The Challenge of Setting “Climate Ready” Ecological Targets for Environmental Flow Planning

Abstract

Implementing environmental flows has emerged as a major river management tool for addressing the impacts of hydrologic alteration in large river systems. The “natural flow paradigm” has been a central guiding principle for determining important ecohydrological relationships. Yet, climate change and associated changes in rainfall run off relationships, seasonality of flows, disruptions to food webs and species life cycle cues mean these existing relationships will, in many circumstances, become obsolete. Revised thinking around setting ecological objectives is required to ensure environmental management targets are achievable, particularly in regions where water scarcity is predicted to increase. Through this lens “climate ready” targets are those that are robust to changing water availability or incorporate future adaptation options. Future objective setting should be based around the inclusion of changing climate and water availability, and the associated species and ecosystem vulnerabilities, and expected outcomes under different policy and adaptation options. This paper uses south eastern Australia as a case study region to review the extent to which current water management plans include climate considerations and adaptation in objective setting. Results show untested climate adaptation inclusions, and a general lack of acknowledgement of changing hydrological and ecological conditions in existing management plans. In response this paper presents a process for setting objectives so they can be considered “climate ready.”

Perceptions of climate change adaptation barriers in environmental water management

“…This decrease in runoff will impact water managers' annual allocations and ability to achieve ecological targets. Although there is significant modelling and projections available on climate change implications across Australia, this has not translated to setting ecological objectives for environmental water planning (Capon and Capon 2017, John et al 2020, Judd et al 2022.…”

“…Flow assessment methods then set recommendations aimed at meeting these ecological objectives through delivery of water at a specified magnitude, duration, frequency, and timing. Objectives are usually set to a desired historic or current condition of flora or fauna assets, such as a specific species, population, habitat, or physical process (Capon et al 2018, Judd et al 2022.…”

“…presented inJudd et al (2022) andHorne et al (2022) Judd et al (2022). suggest a process for setting "climate ready" ecological objectives that incorporate the latest science and community values and iteratively testing objectives against future scenarios until an acceptable trade off (if required) is reached Horne et al (2022).…”

Perhaps, perhaps, perhaps: Navigating uncertainty in environmental flow management

“…Environmental flow assessments (and recommendations) typically aim to restore ecosystems to an historic condition or protect them from further change and use historic flow regimes to make recommendations (Capon et al, 2018;Horne et al, 2022). However the past is not a good representation of the future and climate adaptation is required when determining flow objectives and recommendations for future environmental water (Judd et al, 2022). Under climate change, temperature and rainfall patterns are predicted to change along with rainfall run off relationships and streamflows (Saft et al, 2016).…”

“…Under climate change, temperature and rainfall patterns are predicted to change along with rainfall run off relationships and streamflows (Saft et al, 2016). As these hydro-climatic changes occur, some current ecological relationships are unlikely to remain and consequently objectives are also unlikely to be achievable (Judd et al, 2022). Future water use and flow recommendations need to incorporate climate change adaptation (John et al, 2020).…”