Papers by Charles Lemckert
Architectural Science Review
Building Simulation Conference Proceedings
Pond effluent could be an important alternative water source for agricultural irrigation due to i... more Pond effluent could be an important alternative water source for agricultural irrigation due to its low cost, good pathogen removal rate and nutrient richness, and reliability of supply. The microbial hazards are the primary concern of the public health protection requirements for the use of recycled water. Quantitative microbial risk assessment (QMRA) is promoted in the Australian water recycling guidelines for managing risk of reuse schemes. Using rotavirus as a reference pathogen in characterizing human health hazard, this paper effectively demonstrates how to apply QMRA analysis for decision making in health risk assessment for a water recycling scheme.
Weber, T., McPhee, M.J. and Anderssen, R.S. (eds) MODSIM2015, 21st International Congress on Modelling and Simulation, 2015
Waste stabilisation ponds (WSPs) are widely used for wastewater treatment throughout the world. T... more Waste stabilisation ponds (WSPs) are widely used for wastewater treatment throughout the world. They are shallow constructed basins, typically located at the end of a treatment plant, that use natural microbiological, photosynthetic, biochemical, physico-chemical and hydrodynamic processes to generate a reduction of organic matters and pathogenic organisms in wastewater (Watters et al., 1973). They require little technical attention during operation, and are less demanding in terms of construction cost and energy consumption than other engineered wastewater treatment systems. Practical experience and research over the past few decades have established that hydrodynamics is one of the crucial factors determining WSP's overall treatment performance. The Department of Environment and Planning (1992) in the state of Tasmania surveyed 39 wastewater treatment systems and reported that 74% of the pond systems failed to achieve the discharge requirements, and it is due to the hydraulic problems including short-circuiting, stratification in hot Australian climates, and stagnant fluid in dead zones. Therefore, it is of primary importance that WSP's hydrodynamic performance be improved before WSP treatment efficiency can be guaranteed. A substantial number of numerical modelling studies have been undertaken to look into WSP hydrodynamics, both two-dimensionally and three-dimensionally. It is the ultimate goal of this study to use numerical modelling techniques to investigate measures to improve WSP hydrodynamic performance, consequently to propose retrofitting design. A validated three-dimensional numerical model using MIKE 3 by DHI (Danish Hydraulic Institute) was developed to study a typical pond with a dimension of 50 m (length) by 20 m (width) by 1.5 m (depth). The retrofitting scheme was proposed by placing baffles in the pond with different geometric ratios: the ratio of baffle length Lb to the width of the pond W: L b /W, and the ratio of baffle spacing Δ b to the length of the pond L: Δ b /L. For generalised design guidance, baffles positively contribute to the hydraulic efficiency for ponds with a relatively small L/W ratio. Placing 8 baffles in a pond with L/W = 1.6 results in a λ (hydraulic efficiency) = 0.83 as oppose to λ = 0.23 if the pond is not baffled. However, ponds do not benefit from retrofitting baffles if their L/W ratios are large. Ultimately, this study is to provide regulators, decision makers, water managers and operators with information and tools to best operate and manage WSPs, to protect public and environmental health and optimise uses of the treated water.
In this paper, new formulae are presented to estimate the wave overtopping rate of mass-armoured ... more In this paper, new formulae are presented to estimate the wave overtopping rate of mass-armoured berm breakwaters. In addition to the effects of dimensionless crest freeboard and crest width, the formulae consider the influences of water depth at the toe of the structure and structure slope on the overtopping rate through simple dimensionless parameters. The performances of the new formulae were then compared with those of the existing empirical prediction formulae. Statistical indicators such as Root Mean Square Error (RMSE) showed that the new formulae are better predictors than the existing ones.
Chemical spills caused by shipping incidents can have catastrophic effects on a region's envi... more Chemical spills caused by shipping incidents can have catastrophic effects on a region's environment, population and economy. For that very reason the following paper investigates hypothetical chemical spill modelling for the Derwent River, in southern Tasmania, Australia. The modelling assessed the likely movement and fate of two chemicals (sodium hydroxide and sulphuric acid) released into the estuary under range of seasonal conditions. The modelling study was carried out in stages. Firstly, a validated ocean/coastal model (HYDROMAP) was used to generate tidal current data for the study site. Secondly, the ambient tidal and locally measured wind data were used as input into an advanced 3-dimensional chemical model, CHEMMAP, to assess the likely fate of each chemical and the toxicity to nearby marine organisms. The modelling results indicated that there would be a build up of higher concentrations along the coastline surrounding the Hobart and Risdon Ports, as a result of the s...
Piantadosi, J., Anderssen, R.S. and Boland J. (eds) MODSIM2013, 20th International Congress on Modelling and Simulation, Dec 1, 2013
Waste stabilisation ponds (WSPs) use natural microbiological, photosynthetic, biochemical, physic... more Waste stabilisation ponds (WSPs) use natural microbiological, photosynthetic, biochemical, physico-chemical and hydrodynamic processes to treat wastewater. They require little technical attention during operation and are less demanding in terms of construction cost and energy consumption than other engineered wastewater treatment systems. Practical engineering experience and research over the past few decades have established that hydrodynamics is crucial in determining the treatment efficiency of WSPs. After reviewing a large number of pond systems operated in Australia, Wood et al. (1995) stated that many systems were found to operate below an optimal level due to a reduced retention time of wastewater. It is therefore required that the hydrodynamic retention time distribution be precisely understood so that the hydrodynamic behaviour and the overall treatment efficiency of WSPs can be accurately evaluated.
