Ecological Response Models Research Articles

Development of a computationally efficient floodplain ecological response model for large-scale, data-sparse riparian environments

Quantitative assessment of floodplain ecological response to flow regimes is challenging but essential for setting targets and estimating impacts for environmental water management. This paper proposes a model that takes long-term (90 years) and large-scale (9 million grid cells) flood maps as input to estimate the response of floodplain vegetation using infinitely differentiable functions. The model, named Floodplain Ecological Response Model (FERM), is calibrated against 1-D temporal Leaf Area Index (LAI) data from the WAVES energy and water balance model at a daily timestep, and validated on the entire floodplain using condition data of the Icon Sites of the Murray River aggregated to a yearly timestep. Results show that FERM can adequately simulate the response of different types of vegetation on the floodplain, while reducing the data requirements and runtime drastically compared to other approaches. The FERM modeling approach is a first step towards a quantitative modeling of floodplain forest ecosystems at large scale with realistic data and computation requirements. It is intended to indicate the potential of such an approach in semi-arid systems where data availability is limited, and to encourage the further research needed to improve our understanding of floodplain forests and our capacity to model the impact of floods on their ecological response.

A Bayesian Modelling Framework for Integration of Ecosystem Services into Freshwater Resources Management

Models of ecological response to multiple stressors and of the consequences for ecosystem services (ES) delivery are scarce. This paper describes a methodology for constructing a BBN combining catchment and water quality model output, data, and expert knowledge that can support the integration of ES into water resources management. It proposes “small group” workshop methods for elucidating expert knowledge and analyses the areas of agreement and disagreement between experts. The model was developed for four selected ES and for assessing the consequences of management options relating to no-change, riparian management, and decreasing or increasing livestock numbers. Compared with no-change, riparian management and a decrease in livestock numbers improved the ES investigated to varying degrees. Sensitivity analysis of the expert information in the BBN showed the greatest disagreements between experts were mainly for low probability situations and thus had little impact on the results. Conversely, in our applications, the best agreement between experts tended to occur for the higher probability, more likely, situations. This has implications for the practical use of this type of model to support catchment management decisions. The complexity of the relationship between management measures, the water quality and ecological responses and resulting changes in ES must not be a barrier to making decisions in the present time. The interactions of multiple stressors further complicate the situation. However, management decisions typically relate to the overall character of solutions and not their detailed design, which can follow once the nature of the solution has been chosen, for example livestock management or riparian measures or both.

Evaluation of Ecological Stability in Semi-Arid Open-Pit Coal Mining Area Based on Structure and Function Coupling during 2002–2017

Open-pit coal mining plays an important role in supporting national economic development; however, it has caused ecological problems and even seriously impacted regional ecological stability. Given the importance of maintaining ecological stability in semi-arid coal mining areas, this study used a coupling coordination degree approach based on the structural and functional state transition model (SFSTM) to evaluate the spatio–temporal variation of ecological stability from 2002 to 2017 by using MODIS and Landsat datasets in the semi-arid open-pit coal mining area. Besides, random points were created for different ecological stability levels (containing natural areas, coal mining areas, and reclamation areas) and segment linear regression was conducted to determine the structural change threshold for negative state transitions based on mining and positive state transitions based on reclamation. Furthermore, the impact factors of ecological stability were analyzed. Results showed that ecological stability fluctuated significantly over 16 years, showing a trend of first increasing and then decreasing. It was found that precipitation and temperature were the key natural factors affecting ecological stability, and mining activities constituted the dominant factor. The average perturbation distances to ecological stability from mining activities in the west, southwest, and east mining groups were 7500, 5500, and 8000 m, respectively. SFSTM is appliable to the coal mining ecosystem. Quantitative models of ecological stability response can help resolve ambiguity about management efficacy and the ecological stability results facilitate iterative updating of knowledge by using monitoring data from coal mining areas. Moreover, the proposed ecological structural threshold provides a useful early warning tool, which can aid in the reduction of ecosystem uncertainty and avoid reverse transformations of the positive state in the coal mining areas.

