment processes, suspended sediment transport, bedload transport, and deposited bed morphology, are incorporated into a free surface flow solver, interFoam. This sewer sediment model, called SewerSedFoam, models the impacts of sediment deposition and erosion on flow velocity by using dynamic mesh deformation to capture the movement of the deposited bed and its morphology. Further, three sediment classes, two suspended and one bedload sediment, can be modelled along with some bed stabilization and consolidation effects during deposition and erosion, respectively. The functionality of the overall model in modelling sewer sediment deposition and erosion is promising, although the validation of a large magnitude sediment erosion event has been limited by the availability of granular data in existing case studies.
A Numerical and Field Investigation of Surface Heat Fluxes from Small Wind-Sheltered Waterbodies in Semi-Arid Western Australia
Publisher: Springer Science and Business Media LLC
Date: 2004
Insights of greenhouse gases (CO2, CH4 and N2O) dynamics in sub-tropical estuaries from a coupled hydrodynamic-biogeochemical estuarine model
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-14382
Abstract: & & Coastal waters are typically productive aquatic ecosystems and play an important role in the global greenhouse gas (GHG) budget. However, the uncertainty in the estimation of GHG emission from estuaries remains large due to significant variability in GHG concentrations in time and space. This study aimed to provide a more accurate estimation of GHG emissions from sub-tropical estuaries by validating and analyzing results from a 3D hydrodynamic-biogeochemical model used to capture the temporal and spatial dynamics of the major GHG (CO& sub& & /sub& CH& sub& & /sub& , and N& sub& & /sub& O). The model was applied to the Brisbane, Maroochy, and Noosa Estuary in Queensland, Australia, representing systems under high, median, and low human impacts, and was validated with datasets from long-term monitoring stations and field c aigns along the freshwater-marine continuum. Distinct spatial heterogeneity of GHG distribution was found with the upstream acting as a hotspot for emission to the atmosphere, despite this area occupying a relatively small portion of the rivers. Seasonal variations of & em& & /em& CO& sub& & /sub& at the surface were driven mostly by the changes in water temperature and DIC concentrations, while strong diurnal variation was also found, driven by the changes related to tidal forcing. All GHG showed distinct signatures in the three rivers, related to trophic statues and hydrology. The model allowed us to approximate the fraction of incoming carbon and nitrogen that was lost to the atmosphere as GHG emissions, which is a step towards improving regional and national GHG budgets. A link of the biogeochemical model to a parameter optimization software PEST is being used to assist in uncertainty analysis from the model outputs.& &
Drying microclimates threaten persistence of natural and translocated populations of threatened frogs
Publisher: Springer Science and Business Media LLC
Date: 27-10-2021
DOI: 10.1007/S10531-020-02064-9
Abstract: Defining species habitat requirements is essential for effective conservation management through revealing agents of population decline and identifying critical habitat for conservation actions, such as translocations. Here we studied the habitat-associations of two threatened terrestrial-breeding frog species from southwestern Australia, Geocrinia alba and Geocrinia vitellina , to investigate if fine-scale habitat variables explain why populations occur in discrete patches, why G. alba is declining, and why translocation attempts have had mixed outcomes. We compared habitat variables at sites where the species are present, to variables at immediately adjacent sites where frogs are absent, and at sites where G. alba is locally extinct. Dry season soil moisture was the most important predictor of frog abundance for both species, and explained why G. alba had become extinct from some areas. Sites where G. alba were present were also positively associated with moss cover, and negatively with bare ground and soil conductivity. Modelling frog abundance based exclusively on dry season soil moisture predicted recent translocation successes with high accuracy. Hence, considering dry season soil moisture when selecting future translocation sites should increase the probability of population establishment. We propose that a regional drying trend is the most likely cause for G. alba declines and that both species are at risk of further habitat and range contraction due to further projected regional declines in rainfall and groundwater levels. More broadly, our study highlights that conservation areas in drying climates may not provide adequate protection and may require interventions to preserve critical habitat.
A system of metrics for the assessment and improvement of aquatic ecosystem models
Publisher: Elsevier BV
Date: 06-2020
Surface water as a cause of land degradation from dryland salinity
Publisher: Copernicus GmbH
Date: 23-08-2019
Abstract: Abstract. Secondary dryland salinity is a global land degradation issue. Because drylands are often less-developed, less-well instrumented and less-well understood, we often adapt and impose an understanding from different hydro-geomorphological settings. Dryland catchments are likely to exhibit some functional qualities of wet and hydrologically-connected landscapes, but also those more typical of flat and arid rangelands, smooth plainlands and deserts, where flow (dis)connectivity is an important feature. The functional hydrological mechanisms used to conceptualise causes of dryland salinity, originate from wet and more hydrologically-connected landscapes. They are then imposed with adjustments for rainfall and streamflow quantity to describe how hillslope-recharge processes interact with groundwater to cause dryland salinity. The pervasive understanding concludes that low flow yield from the end-of-catchment gauging stations indicates that land clearing alters water balance in favour of increased infiltration and rising groundwater that bring salts to the surface, causing land degradation from dryland salinity. This paper presents data from an intra-catchment surface flow gauging network run for six years and a surface water–groundwater interaction site to assess the adequacy of our conceptual understanding of secondary dryland salinity in environments with low gradients and runoff yield. The aim is to (re)conceptualise pathways of water and salt redistribution in dryland landscapes, to investigate the role that surface water flows and connectivity plays in land degradation from salinity in low-gradient drylands. Based on the long-term end-of-catchment gauge, average annual runoff yield is only 0.14 % of rainfall. The internal gauging network operated from 2007–2012 found pulses of internal water (also mobilising salt) in years when no flow was recorded at the catchment outlet. Data from a surface water–groundwater interaction site shows top-down recharge of surface water early in the water year, that transitions to a bottom-up system of discharge later in the water year. This connection provides a mechanism for the vertical diffusion of salts to the surface waters, followed by evapo-concentration and downstream export when depression storage thresholds are exceeded. Intervention in this landscape by constructing a broad-based channel to address these processes, resulted in a 25 % increase in flow volume and a 20 % reduction in salinity, by allowing the lower catchment to more effectively support bypassing of the storages in the lower landscape that would otherwise retain water and allow salt to accumulate. Results from this study suggests catchment internal redistribution of relatively fresh runoff onto the valley floor is a major contributor to development of secondary dryland salinity. Seasonally inundated areas are subject to significant transmission losses and drive processes of vertical salt mobility. These surface flow and connectivity processes are not acting in isolation to cause secondary salinity, but are also interact with groundwater systems responding to land clearing and processes recognised in the more conventional understanding of hillslope recharge and groundwater discharge. The study landscape appears to have three functional hydrological components: upland, hillslope flow landscapes that generate fresh runoff valley floor fill landscapes with high transmission losses and poor flow connectivity controlled by the micro-topography that promotes surface–groundwater connection and salt movement and the downstream flood landscapes, where flows are recorded only when internal storages (fill landscapes) are exceeded. This work highlights the role of surface water processes as a contributor to land degradation by dryland salinity in low-gradient landscapes.