Estuarine, Coastal and Shelf Science, 2019
In the Australian spanner crab (Ranina ranina) fishery, management and industry are looking for i... more In the Australian spanner crab (Ranina ranina) fishery, management and industry are looking for improvements to the existing indicators of stock abundance. Prior research linked several oceanographic indices to the catchability of spanner crabs; however, it was unclear whether nearshore (e.g. river-runoff) or region-specific oceanographic features (e.g. eddies and the East Australian Current) are responsible for these effects on catch rates. Using satellite remote sensing and fisheryindependent survey data, we analysed the influence of oceanographic and environmental indices on spanner crab catch rates in southern Queensland. Outputs from Generalised Additive Models (GAM) show that catch rates exhibit a large amount of variability between different regions of the fishery, with highest catch rates at fishing grounds within 40 km from the shelf break. Offshore oceanic waters, transported into various regions by different oceanographic processes, were linked to an increase in catch rates. Lower concentrations of surface chlorophyll a were also correlated with higher catch rates, but only in survey regions exposed to the effects of the Fraser Gyre and at the mouth of bays. Overall, results highlighted that the effects of environmental indices on catch rates were not homogeneous across the fishery. Rather, relationships were linked to region-specific (< 100 km), highly dynamic coastal and oceanographic features that dominate different survey regions. Outcomes from this work show that the spatial variability of oceanographic features should be taken into consideration before incorporating oceanographic indices in fishery stock assessment models.
Renewable and Sustainable Energy Reviews, 2018
Green stormwater infrastructure is a common feature of urban cities which is mostly designed for ... more Green stormwater infrastructure is a common feature of urban cities which is mostly designed for hydrological and water quality purposes. The last decade has seen a rise in research on the environmental impact assessment of vegetated water sensitive urban design (WSUD) technologies. However, the added ecosystem benefits of these systems, such as carbon sequestration, have received less attention. In this study, the life cycle net carbon footprint of various vegetated WSUD technologies namely green roofs, rain gardens, bioretention basins, vegetated swales and stormwater ponds, have been reviewed and analysed including their carbon sequestration potential. The carbon footprint of each vegetated WSUD technology was evaluated through the four phases of the life cycle assessment (LCA): material production, construction, operation and maintenance and end-of-life phases. The results of this study show that the initial embodied carbon associated with production, transportation and construction phases is the major contributor to the carbon footprint for most of the vegetated WSUD technologies. Rain gardens are shown to provide the highest carbon sequestration potential which offsets its carbon footprint. Carbon sequestration of bioretention basins, green roofs, vegetated swales and stormwater ponds can mitigate approximately 70%, 68%, 45% and 8% of their carbon footprint respectively. This study demonstrates the significant role of carbon sequestration in mitigating the carbon footprint from the assigned life time of the vegetated WSUD technologies. The results presented in this study will allow designers and policymakers to include the carbon implication in their WSUD strategies.
Continental Shelf Research, 2016
Transport timescales (TTS), namely residence time and exposure time, were computed for adjacent s... more Transport timescales (TTS), namely residence time and exposure time, were computed for adjacent shallow meso-tidal tropical estuarines system using the Lagrangian model D-Waq Part coupled with the hydrodynamic model Delft3D-Flow, and the Constituent-oriented Age and Residence time Theory, CART. The main results are threefold: (a) The TTS differs more between releases at high or low tide than between those at spring and neap tides. The exposure time was also calculated and found to be larger than the residence time by a few days. (b) The exposure and residence times were used to evaluate the return coefficient (r) for different scenarios. As with residence and exposure times, the return coefficient was found to differ more between releases at high or low tide than between those at spring and neap tides. (c) For the Caravelas Estuary, where the river inflow was low (~4 m 3 s-1), the residence time was found to be much larger than for the Peruípe Estuary, where the river discharge was greater and nearly constant during the sampling period (~20 m 3 s-1). These results shows the importance of advection in decreasing TTS in the Peruípe Estuary compared to the Caravelas Estuary. The influence of the advection and dispersion agrees with previous simple estimates obtained using the newly modified Land Ocean Interaction Coastal Zone (LOICZ) model by Andutta et al. (2014).
The Economy and Politics of the Netherlands Since 1945, 1980
In dealing with the economic problems that existed after World War II, the Dutch have never enter... more In dealing with the economic problems that existed after World War II, the Dutch have never entertained many illusions over the role that could be played by indigenous mineral resources. There were some limited possibilities for increasing the exploitation of the coal seams in the extreme South and also for recovering salt, marl and gravel on an extremely modest scale. For the rest the Dutch had to find their strengths in other qualities and that they did so successfully is described elsewhere in this volume. This does not alter the fact that exploratory borings for oil and gas, suspended during the war, were revived. Shell and Esso worked together in this in the Nederlandse Aardolie Maatschappij (Netherlands’ Petroleum Company) henceforth NAM. Success was modest until, barely twenty years ago, productive natural gas reserves were struck under the mainland in the Northern province of Groningen. On the basis of this discovery near the village of Slochteren, it was estimated that 50 billion m3 of natural gas were present. Although the various successful borings in the region of Slochteren all yielded gas of the same composition as the first Slochteren discovery and at the same pressure of 350 atm., it was not until 1963 that it was realised that these borings comprised the same field. This conclusion meant that in 1963 the recoverable quantity of gas was already being estimated at 1,100 billion m3. It is interesting to note that the concessions were granted on May 30th 1963 and that it was only shortly afterwards that the first realistic estimates of the extent of the reserves were made. By 1965 the official estimates had already climbed to around 1,500 billion m3 and two years later they stood at 2,200 billion m3. Roughly speaking it could be said that not until eight years after the first successful boring was a proper insight gained into the extent of the reserves. If, upto 1967, one could say that there was a continuous, very large, underestimation of the natural gas available (after that date was a period in which the expected level of reserves in the Slochteren field increased little), the share that could be considered as proven reserves continued to increase.
Uploads
Papers by Charles Lemckert