Causes and consequences of deer browsing on red trillium (Trillium erectum) along an elevational gradient

Models of ecological responses to climate warming predict species’ migration towards higher latitudes or elevations. However, models often neglect nonclimatic factors, such as herbivory, which could slow down or prevent geographic range expansion. A previous study in Mont Mégantic National Park (Quebec) found that in one year (2016), browsing by white-tailed deer on Trillium erectum L. was substantially higher at high elevations than low elevations. Under the hypothesis that deer herbivory could limit the upper elevational range expansion of T. erectum, here we ask (i) whether herbivory increased with elevation during two additional years (2017 and 2018), (ii) whether the rate of deer visitation increases with elevation, and (iii) whether the effect of herbivory on relative growth rates increases with elevation. Contrary to the earlier study, we did not find a significant trend of herbivory with elevation, although there was a weak positive relationship between deer visitation and elevation. We found a strong negative impact of browsing on relative growth rates, but the magnitude of this effect did not vary with elevation. Our results thus do not support the hypothesis that herbivory limits the range of T. erectum at high elevation, but herbivory could have a negative impact on populations in general if the browsing rate remains high.

Designing flows to enhance ecosystem functioning in heavily altered rivers.

More than a century of dam construction and water development in the western United States has led to extensive ecological alteration of rivers. Growing interest in improving river function is compelling practitioners to consider ecological restoration when managing dams and water extraction. We developed an Ecological Response Model (ERM) for the Cache la Poudre River, northern Colorado, USA, to illuminate effects of current and possible future water management and climate change. We used empirical data and modeled interactions among multiple ecosystem components to capture system‐wide insights not possible with the unintegrated models commonly used in environmental assessments. The ERM results showed additional flow regime modification would further alter the structure and function of Poudre River aquatic and riparian ecosystems due to multiple and interacting stressors. Model predictions illustrated that specific peak flow magnitudes in spring and early summer are critical for substrate mobilization, dynamic channel morphology, and overbank flows, with strong subsequent effects on instream and riparian biota that varied seasonally and spatially, allowing exploration of nuanced management scenarios. Instream biological indicators benefitted from higher and more stable base flows and high peak flows, but stable base flows with low peak flows were only half as effective to increase indicators. Improving base flows while reducing peak flows, as currently proposed for the Cache la Poudre River, would further reduce ecosystem function. Modeling showed that even presently depleted annual flow volumes can achieve substantially different ecological outcomes in designed flow scenarios, while still supporting social demands. Model predictions demonstrated that implementing designed flows in a natural pattern, with attention to base and peak flows, may be needed to preserve or improve ecosystem function of the Poudre River. Improved regulatory policies would include preservation of ecosystem‐level, flow‐related processes and adaptive management when water development projects are considered.

Dissolved Reactive Phosphorus Loads to Western Lake Erie: The Hidden Influence of Nanoparticles.

Increased dissolved reactive phosphorus (DRP) fluxes in the Maumee River in the Western Lake Erie watershed have been cited as a cause of recent hypoxia and toxic algal blooms in Western Lake Erie. Dissolved reactive P is operationally defined as the molybdate-reactive P that passes through a 0.45-μm filter. Unfortunately, this 0.45-μm cutoff is not based on solute chemistry; rather, it is based on tradition dating back to the 1940s. This dissolved versus particulate operationally defined threshold may be limiting scientific understanding of the transport of reactive P in the Lake Erie watershed (and beyond). Naturally occurring nanoparticles smaller than 0.45 μm can pass through filters, inflating DRP values, as has been suggested by studies in other watersheds. Transmission electron microscopy of filtered samples from the Maumee River revealed nanoparticles of various mineralogy, which are rich in P. By analyzing public data, we estimate that approximately half of the DRP flux in the Maumee River is not truly dissolved orthophosphate; it is instead particulate P that has passed through 0.45-μm filters. We also conducted a centrifugation experiment on previously filtered samples that likewise removed 40% of DRP and 75% of Fe. The influence of nanoparticles on DRP loads to Lake Erie has implications, including (i) helping to elucidate where reactive P originates on the landscape, (ii) designing best management practices, and (iii) improving our models of ecological response of nonpoint P loading.

