Minerva Access is the Institutional Repository of The University of Melbourne Author/s: Greenwood, A. J. Title: Assessing hydrological interception by plantation forestry for application in water resources management Date: 2017 Persistent Link: http://hdl.handle.net/11343/124187 File Description: Assessing hydrological interception by plantation forestry for application in water resources management Terms and Conditions: Terms and Conditions: Copyright in works deposited in Minerva Access is retained by the copyright owner. The work may not be altered without permission from the copyright owner. Readers may only download, print and save electronic copies of whole works for their own personal non-commercial use. Any use that exceeds these limits requires permission from the copyright owner. Attribution is essential when quoting or paraphrasing from these works. UNIVERSITY OF MELBOURNE SCHOOL OF LAND AND ENVIRONMENT Assessing Hydrological Interception BY Plantation Forestry FOR Application IN Water Resources Management A. J. GREENWOOD Submitted in fulfillment of the requirements of the degree of Doctor of Philosophy 13 February 2017 ANNO DOMINI NOSTRI IESU CHRISTI IDIBUS FEBRUARIAS MMDCCLXX ANNO URBIS CONDITAE Abstract 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. page | 3 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. Declaration I hereby certify that: this thesis comprises only my original work towards the PhD except where indicated in the Preface; due acknowledgement has been made in the text to all other material used, and, the thesis is fewer than 100 000 words in length, exclusive of tables, maps, bibliographies and appendices. Ashley Greenwood August 2016 page | 5 Preface IN accordance with university requirements I would like to preface this thesis by acknowledging that Sections 5 and 6 were completed with support and advice provided by co-authors whose contributions are consistent with the work being original and my own as declared in the Contribution to Published Work Forms section below. Specific material contributions were made by Dr Gerrit Schoups who provided the Matlab version of the generalised likelihood that I translated into R; and Dr Eddy Campbell who provided an example of an adaptive Metropolis algorithm which I modified and incorporated into my own code used in Section 6. AJBG August 2016 page | 7 Contribution to Published Work Forms page | 9