Hydrodynamic controls on oxygen dynamics in a riverine salt wedge estuary, the Yarra River estuary, Australia
Publisher: Copernicus GmbH
Date: 10-04-2014
DOI: 10.5194/HESS-18-1397-2014
Abstract: Abstract. Oxygen depletion in coastal and estuarine waters has been increasing rapidly around the globe over the past several decades, leading to decline in water quality and ecological health. In this study we apply a numerical model to understand how salt wedge dynamics, changes in river flow and temperature together control oxygen depletion in a micro-tidal riverine estuary, the Yarra River estuary, Australia. Coupled physical–biogeochemical models have been previously applied to study how hydrodynamics impact upon seasonal hypoxia however, their application to relatively shallow, narrow riverine estuaries with highly transient patterns of river inputs and sporadic periods of oxygen depletion has remained challenging, largely due to difficulty in accurately simulating salt wedge dynamics in morphologically complex areas. In this study we overcome this issue through application of a flexible mesh 3-D hydrodynamic–biogeochemical model in order to predict the extent of salt wedge intrusion and consequent patterns of oxygen depletion. The extent of the salt wedge responded quickly to the sporadic riverine flows, with the strength of stratification and vertical density gradients heavily influenced by morphological features corresponding to shallow points in regions of tight curvature ("horseshoe" bends). The spatiotemporal patterns of stratification led to the emergence of two "hot spots" of anoxia, the first downstream of a shallow region of tight curvature and the second downstream of a sill. Whilst these areas corresponded to regions of intense stratification, it was found that antecedent conditions related to the placement of the salt wedge played a major role in the recovery of anoxic regions following episodic high flow events. Furthermore, whilst a threshold salt wedge intrusion was a requirement for oxygen depletion, analysis of the results allowed us to quantify the effect of temperature in determining the overall severity and extent of hypoxia and anoxia. Climate warming scenarios highlighted that oxygen depletion is likely to be exacerbated through changes in flow regimes and warming temperatures however, the increasing risk of hypoxia and anoxia can be mitigated through management of minimum flow allocations and targeted reductions in organic matter loading. A simple statistical model (R2 0.65) is suggested to relate riverine flow and temperature to the extent of estuary-wide anoxia.
Ensuring consideration of water quality in nexus approaches in the science–practice continuum: reply to discussion of “Water quality: the missing dimension of water in the water–energy–food nexus?”
Publisher: Informa UK Limited
Date: 08-06-2022
Surface water as a cause of land degradation from dryland salinity
Publisher: Copernicus GmbH
Date: 17-02-2020
Abstract: Abstract. Secondary dryland salinity is a global land degradation issue. Drylands are often less developed, less well instrumented and less well understood, requiring us to adapt and impose understanding from different hydro-geomorphological settings that are better instrumented and understood. Conceptual models of secondary dryland salinity, from wet and more hydrologically connected landscapes imposed with adjustments for rainfall and streamflow, have led to the pervasive understanding that land clearing alters water balance in favour of increased infiltration and rising groundwater that bring salts to the surface. This paper presents data from an intra-catchment surface flow gauging network run for 6 years and a surface-water–groundwater (SW–GW) interaction site to assess the adequacy of our conceptual understanding of secondary dryland salinity in environments with low gradients and runoff yield. The aim is to (re-)conceptualise pathways of water and salt redistribution in dryland landscapes and to investigate the role that surface water flows and connectivity plays in land degradation from salinity in low-gradient drylands. Based on the long-term end-of-catchment gauge, average annual runoff yield is only 0.14 % of rainfall. The internal gauging network that operated from 2007–2012 found pulses of internal water (also mobilising salt) in years when no flow was recorded at the catchment outlet. Data from a surface-water–groundwater interaction site show top-down recharge of surface water early in the water year that transitions to a bottom-up system of discharge later in the water year. This connection provides a mechanism for the vertical diffusion of salts to the surface waters, followed by evapo-concentration and downstream export when depression storage thresholds are exceeded. Intervention in this landscape by constructing a broad-based channel to address these processes resulted in a 25 % increase in flow volume and a 20 % reduction in salinity by allowing the lower catchment to more effectively support bypassing of the storages in the lower landscape that would otherwise retain water and allow salt to accumulate. Results from this study suggest catchment internal redistribution of relatively fresh runoff onto the valley floor is a major contributor to the development of secondary dryland salinity. Seasonally inundated areas are subject to significant transmission losses and drive processes of vertical salt mobility. These surface flow and connectivity processes are not only acting in isolation to cause secondary salinity but are also interacting with groundwater systems responding to land clearing and processes recognised in the more conventional understanding of hillslope recharge and groundwater discharge. The study landscape appears to have three functional hydrological components: upland, hillslope “flow” landscapes that generate fresh runoff valley floor “fill” landscapes with high transmission losses and poor flow connectivity controlled by the micro-topography that promotes a surface–groundwater connection and salt movement and the downstream “flood” landscapes, where flows are recorded only when internal storages (fill landscapes) are exceeded. This work highlights the role of surface water processes as a contributor to land degradation by dryland salinity in low-gradient landscapes.
Eutrophication, agriculture and water level control shift aquatic plant communities from floating-leaved to submerged macrophytes in Lake Chini, Malaysia
Publisher: Springer Science and Business Media LLC
Date: 03-12-2012
Macrophyte-induced thermal stratification in a shallow urban lake promotes conditions suitable for nitrogen-fixing cyanobacteria
Publisher: Springer Science and Business Media LLC
Date: 16-09-2018
Growth, condition, and maturity schedules of an estuarine fish species change in estuaries following increased hypoxia due to climate change
Publisher: Wiley
Date: 25-06-2018
DOI: 10.1002/ECE3.4236
Assessing artificial oxygenation in a riverine salt-wedge estuary with a three-dimensional finite-volume model
Publisher: Elsevier BV
Date: 08-2018
Climate change overtakes coastal engineering as the dominant driver of hydrologic change in a large shallow lagoon
Publisher: Copernicus GmbH
Date: 05-06-2020
Abstract: Abstract. Ecosystems in shallow, micro-tidal lagoons are particularly sensitive to hydrologic changes. Lagoons are also highly complex transitional ecosystems between land and sea, and the signals of direct human disturbance to the lagoon can be confounded by variability of the climate system, but from an effective estuary management perspective the effects of climate versus direct human engineering interventions need to be identified separately. Although many estuarine lagoons have undergone substantial human interventions, such as artificial channels, the effects from the interaction of climate change with engineering interventions have not been well evaluated. This study developed a 3D finite-volume hydrodynamic model to assess changes in hydrodynamics of the Peel-Harvey Estuary, a large chocked-type lagoon, considering how attributes such as water retention time, salinity and stratification have responded to a range of factors, focusing on the drying climate trend and the opening of a large artificial channel over the period from 1970 to 2016, and how they will evolve under current climate projections. The results show that the drying climate has fundamentally changed the hydrology by comparable magnitudes to that of the opening of the artificial channel, and also highlight the complexity of their interacting impacts. Firstly, the artificial channel successfully improved the estuary flushing by reducing average water ages by 20–110 days while in contrast the reduced precipitation and catchment inflow had a gradual opposite effect on the water ages, and during the wet season this has almost counteracted the reduction brought about by the channel. Secondly, the drying climate caused an increase in the salinity of the lagoon by 10–30 PSU whilst the artificial channel increased the salinity during the wet season, it has reduced the likelihood of hypersalinity ( 40 PSU) during the dry season in some areas. The impacts also varied spatially in this large lagoon. The southern estuary, which has the least connection with ocean through the natural channel, is the most sensitive to climate change and the opening of the artificial channel. The projected future drying climate is shown to slightly increase the retention time and salinity in the lagoon, and increase the hypersalinity risk in the rivers. The significance of these changes for nutrient retention and estuary ecology are discussed, highlighting the importance of these factors when setting up monitoring programs, environmental flow strategies and nutrient load reduction targets.