Grounding simulation models with qualitative case studies: Toward a holistic framework to make climate science usable for US public land management

Policies directing agencies and public land managers to incorporate climate change into management face several barriers. These stem, in part, from a disconnect between the information that is produced and the information needs of local resource managers. A disproportionate focus on the natural and physical sciences in climate vulnerability and adaptation assessment obscure understandings of complex social systems and the interactions and feedbacks in social-ecological systems. We use a qualitative case study of bison management on Department of the Interior-managed and tribal lands to explore how a social-science driven Determinants and Analogue Vulnerability Assessment (DAVA) can inform ecological response models, specifically simulation models that account for multiple drivers of change. First, we illustrate how a DAVA approach can help to: 1) identify key processes, entities, and interactions across scales; 2) document local impacts, indicators, and monitoring efforts of drought and climate; and 3) identify major tradeoffs and uncertainties. We then demonstrate how qualitative narratives can inform simulation models by: 1) prioritizing model components included in modeling efforts; 2) framing joint management and climate scenarios; and 3) parameterizing and evaluating model performance. We do this by presenting a conceptual joint agent-based/state-and-transition simulation modeling framework. Simulation models can represent multiple interacting variables and can identify surprising, emergent outcomes that might not be evident from qualitative analysis alone, and we argue that qualitative case studies can ground simulation models in local contexts and help make them more structurally realistic and useful. Together, these can provide a step toward developing actionable climate change adaptation strategies.

Recent advances in environmental flows science and water management—Innovation in the Anthropocene

Abstract The implementation of environmental flow regimes offers a promising means to protect and restore riverine, wetland and estuarine ecosystems, their critical environmental services and cultural/societal values. This Special Issue expands the scope of environmental flows and water science in theory and practice, offering 20 papers from academics, agency researchers and non‐governmental organisations, each with fresh perspectives on the science and management of environmental water allocations. Contributions confront the grand challenge for environmental flows and water management in the Anthropocene—the urgent need for innovations that will help to sustain the innate resilience of social–ecological systems under dynamic and uncertain environmental and societal futures. Basin‐scale and regional assessments of flow requirements mark a necessary advance in environmental water science in the face of rapid changes in water‐resource management activities worldwide (e.g. increases in dams, diversions, retention and reuse). Techniques for regional‐scale hydrological and ecohydrological modelling support ecological risk assessment and identification of priority flow management and river restoration actions. Changing flood–drought cycles, long‐term climatic shifts and associated effects on hydrological, thermal and water quality regimes add enormous uncertainty to the prediction of future ecological outcomes, regardless of environmental water allocations. An improved capacity to predict the trajectories of ecological change in rivers degraded by legacies of past impact interacting with current conditions and future climate change is essential. Otherwise, we risk unrealistic expectations from restoration of river and estuarine flow regimes. A more robust, dynamic and predictive approach to environmental water science is emerging. It encourages the measurement of process rates (e.g. birth rate, colonisation rate) and species traits (e.g. physiological requirements, morphological adaptations) as well as ecosystem states (e.g. species richness, assemblage structure), as the variables representing ecological responses to flow variability and environmental water allocations. Another necessary development is the incorporation of other environmental variables such as water temperature and sedimentary processes in flow–ecological response models. Based on contributions to this Special Issue, several recent compilations and the wider literature, we identify six major scientific challenges for further exploration, and seven themes for advancing the management of environmental water. We see the emerging frontier of environmental flows and water science as urgent and challenging, with numerous opportunities for reinvigorated science and methodological innovation in the expanding enterprise of environmental water linked to ecological sustainability and social well‐being.

Process of land use transition and its impact on regional ecological quality in the Middle Reaches of Heihe River, China

Land use transition is one of the main drivers of regional ecosystem change in arid area, which directly affects human well-being. Based on the satellite images of 1987, 2001 and 2016, the change detection assessment model and ecological response model were used to analyze the process of land use transition and response of ecological quality during 1987-2016 in the ecologically fragile middle reaches of the Heihe River. The results showed that the land use change was significant during 1987-2016 and the total change increased significantly, as well as the continuous increase of the cultivated land and construction land. There was a strong tendency of transform from grassland to cultivated land, while the tendency of transforming unused land to other land classes was not strong under a random process of gain or loss. During 1987-2016, the ecological quality of the study area displayed a decreasing trend as a whole and the ecological land decreased by 2.8%. The land use transition with the greatest impact on the ecological environment degradation was the transition of the grassland to the cultivated land and unused land. Therefore, in order to promote the sustainable use of regional land resources and to improve the regional ecological quality, it is necessary to allocate the proportion of production land and ecological land according to the regional water resources.

