Showing papers in "Australian journal of water resources in 2002"
TL;DR: In this paper, three case studies are used to show that, generally, two factors limit the volumetric performance of a scheme using stormwater and/or wastewater, namely mismatches between stormwater availability and water demand; and the size of the storage required to smooth out the temporal disparities in (a).
Abstract: Alternatives to conventional methods of providing urban water services, such as making use of stormwater and wastewater resources within urban areas, are receiving increasing attention throughout the world. Such alternatives can offer multiple benefits by stabilising or decreasing the demand on water imported into the area and/or reducing stormwater and wastewater discharge. The performance of a given system is location dependent due to a number of factors, including the prevailing climate, land use characteristics, demands for water, the quality required, and the availability of stormwater and wastewater. Three case studies are used in this paper to show that, generally, two factors limit the volumetric performance of a scheme using stormwater and/or wastewater, namely: (a) mismatches between stormwater and/or wastewater availability and water demand; and (b) the size of the storage required to smooth out the temporal disparities in (a).
54Â citations
TL;DR: In this article, the authors present a method for determining the impact of farm dams on streamflows independent of changes in climate and other land-use, which has been successfully applied to a number of catchments throughout Australia.
Abstract: This paper presents a method for determining the impact of farm dams on streamflows independent of changes in climate and other land-use. The method is comprised of two components: first, the assessment of the statistical significance of trends in streamflows independent of climatic variation, and secondly, the use of a simulation model to determine the proportion of the assessed trend which is attributable to the impact of farm dams. The method has been successfully applied to a number of catchments throughout Australia. Two case studies have been selected to illustrate its practical application, namely the Marne River catchment in South Australia and the Yass River catchment in New South Wales. The results obtained for these catchments indicate that the nature and magnitude of trends estimated by the two largely independent methods is entirely consistent with the documented changes in farm dam development and other land use changes. There would appear to be a direct correlation between the volume of farm dam development and the decrease in streamflow yield, such that for every 1 ML of farm dam development there is a corresponding decrease in streamflows of between 1 ML to 1.3 ML.
39Â citations
TL;DR: In this paper, the role played by initial loss modelling in flood estimation for selected Victorian catchments is examined, where the large variability of initial loss for different flood events in a catchment is represented by a four-parameter Beta distribution fitted to the observed initial loss data.
Abstract: The magnitude of the flood generated from a storm depends to a significant degree on how much of the rainfall is converted into surface runoff and how much of it is 'lost'. For design flood estimation, lumped conceptual loss models such as the 'initial loss - continuing loss model' are frequently adopted in Australia. This paper examines the role played by initial loss modelling in flood estimation for selected Victorian catchments. The large variability of initial loss for different flood events in a catchment is represented by a four-parameter Beta distribution fitted to the observed initial loss data. These stochastic losses are used in a Monte Carlo simulation technique with stochastically generated design rainfall events to determine derived flood frequency curves. It has been found that, in the range of relatively frequent floods, the derived flood frequency curves are quite sensitive to details of the adopted loss modelling approach. The paper shows the potential of adopting stochastic losses in design flood estimation.
36Â citations
TL;DR: The usefulness of scientific panels for river management issues such as environmental flow assessment may decline unless there is investment to overcome key knowledge gaps such as the preferred flow regime of important riverine species or communities.
Abstract: 'Scientific' or 'Expert' Panels have played an important role in water resource management in Australia in recent years. Scientific Panels have been an excellent knowledge exchange mechanism, providing a synthesis of multidisciplinary information and expertise on various river management issues, such as approaches to river rehabilitation, the setting of river health objectives or in developing environmental flow recommendations for regulated rivers. Many Panels have been convened to provide recommendations on environmental flows for regulated river systems within a relatively short time frame (eg rapid appraisals over 6-12 months) because of demanding Federal and State initiatives. As rapid appraisals utilise best-available information, they can be limited by the quality of existing information and the experience of Panel members. Indeed, many Scientific Panels are consistently confronted with the same range of information or knowledge gaps, particularly on the relationship between flow regime and the distribution and abundance of biota. The usefulness of Scientific Panels, as applied to river management issues such as environmental flow assessment, may decline unless there is investment to overcome key knowledge gaps such as the preferred flow regime of important riverine species or communities. The ongoing use of Scientific Panels for determining environmental flows would also be bolstered by the development of a clear process for selecting Panel members, protocols to guide the conduct of Panels, and guidelines for presenting the strength of evidence used in decision making.