Matching ecosystem functions with adaptive ecosystem management: Decision pathways to overcome institutional barriers
Publisher: MDPI AG
Date: 23-05-2018
DOI: 10.3390/W10060672
A three dimensional model ofCryptosporidiumdynamics in lakes and reservoirs: A new tool for risk management
Publisher: Informa UK Limited
Date: 09-2004
Nested 3D modeling of the spatial dynamics of nutrients and phytoplankton in a Lake Ontario nearshore zone
Publisher: Elsevier BV
Date: 2012
“Panta Rhei—Everything Flows”: Change in hydrology and society—The IAHS Scientific Decade 2013–2022
Publisher: Informa UK Limited
Date: 05-07-2013
Novel approaches to address challenges in modelling aquatic ecosystems
Publisher: Elsevier BV
Date: 11-2014
Intraguild predation dynamics in a lake ecosystem based on a coupled hydrodynamic-ecological model: The example of lake kinneret (Israel)
Publisher: MDPI AG
Date: 29-03-2017
Physical circulation and spatial exchange dynamics in a shallow floodplain wetland
Publisher: International Information and Engineering Technology Association
Date: 05-09-2012
In situ evidence for the association of total coliforms and Escherichia coli with suspended inorganic particles in an Australian reservoir
Publisher: Springer Science and Business Media LLC
Date: 02-2006
Stormwater nutrient attenuation in a constructed wetland with alternating surface and subsurface flow pathways: Event to annual dynamics
Publisher: Elsevier BV
Date: 12-2016
DOI: 10.1016/J.WATRES.2016.10.005
Abstract: Among different Water Sensitive Urban Design (WSUD) options, constructed wetlands (CWs) are widely used to protect and support downstream urban waterways from stormwater nutrients. This analysis assessed the nutrient attenuation ability of a novel CW in Western Australia that combined multiple alternating surface flow (SF) and laterite-based subsurface flow (SSF) compartments within a parkland context to improve the urban landscape and amenity. The CW was designed to maximise nutrient reduction despite experiencing a large range of hydrologic conditions, from low transit time nutrient-rich pulses during the wet periods to prolonged low to zero flow conditions during the dry periods. The CW design was further complicated by the possibility of ungauged water inputs after wet antecedent conditions, seasonal macrophyte senescence and a recirculation system to maintain flow during the dry periods. From analysis of data over a range of time scales, we determined that overall the CW attenuated up to 62% total nitrogen (TN) and 99% total phosphorus (TP) loads during dry weather conditions, and 54-76% TN and 27-68% TP during episodic flow pulses. N species attenuation was dominant in the SF compartments, while P species were attenuated mostly within the SSF compartments. Nutrient accumulation in the sediments, and above and below ground biomass of the macrophytes were found to increase during the early stages of operation, suggesting the system reached equilibrium within four years. Further, by comparing trends in nutrient attenuation within the context of diel changes in high frequency oxygen data from different compartments, it was demonstrated that changes in dissolved oxygen were related to changes in nutrient concentration across the CW, although interpretation of this was complicated by changing hydro-climatological conditions. The implementation of this CW concept in a highly seasonal Mediterranean climate demonstrates that urban liveability and environmental health can both be improved through careful design.
Shifts of Resilience and Recovery of Aquatic Metabolism in Stormwater Green Infrastructure
Publisher: Springer International Publishing
Date: 09-2019
Quantifying spatial correlations and trends in rainfall data under a Mediterranean climate using non-parametric statistical and machine learning approaches
Publisher: Copernicus GmbH
Date: 04-03-2024
DOI: 10.5194/EGUSPHERE-EGU21-5701
Abstract: & & Numerous studies have highlighted the rapid pace of climate change in South Western Australia and quantifying hydrological shifts may provide insights into climate impacts in other Mediterranean regions. Identifying connections in data from spatially distributed rainfall stations using different interpolation approaches, can fill gaps in historical datasets and allow effective installation of new rain gauges based on optimal density and location. Different insights were revealed by using multiple approaches across the time series: the Seasonal Mann-Kendall Test, the Mann-Kendall Test under the Scaling Hypothesis (MKLTP), the Lanzante& #8217 s test (LAT) as single change point detection tests, the E-Agglomerative (ECP) and E-Divisive (EDP) change detection algorithms as multiple change point detection tests. Twenty seven loading factors (e.g. seasonal and annual Sen& #8217 s slope, the year and number of change points) were calculated from daily rainfall data collected over 100 years (1920-2019) from 107 meteorological stations in South Western Australia. The results illustrated that the rate of rainfall fluctuation in terms of Sen& #8217 s slope varied from -2.6 mm yr& sup& -1 & /sup& in coastal areas to 0.9 mm yr& sup& -1& /sup& in inland areas. The scaling trend analysis identified that 53% of the stations were effected by long-term persistence in the wet season, in contrast to only 20% in the dry season. The single change point methods identified a change in the 1940s-1950s and the multiple change point methods identified two changes, in the 1940s and 2000s. The spatial correlation of stations were also mapped using an unsupervised machine learning approach (K-Means), the Multiscale Bootstrap Res ling (MBR), and loading factors, into three optimal clusters, indicating that rainfall in the coastal areas continue to decline, whereas rainfall in the inland areas has increased over the previous 100 years. These statistical and machine learning approaches are effective in identifying spatial and temporal variability in climate change trends.& &
Source tracking using microbial community fingerprints: Method comparison with hydrodynamic modelling
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.WATRES.2016.11.043
Abstract: Urban estuaries around the world are experiencing contamination from diffuse and point sources, which increases risks to public health. To mitigate and manage risks posed by elevated levels of contamination in urban waterways, it is critical to identify the primary water sources of contamination within catchments. Source tracking using microbial community fingerprints is one tool that can be used to identify sources. However, results derived from this approach have not yet been evaluated using independent datasets. As such, the key objectives of this investigation were: (1) to identify the major sources of water responsible for bacterial loadings within an urban estuary using microbial source tracking (MST) using microbial communities and (2) to evaluate this method using a 3-dimensional hydrodynamic model. The Yarra River estuary, which flows through the city of Melbourne in South-East Australia was the focus of this study. We found that the water sources contributing to the bacterial community in the Yarra River estuary varied temporally depending on the estuary's hydrodynamic conditions. The water source apportionment determined using microbial community MST correlated to those determined using a 3-dimensional hydrodynamic model of the transport and mixing of a tracer in the estuary. While there were some discrepancies between the two methods, this investigation demonstrated that MST using bacterial community fingerprints can identify the primary water sources of microorganisms in an estuarine environment. As such, with further optimization and improvements, microbial community MST has the potential to become a powerful tool that could be practically applied in the mitigation of contaminated aquatic systems.
Hydrological controls on carbon metabolism in wetlands
Publisher: Elsevier BV
Date: 2013
Predicting the resilience and recovery of aquatic systems: A framework for model evolution within environmental observatories
Publisher: American Geophysical Union (AGU)
Date: 09-2015
DOI: 10.1002/2015WR017175
Generating community-built tools for data sharing and analysis in environmental networks
Publisher: Informa UK Limited
Date: 2016
DOI: 10.1080/IW-6.4.889
Integration of submerged aquatic vegetation motion within hydrodynamic models
Publisher: Wiley
Date: 09-05-2020
Modelling the effects of Po River discharge, internal nutrient cycling and hydrodynamics on biogeochemistry of the Northern Adriatic Sea
Publisher: Elsevier BV
Date: 04-2017
Storm event-scale nutrient attenuation in constructed wetlands experiencing a Mediterranean climate: A comparison of a surface flow and hybrid surface-subsurface flow system
Publisher: Elsevier BV
Date: 11-2017
DOI: 10.1016/J.SCITOTENV.2017.04.044
Abstract: Among different Water Sensitive Urban Design options, constructed wetlands (CWs) are used to protect and restore downstream water quality by attenuating nutrients generated by stormwater runoff. This research compared the nutrient attenuation ability during a erse population of storm events of two CWs: (a) a hybrid CW with multiple alternating surface flow (SF) and laterite-based subsurface flow (SSF) compartments, and (b) a single stage SF CW. Within-storm variability, nutrient concentrations were assessed at 2 to 3-h intervals at both the main inlet and outlet of each CW. Dissolved oxygen concentrations of the surface waters were also monitored at 10-min intervals using high frequency in situ sensors. Nutrient loads into the CWs were observed to be higher when a high rainfall event occurred, particularly after longer antecedent dry conditions. Longer hydraulic retention times promoted higher attenuation at both sites. However, the relative extent of nutrient attenuation differed between the CW types the mean total nitrogen (TN) attenuation in the hybrid and SF CW was 45 and 48%, respectively. The hybrid CW attenuated 67% total phosphorus (TP) loads on average, while the SF CW acted as a net TP source. Periodic storm events transitioned the lentic CW into a lotic CW and caused riparian zone saturation it was therefore hypothesized that such saturation of organic matter rich-riparian zones led to release of TP in the system. The hybrid CW attenuated the released TP in the downstream laterite-based SSF compartments. Diel oxygen metabolism calculated before and after the storm events was found to be strongly correlated with water temperature, solar exposure and antecedent dry condition during the pre-storm conditions. Furthermore, the SF CW showed a significant relationship between overall nutrient load attenuation and the change in oxygen metabolism during the storm perturbation, suggesting oxygen variation could be a useful proxy indicator of CW function.