Minimising biases in expert elicitations to inform environmental management: Case studies from environmental flows in Australia

Environmental managers often do not have sufficient empirical data to inform decisions, and instead must rely on expert predictions. However, the informal methods often used to gather expert opinions are prone to cognitive and motivational biases. We developed a structured elicitation protocol, where opinions are directly incorporated into Bayesian Network (BBN) models. The 4-stage protocol includes approaches to minimise biases during pre-elicitation, workshop facilitation and output analysis; and results in a fully functional BBN model. We illustrate our protocol using examples from environmental flow management in Australia, presenting models of vegetation responses to changes in riverine flow regimes. The reliance on expert opinion and the contested nature of many environmental management decisions mean that our structured elicitation protocol is potentially of great value for developing robust environmental recommendations. This method also lends itself to effective adaptive management, because the expert-populated ecological response models can be readily updated with field data.

Informing Environmental Water Management Decisions: Using Conditional Probability Networks to Address the Information Needs of Planning and Implementation Cycles.

One important aspect of adaptive management is the clear and transparent documentation of hypotheses, together with the use of predictive models (complete with any assumptions) to test those hypotheses. Documentation of such models can improve the ability to learn from management decisions and supports dialog between stakeholders. A key challenge is how best to represent the existing scientific knowledge to support decision-making. Such challenges are currently emerging in the field of environmental water management in Australia, where managers are required to prioritize the delivery of environmental water on an annual basis, using a transparent and evidence-based decision framework. We argue that the development of models of ecological responses to environmental water use needs to support both the planning and implementation cycles of adaptive management. Here we demonstrate an approach based on the use of Conditional Probability Networks to translate existing ecological knowledge into quantitative models that include temporal dynamics to support adaptive environmental flow management. It equally extends to other applications where knowledge is incomplete, but decisions must still be made.

An evidence-based approach for integrating ecological, hydrological and consumptive models to optimize flow management: a proof of concept

ABSTRACTImplementing policies to return water to the environment is challenging. We developed an approach to integrate ecological responses with river management models to provide a link between flow and ecology. This paper aims to summarize the findings of a multifaceted project bringing together multiple lines of evidence to achieve a proof-of-concept approach for optimizing water use to support water policy and management decisions. We developed an eco-hydrology model that represents rivers, water storages, operational constraints, flow management, an ecological response and consumptive irrigation demands, which is linked to climate. To demonstrate the proof of concept, we describe a case study where modelling optimization seeks solutions to minimize terrestrial vegetation encroachment (an ecological response) and maximize irrigation net value through flow management. The solutions provide a range of alternative ‘optimal’ management options to consider. Ultimately, hydrological modelling that integrates both consumptive use and ecological response simultaneously is important to enhance stakeholder understanding of the complexities and trade-offs involved in implementing different decisions. Although proof of concept at this stage, the approaches offer potential for integration of river management models and quantitative ecological response models (derived by considering available evidence from many sources) to support water policy and management decisions.

Drawing together multiple lines of evidence from assessment studies of hydropeaking pressures in impacted rivers

Hydropeaking has negative effects on aquatic biota, but the causal relationships have not been studied extensively, especially when hydropeaking occurs in combination with other environmental pressures. The available evidence comes mainly from case studies demonstrating river-specific effects of hydropeaking that result in modified microhabitat conditions and lead to declines in fish populations. We used multiple lines of evidence to attempt to strengthen the evidence base for models of ecological response to flow alteration from hydropeaking. First, we synthesized evidence of ecological responses from relevant studies published in the scientific literature. We found considerable evidence of the ecological effects of hydropeaking, but many causal pathways are poorly understood, and we found very little research on the interactive effects of hydropeaking and other pressures. As a 2nd line of evidence, we used results from analyses of large-scale data sets. These results demonstrated the extent to which hydropeaking occurs with other pressures, but did not elucidate individual or interactive effects further. Thus, the multiple lines of evidence complemented each other, but the main result was to identify knowledge gaps regarding hydropeaking and a consequent pressing need for novel approaches, new questions, and new ways of thinking that can fill them.

