Legacies, lags and long‐term trends: Effective flow restoration in a changed and changing world

EXECUTIVE SUMMARY Ecological restoration, when implemented effectively and sustainably, contributes to protecting biodiversity; improving human health and wellbeing; increasing food and water security; delivering goods, services, and economic prosperity; and supporting climate change mitigation, resilience, and adaptation. It is a solutions-based approach that engages communities, scientists, policymakers, and land managers to repair ecological damage and rebuild a healthier relationship between people and the rest of nature. When combined with conservation and sustainable use, ecological restoration is the link needed to move local, regional, and global environmental conditions from a state of continued degradation, to one of net positive improvement. The second edition of the International Principles and Standards for the Practice of Ecological Restoration (the Standards) presents a robust framework for restoration projects to achieve intended goals, while addressing challenges including effective design and implementation, accounting for complex ecosystem dynamics (especially in the context of climate change), and navigating trade-offs associated with land management priorities and decisions. The Standards establish eight principles that underpin ecological restoration. Principles 1 and 2 articulate important foundations that guide ecological restoration: effectively engaging a wide range of stakeholders, and fully utilizing available scientific, traditional, and local knowledge, respectively. Principles 3 and 4 summarize the central approach to ecological restoration, by highlighting ecologically appropriate reference ecosystems as the target of restoration and clarifying the imperative for restoration activities to support ecosystem recovery processes. Principle 5 underscores the use of measurable indicators to assess progress toward restoration objectives. Principle 6 lays out the mandate for ecological restoration to seek the highest attainable recovery. Tools are provided to identify the levels of recovery aspired to and to track progress. Principle 7 highlights the importance of restoration at large spatial scales for cumulative gains. Finally, ecological restoration is one of several approaches that address damage to ecosystems and Principle 8 clarifies its relationships to allied approaches on a “Restorative Continuum”. The Standards highlight the role of ecological restoration in connecting social, community, productivity, and sustainability goals. The Standards also provide recommended performance measures for restorative activities for industries, communities, and governments to consider. In addition, the Standards enhance the list of practices and actions that guide practitioners in planning, implementation, and monitoring activities. The leading practices and guidance include discussion on appropriate approaches to site assessment and identification of reference ecosystems, different restoration approaches including natural regeneration, consideration of genetic diversity under climate change, and the role of ecological restoration in global restoration initiatives. This edition also includes an expanded glossary of restoration terminology. SER and its international partners produced the Standards for adoption by communities, industries, governments, educators, and land managers to improve ecological restoration practice across all sectors and in all ecosystems, terrestrial and aquatic. The Standards support development of ecological restoration plans, contracts, consent conditions, and monitoring and auditing criteria. Generic in nature, the Standards framework can be adapted to particular ecosystems, biomes, or landscapes; individual countries; or traditional cultures. The Standards are aspirational and provide tools that are intended to improve outcomes, promote best practices, and deliver net global environmental and social benefits. As the world enters the UN Decade on Ecosystem Restoration (2021–2030), the Standards provide a blueprint for ensuring ecological restoration achieves its full potential in delivering social and environmental equity and, ultimately, economic benefits and outcomes.

<p>Many hydrological models (GR4J, Sacramento and SIMHYD for example) currently exist to reproduce hydrological response at a catchment scale. Some models (IQQM, Source for example) also exist to assess the impacts of human interventions designed to in some way optimise the use of water in regulated river systems. There are however a much smaller number of models designed to assess the impacts of water resources management on socio-economics, the community and the environment more broadly.</p><p>A current program of work known as MD-WERP – the Murray-Darling Water and Environment Research Program, seeks to improve the understanding and representation of key processes in hydrological models used to underpin basin analysis and planning. We are working with policy makers and water managers in State and Federal government to apply these models to assess the impacts of water resource management options on hydrological, ecological and socio-economic outcomes in the Murray-Darling Basin. This will allow planners to consider a wide range of management options in the review and revision of the Murray-Darling Basin Plan that is scheduled for the next few years.</p><p>The vast majority of global and regional climate models, as well as understanding of changes in global and regional circulation patterns suggest a drier future for the Murray-Darling Basin with consequently more frequent and severe droughts. The management options to be assessed therefore are primarily those that minimise the impacts of drier conditions on the environment, irrigators and the Basin community, along with models that allow assessments of trade-offs between these disparate water users to be made.</p><p>The models that are required to assess these adaptation options need to be diverse, covering not only things such as changes in rainfall and hydrological response, but also climate adaptation options in river system operations, conjunctive use of groundwater and surface water, water trading and allocation, and consequent impacts on the environment, irrigators, basin communities and First Nations groups.</p><p>This presentation will provide an overview of MD-WERP with a focus on the climate adaptation and hydrology themes, assessing how modelling tools can be used to better inform Basin-wide water resources policy and planning.</p>