Developing and Validating a Model to Assess Sewer Sediment Issues from Changing Wastewater Inflows and Concentration
Publisher: Springer International Publishing
Date: 09-2019
Developing predictive insight into changing water systems: use-inspired hydrologic science for the Anthropocene
Publisher: Copernicus GmbH
Date: 20-06-2013
DOI: 10.5194/HESSD-10-7897-2013
Abstract: Abstract. Globally, many different kinds of water resources management issues call for policy and infrastructure based responses. Yet responsible decision making about water resources management raises a fundamental challenge for hydrologists: making predictions about water resources on decadal-to-century long timescales. Obtaining insight into hydrologic futures over 100 yr timescales forces researchers to address internal and exogenous changes in the properties of hydrologic systems. To do this, new hydrologic research must identify, describe and model feedbacks between water and other changing, coupled environmental subsystems. These models must be constrained to yield useful insights, despite the many likely sources of uncertainty in their predictions. Chief among these uncertainties are the impacts of the increasing role of human intervention in the global water cycle – a defining challenge for hydrology in the Anthropocene. Here we present a research agenda that proposes a suite of strategies to address these challenges. The research agenda focuses on the development of co-evolutionary hydrologic modeling to explore coupling across systems, and to address the implications of this coupling on the long-time behavior of the coupled systems. Three research directions support the development of these models: hydrologic reconstruction, comparative hydrology and model-data learning. These strategies focus on understanding hydrologic processes and feedbacks over long timescales, across many locations, and through strategic coupling of observational and model data in specific systems. We highlight the value of use-inspired and team-based science that is motivated by real-world hydrologic problems but targets improvements in fundamental understanding to support decision-making and management.
Stable isotopes reduce parameter uncertainty of an estuarine carbon cycling model
Publisher: Elsevier BV
Date: 05-2016
Correction to: Drying microclimates threaten persistence of natural and translocated populations of threatened frogs
Publisher: Springer Science and Business Media LLC
Date: 11-11-2020
Estuaries as Sources and Sinks of N2O Across a Land Use Gradient in Subtropical Australia
Publisher: American Geophysical Union (AGU)
Date: 05-2018
DOI: 10.1029/2017GB005826
An investigation into the impacts of water demand management and decentralized water recycling on excess sewer sediment deposition
Publisher: Elsevier BV
Date: 02-2021
Feedback between sediment and light for seagrass: Where is it important?
Publisher: Wiley
Date: 24-06-2016
DOI: 10.1002/LNO.10319
Quantifying Lake Water Quality Evolution: Coupled Geochemistry, Hydrodynamics, and Aquatic Ecology in an Acidic Pit Lake
Publisher: American Chemical Society (ACS)
Date: 16-08-2017
Abstract: Assessment of water quality evolution in the thousands of existing and future mine pit lakes worldwide requires new numerical tools that integrate geochemical, hydrological, and biological processes. A coupled model was used to test alternative hypothesized controls on water quality in a pit lake over ∼8 years. The evolution of pH, Al, and Fe were closely linked field observations were reproduced with generic solubility equilibrium controls on Fe(III) and Al and a commonly reported acceleration of the abiotic Fe(II) oxidation rate by 2-3 orders of magnitude. Simulations indicated an ongoing acidity loading at the site, and the depletion of Al mineral buffering capacity after ∼5 years. Simulations also supported the existence of pH limitation on nitrification, and a limitation on phytoplankton growth other than the commonly postulated P and DIC limitations. Furthermore, the model reproduced the general patterns of salinity, pH, Al, and Fe during an uncontrolled river breach in 2011, however, incorporating sediment biogeochemical feedbacks is required to reproduce the observed postbreach internal alkalinity generation in the lake. The modeling approach is applicable to the study of hydrological, geochemical, and biological interactions for a range of lake and reservoir management challenges.
Changing sediment and surface water processes increase CH4 emissions from human-impacted estuaries
Publisher: Elsevier BV
Date: 07-2020
Effect of seasonal flushing on nutrient export characteristics of an urbanizing, remote, ungauged coastal catchment
Publisher: Informa UK Limited
Date: 20-12-2017
Controls on oxygen dynamics in a riverine salt-wedge estuary – a three-dimensional model of the Yarra River estuary, Australia
Publisher: Copernicus GmbH
Date: 24-09-2021
DOI: 10.5194/HESSD-10-9799-2013
Abstract: Abstract. Oxygen depletion in estuarine waters is an important factor governing water quality and ecological health. A complex and dynamic balance of physical and biogeochemical factors drive the extent and persistence of hypoxia and anoxia making it difficult to predict. An increased understanding of the effect of changing flow regimes and temperature on patterns of estuarine oxygen depletion is required to support ongoing management. Coupled physical and biogeochemical models have been applied to study the interaction of physical processes and seasonal hypoxia, however, application to riverine estuaries with tight curvature and more sporadic periods of oxygen depletion is rare. In this study we apply a finite volume 3-D hydrodynamic-biogeochemical model (TUFLOW-FV–FABM) to the Yarra River estuary, Australia, in order to predict the extent of salt-wedge intrusion and consequent patterns of oxygen depletion. The predictive capacity of the model was evaluated using a series of model verification metrics and the results evaluated to determine the dominant mechanisms affecting salt-wedge position and the extent and persistence of anoxia and hypoxia. Measures of model fit indicated that the model reasonably captured the strength of stratification and the position and extent of the salt wedge (r2 ~ 0.74). The extent of the salt wedge intrusion was controlled by riverine flow and the strength of stratification or mixing dominated by topographical features corresponding to areas of tight curvature ("horseshoe" bends). The model predicted that the extent of anoxic waters generally mimicked the extent of the salt wedge (r2 ~ 0.65) increasing during periods of low flow and reduced following episodic high flow events. The results showed two sporadically isolated "hot spots" of anoxia, the first downstream of the horseshoe bend and the second downstream of a sill. Simulated oxygen concentrations indicated that whilst a threshold salt wedge intrusion was a requirement of oxygen depletion, temperature was critical in determining the extent of hypoxia and anoxia in the estuary. These findings highlight the importance of how seasonal changes in flow events and environmental flow management can impact on estuarine oxygen depletion in a warming climate. This study provides an improved understanding of the controls on hypoxia and anoxia in riverine estuaries, which is essential to support improved prediction of nutrient dynamics and ecological heath.
