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University of Melbourne (2017)

Assessing hydrological interception by plantation forestry for application in water resources management

Greenwood, A. J

Titre : Assessing hydrological interception by plantation forestry for application in water resources management

Auteur : Greenwood, A. J

Université de soutenance : University of Melbourne

Grade : Doctor of Philosophy (PhD) 2017

Résumé
IN the early to mid-1990s, Australia governments adopted significant forestry and water policy agendas. The forest policy stimulated plantation expansion, and articulated benefits to water resource degradation which became a focus of the water agenda. The prospect of changing water availability during a severe drought resulted in the National Water Initiative (NWI), which sought to protect the integrity of water entitlements from plantation expansion. State government agendas provided additional complexity, notably in South Australia where forest water use became subject to regional regulation in 2004, reminiscent of South African experiences in 1972. Inconsistencies between assessments used to support/contest the sustainability of plantation developments resulted in the amendment of South Australian planning frameworks, to ensure competing policy issues were addressed in a balanced manner. Mixed progress in implementing the interception clauses of the NWI have been relegated to unfinished business without critically evaluating its capacity to deliver the required policy and scientific outcomes. Here, national and jurisdictional forest water policies are analysed and weaknesses identified in the lack of a cohesive national policy agenda arising from jurisdictional independence under the Australian Constitution. Inefficiencies in implementation are traced to : competing agendas ; the complexities of their inter/intra-jurisdictional administration ; a lack of regard to relevant international precedents and a tendency for Australian water reform to be initiated as short-term responses to predictable disasters rather than long-term planning. Reforms under the NWI are found to have had little direct effect in progressing jurisdictional forest water management agendas. Australian empirical hydrological assessment approaches used to support forest water decision-making are examined in the context of international systems and learnings from South Africa. An approach for evaluating and transparently integrating Australia’s limited forest hydrology datasets with modelled information is developed to improve confidence in decision-making. A similar group of empirically-based models are subjected to a comprehensive Bayesian evaluation with South African and American approaches to identify an option with the greatest integrity to underpin current Australian forest water management. Systemic limitations in a widely used approach developed by a leading Australian research organisation are confirmed and revealed as being compounded by weak model structure, highlighting the challenges faced by water management agencies in securing research to support defensible decision-making. Challenges associated with agency capacity limitations and the inevitability of using more complex modelling in supporting future Australian forest water management are addressed by noting South African learnings which identify the importance of growth in plantation water use ; and exploring the feasibility of using simpler elements of a sophisticated Bayesian assessment to establish confidence in a plant growth model. Complexity introduced into the 3-PG plant process model is shown to improve the model’s ability to extract information from data providing greater confidence in its potential for future development as a water management tool than more exhaustive, integrated assessments focused on marginal improvements in performance. Results are discussed in the context of water management and their implications for future research and policy developments

Mots clés : hydrology ; forest hydrology ; modelling ; water resources management

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Page publiée le 11 juillet 2017