Physiologically grounded metrics of model skill: a case study estimating heat stress in intertidal populations.

Models of ecological responses to climate change fundamentally assume that predictor variables, which are often measured at large scales, are to some degree diagnostic of the smaller-scale biological processes that ultimately drive patterns of abundance and distribution. Given that organisms respond physiologically to stressors, such as temperature, in highly non-linear ways, small modelling errors in predictor variables can potentially result in failures to predict mortality or severe stress, especially if an organism exists near its physiological limits. As a result, a central challenge facing ecologists, particularly those attempting to forecast future responses to environmental change, is how to develop metrics of forecast model skill (the ability of a model to predict defined events) that are biologically meaningful and reflective of underlying processes. We quantified the skill of four simple models of body temperature (a primary determinant of physiological stress) of an intertidal mussel, Mytilus californianus, using common metrics of model performance, such as root mean square error, as well as forecast verification skill scores developed by the meteorological community. We used a physiologically grounded framework to assess each model's ability to predict optimal, sub-optimal, sub-lethal and lethal physiological responses. Models diverged in their ability to predict different levels of physiological stress when evaluated using skill scores, even though common metrics, such as root mean square error, indicated similar accuracy overall. Results from this study emphasize the importance of grounding assessments of model skill in the context of an organism's physiology and, especially, of considering the implications of false-positive and false-negative errors when forecasting the ecological effects of environmental change.

Tidal Marsh Susceptibility to Sea-Level Rise: Importance of Local-Scale Models

Abstract Increasing concern over sea-level rise impacts to coastal tidal marsh ecosystems has led to modeling efforts to anticipate outcomes for resource management decision making. Few studies on the Pacific coast of North America have modeled sea-level rise marsh susceptibility at a scale relevant to local wildlife populations and plant communities. Here, we use a novel approach in developing an empirical sea-level rise ecological response model that can be applied to key management questions. Calculated elevation change over 13 y for a 324-ha portion of San Pablo Bay National Wildlife Refuge, California, USA, was used to represent local accretion and subsidence processes. Next, we coupled detailed plant community and elevation surveys with measured rates of inundation frequency to model marsh state changes to 2100. By grouping plant communities into low, mid, and high marsh habitats, we were able to assess wildlife species vulnerability and to better understand outcomes for habitat resiliency. Starting study-site conditions were comprised of 78% (253-ha) high marsh, 7% (30-ha) mid marsh, and 4% (18-ha) low marsh habitats, dominated by pickleweed Sarcocornia pacifica and cordgrass Spartina spp. Only under the low sea-level rise scenario (44 cm by 2100) did our models show persistence of some marsh habitats to 2100, with the area dominated by low marsh habitats. Under mid (93 cm by 2100) and high sea-level rise scenarios (166 cm by 2100), most mid and high marsh habitat was lost by 2070, with only 15% (65 ha) remaining, and a complete loss of these habitats by 2080. Low marsh habitat increased temporarily under all three sea-level rise scenarios, with the peak (286 ha) in 2070, adding habitat for the endemic endangered California Ridgway’s rail Rallus obsoletus obsoletus. Under mid and high sea-level rise scenarios, an almost complete conversion to mudflat occurred, with most of the area below mean sea level. Our modeling assumed no marsh migration upslope due to human levee and infrastructure preventing these types of processes. Other modeling efforts done for this area have projected marsh persistence to 2100, but our modeling effort with site-specific datasets allowed us to model at a finer resolution with much higher local confidence, resulting in different results for management. Our results suggest that projected sea-level rise will have significant impacts on marsh plant communities and obligate wildlife, including those already under federal and state protection. Comprehensive modeling as done here improves the potential to implement adaptive management strategies and prevent marsh habitat and wildlife loss in the future.