Sensitivity analysis for complex ecological models - A new approach
Publisher: Elsevier BV
Date: 02-2011
An analysis of the relationship between phytoplankton internal stoichiometry and water column N: P ratios in a dynamic lake environment
Publisher: Elsevier BV
Date: 03-2013
Water management can reinforce plant competition in salt-affected semi-arid wetlands
Publisher: Elsevier BV
Date: 09-2017
Optimal migration energetics of humpback whales and the implications of disturbance
Publisher: Oxford University Press (OUP)
Date: 2015
Fragment dispersal and plant-induced dieback explain irregular ring-shaped pattern formation in a clonal submerged macrophyte
Publisher: Elsevier BV
Date: 11-2201
Marked deleterious changes in the condition, growth and maturity schedules of Acanthopagrus butcheri (Sparidae) in an estuary reflect environmental degradation
Publisher: Elsevier BV
Date: 08-2011
A General Lake Model (GLM 2.4) for linking with high-frequency sensor data from the Global Lake Ecological Observatory Network (GLEON)
Publisher: Copernicus GmbH
Date: 20-11-2017
DOI: 10.5194/GMD-2017-257
Abstract: Abstract. The General Lake Model (GLM) is a one-dimensional open-source model code designed to simulate the hydrodynamics of lakes, reservoirs and wetlands. GLM was developed to support the science needs of the Global Lake Ecological Observatory Network (GLEON), a network of lake sensors and researchers attempting to understand lake functioning and address questions about how lakes around the world vary in response to climate and land-use change. The scale and ersity of lake types, locations and sizes, as well as the observational data within GLEON, created the need for a robust community model of lake dynamics with sufficient flexibility to accommodate a range of scientific and management needs of the GLEON community. This paper summarises the scientific basis and numerical implementation of the model algorithms, including details of sub-models that simulate surface heat exchange and ice-cover dynamics, vertical mixing and inflow/outflow dynamics. A summary of typical parameter values for lakes and reservoirs collated from a range of sources is included. GLM supports a dynamic coupling with biogeochemical and ecological modelling libraries for integrated simulations of water quality and ecosystem health. An overview of approaches for integration with other models, and utilities for the analysis of model outputs and for undertaking sensitivity and uncertainty assessments is also provided. Finally, we discuss application of the model within a distributed cloud-computing environment, and as a tool to support learning of network participants.
Implementation of ecological modeling as an effective management and investigation tool: Lake Kinneret as a case study
Publisher: Elsevier BV
Date: 07-2009
A prototype framework for models of socio-hydrology: Identification of key feedback loops and parameterisation approach
Publisher: Copernicus GmbH
Date: 13-06-2014
DOI: 10.5194/HESS-18-2141-2014
Abstract: Abstract. It is increasingly acknowledged that, in order to sustainably manage global freshwater resources, it is critical that we better understand the nature of human–hydrology interactions at the broader catchment system scale. Yet to date, a generic conceptual framework for building models of catchment systems that include adequate representation of socioeconomic systems – and the dynamic feedbacks between human and natural systems – has remained elusive. In an attempt to work towards such a model, this paper outlines a generic framework for models of socio-hydrology applicable to agricultural catchments, made up of six key components that combine to form the coupled system dynamics: namely, catchment hydrology, population, economics, environment, socioeconomic sensitivity and collective response. The conceptual framework posits two novel constructs: (i) a composite socioeconomic driving variable, termed the Community Sensitivity state variable, which seeks to capture the perceived level of threat to a community's quality of life, and acts as a key link tying together one of the fundamental feedback loops of the coupled system, and (ii) a Behavioural Response variable as the observable feedback mechanism, which reflects land and water management decisions relevant to the hydrological context. The framework makes a further contribution through the introduction of three macro-scale parameters that enable it to normalise for differences in climate, socioeconomic and political gradients across study sites. In this way, the framework provides for both macro-scale contextual parameters, which allow for comparative studies to be undertaken, and catchment-specific conditions, by way of tailored "closure relationships", in order to ensure that site-specific and application-specific contexts of socio-hydrologic problems can be accommodated. To demonstrate how such a framework would be applied, two socio-hydrological case studies, taken from the Australian experience, are presented and the parameterisation approach that would be taken in each case is discussed. Preliminary findings in the case studies lend support to the conceptual theories outlined in the framework. It is envisioned that the application of this framework across study sites and gradients will aid in developing our understanding of the fundamental interactions and feedbacks in such complex human–hydrology systems, and allow hydrologists to improve social–ecological systems modelling through better representation of human feedbacks on hydrological processes.
A model of the socio-hydrologic dynamics in a semiarid catchment: Isolating feedbacks in the coupled human-hydrology system
Publisher: American Geophysical Union (AGU)
Date: 08-2015
DOI: 10.1002/2015WR017048
ML-SWAN-v1: a hybrid machine learning framework for the concentration prediction and discovery of transport pathways of surface water nutrients
Publisher: Copernicus GmbH
Date: 15-09-2020
Abstract: Abstract. Nutrient data from catchments discharging to receiving waters are monitored for catchment management. However, nutrient data are often sparse in time and space and have non-linear responses to environmental factors, making it difficult to systematically analyse long- and short-term trends and undertake nutrient budgets. To address these challenges, we developed a hybrid machine learning (ML) framework that first separated baseflow and quickflow from total flow, generated data for missing nutrient species, and then utilised the pre-generated nutrient data as additional variables in a final simulation of tributary water quality. Hybrid random forest (RF) and gradient boosting machine (GBM) models were employed and their performance compared with a linear model, a multivariate weighted regression model, and stand-alone RF and GBM models that did not pre-generate nutrient data. The six models were used to predict six different nutrients discharged from two study sites in Western Australia: Ellen Brook (small and ephemeral) and the Murray River (large and perennial). Our results showed that the hybrid RF and GBM models had significantly higher accuracy and lower prediction uncertainty for almost all nutrient species across the two sites. The pre-generated nutrient and hydrological data were highlighted as the most important components of the hybrid model. The model results also indicated different hydrological transport pathways for total nitrogen (TN) export from two tributary catchments. We demonstrated that the hybrid model provides a flexible method to combine data of varied resolution and quality and is accurate for the prediction of responses of surface water nutrient concentrations to hydrologic variability.
Physical controls on the spatial evolution of a dinoflagellate bloom in a large lake
Publisher: Wiley
Date: 11-2011
Unravelling the metabolism black-box in a dynamic wetland environment using a hybrid model framework: Storm driven changes in oxygen budgets
Publisher: Elsevier BV
Date: 06-2020
Temporal dynamics of stormwater nutrient attenuation of an urban constructed wetland experiencing summer low flows and macrophyte senescence
Publisher: Elsevier BV
Date: 05-2017
The Impact of Landscape Characteristics on Groundwater Dissolved Organic Nitrogen: Insights From Machine Learning Methods and Sensitivity Analysis
Publisher: American Geophysical Union (AGU)
Date: 07-2018
DOI: 10.1029/2017WR021749
Modelling the propagation of turbid density inflows into a stratified lake: Daecheong Reservoir, Korea
Publisher: Elsevier BV
Date: 12-2009
Comparison of Machine Learning Techniques and Variables for Groundwater Dissolved Organic Nitrogen Prediction in an Urban Area
Publisher: Elsevier BV
Date: 2016
Application of a 3D hydrodynamic–biological model for seasonal and spatial dynamics of water quality and phytoplankton in Lake Erie
Publisher: Elsevier BV
Date: 03-2011
Adaptation tipping points of urban wetlands under a drying climate
Publisher: Copernicus GmbH
Date: 16-06-2017
Abstract: Abstract. Urban wetlands experience considerable alteration to their hydrology, which typically contributes to a decline in their overall ecological integrity. Wetland management strategies aim to repair wetland hydrology and attenuate wetland loss associated with climate change. However, decision makers often lack the data needed to support complex social environmental systems models, making it difficult to assess the effectiveness of current or past practices. Adaptation Tipping Points (ATPs) is a method that can be useful in these situations. The method assesses thresholds exceedance of ecological objectives obtained from policy and informs about the effectiveness of the management strategy to the delivery of certain social or environmental goals. Here we trial the method on an urban wetland in a region experiencing a markedly drying climate. ATPs were defined by linking key ecological objectives identified by policy documents to threshold values for water depth. We then used long-term hydrologic data (1978–2012) to assess if and when thresholds were breached. We found that from the mid-1990s declining wetland water depth caused ATPs for the majority of the wetland objectives. We conclude that the wetland management strategy has been ineffective from the mid-1990s when the region's climate dried markedly. Empirical verification of the ATP assessment is required to validate the suitability of the method. However, in general we consider ATPs to be a useful desktop method to assess the suitability of management when rigorous ecological data are lacking.