35Â citations
TL;DR: In the Murray-Darling Basin, it is recognised that rivers are being degraded by changes to flow caused by development of water resources as mentioned in this paper, and a possible way forward is to use an adaptive management approach to the implementation of environmental flows.
Abstract: Throughout the Murray-Darling Basin it is recognised that rivers are being degraded by changes to flow caused by development of water resources. Proposals to reverse this degradation include the provision of environmental flows, that is, water specifically managed to meet environmental needs. So far, implementation of environmental flows has proved difficult because of competition for water and uncertainties in environmental water requirements. Economic losses from allocating water to the environment are easy to quantify but the benefits can only be vaguely specified, which makes changes difficult to justify. A possible way forward is to use an adaptive management approach to the implementation of environmental flows. Adaptive management is more likely to be successful where there are few, well defined points of intervention, early successes for experimental management, shared goals and strong political support.
31Â citations
TL;DR: The Flow Events Method as mentioned in this paper is a procedure for assessing the ecological impact of flow regulation, developing environmental flow rules and optimising the operation of a water resource scheme to maximise environmental performance.
Abstract: The Flow Events Method is a procedure for (i) assessing the ecological impact of flow regulation, (ii) developing environmental flow rules and (iii) optimising the operation of a water resource scheme to maximise environmental performance. The method is a systematic, transparent and defensible tool for use in environmental flows studies that makes use of available knowledge and facilitates the inclusion of expert opinion where necessary. It is not presented as a new technique, rather it is a logical and transparent procedure for integrating the concepts and data commonly used in environmental flow studies in Australia. The primary component of the method is the assessment of flow regulation based on changes in flow events that are considered to be important for specific ecological processes. This paper describes the application of the Flow Events Method to assess the impact of flow regulation in the Broken River catchment, including data and modelling requirements for this study. Six aspects of the flow regime are considered: (i) rapid increases in flows, (ii) rapid reduction in flows, (iii) the availability of slow water habitats, (iv) drying of the streambed, (v) the availability of shallow water habitats and (vi) inundation of channel benches.
18Â citations
TL;DR: In this paper, the authors summarise the results of a 3-year research project by the CRC for Catchment Hydrology (CRCCH) on the joint probability approach (Monte Carlo simulation technique) to design flood estimation and the subsequent research activities to further the CRCCH method towards industrial applications.
Abstract: This paper summarises the results of a 3-year research project by the CRC for Catchment Hydrology (CRCCH) on the joint probability approach (Monte Carlo simulation technique) to design flood estimation and the subsequent research activities to further the CRCCH method towards industrial applications. It identifies significant shortcomings in the current design event approach to rainfall-based design flood estimation, and argues that substantial improvements in the accuracy and reliability of flood estimates can be obtained from a more rigorous treatment of probability aspects in the generation of design floods. Applications of the proposed Monte Carlo simulation approach to test catchments in Victoria and Queensland have produced promising results, and demonstrated the feasibility and in-principle advantages of the approach. More recently, the Monte Carlo simulation approach has been integrated with the industry-based flood estimation model URBS thus significantly broadening its range of application. The paper discusses how far the recent research on the joint probability approach has advanced towards resolving the main research issues, and outlines desirable future development work to allow the new method to be routinely applied as a design tool.
18Â citations
TL;DR: A discussion of Benchmarking a new design flood estimation system published in 'Australian Journal of Water Resources Vol 6 No 1' is presented in this paper, where the authors' reply to the discussion issues raised is also presented.
Abstract: A discussion of 'Benchmarking a new design flood estimation system' article published in 'Australian Journal of Water Resources Vol 6 No 1' is presented. The authors' reply to the discussion issues raised is also presented.
15Â citations
TL;DR: In this article, the authors explored the link between flow variability and stream morphology in the context of the geomorphic component of environmental flow assessment and provided a realistic perspective on the potential for environmental flows to either maintain or improve channel functioning.