Reconstructing long-term trophic histories for lakes using two independent approaches: Application of dynamic computer modelling and palaeolimnology to Lough Mask, Ireland

An understanding of the extent to which natural variability has been and is being exceeded by the effects of human activity can make an important contribution to the effective management of impacted water bodies, including their restoration. Frequently, however, the required monitoring data are not available, particularly for the period prior to human impact, or are of insufficient quality. Two methodological solutions to this problem are often proposed, both of which involve the reconstruction of past variations in water quality and associated ecological conditions through indirect means: computer (hindcast) modelling and sedimentary (palaeolimnological) analyses. Both proposed solutions are not without their own challenges, however. Here a series of dynamic computer models (a catchment model and an in-lake ecological response model) and palaeolimnological techniques (including sediment-based diatom-inferred total phosphorus, DI-TP), were used to reconstruct total phosphorus (TP) concentrations and measures of primary productivity in Lough Mask, Co. Mayo, for the period ad 1905–2006. Although results from both approaches indicated similar patterns of nutrient enrichment in the lake during the twentieth century, sediment-based DI-TP values were consistently higher than hindcast-modelled in-lake TP concentrations. Both approaches indicated oligotrophic to mesotrophic conditions in Lough Mask prior to c. ad 1950. Elevated trophic conditions (in the range mesotrophic–eutrophic) were evident from c. ad 1970. Modelling results indicated that increased diffuse phosphorus loading from agricultural sources was the main driver of nutrient enrichment from c. ad 1970. Eutrophication was also concurrent with climatic warming, which was manifested in strengthened thermal stratification in model simulations. Results generated by the two approaches suggest that pre-ad 1950 trophic conditions could be used as a reference baseline, representing conditions prior to major impacts from agricultural intensification, for defining current water quality management targets.

Reconstructing long-term trophic histories for lakes using two independent approaches: Application of dynamic computer modelling and palaeolimnology to Lough Mask, Ireland

An understanding of the extent to which natural variability has been and is being exceeded by the effects of human activity can make an important contribution to the effective management of impacted water bodies, including their restoration. Frequently, however, the required monitoring data are not available, particularly for the period prior to human impact, or are of insufficient quality. Two methodological solutions to this problem are often proposed, both of which involve the reconstruction of past variations in water quality and associated ecological conditions through indirect means: computer (hindcast) modelling and sedimentary (palaeolimnological) analyses. Both proposed solutions are not without their own challenges, however. Here a series of dynamic computer models (a catchment model and an in-lake ecological response model) and palaeolimnological techniques (including sediment-based diatom-inferred total phosphorus, DI-TP), were used to reconstruct total phosphorus (TP) concentrations and measures of primary productivity in Lough Mask, Co. Mayo, for the period AD 1905 2006. Although results from both approaches indicated similar patterns of nutrient enrichment in the lake during the twentieth century, sediment-based DI-TP values were consistently higher than hindcast-modelled in-lake TP concentrations. Both approaches indicated oligotrophic to mesotrophic conditions in Lough Mask prior to c. AD 1950. Elevated trophic conditions (in the range mesotrophic eutrophic) were evident from c. AD 1970. Modelling results indicated that increased diffuse phosphorus loading from agricultural sources was the main driver of nutrient enrichment from c. AD 1970. Eutrophication was also concurrent with climatic warming, which was manifested in strengthened thermal stratification in model simulations. Results generated by the two approaches suggest that pre-AD 1950 trophic conditions could be used as a reference baseline, representing conditions prior to major impacts from agricultural intensification, for defining current water quality management targets.

