Avril Horne

Using optimization to develop a designer environmental flow regime

There are increasing numbers of rivers with large storages, resulting in changes to environmental condition downstream. In these systems, environmental flow regimes that are specifically designed to meet environmental management objectives, whilst continuing to support economic needs, may be the best approach. A challenge remains as to how best to design these novel flow regimes. Decision support tools such as optimization provide a potential tool to achieve this. In existing tools environmental outcomes are not represented with sufficient realism and this is a major barrier to successful adoption by decision-makers. Here, we employ conditional probability networks as a promising approach that provides both ease of modelling and a direct link to ecological outcomes and processes. We present a generic model that can be used to represent any ecological endpoint within a river system. We then demonstrate the approach using two fish species in the Yarra River, Victoria.

Optimization tools for environmental water decisions

Public investment in river restoration through environmental watering has increased substantially in recent years. To sustain public support for such investment, management of environmental water must achieve the best possible outcomes in a transparent and defensible manner. The current management of environmental water relies on the ability of managers to estimate the impacts of their decisions under complex scenarios, often with multiple interdependent decisions that span over different spatial and temporal scales. Optimization modeling has been widely used in other forms of conservation management and an increasing body of literature documents the development of optimization models that could be used to improve environmental water decisions. This paper reviews this disparate research, showing that there are a range of different questions addressed using this modeling approach and that the representation of environmental outcomes varies. Future work must focus on improved adoption through engagement with end users and stakeholders during model development. Environmental water managers currently rely mainly on their experience to make complex decisions to best use limited volumes of water to achieve maximum benefit for the environment.The development of optimization tools to assist environmental water management is a growing area of research with a sharp increase in the number of publications in the last ten years.Considerable challenges remain concerning how best to represent the complex physical and environmental systems as both meaningful and solvable optimization problems; particularly the representation of environmental outcomes and objective functions.Benefits of optimization modeling are both in the improved understanding of the system being analysed gained through the model development phase, and in the model outputs providing information to assist decision making. Realizing these benefits requires end-user engagement.However, to date there has limited uptake of these models in practice.

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.

Purchasing Water for the Environment in Unregulated Systems - What Can We Learn from the Columbia Basin?

Abstract Environmental flows in unregulated rivers require a different management approach to regulated systems, where reservoirs allow more adaptive management of flows and water markets are well established. Governments in Australia have been investigating tender approaches to buy back water in unregulated systems. A number of organisations in the Columbia Basin in northwest America have been actively purchasing water for the environment in unregulated systems. This paper outlines some of the key lessons learnt about purchasing water for the environment in the Columbia Basin and discusses their possible application in the Australian context.

Water, Land Use Change and 'New Forests': What Are the Challenges for South-western Victoria?

Summary Land use change has occurred rapidly in south-western Victoria over the last decade and is expected to continue, albeit at a slower pace over the coming decades. One of those changes has been the development of ‘new forests’—industrial and farm forestry plantations and environmental plantings using indigenous or other species. This paper discusses some of the challenges that these land use changes pose for water and natural resource managers, drawing on results from a ‘Water and Land Use Change’ study. Land use change is expected to substantially reduce potential water yield in four of the regions seven drainage basins. Losses in potential water yield of 8–20% are predicted for these basins and of 7–8% for the region as a whole. New forest development will be the major driver of the hydrologic change that is following land use change. While land use change is not expected to greatly influence yield to the regions major water storages, it is expected to add considerably to the already high level of flow-related stress in the upper and middle reaches of the Lake Corangamite, Hopkins and Glenelg drainage basins.

Mechanisms to Allocate Environmental Water

Abstract Environmental water can be implemented using a range of different allocation mechanisms that are legal or policy tools that enable the provision of water for environmental purposes. This chapter identifies five allocation mechanisms and classifies these based on their legal characteristics, function, and operation. There are three allocation mechanisms that provide environmental water by imposing conditions on other water users: caps on consumptive water use, conditions on private water users, and conditions on storage or water resource operators. There are two allocation mechanisms that create specific legal rights for the environment itself: ecological/environmental reserves, and environmental water rights. These allocation mechanisms can be used singly or in combination within the same river system. The main factors that influence the selection of an allocation mechanism(s) in a particular system, and outline the main implementation options and constraints, operational requirements, security, and adaptability of each mechanism are discussed. Case studies from Australia, the United States, South Africa, and China are used to illustrate and explore the implementation of these allocation mechanisms, including several of the factors driving or constraining success.