Since 1857 new Australians have constructed many thousands of weirs (3600 in the Murray–Darling Basin alone) and floodplain levee banks, 446 large dams (>10 m crest height) and over 50 intra‐ and inter‐basin water transfer schemes to secure water supplies for human use. Flow regulation has changed the hydrology of major rivers on three temporal sales–the flood pulse (days to weeks), flow history (weeks to years) and the long‐term statistical pattern of flows, or flow regime (decades or longer). The regulation of river flows is widely acknowledged as a major cause of deteriorating conditions in many Australian river and floodplain ecosystems. In response to mounting environmental concerns, all states, territories and the Commonwealth Government have committed the nation to the principles of ecologically sustainable development and a process of national water reform. Rivers and wetlands are now recognized as legitimate ‘users’ of water, and jurisdictions must provide water allocations to sustain and where necessary restore ecological processes and the biodiversity of water‐dependent ecosystems. Progress in the protection and restoration of river and wetland water regimes has been significant, with over half of mainland aquatic systems designated to receive water allocations of some sort. However, exactly how much water they will receive or retain is unclear from the data available. Moreover, the ecological outcomes and benefits of water allocations are not yet apparent in most aquatic ecosystems, with the exception of certain waterbird breeding events, the disruption of algal blooms in weirs and improved fish passage. After reviewing these issues, this paper addresses two vital questions: How much water does a river need? and How can this water be clawed back from other users? Studies conducted to date in Queensland rivers suggest that around 80–92% of natural mean annual flow (and other ecologically relevant hydrological indicators) may be needed to maintain a low risk of environmental degradation. In the Top End of the Northern Territory, some rivers are maintained at 80% of their natural flow, whereas two‐thirds of various flow indicators has been proposed as the restoration target for the River Murray, and 28% of natural mean annual flow has been negotiated for the Snowy River in Victoria. To validate these estimates, ecologists are seeking opportunities to turn river restoration projects into long‐term hypothesis‐driven experiments in ecological restoration, and the funding, time and institutional support to do so. The paper ends with some suggestions to advance the water reforms and achieve higher levels of water allocation for the environment. Copyright © 2003 John Wiley & Sons, Ltd.

River flows in the Murray–Darling Basin, as in many regions in the world, are vulnerable to climate change, anticipated to exacerbate current, substantial losses of freshwater biodiversity. Additional declines in water quantity and quality will have an adverse impact on existing freshwater ecosystems. We critique current river-management programs, including the proposed 2011 Basin Plan for Australia’s Murray–Darling Basin, focusing primarily on implementing environmental flows. River management programs generally ignore other important conservation and adaptation measures, such as strategically located freshwater-protected areas. Whereas most river-basin restoration techniques help build resilience of freshwater ecosystems to climate change impacts, different measures to enhance resilience and reoperate water infrastructure are also required, depending on the degree of disturbance of particular rivers on a spectrum from free-flowing to highly regulated. A crucial step is the conservation of free-flowing river ecosystems where maintenance of ecological processes enhances their capacity to resist climate change impacts, and where adaptation may be maximised. Systematic alteration of the operation of existing water infrastructure may also counter major climate impacts on regulated rivers.

In dryland environments, freshwater ecosystems often suffer extensive degradation through habitat modification and water regime changes. The Macquarie Marshes are located in the Murray–Darling Basin in south‐eastern Australia. They are an example of an ecosystem that has experienced significant degradation in recent decades owing to upstream water diversions. Recent reforms of water management in the Murray–Darling Basin have attempted to balance environmental needs against consumptive uses of water. This paper examines the role a protected area has played in conserving the Macquarie Marshes freshwater ecosystem and discusses how Murray–Darling Basin water reform, together with social expectations of public land managers, have had impacts on the management of the Macquarie Marshes Nature Reserve. Protected areas may limit adverse impacts on habitat associated with local‐scale agricultural production but struggle without formal water management arrangements to protect water‐dependent ecosystems from threats operating at a catchment scale. Protected area managers balance demands from stakeholders to address local issues, such as fire management and geomorphic changes, against contributing to the achievement of environmental goals in a water planning system that operates at the catchment scale. European settlement and water resource development has marginalized local Aboriginal people from any role in land and water management activities. The water reforms have given them more opportunities for involvement in decision‐making processes, but opportunities for increased access to water for cultural and spiritual purposes remain limited. Protected areas offer a means of providing greater access for Aboriginal people to their ancestral lands. The strategies and processes developed to maintain and enhance the Macquarie Marshes exemplify the evolution in understanding of freshwater ecosystem protection in Australia, and are relevant globally to water resource management in complex social‐ecological systems. Copyright © 2016 John Wiley & Sons, Ltd.