Developing predictive insight into changing water systems: use-inspired hydrologic science for the Anthropocene
Publisher: Copernicus GmbH
Date: 12-12-2013
DOI: 10.5194/HESS-17-5013-2013
Abstract: Abstract. Globally, many different kinds of water resources management issues call for policy- and infrastructure-based responses. Yet responsible decision-making about water resources management raises a fundamental challenge for hydrologists: making predictions about water resources on decadal- to century-long timescales. Obtaining insight into hydrologic futures over 100 yr timescales forces researchers to address internal and exogenous changes in the properties of hydrologic systems. To do this, new hydrologic research must identify, describe and model feedbacks between water and other changing, coupled environmental subsystems. These models must be constrained to yield useful insights, despite the many likely sources of uncertainty in their predictions. Chief among these uncertainties are the impacts of the increasing role of human intervention in the global water cycle – a defining challenge for hydrology in the Anthropocene. Here we present a research agenda that proposes a suite of strategies to address these challenges from the perspectives of hydrologic science research. The research agenda focuses on the development of co-evolutionary hydrologic modeling to explore coupling across systems, and to address the implications of this coupling on the long-time behavior of the coupled systems. Three research directions support the development of these models: hydrologic reconstruction, comparative hydrology and model-data learning. These strategies focus on understanding hydrologic processes and feedbacks over long timescales, across many locations, and through strategic coupling of observational and model data in specific systems. We highlight the value of use-inspired and team-based science that is motivated by real-world hydrologic problems but targets improvements in fundamental understanding to support decision-making and management. Fully realizing the potential of this approach will ultimately require detailed integration of social science and physical science understanding of water systems, and is a priority for the developing field of sociohydrology.
Modelling of nearshore microbial water quality at confluence of a local tributary in Lake St. Clair
Publisher: Elsevier BV
Date: 04-2022
Corrigendum to “Application of a 3D hydrodynamic-biological model for seasonal and spatial dynamics of water quality and phytoplankton in Lake Erie” [J. Great Lakes Res. 2011, Vol 37: pages 41-53]
Publisher: Elsevier BV
Date: 04-2016
Hydro-climatological non-stationarity shifts patterns of nutrient delivery to an estuarine system
Publisher: Copernicus GmbH
Date: 22-08-2013
DOI: 10.5194/HESSD-10-11035-2013
Abstract: Abstract. The influence of hydro-climatological variability on catchment nutrient export was assessed by a retrospective analysis of rainfall, discharge, and total and dissolved nutrient loads for three sub-basins (Serpentine, Murray and Harvey) of the Peel–Harvey catchment, Western Australia. Both, temporal trends and their variability for different hydrological conditions (dry, normal or wet years) were analyzed from 1984 to 2011. Rainfall declined below median values for the study period over the last two decades and runoff decreased significantly in two of the three main rivers. Since Nitrogen (N) and Phosphorus (P) loads were strongly correlated with river discharge, nutrient exports decreased. However, when nutrient loads were flow-adjusted, increases in Total P (TP) and Total N (TN) were observed in the Serpentine and Murray rivers respectively, suggesting new sources of TP and TN and that the flow–export relationship is non-stationary. Dissolved Inorganic Phosphorus (DIP), showed a decreasing tendency in the last decade but the trend in DIN loads is not clear and it appears to show a decreasing trend until 2004 and an increasing trend from 2004, accompanied with large inter-annual variability. The analysis of TP, TN, DIP and DIN in relation to dry and wet years, indicated that there is a significantly higher load in wet years for all three rivers, except for DIP in the Murray sub-catchment, explained by a higher proportion of soils with a higher Phosphorus Retention Index (PRI). Hydrological conditions, specific sub-catchment characteristics (e.g. soil type) and chemical properties of the nutrients altered the degree of nutrient partitioning (defined as dissolved inorganic to total nutrient concentration). For ex le, DIP increased to more than 50% of TP in wet years in Harvey and Serpentine but not in the Murray sub-catchment due to a higher PRI, while DIN behaved more randomly and did not show a link to discharge or the catchment soil type. We also found a mild association between nutrient partitioning and the rate of population growth which indicates that rapid change in population growth is accompanied by an increase in nutrient dissolved species. Changes in hydrological conditions between seasons did result in changes in the TN : TP and DIN : DIP ratio, but on an annual scale these ratios were not sensitive to whether a year was classified as wet or dry. The findings indicate that the quantity and nature of nutrient export varies in response to climate variability, which is superimposed on effects from changing land-use characteristics.
Resilience and Adaptive Capacity of the Swan Coastal Plain Wetlands
Publisher: Frontiers Media SA
Date: 11-2021
Abstract: An estimated 90% of the Swan Coastal Plain (SCP) wetlands, located in southwestern Australia, have been lost because of infilling or drainage. This loss continues despite the well-known causes, which include nutrient enrichment the invasion of exotic flora and fauna loss of fringing vegetation and altered hydrological regimes caused by groundwater abstraction urbanization and a drying climate. Further loss is expected with climate change exacerbating the undesirable ecosystem changes of remaining wetlands. In this study, we consider these wetlands as ex les of social-ecological systems (SES) which are characterized by a close interaction of the ecosystem with the social system. We take the theory of resilient SES as a starting point to identify the adaptive capacity and resilience of the wetlands. We argue that resilience provides a useful framework to analyze adaptation processes and to identify appropriate policy responses. We explore incremental adjustments and transformative action and demonstrate that policy responses arise across multiple scales and levels of jurisdiction and institution. By applying the theoretical framework of resilience to the SCP wetlands, we identified (un)desired ecosystem states of wetlands (hydrology and ecology) through different set of policy actions. Our results show that current wetland management is inadequate to maintain the ecosystem's functioning. We recommend cross-jurisdictional collaboration and the use of conceptual eco-hydrological models to depict gradual ecological change and types of regime shifts (thresholds, hysteresis, and irreversible changes). The different adaption options inform decision-makers to adequately adapt wetland management practices when uncertainty in ecosystem responses exist. Empirical data on how multiple jurisdictions operate and decide could help to further support decision-making. With this research we aim to narrow the science-policy interface which depends on corresponding cross-jurisdictional and institutional responses to coordinate wetland management policies and actions.
Optimizing withdrawal from drinking water reservoirs to reduce downstream temperature pollution and reservoir hypoxia
Publisher: Elsevier BV
Date: 07-2017
DOI: 10.1016/J.JENVMAN.2017.03.020
Abstract: Sustainable management of drinking water reservoirs requires balancing the demands of water supply whilst minimizing environmental impact. This study numerically simulates the effect of an improved withdrawal scheme designed to alleviate the temperature pollution downstream of a reservoir. The aim was to identify an optimal withdrawal strategy such that water of a desirable discharge temperature can be supplied downstream without leading to unacceptably low oxygen concentrations within the reservoir. First, we calibrated a one-dimensional numerical model for hydrodynamics and oxygen dynamics (GLM-AED2), verifying that the model reproduced water temperatures and hypolimnetic dissolved oxygen concentrations accurately over a 5 year period. Second, the model was extended to include an adaptive withdrawal functionality, allowing for a prescribed withdrawal temperature to be found, with the potential constraint of hypolimnetic oxygen concentration. Scenario simulations on epi-/metalimnetic withdrawal demonstrate that the model is able to autonomously determine the best withdrawal height depending on the thermal structure and the hypolimnetic oxygen concentration thereby optimizing the ability to supply a desirable discharge temperature to the downstream river during summer. This new withdrawal strategy also increased the hypolimnetic raw water volume to be used for drinking water supply, but reduced the dissolved oxygen concentrations in the deep and cold water layers (hypolimnion). Implications of the results for reservoir management are discussed and the numerical model is provided for operators as a simple and efficient tool for optimizing the withdrawal strategy within different reservoir contexts.
