Bribie Island is a large, heterogeneous, sand barrier island that contains groundwater aquifers of commercial and environmental significance. Population growth has resulted in expanding residential developments and consequently increased demand for water. Caboolture Shire Council (CSC) has proposed to increase groundwater extraction by a new borefield. Two aquifers exist within the Quaternary sandmass which are separated by an indurated sand layer that is ubiquitous in the area. A shallow aquifer occurs in the surficial, clean sands and is perched on the indurated sands. Water levels in the shallow water table aquifer follow the topography and groundwater occurs under unconfined conditions in this system. A basal aquifer occurs beneath the indurated sands, which act as a semi-confining layer in the island system. The potentiometric surface of the basal aquifer occurs as a gentle groundwater mound. The shallow groundwater system supports water-dependent ecosystems including wetlands, native woodlands and commercial pine plantations. Excessive groundwater extraction could lower the water table in the shallow aquifer to below the root depth of vegetation on the island. Groundwater discharge along the coastline is essential to maintain the position of the saline water - fresh groundwater boundary in this island aquifer system. Any activity that changes the volume of fresh water discharge or lowers the water table or potentiometric surface below sea level will result in a consequent change in the saline water – freshwater interface and could lead to saline water intrusion. Groundwater level data was compared with the residual rainfall mass curve (RRMC) on hydrographs, which revealed that the major trends in groundwater levels are related to rainfall. Bribie Island has a sub-tropical climate, with a mean annual rainfall of around 1358mm/year (Bongaree station). Mean annual pan evaporation is around 1679mm/year and estimates of the potential evapotranspiration rates range from 1003 to 1293mm/year. Flows from creeks, the central swale and groundwater discharged from the area have the potential to affect water quality within the tidal estuary, Pumicestone Passage. Groundwater within the island aquifer system is fresh with electrical conductivity ranging from 61 to 1018ìS/cm while water near the coast, canals or tidal creeks is brackish to saline (1596 to 34800ìS/cm). Measurements of pH show that all groundwater is acidic to slightly acidic (3.3-6.6), the lower values are attributed to the breakdown of plant material into organic acids. Groundwater is dominated by Na-Cl type water, which is expected in a coastal island environment with Na-Cl rainfall. Some groundwater samples possess higher concentrations of calcium and bicarbonate ions, which could be due to chemical interactions with buried shell beds while water is infiltrating to depth and due to the longer residence times of groundwater in the basal aquifer. A steady-state, sub-regional groundwater flow model was developed using the Visual MODFLOW computer package. The 4 layer, flow model simulated the existing hydrogeological system and the dominant groundwater processes controlling groundwater flow. The numerical model was calibrated against existing data and returned reasonable estimates of groundwater levels and hydraulic parameters. The model illustrated that: .. The primary source of groundwater recharge is infiltration of rainfall for the upper, perched aquifer (Layer 1). Recharge for the lower sand layers is via vertical leakage from the upper, perched aquifer, through the indurated sands (Layers 2 and 3) to the semi-confined, basal aquifer (Layer 4). .. The dominant drainage processes on Bribie Island are evapotranspiration (15070m3/day) and groundwater seepage from the coast, canals and tidal creeks (9512m3/day). Analytical calculations using Darcy’s Law estimated that approximately 8000m3/day of groundwater discharges from central Bribie Island, approximately 16% less than the model. .. As groundwater flows preferentially toward the steepest hydraulic gradient, the main direction of horizontal groundwater flow is expected to be along an eastwest axis, towards either the central swale or the coastline. The central swale was found to act as a groundwater sink in the project area.