Evolving restoration principles in a changing world

Water buybacks in the Murray–Darling Basin entail compensation at market prices for water sold by farmers to the Commonwealth. Despite this, the Murray Darling Basin Authority met with hostility at public meetings in basin communities late in 2010. This reflects hardship arising from three consecutive years of drought rather than the consequences of buybacks. Dynamic CGE modelling results indicate that around 6000 jobs were lost due to the 2006–07 to 2008–09 drought in the Murray Darling Basin. Even in the long run, years after a rainfall recovery, jobs will remain 1500 below forecast due to lost years of investment during prolonged drought. This contrasts with 500 jobs lost across the basin due to buybacks. Some industry groups and politicians have asserted that buybacks will result in rural catastrophe. This underestimates the adaptability of farmers in response to a voluntary and fully compensated process, and confuses the impacts of drought and buybacks. Nevertheless, there are aspects of the 2007 Water Act that warrant modification in order to move towards a socially optimal restoration of environmental flows in the Murray–Darling Basin.

Water markets and freshwater ecosystem services: Policy reform and implementation in the Columbia and Murray-Darling Basins

Climate change threatens water resources from local to global scales. However, there are significant challenges in assessing climate risk for large river basins, especially those with multiple jurisdictions and competing management objectives. Traditional methods follow a top-down approach, where the impacts of climate projections by climate models are simulated using hydrological and water resource models. While these methods can provide a detailed snapshot of how rivers are impacted under a small number of projected future climates, their computational burden, and challenges in linking water resource models owned by different jurisdictions mean it is difficult to robustly explore the implications of aleatory (from hydroclimate variability) and epistemic (from hydroclimate change) uncertainty. Unlike top-down approaches, bottom-up approaches can be used to better understand vulnerability under a range of possible future climate. Bottom-up approaches begin with a sensitivity analysis of important management objectives to multiple hydroclimate stressors. Unfortunately, bottom-up approaches are constrained when using complex system models in large river basins, as their methodologies typically require many times more simulations than top-down approaches.The Murray Darling basin (MDB) is Australia’s most significant river basin. Irrigation in the basin supports over $30 billion (AUD) in agriculture and livelihoods for the 2.4 million residents. The MDB has significant environmental values, with RAMSAR wetlands, many endemic and threatened species, and it is the traditional land of over 50 first nations groups. We assessed the impacts of climate change on basin-wide inflows and key indicator sites using both top-down and bottom-up approaches. We stochastically generated multiple sequences of future hydroclimate conditions, which helps separate the influence of climate variability from climate change. We deliberately traded-off detail in our assessment by deriving simple functional relationships between sub-basin inflows and 21 key indicator sites using existing scenarios from the complex jurisdictional water resource models. This allowed us to assess far more replicates of stochastic data, more climate scenarios, and conduct a more rigorous stress test within the bottom-up framework than would normally be permitted using complex models.The top-down approach provides a scenario-based assessment of likely conditions for water resources in the MDB, and spatially coherent projections of future inflows and river management metrics. The bottom-up approach provides more insight into spatial differences in sensitivity across the river catchments that make up the MDB, and can be used to both augment and help interpret outcomes from the top-down approach. The bottom-up approach also yields important thresholds in hydroclimate conditions which compromise basin-wide objectives (assessed through flow at the Murray River mouth which prevents the important lower lake system from becoming too saline). We consider top-down and bottom-up approaches to be complementary in assessing and adapting river systems to the impacts of climate change.The simple methods used here are complementary with other more detailed impact models. The ease of undertaking simulations and computational efficiency means simple methods can filter down the range of possible conditions or stressors that contribute to uncertainty, allowing a more targeted set of simulations to be undertaken using detailed, but costly, water resource models.

Human actions have altered global environments and reduced biodiversity by causing extinctions and reducing the population sizes of surviving species. Increasing human population size and per capita resource use will continue to have direct and indirect ecological and evolutionary consequences. As a result, future generations will inhabit a planet with significantly less wildlife, reduced evolutionary potential, diminished ecosystem services, and an increased likelihood of contracting infectious disease. The magnitude of these effects will depend on the rate at which global human population and/or per capita resource use decline to sustainable levels and the degree to which population reductions result from increased death rates rather than decreased birth rates.

