Proposed guidance for developing ecohydrological models

Water resource development, including infrastructure and extraction, has long been recognized to change water-dependent species, populations, their habitats and supporting processes.Management of the flow in rivers through environmental flows is one way to limit adverse environmental change.Environmental flows describe the quantity, timing and quality of water to support ecosystems and the human livelihoods that are reliant on these.Since the formalisation of environmental flow science in the late 1940's, a range of environmental flow frameworks have been developed ranging from the simple to the complex, from hydrological to socioecological systems-based approaches.The development of ecohydrological models has been a critical part of such frameworks, with many applications presented in the literature.Such a broad range of applications has created a rich variety of ecohydrological models that are available for researchers and practitioners to choose from.However, there are many aspects to this decision process that are required to ensure the approach taken is fit for the intended purpose.Whilst there is a rich literature of ecohydrological frameworks and modelling approaches, to date there have been few attempts to guide practitioners in how to go about selecting the most appropriate ecohydrological model to suite their purpose.This paper is intended to guide practitioners in their decisions for ecohydrological modelling.We contend that the selection and development of ecohydrological models is based on the following key questions:• What is the model purpose?• Over what scales does the model need to be applied?• What is the 'right' balance of model uncertainty and credibility?• What are the choice of indicators, given purpose and scale?• What are common ecohydrological modeling approaches that are available?In this paper, we discuss each of these considerations, with examples drawn from the Murray-Darling Basin.We discuss how different modeling families are often applied in a context of assessing environmental flows given their underlying structure, data requirements and the level of uncertainty, noting the various sources of uncertainty and how this relates to fit for purpose modelling in a management context.