Design-A-Wetland a hypothetical model structure integrating multi-functional wetland design and decision support for holistic water management.

Carolina Casaril (2011). Design-A-Wetland a hypothetical model structure integrating multi-functional wetland design and decision support for holistic water management. PhD Thesis, School of Geography, Planning & Env Management, The University of Queensland.

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Author Carolina Casaril
Thesis Title Design-A-Wetland a hypothetical model structure integrating multi-functional wetland design and decision support for holistic water management.
School, Centre or Institute School of Geography, Planning & Env Management
Institution The University of Queensland
Publication date 2011-08
Thesis type PhD Thesis
Supervisor Robert Beeton
Kim Bryceson
Total pages 213
Total colour pages 12
Total black and white pages 201
Language eng
Subjects 090701 Environmental Engineering Design
050209 Natural Resource Management
090509 Water Resources Engineering
Abstract/Summary Abstract This dissertation presents the results of a study into constructed wetlands. Natural and constructed wetlands perform many functions and provide many services, often becoming key components of landscapes and communities. However constructed wetland design tools continue to focus on nutrient removal despite evidence that the wetlands, once constructed, need to be managed for many, often conflicting, functions from habitat conservation to food production. Wetlands designed from a hydraulic engineering perspective, with only pollutant removal in mind, frequently fail to take into account many externalities, including ecological succession of flora and fauna populations, impacts of people and even surrounding climatic and geological variables. As a result, constructed systems often fail to meet their anticipated nutrient removal targets, and occasionally collapse entirely, becoming non-functioning systems. They may also negatively impact surrounding systems and create potential health and safety problems. This study investigates whether a wetland design tool could be developed that goes beyond nutrient removal to include the many potential functions of a wetland. Such a wetland design tool should be capable of integrating biophysical variables and wetland design rules with the externalities of surrounding landscapes and human communities. It also should generate decision alternatives for wetland construction and management. The first stage of this study involved identifying links between the processes and functions occurring in wetlands and their design. The literature review provided information useful for wetland design however challenges arose due to the limitation of current knowledge. Studies investigating the links between design and function were not widely available and consequently achieving a framework required the analysis of a number of studies from a perspective that differed from the normal themes in the literature. This exercise created a decision support system which could deal with the large amounts of information and make it useful as a decision making tool for designing a wetland. Key stages of the tool’s development are discussed in this dissertation, highlighting the challenges of each stage and how the vital lessons were carried forward into the next stage until the final version of the tool could be proposed. The stages include a reversible and web based model, an initial prototype and a final version of the tool. The final version of the tool includes a decision support system linking functions and design parameters, a set of wetland cells, a basic wetland assessment prototype, and additional design and management options with trouble shooting tables to add functionality to the wetland. The major challenges encountered revolved around predicting the nutrient removal capacity of the nominal wetland designs, as well as using nutrient removal equations, derived from other studies, to anticipate design. Much of the science which underpins the development of this tool relies on observations and descriptive modelling associated with particular wetlands each with their own unique characteristics. Formulae representing nutrient removal processes were difficult to transfer out of context, because constructed wetlands, once built, evolve into natural systems with chaotic characteristics, making precise nutrient removal inherently hard to predict. This study concluded however, that precise nutrient removal projection is not required for wetland design. The final version of the tool therefore focuses on the multi-functional design of a treatment wetland as well as, in the light of inherently unpredictable nutrient removal capacity, an option for monitoring and adaptive management in order to optimise the functioning of the wetland throughout its life. The study makes the following six recommendations for wetland construction: 1. Clearly identify and prioritise the multiple functions required of the wetland; 2. Construct the wetland in carefully ordered sections, or cells, which will each have a small number of functions; 3. Include the ability to add additional flexible elements (design extras) to the base wetland cells in order to optimise the multiple functions of the wetland once it is operating; 4. Anticipate future management in the initial design to complement design extras, and carry out ongoing management. Wetlands are constantly evolving systems and therefore will have changes in function and management requirements throughout their lives; 5. Monitor and assess the wetland processes post-construction. This study emphasises the fact that optimal constructed wetland system should be managed post-construction; 6. Finally, this study recommends a new approach be taken to constructed wetland design. One that acknowledges that optimal use of constructed wetland technology should go beyond nutrient removal and water treatment to include multiple other functions of which wetlands are capable thanks to their natural diversity. Wetlands are flexible, resilient and adaptive, and it follows that their optimal use is one that takes advantage of these strengths. This study concludes that a wetland design tool that emphasises flexible and multiple outcomes serve a greater purpose than precise water treatment, for which there are many other technologies available. Potential applications of a tool such as this one are wide ranging, from wastewater management in municipal, mining or agricultural systems, to facilitating climate change adaptation, or as buffers for protecting riparian zones.
Keyword Wetland design
water management
Constructed Wetlands
decision support system
Additional Notes Pages in Colour: 78,86,108,116,121,139,143,144,145,160,164,173 Pages in Landscape: 92,93,137,138,151,152,155,156,158,159 no A3 pages.

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Created: Mon, 28 May 2012, 15:03:04 EST by Ms Carolina Casaril on behalf of Library - Information Access Service