In the recent past I had the opportunity of participating in three conferences, each of which was sustainabilityfocused with an engineering orientation. As is typical these days, sustainability discussion always begins with unsustainability of consumption in contrast to declining natural resources. Engineering research community has responded with the idea of dematerialization, which is first and foremost an attempt to decouple economic growth, such as increase in gross domestic product (GDP), from adverse environmental impact. This has been shown in some cases to have already been achieved partially; however, the goal remains to be full decoupling. Secondarily, dematerialization is directed towards reducing use of limited natural resources to satisfy the growing functional need of consumption. Dematerialization, while providing a useful idea towards efficient resource use, does not guarantee less consumption per capita. Great innovations in the future can be expected to come from scientific and engineering research to meet the decoupling objective. Directing research directly to reducing per capita consumption of material and energy, however, is another objective which could use the idea of dematerialization. The argument for sustainable consumption goes like this: the developed countries are unfairly using, on a comparative basis, far more material and energy consumption per capita than the developing countries. According to this line of thinking, the standard of living is not necessarily tied to larger per capita resource use. One illustrative example is the use of automobiles. Personal ownership of automobiles is not central to enjoying the function or service that automobiles deliver. Thus, if the ownership could be restricted in favor of rental, the same benefit can be obtained with fewer automobiles per capita, thereby reducing per capita resource use, pollution creation and environmental footprint. Some congested parts of the developed world, such as New York City and Washington, DC, already use this idea to a small extent. Greater good is and can be served by public transportation as well. Similarly, one could argue that per capita living space in square feet per person, which is comparatively large in developing nations, could also be reduced without reducing comfort and standard of living, thereby reducing environmental footprint and saving valuable resources for the future generation. If one continues to argue in this fashion, one arrives at the inevitable conclusion that human progress can be decoupled from personal consumption. The problem is that the acceptance of this decoupling can only be forced, as people will tend to spend when they earn. Thus, earnings need to be restricted. There is no science or engineering in this prospect. The only ways restriction of consumption or earnings can be implemented is either voluntary societal choice, which is unlikely, or force, which only a government can, in theory, exercise uniformly on all people. I asked one passionate adherent to sustainable consumption, who organized one of the conferences, if forced societal choice is different from socialism. He vehemently opposed this proposition, but still held that scientific and engineering research can provide solutions for a sustainable planet, which must of necessity, enjoy restriction on consumption. There will be myriads of innovative engineering solutions in the future that will bring that about, without the need to resort to force. Instruments of political economy, such as taxation and tariff, can effectively be used to curb demand. Unsustainability of our consumption is so dire, he argued, S. K. Sikdar (&) National Risk Management Research Lab/USEPA, 26 W. M.L. King Dr., Cincinnati, OH 45268, USA e-mail: sikdar.subhas@epa.gov

Invasive species are often more able to rapidly and efficiently utilise resources than natives, and comparing per capita resource use at different resource densities among invaders and trophically analogous natives could allow for reliable predictions of invasiveness. In South Africa, invasion by the Mediterranean mussel Mytilus galloprovincialis has transformed wave-exposed shores, negatively affecting native mussel species. Currently, South Africa is experiencing a second mussel invasion with the recent detection of the South American Semimytilus algosus. We tested per capita uptake of an algal resource by invading M. galloprovincialis, S. algosus, and the native Aulacomya atra at different algal concentrations and temperatures, representing the west and south coasts of South Africa, to examine whether their per capita resource use could be a predictor of their spread and subsequent invasiveness. Regardless of temperature, M. galloprovincialis was the most efficient consumer, significantly reducing algal cells compared to the other species when the resource was presented in both low and high starting densities. Furthermore, these findings aligned with a greater biomass of M. galloprovincialis on the shore in comparison with the other species. Resource use by the new invader S. algosus was dependent on the density of resource and, although this species was efficient at low algal concentrations at cooler temperatures, this pattern broke down at higher algal densities. This was once more reflected in lower biomass in surveys of this species along the cool west coast. We therefore forecast that S. algosus will be become established along the south coast; however, we also predict that M. galloprovincialis will maintain dominance on these shores.