Abstract: This paper explores the link between flow variability and stream morphology in the context of the geomorphic component of environmental flow assessment. It also attempts to bring some methodological order to the contribution by geomorphologists to environmental flow assessment. The main stage of any environmental flow assessment would be to place the significance of flow regulation as an agent of geomorphic change within this wider context. It will provide a realistic perspective on the potential for environmental flows to either maintain or improve channel functioning.
15Â citations
TL;DR: In this article, the authors highlighted three areas where improved knowledge of ecology-flow relationships for riverine and riparian plants could considerably advance environmental flows: development of conceptual tools to identify species groups of particular functional relevance and at different spatial scales; incorporating flow regime requirements of alien and native transformer species; spatial descriptions that move away from conventional floristic mapping to emphasise functional processes.
Abstract: Knowledge of ecology-flow relationships is the basis of establishing environmental flows for rivers. In the case of riverine and riparian plants, much of this knowledge is species-focused and this has made a valuable contribution to environmental flows in south-eastern Australia. However, examination of scientific references used in an ecological source book reveals bias in the species and growth forms studied, in aspects of water regime considered, and in habitats represented, with major gaps in relation to seasonal responses, and to shrubs, non-eucalypt trees and grasses. More strategic studies are needed to address long-term scientific questions about ecological processes and riverine and riparian plant communities. These should include comparative and multiple species experiments, testing hypotheses and theory at reach scales, establishing trait-based species groups, and developing some predictive capacity. Three areas are highlighted where improved knowledge of ecology-flow relationships for riverine and riparian plants could considerably advance environmental flows: development of conceptual tools to identify species groups of particular functional relevance and at different spatial scales; incorporating flow regime requirements of alien and native transformer species; spatial descriptions that move away from conventional floristic mapping to emphasise functional processes, particularly linkages with geomorphology and hydrology.
14Â citations
TL;DR: In this paper, the authors present an approach to apply the known responses of indicator species to an ecosystem where the hydrology is poorly understood, and assess the ecological impacts of hydrological change and recommended compensatory water provisions.
Abstract: Plans to provide water to floodplain ecosystems are frequently constrained by insufficient ecological and hydrological data. Published ecological studies provide a range of indicator species to assess the impacts and to predict the responses of water management. However, this information is only useful if the ecology and hydrology of the system in question is sufficiently well known to apply this information in its proper context. This paper presents an approach to apply the known responses of indicator species to an ecosystem where the hydrology is poorly understood. Gunbower Forest, a River Murray floodplain ecosystem in northern Victoria, has experienced reduced flooding as a consequence of river regulation and diversions. This project assessed the ecological impacts of hydrological change and recommended compensatory water provisions. Foresters had previously mapped the spatial distribution of timber quality classes in Gunbower Forest. The known relationship between timber quality and flooding at Barmah Forest was applied to Gunbower Forest to map hydrological classes. The flora and fauna associated with these classes were attributed from known hydrological relationships at Barmah Forest and the wider scientific literature. A key finding of the project was that low flows are important in rehabilitating permanent wetlands in the forest. The current framework for providing environmental flows is inadequate in this respect. Floodplain ecosystems are generally provided with large, infrequent flows from allocations of surplus flows. However, small, frequent inflows require allocations of secure water which are not widely available to the environment.
TL;DR: The River Murray Project as mentioned in this paper addresses the main cause of degradation in the River Murray System and provides an inclusive project organisational structure to obtain information and support across different States, and from a range of stakeholder groups.
Abstract: The River Murray is a 'working river' in the sense that its regulation and management delivers significant economic wealth and social benefits to local communities and wider Australia. This paper reports progress on the main aspects of the Project to date. A review of the impacts of flow regulation on the health of the River Murray revealed evidence for decline, but in many instances the case for flow regulation as the sole or main cause is circumstantial or uncertain. The Project addresses this recognised main cause of degradation in the River Murray System. Establishment of an inclusive project organisational structure has proved to be critical, and will continue to be critical, to obtaining information and support across different States, and from a range of stakeholder groups.