Using Inverse Modeling and Dual Isotopes (δ15N and δ18O of NO3) to Determine Sources of Nitrogen Export From a Complex Land Use Catchment
Publisher: American Geophysical Union (AGU)
Date: 10-2022
DOI: 10.1029/2022WR031944
Abstract: Attributing nitrogen export to specific land use within heterogeneous catchments remains a challenge due to the spatio‐temporal variability in conditions influencing the mobilization and fate of nitrogen species. This study demonstrates that the measurement of dual stable isotopes of nitrate, taken along with routine tributary measurement of nitrogen in nitrate (NO 3 − ‐N) and ammonium (NH 4 + ‐N), aids in apportioning sources of the overall nitrogen load during wet periods. An inverse modeling technique was developed to estimate the land use‐specific export rates of NO 3 − ‐N and NH 4 + ‐N from the Caboolture River Catchment in Queensland, Australia. Measurements of nitrogen in streamflow at 51 locations during six s ling c aigns (May 2012 to April 2013) were made along with catchment geospatial data that was used to disaggregate sub‐catchments into six land use fractions. A hydrological model was applied to compute the runoff from each fraction and water routing through the stream network. This data was used within a nitrogen mixing model with inclusion δ 15 N NO3 and δ 18 O NO3 . The land uses specific export rate was computed inversely as the posterior of a Bayesian interference applied to the model. During higher rainfall periods when export rates were highest, the main land use exporting nitrogen was wetland (110 g/ha/day NO 3 − ‐N, 27 g/ha/day NH 4 + ‐N) resulted from mineralization and nitrification of organic N, followed by urban (16 g/ha/day NO 3 − ‐N, 2.3 g/ha/day NH 4 + ‐N). The advantage of using the dual isotopes in conjunction with the nitrogen concentration data was demonstrated by reduced uncertainty in the computed rates during the higher rainfall periods, relative to calculations without δ 15 N NO3 and δ 18 O NO3 .
Exploring the role of fish in a lake ecosystem (Lake Kinneret, Israel) by coupling an individual-based fish population model to a dynamic ecosystem model
Publisher: Canadian Science Publishing
Date: 07-2011
DOI: 10.1139/F2011-051
Abstract: To explore the role that fish play in aquatic ecosystems, a hydrodynamic–ecological model (DYRESM–CAEDYM) was coupled to a novel fish population model. The coupled model (DYCD–FISH) combined two modelling approaches: a complex dynamic model and an in idual-based model. The coupled model simulates fish growth population dynamics and predicts fish impacts on various ecosystem components, including nutrients and lower trophic levels. The model was employed to explore the role of the dominant fish in Lake Kinneret (Israel), Acanthobrama terraesanctae (Kinneret bleak, or in Hebrew, lavnun ha’kinneret hereafter lavnun). Model results suggested that the lavnun has a significant impact (p 0.05) on the magnitude of output variables including its prey food (the predatory and microzooplankton), major nutrients such as ammonium (NH 4 ) and phosphate (PO 4 ), and on several phytoplankton species, but not on the seasonality of any of the output variables. Since the model incorporates trophic levels from nutrients to fish, it revealed the nonlinear dynamic impacts of fish on different ecosystem components and in particular has led to quantitative insights into the relative influence of top-down control on water quality attributes. Besides being an ecosystem research tool, DYCD–FISH can also be employed as a fishery management tool, and in particular facilitate ecosystem-based fishery management.
A spatially resolved model of seasonal variations in phytoplankton and clam (Tapes philippinarum) biomass in Barbamarco Lagoon, Italy
Publisher: Elsevier BV
Date: 08-2008
A risk-based approach to the design of rural water supply catchments across Western Australia
Publisher: Informa UK Limited
Date: 10-2003
The influence of physical and physiological processes on the spatial heterogeneity of a Microcystis bloom in a stratified reservoir
Publisher: Elsevier BV
Date: 10-2014
A multi-functional and multi-compartment constructed wetland to support urban waterway restoration
Publisher: IWA Publishing
Date: 12-2018
DOI: 10.2166/WPT.2018.086
Abstract: This study assessed the significance of a multi-functional and multi-compartment constructed wetland (CW) implemented to restore a degraded urban waterway in Western Australia. The wetland was initially constructed as a surface flow system, then modified through the incorporation of the additional laterite-based subsurface flow system, with the potential for operation of a recirculation scheme and groundwater top-up during low water flows in summer. The CW performance was assessed by comparing nitrogen (N) and phosphorus (P) attenuation during base flow, high flow and episodic storm flow conditions. The performance varied from approximately 41% total nitrogen (TN) and 66% total phosphorus (TP) loads reduction during storm events, increasing up to 62% TN and 99% TP during low flow and summer recirculation periods. In overall, the CW attenuated about 45% TN and 65% TP loads from being delivered to the downstream sensitive river between 2009 and 2015. The CW design proved to be not only highly effective at reducing nutrient loads, but also improved the ecological services of the urban waterway by providing a erse area for habitat and recreational activities.
ML-SWAN-v1: a hybrid machine learning framework for the prediction of daily surface water nutrient concentrations
Publisher: Copernicus GmbH
Date: 06-04-2020
DOI: 10.5194/GMD-2020-4
Abstract: Abstract. Nutrient data from catchments discharging to receiving waters are necessary to monitor and manage water quality, however, they are often sparse in time and space and have non-linear responses to environmental factors, making it difficult to systematically analyse long- and short-term trends and undertake nutrient budgets. To address these challenges, we developed a hybrid machine learning (ML) framework that first separated baseflow and quickflow from total flow, and then generated data for missing nutrient species, using relationships with hydrological data, rainfall, and temporal data. The generated nutrient data were then included as additional variables in a final simulation of tributary water quality. Hybrid random forest (RF) and gradient boosting machines (GBM) models were employed and their performance compared with a linear model, a multivariate weighted regression model and stand-alone RF and GBM models that did not pre-generate nutrient data. The six models were used to predict TN, TP, NH3, dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and filterable reactive phosphorus (FRP) discharged from two study sites in Western Australia: Ellen Brook (small and ephemeral) and the Murray River (large and perennial). Our results showed that the hybrid RF and GBM models had significantly higher accuracy and lower prediction uncertainty for almost all nutrient species across the two sites. We demonstrated that the hybrid model provides a flexible method to combine data of varied resolution and quality, and is accurate for the prediction of responses of surface water nutrient concentrations to hydrologic variability.
Integration of Submerged Aquatic Vegetation Motion Within Hydrodynamic Models
Publisher: American Geophysical Union (AGU)
Date: 08-2020
DOI: 10.1029/2020WR027369
Abstract: Aquatic models used for both freshwater and marine systems frequently need to account for submerged aquatic vegetation (SAV) due to its influence on flow and water quality. Despite its importance, parameterizations are generally adopted that simplify feedbacks from SAV, such as canopy properties (e.g., considering the deflected vegetation height) and the bulk friction coefficient. This study reports the development of a fine‐scale non‐hydrostatic model that demonstrates the two‐way effects of SAV motion interaction with the flow. An object‐oriented approach is applied to capture the multiphase phenomena, whereby a leaf‐scale SAV model based on a discrete element method is combined with a flow dynamics model to resolve stresses from currents and waves. The model is verified through application to a laboratory‐scale seagrass bed. A force balance analysis revealed that leaf elasticity and buoyancy are the most significant components influencing the horizontal and vertical momentum equations, respectively. The sensitivity of canopy‐scale bulk friction coefficients to water depth, current speeds, and vegetation density of seagrass was explored. Deeper water was also shown to lead to a smaller decrease in vegetation height. The model approach can contribute to improving assessment of processes influencing water quality, sediment stabilization, carbon sequestration, and SAV restoration, thereby supporting an understanding of how waterways and coasts will respond to changes brought about by development and a changing climate.