The Environmental Water Management Cycle

Abstract Environmental water management is inherently a multidisciplinary endeavor, but until now there has been no single book that engages experts across all relevant areas of practice and scholarship. This book reflects the growing maturity of environmental water management as a cohesive and specialized field, which finally makes it possible to address this gap. This book pulls together the collective knowledge of experts from around the world to provide a holistic view of progress, a set of tools for new and experienced policy makers and practitioners, and a focus on the remaining challenges associated with managing environmental water. In doing so, we hope this book will establish a coherent approach to best practice for environmental water planning and management.

Establishment of environmental water in the Murray- Darling Basin: An analysis of two key policy initiatives

Abstract Policy to protect river ecosystems has changed rapidly in Australia, and the mechanisms to both establish and manage environmental water are still evolving. Policy has moved from providing a fixed environmental target (albeit varying between years) to one in which the environment can actively participate in the market, with the possibility of better fulfilling variable water requirements. However, the inherent nature of the sustainable diversion limit (SDL), established under the Water Act 2007, is that it represents a fixed allocation to the environment. This paper considers the interaction of the new SDL for the Murray-Darling Basin and potential issues arising from the interaction with the government buyback initiative. While both the SDL and buyback have been discussed extensively, the interaction between the two policies has received little debate. Pairing these two policy initiatives will have implications for the flexibility of management of the environmental water, and the ability for on-going trade between the environment and consumptive water users. Our position is that the SDL, or preferably rules-based water, should reflect an absolute minimum limit on environmental water requirements, while the buyback should provide the environmental water as tradable water rights with the flexibility to respond to shifts in the environmental water demand curve by providing environmental water over and above the SDL. If both a buyback and minimum flow rules are in place, the SDL will provide little additional benefits but increase administrative costs and reduce flexibility. This has significant implications for the way the SDL and buyback strategy are structured.

Understanding Hydrological Alteration

Abstract Water enters the terrestrial phase of the water cycle when precipitation exceeds evapotranspiration at the land surface. Downstream drainage of this water via surface and subsurface flow paths including transient storage in snowpack, soils, aquifers, and lakes combine to produce the water regimes of freshwater ecosystems. Humans have altered these processes through changes in climate and atmospheric CO2 concentrations, modifications to the land surface including tree clearing and urbanization, construction of surface water impoundments that are generally operated for water supply, flood control or hydropower generation, diversion of surface water, extraction of groundwater, draining of wetlands, agricultural irrigation and drainage practices, and flood alleviation works in floodplain rivers. Most aspects of the terrestrial water cycle have been modified, leading to widespread changes in the hydrology of freshwater ecosystems. Many of these human impacts are expected to increase in the future, which underlines the urgency of implementing effective environmental water practices. Much of the environmental water literature has focused on environmental water requirements downstream of large dams. In the future, comprehensive environmental water planning should address the broader range of hydrological alterations that affect river ecosystems.

The Brisbane Declaration and Global Action Agenda on Environmental Flows (2018)

A decade ago, scientists and practitioners working in environmental water management crystallized the progress and direction of environmental flows science, practice, and policy in The Brisbane Declaration and Global Action Agenda (2007), during the 10th International Riversymposium and International Environmental Flows Conference held in Brisbane, Australia. The 2007 Declaration highlights the significance of environmental water allocations for humans and freshwater-dependent ecosystems, and sets out a nine-point global action agenda. This was the first consensus document that bought together the diverse experiences across regions and disciplines, and was significant in setting a common vision and direction for environmental flows internationally. After a decade of uptake and innovation in environmental flows, the 2007 declaration and action agenda was revisited at the 20th International Riversymposium and Environmental Flows Conference, held in Brisbane, Australia, in 2017. The objective was to publicize achievements since 2007 and update the declaration and action agenda to reflect collective progress, innovation, and emerging challenges for environmental flows policy, practice and science worldwide. This paper on The Brisbane Declaration and Global Action Agenda on Environmental Flows (2018) describes the inclusive consultation processes that guided the review of the 2007 document. The 2018 Declaration presents an urgent call for action to protect and restore environmental flows and aquatic ecosystems for their biodiversity, intrinsic values, and ecosystem services, as a central element of integrated water resources management, and as a foundation for achievement of water-related Sustainable Development Goals (SDGs). The Global Action Agenda (2018) makes 35 actionable recommendations to guide and support implementation of environmental flows through legislation and regulation, water management programs, and research, linked by partnership arrangements involving diverse stakeholders. An important new element of the Declaration and Action Agenda is the emphasis given to full and equal participation for people of all cultures, and respect for their rights, responsibilities and systems of governance in environmental water decisions. These social and cultural dimensions of e-flow management warrant far more attention. Actionable recommendations present a pathway forward for a new era of scientific research and innovation, shared visions, collaborative implementation programs, and adaptive governance of environmental flows, suited to new social, and environmental contexts driven by planetary pressures, such as human population growth and climate change.