TL;DR: In this article, the NWS FLDWAV model was applied to simulate the dam break flood wave for a typical ring tank using a planar surface of varying slope and roughness, and the model output was then analyzed with regard to vehicle stability to determine a safe buffer distance between the ring tank and road.
Abstract: On the Darling Downs in Queensland there is a proliferation of offstream water supply storages (known locally as ring tanks), used mainly for irrigation of broad-acre crops. Many ring tanks are sited close to public roads for many reasons; the sealed roads provide allweather access to irrigation areas and particularly waterharvesting pumps but also provide a hard catchment in close proximity to the storage thus improving the frequency of harvestable overland flows. There are many ring tanks in the district located within 50m of public roads. The question immediately arises of the potential safety hazard to road users in the event of dam failure. In this paper the NWS FLDWAV model was applied to simulate the dam break flood wave for a typical ring tank using a planar surface of varying slope and roughness. The model output was then analysed with regard to vehicle stability to determine a safe buffer distance between the ring tank and road. It was found that the flood wave would produce a subcritical flow on outlet slopes typical of the area for which vehicle stability would be controlled by buoyancy rather than inertia. The impact of the dam break wave on stability would be reduced by the hydraulic effect of the elevated roadway and through the maintenance of a smooth outlet. A minimum buffer distance of 250m is recommended for smooth, mild outlet slopes in which the flow is impeded by an elevated roadway, increasing to up to 400m depending on the final breach width.
TL;DR: The authors describes some aspects of the writer's career in civil engineering, mostly as an academic staff member at The University of Queensland, focusing on teaching in fluid mechanics and hydraulics, experimental research on flows past bluff bodies including bridges and buildings.
Abstract: The paper describes some aspects of the writer's career in civil engineering, mostly as an academic staff member at The University of Queensland. The discussion is grouped around a number of recurring themes: teaching in fluid mechanics and hydraulics, experimental research on flows past bluff bodies including bridges and buildings, computational fluid dynamics, computational hydraulics, hydraulic models and hydraulic structures.
TL;DR: In this article, a scientific panel was assembled to help develop the recommendations, the objective being to define an upper limit on diversions beyond which there is an unacceptable risk that additional extractions would degrade the environment.
Abstract: This paper describes the process used to define a sustainable limit on diversions over the winterfill period in Victorian catchments. A scientific panel was assembled to help develop the recommendations, the objective being to define an upper limit on diversions beyond which there is an unacceptable risk that additional extractions would degrade the environment. The panel was comprised of researchers and practitioners with knowledge of stream ecology, water quality, geomorphology, hydrology, wetlands, and catchment management. Recommendations were developed by trialing various diversion rules on streamflow data obtained for 170 gauged sites. The suitability of different rules was assessed by investigating the impacts of diversions on a range of hydrologic criteria judged to be of ecological importance. The components of the hydrologic regime considered included the frequency and duration of spells above a range of thresholds, the magnitude and sequencing ofselected flows, and the magnitude offrequ...
TL;DR: In this article, the use of modern data logging equipment to record water level depths at the site is discussed, and a technique using surface water slope for estimating discharge is outlined and, finally, an example application is discussed.
Abstract: This paper deals with estimating discharge at an ungauged site. Firstly, we discuss the use of modern data logging equipment to record water level depths at the site. Next, establishing a stage-discharge relationship at the site including measuring discharge by current meter is described. A technique using surface water slope for estimating discharge is outlined and, finally, an example application is discussed.
TL;DR: In this paper, the authors investigated automated image processing techniques for detecting, counting and classifying dams in the Upper Wimmera catchment from remotely sensed imagery, and showed that automatic interpretation of high-resolution remotely sensed data has great potential for mapping, monitoring and measuring dams in rural Australia.