Effects of streamflow reductions on aquatic macroinvertebrates: linking groundwater withdrawals and assemblage response in southern New Jersey streams, USA

A comprehensive hydro-ecological investigation was conducted to determine the ecological response of increased groundwater withdrawals from the Kirkwood-Cohansey aquifer system, an important source of water supply in southern New Jersey, USA. Collocated observations were made of aquatic-macroinvertebrate assemblages and stream hydrologic attributes to develop flow–ecology response relations. A sub-regional transient groundwater flow model (MODFLOW) was used to simulate three plausible high-stress groundwater-withdrawal scenarios which resulted in stream baseflow reductions of approximately 0.12, 0.20, and 0.26 m3 s-1. These reduction scenarios were used to construct flow-alteration ecological response models to evaluate aquatic-macroinvertebrate response to streamflow reduction. For example, flow-alteration ecological response models indicate that if groundwater withdrawals diminish mean annual streamflow from 1.1 to 0.6 m3 s-1, the abundance of intolerant taxa could be reduced by as much as 20%. These flow-alteration ecological response modelling results could be used by resource professionals to evaluate alternative water management strategies to determine maximum basin withdrawal rates that meet ongoing human water demand while protecting biological integrity.Editor D. Koutsoyiannis; Guest editor M. AcremanCitation Kennen, J.G., Riskin, M.L., and Charles, E.G., 2014. Effects of streamflow reductions on aquatic macroinvertebrates: linking groundwater withdrawals and assemblage response in southern New Jersey streams, USA. Hydrological Sciences Journal, 59 (3–4), 545–561.

Overcoming the challenges of monitoring and evaluating environmental flows through science–management partnerships

ABSTRACTEnvironmental flows programmes can be controversial, given that they transfer water from consumptive to environmental uses. It is, therefore, imperative that their performance is assessed against their anticipated ecological benefits. However, environmental flows present both technical and institutional challenges that cannot be addressed by traditional approaches to monitoring and evaluation. We present a framework that is currently being employed to evaluate the effectiveness of environmental flows in Victoria, Australia. The framework encourages a shift from expert-based models of ecological response to flow variation to those developed using the so-called ‘evidence-based’ methods that have become commonplace in medicine. The framework relies on close collaboration between scientists and managers for the design of monitoring programmes, collection and collation of data, and analysis and interpretation of results. Results will inform adaptive management of environmental flows in Victoria and improve basic understanding of the ecological impacts of changes in flow regime. Our experience suggests that the technical and institutional challenges for monitoring and evaluating environmental flows can be mostly overcome by close and continuing collaboration between managers and researchers. We are unaware of any equivalent programmes anywhere in the world and believe that our framework is transferable to any other large-scale environmental flows monitoring programme.

Ecohydrological and socioeconomic integration for the operational management of environmental flows

Investment in and operation of flow control infrastructure such as dams, weirs, and regulators can help increase both the health of regulated river ecosystems and the social values derived from them. This requires high-quality and high-resolution spatiotemporal ecohydrological and socioeconomic information. We developed such an information base for integrated environmental flow management in the River Murray in South Australia (SA). A hydrological model was used to identify spatiotemporal inundation dynamics. River ecosystems were classified and mapped as ecohydrological units. Ecological response models were developed to link three aspects of environmental flows (flood duration, timing, and inter-flood period) to the health responses of 16 ecological components at various life stages. Potential infrastructure investments (flow control regulators and irrigation pump relocation) were located by interpreting LiDAR elevation data, digital orthophotography, and wetland mapping information; and infrastructure costs were quantified using engineering cost models. Social values were quantified at a coarse scale as total economic value based on a national survey of willingness-to-pay for four key ecological assets; and at a local scale using mapped ecosystem service values. This information was integrated using a constrained, nonlinear, mixed-integer, compromise programming optimization model and solved using a stochastic Tabu search algorithm. We tested the model uncertainty and sensitivity using 390 Monte Carlo model runs at varying weights of ecological health vs. social values. Integrating ecohydrological and socioeconomic information identified environmental flow management regimes that efficiently achieved both ecological and social objectives. Using an ecologically weighted efficient and socially weighted efficient scenario, we illustrated model outputs including a suite of cost-effective infrastructure investments and an operational plan for new and existing flow control structures including dam releases, weir height manipulation, and regulator operation on a monthly time step. Both the investments and management regimes differed substantially between the two scenarios, suggesting that the choice of weightings on ecological and social objectives is important. This demonstrates the benefit of integrating high-quality and high-resolution spatiotemporal ecohydrological and socioeconomic information for guiding the investment in and operational management of environmental flows.