School of Geography - Theses
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ItemAlternative community states in reservoirs of the Central Highlands region( 2001)The occurrence of nuisance algae within reservoirs of the Central Highlands region is a problem facing Central Highlands Water and the communities they serve. Therefore, there is a need to know how to manage this threat. Management of the causal factors contributing to the development of algal blooms within the Central Highlands region, and Victoria as a whole, has tended to focus on reducing nutrient loads into the system. However, in shallow lakes nutrient control alone is often ineffective in managing the undesirable effects of eutrophication including algal blooms. The main reason for this is thought to be due to existence of alternative clear, macrophyte-dominated and turbid, phytoplankton-dominated stable states in shallow freshwater systems. This thesis presents analyses of two field studies carried out to investigate the alternative stable states hypothesis on shallow reservoirs of the Central Highlands region. First an assessment of spatial variation in chlorophyll a, macrophyte abundance and key growth regulating variables has shown that within reservoir spatial variation that is often assumed to be insignificant, is significant. Such spatial variation can lead to different conclusions being drawn regarding the application of ecological models and processes that may have caused observed patterns. Consequently, an appreciation of the effects of scale is vital to ensure ecological models, such as the theory of alternative stable states, are applied correctly and the outcomes of field experiments are not confounded by spatial variation. Second an investigation of shallow reservoirs of the Central Highlands region revealed that the presence of macrophytes is associated with low algal biomass. Parallels were drawn between study sites and the model of phase changes of shallow lakes undergoing eutrophication (Moss et al., 1996). A majority of reservoirs were characterised as potentially being within the clear, macrophyte-dominated alternative state, either in the unique clear Phase I or transitional Phase n. However, several reservoirs of the Central Highlands region did not bear a resemblance to any of the alternative states (phases) identified in the literature. Accordingly, it can be concluded that reservoirs of the Central Highlands region may support alternative states but that phase changes used to describe communities of the Northern Hemisphere lakes need to be modified to suit Australian conditions. This study emphasises the need to adopt a holistic approach to managing the undesirable effect of eutrophication such as algal blooms. Within the Central Highlands region a holistic approach should include management of the macrophyte communities, water level manipulation and potentially biomanipulation in addition to nutrient control.
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ItemIdentifying the real monetary cost of Eildon's water( 1999)In order to understand the real monetary cost of water supply from an impoundment like Eildon Dam there needs to be clear definition of the various costs and benefits associated with it's supply. Some costs, relate to downstream environmental impacts and are difficult to define whilst some benefits like recreational benefits are deemed "non marketable" and are not normally accounted for. This study attempted to explore the different costs and benefits associated with Eildon's water over various time periods, and analyse key cost benefit factors asset value and recreational costs and benefits. An attempt was made to investigate the real monetary cost of Eildon's water and also determine the feasibility of charges being set for recreational use. Review of the costs of Eildon's water revealed that prior to 1994 only maintenance and operational costs had been covered by water tariffs and currently full environmental and recreational costs were not being charged. The real monetary cost of Eildon's water was found to be $3.12/ML and the value of recreation was found via the Travel Cost method to be worth $8.73million / annum although it is important to recognise that their are many non marketable recreational benefits like social and community benefits that make the lake far more valuable than just this. The study concluded that recreational users should pay for their use of Lake Eildon based on the user pays system, with charges weighted towards high impact users like water skiers. It was felt that a charge of $10 per day was affordable by water skiers and would not restrict this activity.