Abstract: In the winter of 2000, the Department of Geomatics at the University of Melbourne was commissioned to investigate automated image processing techniques for detecting, counting and classifying dams in the Upper Wimmera catchment from remotely sensed imagery. Determination of the number and size of dams is an important aspect of water resource management as it provides an indication of the total volume of water harvested by on-farm dams and, through appropriate modelling, the subsequent impact of the dams on streamflows. In the course of the investigation, colour aerial photography was acquired for the entire Upper Wimmera catchment as well as the Avoca sub-catchment. In addition, high resolution satellite imagery was acquired for an 8km by 8km region within the Upper Wimmera catchment. Image processing techniques were developed to automatically extract dam features from this digital imagery. As a result, it was shown that automatic interpretation of high resolution remotely sensed data has great potential for mapping, monitoring and measuring dams in rural Australia.
TL;DR: The use and selection of biological indicators to determine the effectiveness of river management is currently the focus of much interest as discussed by the authors, and the assessment of the ecological benefits of environmental flows in Australia is still in its infancy.
Abstract: Recent reviews of the principles underlying the management of large rivers stress the need for a better understanding of the relationships between elements of the flow regime and ecological processes. The use and selection of biological indicators to determine the effectiveness of river management is currently the focus of much interest. The assessment of the ecological benefits of environmental flows in Australia is still in its infancy. Issues that need to be considered when developing a monitoring program for assessing how effective environmental flow releases are highlighted by conducting experimental trials and field validation of biological indicators.
TL;DR: In this article, the spatial mapping of sediment deposition within pollution control ponds complements water quality data, providing information on the efficiency and sustainability of the system as a pollution abatement facility.
Abstract: Wetlands systems are often monitored to assess their performance during a flow through event. The spatial mapping of sediment deposition within pollution control ponds complements water quality data, providing information on the efficiency and sustainability of the system as a pollution abatement facility. The characterisation of the sediments and associated pollutants allows a better understanding of the role of sedimentation in the overall improvements to water quality. In stormwater systems, the efficiency with which pollutants such as TSS and pre-dominantly sediment-bound contaminants such as phosphorus, metals and polycyclic aromatic hydrocarbons are removed is intrinsically related to the characteristics of the sediment inflow to the wetland. The sediment-bound pollutants are known to have a higher association with the finer range of sediment sizes and targeting the removal of the appropriate particle size fraction is necessary in designing stormwater pollutant abatement facilities. This paper presents the results for two studies of sediment characteristics: the first is at The Monash University Research Wetland in Australia and the second at the Braunebach Wetland pollution abatement facility in Germany. Sediment cores were taken at regular grid intervals to identify the physical characteristics of the accumulated sediments in these wetland systems. Defining the spatial sediment deposition patterns and the associated particle size distribution provided a greater understanding of each system's water quality improvement function. This understanding of sediment characteristics has direct implications for the management of pollution control facilities and enables modifications to be suggested for future designs.
TL;DR: In this paper, a short-timescale rainfall model DRIP is applied to the output series of a two-state Hidden Markov Model (HSM) model, which assumes that the rainfall in a particular year is in either a wet state or a dry state with different rainfall distributions depending on the state.
Abstract: Inter-annual persistence, a characteristic feature of Australian hydroclimatological series, is often difficult for event-based rainfall models to reproduce. This persistence can lead to poor reproduction of variables important in design such as intensity-Frequency-Duration (IFD) curves and drought risk. This paper outlines the conditioning of a short-timescale rainfall model DRIP on the output series of a two-state Hidden Markov Model (HSM). The HSM model assumes that the rainfall in a particular year is in either a wet state or a dry state, with different rainfall distributions depending on the state. The inclusion of HSM into DRIP has produced a model that has improved capability to adequately reproduce rainfall characteristics including persistence for a variety of sites throughout Australia for timescales ranging from six minutes up to a year.
TL;DR: In this article, a review of land surface models designed for climate models focussing on the modelling of run-off and soil moisture is presented, and it is argued that the modeling of runoff contains some skill and results from climate models can be used with care.
Abstract: A review of land surface models designed for climate models is presented focussing on the modelling of run-off and soil moisture. It is argued that the modelling of run-off contains some skill and results from climate models can be used with care. The simulation of soil moisture is more uncertain and the actual soil moisture amounts simulated by land surface schemes are not currently useful in impacts work (although the change in soil moisture might be). The methods for representing horizontal heterogeneity and sub-grid scale processes are discussed as an indication of an area where progress is being made. Future directions currently under consideration within the international community are noted.
