Practical Implementation of the Scenario-Neutral Approach to Climate Impact Assessments for Hydrological Systems
Date
2017
Authors
Guo, Danlu
Editors
Advisors
Westra, Seth
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Abstract
Understanding the impacts of climate change has particular significance for the future planning, design and operation of water resource systems. Scenario-neutral approaches are used increasingly to assess these possible impacts. These approaches allow water resource systems to be assessed independently of climate change projections, instead focusing on the sensitivity of specific systems to a large number of plausible climate change conditions. Once developed, these approaches can be used to better understand water resource system vulnerability, and provides a mechanism to incorporate multiple lines of evidence on possible future climatic changes into the climate impact assessment. The aim of this research therefore is to improve the practical implementation of scenario-neutral approaches by focusing on two key limitations: (1) limited capacity to generate a comprehensive climate exposure space to describe a large number of plausible future climate conditions; and (2) lack of understanding of how the physical process representation in rainfall-runoff models can affect future runoff projections. The first limitation was addressed by developing an inverse approach to generate a climate exposure space that can represent a range of plausible future changes in rainfall and evapotranspiration. This is achieved by firstly identifying a set of climate variables (e.g. rainfall, temperature) and attributes of those variables (e.g. annual average, extremes) that might change in the future, and then modifying the parameters of a weather generator to perturb these variables and attributes within plausible ranges. This overcomes a long-standing problem in scenario-neutral studies, which have tended to focus only on a small subset of variables and attributes that might change in the future. The second limitation was addressed by examining the impact of alternative evapotranspiration representations within rainfall-runoff models, and assessing how this representation interacts with future evapotranspiration and runoff projections. The research showed that although the calibration and validation performance of alternative rainfall-runoff models may be similar under historical climate conditions, the process representation can have a significant impact on future projections, highlighting the importance of model selection as part of the climate impact assessment process. The outcomes of this research are demonstrated by implementing the enhanced scenario-neutral approach to a case study in Scott Creek catchment in South Australia. The results are used to show how different measures of runoff change as a function of different climate perturbations, and the climate variables most important for the system under plausible future climate conditions. This research therefore provides guidance for the future implementations of scenario-neutral framework, and thus greatly extends the applicability of this framework to a larger range of climate impact assessment problems.
School/Discipline
School of Civil, Environmental and Mining Engineering
Dissertation Note
Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2017
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