Biological invasions are among the biggest threats to freshwater biodiversity. This is increasingly relevant in the Murray–Darling Basin, Australia, particularly since the introduction of the common carp (Cyprinus carpio). This invasive species now occupies up to ninety per cent of fish biomass, with hugely detrimental impacts on native fauna and flora. To address the ongoing impacts of carp, cyprinid herpesvirus 3 (CyHV-3) has been proposed as a potentially effective biological control agent. Crucially, however, it is unknown whether CyHV-3 and other cyprinid herpesviruses already exist in the Murray–Darling. Further, little is known about those viruses that naturally occur in wild freshwater fauna, and the frequency with which these viruses jump species boundaries. To document the evolution and diversity of freshwater fish viromes and better understand the ecological context to the proposed introduction of CyHV-3, we performed a meta-transcriptomic viral survey of invasive and native fish across the Murray–Darling Basin, covering over 2,200 km of the river system. Across a total of thirty-six RNA libraries representing ten species, we failed to detect CyHV-3 nor any closely related viruses. Rather, meta-transcriptomic analysis identified eighteen vertebrate-associated viruses that could be assigned to the Arenaviridae, Astroviridae, Bornaviridae, Caliciviridae, Coronaviridae, Chuviridae, Flaviviridae, Hantaviridae, Hepeviridae, Paramyxoviridae, Picornaviridae, Poxviridae, Reoviridae and Rhabdoviridae families, and a further twenty-seven that were deemed to be associated with non-vertebrate hosts. Notably, we revealed a marked lack of viruses that are shared among invasive and native fish sampled here, suggesting that there is little virus transmission from common carp to native fish species, despite co-existing for over fifty years. Overall, this study provides the first data on the viruses naturally circulating in a major river system and supports the notion that fish harbour a large diversity of viruses with often deep evolutionary histories.

Climate change and the proposed Murray-Darling Basin Plan both result in less water for irrigation. Climate change is projected to take water from all uses including the environment, whereas the likely sustainable diversion limit in the Plan aims (amongst other things) to return water to the environment. We examine the impact on flows and the returns to irrigation of potential reductions in irrigation allocations, and the interaction with projected climate change impacts. Our analysis is based on an integrated hydrology – economics model of the Murray- Darling Basin, described in Kirby et al. (2012a). The model can quickly and easily run new climate or other scenarios, accounting for flows at key environmental assets. It uses a statistically calibrated economic model that can closely predict drought outcomes accounting for allocation, climate and price circumstances. We examined a 2,800 GL reduction to diversions, and compared it to a base case of no reductions. We modelled the flows and irrigation returns for the no reduction and reduction cases under the assumption of historical climate, a median climate change and a more severe climate change. The climate change projections were those examined in the CSIRO Murray-Darling Basin Sustainable Yields project, slightly extended for more recent years. The broad results of this analysis are that: • The reduction of water available to irrigation under the sustainable diversion limit results in a less than proportional reduction in returns to irrigation. A 25 % reduction in water available on average over 114 years is estimated to reduce the gross value of of irrigated agricultural production by about 3 % on average. This is consistent with observation of reduced water availability in the drought (Kirby et al., 2012b, Conner et al., 2012). • Future droughts projected under climate change might be more severe that those experienced to date, with an expectation of greater economic impact; • A median climate change projection removes from the overall system slightly more water than is gained for the environment under the sustainable diversion limit. Under current sharing rules, this reduction in water comes primarily from the environment. The exact impact on flows varies from valley to valley. The impact of climate change is not considered in other analyses of the Murray-Darling Basin plan. 3 • The returns to irrigation are not much affected by a median climate change, with a 2 % reduction in gross value resulting from 3 % reduction in water availability (on top of the reductions due to the diversion limit). This detail in this result depends on the exact form of water sharing rules, and rules will change in the future; we used a default assumption that the behaviour resulting from the rules will be much as it is now.

The Murray–Darling river system is highly regulated and is Australia's major surface water resource. It is subject to blooms of the toxic cyanobacterium Anabaena circinalis, which present significant water quality problems. As a result of these blooms, an algal management strategy has been developed for the Murray–Darling basin. One of the major objectives of the strategy is the development of flow management strategies for key reaches of the river system. Intensive studies in the Murrumbidgee River, Australia, have indicated that persistent thermal stratification is a requirement for blooms of this cyanobacterium to occur. In the lower Murray, mean wind speed was found to be the major factor affecting the degree of thermal stratification under low flow conditions, which generally exist during the months of December to March. In this paper, the effect of various flow management scenarios on the likelihood of the occurrence of blooms in the River Murray at Morgan, South Australia, are assessed. A frequency analysis is carried out on 30 years of wind speed data to determine the probability of occurrence of persistent thermal stratification under a number of flow regimes. The scenarios evaluated include existing base flow conditions, altered base flow regimes, temporary releases from an upstream storage (Lake Victoria) and the temporary reduction of weir pool levels. The results obtained indicate that the dispersal of existing blooms by simultaneously reducing the weir pool levels at Locks 1–3 is the most effective and economical strategy for combating bloom formation by A. circinalis in the River Murray at Morgan. Copyright © 2001 John Wiley & Sons, Ltd.