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Accueil du site → Doctorat → Australie → 2017 → Towards improved rainfall-runoff modelling in changing climatic conditions

University of Melbourne (2017)

Towards improved rainfall-runoff modelling in changing climatic conditions

Fowler, Keirnan

Titre : Towards improved rainfall-runoff modelling in changing climatic conditions

Auteur : Fowler, Keirnan

Université de soutenance : University of Melbourne

Grade : Doctor of Philosophy (PhD) 2017

Résumé partiel
Rainfall-runoff models are useful tools in water resource planning under climate change. They are commonly used to quantify the impact of changes in climatic variables, such as rainfall, on water availability for human consumption or environmental needs. Many parts of the world are likely to see changes in future climate, and some regions are projected to be substantially drier, possibly with threatened water resources. Given the importance of water to the economy, environment, geopolitical stability and social wellbeing, reliable tools for understanding future water availability are vital. However, literature would suggest that the current generation of rainfall-runoff models are not reliable when applied in changing climatic conditions. Simulations of historic case studies such as the Millennium Drought in South East Australia indicate that models often perform poorly, underestimating the sensitivity of runoff to a given change in precipitation. Many hydrologists have assumed that these deficiencies are due to the model structures themselves - that is, the underlying model equations. However, it is possible that the explanation is broader, and can only be understood via holistic approaches that examine the entire modelling process. This research, presented in four parts, aims to understand and improve various elements of this process.
Part 1 investigates whether poor model performance is due to insufficient model calibration and evaluation techniques. An approach based on Pareto optimality is used to explore trade-offs between model performance in different climatic conditions. Five conceptual rainfall-runoff model structures are tested in 86 catchments in Australia. Comparison of Pareto results with a commonly used calibration method reveals that the latter often misses potentially promising parameter sets within a given model structure, giving a false negative impression of the capabilities of the model. This suggests that existing model structures may be more capable under changing climatic conditions than previously thought. The aim of Part 1 is to critically assess commonly used methods of model calibration and evaluation, rather than to develop an alternative calibration strategy. The results indicate that caution is needed when interpreting the results of differential split sample tests.

Mots clés : rainfall-runoff modelling ; calibration ; drought ; climate change

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