TL;DR: In this paper, the authors describe a procedure for the identification of regions of low flow homogeneity for the operational specification of environmental flows, based on a weighted function comprised of hydrologic similarity and geographic proximity.
Abstract: This paper describes the development of a procedure for the identification of regions of low flow homogeneity for the operational specification of environmental flows. The objective of the procedure is to assign ungauged catchments to a small number of 'indicator' streamflow gauges that can be considered to behave in a similar manner during low flow conditions. Thus, when flows at the indicator site fall below some selected percentile, it may be assumed that flows in the hydrologically similar regions also fall below the same percentile. The method assigns an ungauged catchment to an indicator station using a weighted function comprised of hydrologic similarity and geographic proximity. Hydrologic similarity is assessed simply as the distance between points on a simple linear scatter plot (of selected principal components), where the position of each point represents the combined physiographic attributes that govern low flow conditions. Geographical proximity is used as a surrogate to ensure that catchments have experienced a similar recent sequence of climatic conditions, and hence are subject to the same degree of hydrologic stress. The procedure provides an objective assessment that can be easily undertaken by nonspecialists for operational purposes, and also provides a framework for the incorporation of subjective judgement concerning the influence of other catchment-specific issues.
TL;DR: In this paper, a methodology for incorporating rainfall runoff models in risk-based assessment that is both efficient in terms of computational effort and accurate is presented, which has been tested on two hypothetical catchments and 47 small gauged catchments in Queensland.
Abstract: The management and design of hydraulic infrastructure requires detailed analysis of the rainfall-runoff process, as well as the allocation of an acceptable level of risk. Risk-based assessment of the rainfall-runoff process requires methodologies that are both accurate and efficient. Although the Rational Method has been a popular analysis tool in risk based assessment, it has many short comings requiring significant subjective judgement by the engineer. Rainfall-runoff models have become increasingly popular in this regard, as they provide accurate tools to predict the deterministic processes taking place in the catchment. A methodology is presented in this paper for incorporating rainfall-runoff models in risk-based assessment that is both efficient in terms of computational effort and accurate. The method relies on the adoption of a storm pattern that embodies the characteristics contained within the statistically based rainfall data that is generally adopted in practice. The methodology has been tested on two hypothetical catchments and 47 small gauged catchments in Queensland. It is shown that using this methodology, statistically based peak run-off can be predicted at all locations in the catchment where suitable catchment subdivision had been undertaken.
TL;DR: In this article, a simple and efficient method of estimating the probability of failure of a hydraulic system is presented, which does not require one to estimate or assume the probability density function of the performance function, describing the behaviour of the hydraulic system.
Abstract: This paper illustrates a simple, accurate and efficient method of estimating the probability of failure of a hydraulic system. The proposed method requires the same information as that of conventional methods. It does not require one to estimate or assume the probability density function of the performance function, describing the behaviour of the hydraulic system. The proposed method does assume that the system response is a strictly monotonic function with respect to one of the random variables. Many hydraulic and hydrological systems possess the property of monotonicity.
TL;DR: In this paper, a wider understanding of the relationship between numerical modelling and data collection in the field, the strong coupling of the involved physical processes and quality assurance (verification) of the final solutions is discussed.
Abstract: Three-dimensional hydrodynamic models are increasingly being seen in the context of morphological and water quality applications and are gradually being associated with major coastal projects in Australia. They offer the benefits of full dynamic linking of a number of forcing factors such as tide, wind and waves with sediment and pollutant transport in the form of application superstructures and allow complex chemical and ecological processes to be simulated within acceptable timeframes at realistic cost, thereby providing powerful tools for the assessment of environmental issues and proposed infrastructure. The need for 3D modelling is likely to grow in keeping with the demand for more sustainable (responsible) practices when developing infrastructure. However, there needs to be a wider understanding of three key issues in the modelling process: the close relation between numerical modelling and data collection in the field, the strong coupling of the involved physical processes and quality assurance (verification) of the final solutions. This paper addresses briefly the essentials of the three issues, with emphasis on the best practice in the processes of data collection and 3D modelling.