A multi-lake comparative analysis of the General Lake Model (GLM): Stress-testing across a global observatory network
Publisher: Elsevier BV
Date: 04-2018
Fate and transport of pathogens in lakes and reservoirs
Publisher: Elsevier BV
Date: 07-2004
Modelling shallow and narrow urban salt-wedge estuaries: Evaluation of model performance and sensitivity to optimise input data collection
Publisher: Elsevier BV
Date: 02-2019
An integrated modelling system for water quality forecasting in an urban eutrophic estuary: The swan-canning estuary virtual observatory
Publisher: Elsevier BV
Date: 11-2019
A General Lake Model (GLM 3.0) for linking with high-frequency sensor data from the Global Lake Ecological Observatory Network (GLEON)
Publisher: Copernicus GmbH
Date: 29-01-2019
Abstract: Abstract. The General Lake Model (GLM) is a one-dimensional open-source code designed to simulate the hydrodynamics of lakes, reservoirs, and wetlands. GLM was developed to support the science needs of the Global Lake Ecological Observatory Network (GLEON), a network of researchers using sensors to understand lake functioning and address questions about how lakes around the world respond to climate and land use change. The scale and ersity of lake types, locations, and sizes, and the expanding observational datasets created the need for a robust community model of lake dynamics with sufficient flexibility to accommodate a range of scientific and management questions relevant to the GLEON community. This paper summarizes the scientific basis and numerical implementation of the model algorithms, including details of sub-models that simulate surface heat exchange and ice cover dynamics, vertical mixing, and inflow–outflow dynamics. We demonstrate the suitability of the model for different lake types that vary substantially in their morphology, hydrology, and climatic conditions. GLM supports a dynamic coupling with biogeochemical and ecological modelling libraries for integrated simulations of water quality and ecosystem health, and options for integration with other environmental models are outlined. Finally, we discuss utilities for the analysis of model outputs and uncertainty assessments, model operation within a distributed cloud-computing environment, and as a tool to support the learning of network participants.
Data assimilation, sensitivity analysis and uncertainty quantification in a semi-arid terminal catchment subject to rainfall decline
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-14038
Abstract: & & Quantification of long-term hydrologic change in groundwater often requires the comparison of states pre- and post- change. The assessment of these changes in ungauged catchments is particularly difficult from a conceptual point of view and due to parameter non-uniqueness and associated uncertainty of quantitative frameworks. In these contexts, the use of data assimilation, sensitivity analysis and uncertainty quantification techniques are critical to maximise the use of available data both in terms of conceptualisation and quantification. This paper summarises findings of a study undertaken in the Lake Muir-Unicup Natural Diversity Recovery Catchment (MUNDRC), where a number of techniques were applied to inform both conceptual and numerical models. The MUNDRC is and small-scale endorheic basin located in southwestern Australia listed under the Ramsar Convention as a Wetland of International Importance and have been subject to a systematic decline in rainfall rates since 1970. Conceptual and numerical frameworks have been development to understand and quantify impacts of rainfall decline on the catchment using a variety of metrics involving groundwater and lake levels, as well as fluxes between these compartments and mass balance components. Conceptualisation was facilitated with the use a novel data-driven method relating rainfall and groundwater response running backwards in time, allowing the establishment of baseline conditions prior to rainfall decline, estimation of net recharge rates and providing initial heads for the forward numerical modelling. Parameter and predictive uncertainties associated with data gaps have been minimised and quantified utilising an Iterative Ensemble Smoother (White, 2018), while further refinement of conceptual model was undertaken following results from sensitivity analysis, where major parameter controls groundwater levels and other predictions of interest were quantified.& &
A generic, process-based model of microbial pollution in aquatic systems
Publisher: American Geophysical Union (AGU)
Date: 07-2008
DOI: 10.1029/2007WR006395
A three-dimensional hydro-geochemical model to assess lake acidification risk
Publisher: Elsevier BV
Date: 11-2014
Environmental Flow Requirements of Estuaries: Providing Resilience to Current and Future Climate and Direct Anthropogenic Changes
Publisher: Frontiers Media SA
Date: 17-11-2021
DOI: 10.3389/FENVS.2021.764218
Abstract: Estuaries host unique bio ersity and deliver a range of ecosystem services at the interface between catchment and the ocean. They are also among the most degraded ecosystems on Earth. Freshwater flow regimes drive ecological processes contributing to their bio ersity and economic value, but have been modified extensively in many systems by upstream water use. Knowledge of freshwater flow requirements for estuaries (environmental flows or E-flows) lags behind that of rivers and their floodplains. Generalising estuarine E-flows is further complicated by responses that appear to be specific to each system. Here we critically review the E-flow requirements of estuaries to 1) identify the key ecosystem processes (hydrodynamics, salinity regulation, sediment dynamics, nutrient cycling and trophic transfer, and connectivity) modulated by freshwater flow regimes, 2) identify key drivers (rainfall, runoff, temperature, sea level rise and direct anthropogenic) that generate changes to the magnitude, quality and timing of flows, and 3) propose mitigation strategies (e.g., modification of dam operations and habitat restoration) to buffer against the risks of altered freshwater flows and build resilience to direct and indirect anthropogenic disturbances. These strategies support re-establishment of the natural characteristics of freshwater flow regimes which are foundational to healthy estuarine ecosystems.
Water quality: the missing dimension of water in the water–energy–food nexus
Publisher: Informa UK Limited
Date: 25-03-2021
The nearshore shunt and the decline of the phytoplankton spring bloom in the Laurentian Great Lakes: insights from a three-dimensional lake model
Publisher: Springer Science and Business Media LLC
Date: 28-08-2013
Sensitivity of emergent sociohydrologic dynamics to internal system properties and external sociopolitical factors: Implications for water management
Publisher: American Geophysical Union (AGU)
Date: 06-2016
DOI: 10.1002/2015WR017944
Adaptation tipping points of awetland under a drying climate
Publisher: MDPI AG
Date: 24-02-2018
DOI: 10.3390/W10020234
The Impact of Extreme Low Flows on the Water Quality of the Lower Murray River and Lakes (South Australia)
Publisher: Springer Science and Business Media LLC
Date: 27-07-2012
Relative Value of Surrogate Indicators for Detecting Pathogens in Lakes and Reservoirs
Publisher: American Chemical Society (ACS)
Date: 18-10-2005
DOI: 10.1021/ES050821+
Abstract: This study investigated the relative behavior of pathogens, fecal indicator organisms, and particles of varying size during transport through a reservoir following a storm event inflow in Myponga Reservoir, South Australia. During the inflow, s les were collected from the river and at various locations within the reservoir to determine the fate and transport of microroganisms as they progressed through the water body. Microbiological analysis included the indicator organisms Escherichia coli, enterococci, Clostridium perfringens, aerobic spores, and somatic coliphages, the protozoan pathogens Cryptosporidium spp. and Giardia spp., and the potential physical surrogates of pathogen contamination including particle size and turbidity. Of the microbial indicator groups, C. perfringens spores were the most highly correlated with Cryptosporidium spp. concentrations (Spearman Rho = 0.58), closely followed by enterococci (Spearman Rho = 0.57). Cryptosporidium spp. oocysts were predominantly associated with small sized particles (range of 14.3-27.7 microm). All of the microbial indicator groups tested were associated with larger sized particle ranges (> 63.3 microm) except C. perfringens spores which were associated with particles in the size range of 45.5-63.3 microm. Although indicators may rank correlate with Cryptosporidium spp., the variation in settling rates of different microorganisms has significant implications for the use of surrogates to estimate pathogen attenuation within reservoirs. For ex le, concentrations of Cryptosporidium spp. oocysts were reduced by a factor of 3 on reaching the dam wall, whereas enterococci were reduced by a factor of 10.
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