University of Technology, Sydney. Faculty of Engineering. / Although extensive worldwide literature on urban stormwater runoff exists, very few publications describe runoff development in terms of its basic building blocks or processes and their individual and accumulative significance in response to varying inputs and boundary conditions. Process algorithms should respond accurately to varying input magnitudes and characteristics as well as to changes in antecedent conditions. The present state of estimation errors involved in many current numerical simulation techniques has been reviewed in this thesis. A significant amount of errors that are presently encountered for have been explained in terms of undefined process response not explicitly included within many modelling methodologies. Extensive field monitoring of intra-catchment rainfall and runoff within an urban catchment at Giralang in Canberra, which is typical of Australian urban catchments, was carried out over a 3-year period to define and measure individual runoff processes. This monitoring work led to a greater understanding of the processes driving the aggregation of local runoff from many sub-areas into the runoff observed at full catchment scale. The results from the monitoring process prompted a number of approaches to potentially reduce standard errors of estimate from model-attributable errors based on improvements to definable catchment response mechanisms. The research isolated a number of basic building blocks associated with typical residential allotments, that can be grouped into roof drainage, yard drainage and adjacent road drainage. A proposed modelling approach was developed that allowed these building blocks at an allotment scale to be simply computed using storage routing techniques. This then aggregated via the total catchment’s public drainage system isochronal characteristics utilising a “process tree” approach to provide full catchment scale runoff response. The potential reduction in estimation errors utilising the developed procedure was assessed using a large number of recorded events from the Giralang catchment monitoring data. The proposed numerical modelling approach was found to provide significant improvements over current methods and offered a scale-independent and stormindependent methodology to model catchments of any size without the need for changes to any of the runoff routing parameters. Additionally the approach permits the flexible sequencing and inclusion of a wide range of different urban drainage structures within a catchment that are representative of the local characteristics. The developed procedure also includes a spatially varied water balance approach to infiltration estimation that is more suited to future continuous simulation models. The developed “flexible process tree” approach provides an important step forward in the numerical modelling of complex urban drainage systems. This can reduce errors of estimate by improving intra-catchment process representation.

[Abstract]This thesis investigates a common problem of land use impacts on flood damage costs on a catchment scale. It does this through a particular case study, to quantify the technical upstream-downstream dependencies and highlights the externalities through hydroeconomicanalysis of flood damages and mitigation costs. The substantive content of the project is cross disciplinary.Peak and volume of river flows are functions of the catchment surface characteristics. This means that any impacts to the run-off regime (for example surface sealing or river training) could affect people and land users in the lower catchment. Thus, upstream activities cancause higher flood peaks, and also entail higher damages downstream. These damages are either borne by the affected parties or they are mitigated by state financed flood defence works or offset with financial compensation. These costs are usually not included in the economic considerations of the upstream land user who is partially causing them. In economic terms, these effects are referred to as unidirectional externalities. This means that a producer can export parts of his production costs to third parties and these are not included in the price of the product.The Herzogbach is a small tributary of the Danube River in Lower Bavaria. It is located in a rural area, dominated by intensive farming practices. Two villages (Bachling and Buchhofen) in the headwaters and middle section of the catchment and one city (Osterhofen) in the lowercatchment were analysed to determine the impact of upstream land use practices on the flood situation.A combination of hydrological and hydraulic modelling provided the core data to allow the interpretation of economic data, using methods of cost damage estimation. A hydrological model of the catchment provided hydrograph simulations based on (a) a regionalisation approach,(b) hydrologic flood routing and (c) hydrologic reservoir routing. A two dimensional stream flow model was then used to convert the hydrographs into flood levels, to simulatethe run-off in settled areas and determine the flood affected areas, flood levels and flow velocities. Estimates for flood damages or mitigation costs resulting from different hydrological scenarios were compared. The scenarios are based on different land uses and alloweconomic externalities to be estimated.It was found that intensive farming and river training increase the peaks, shape and volume of flood waves in comparison to extensive land use, grassland or forest. In the study area, especially river training reduced the detention effect of the river bed and the natural floodplain. These significant changes to the natural run-off regime directly affect land use in the lower catchment through flood damages and increased flood risk, and by reducing the effectiveness of planned or existing flood protection works.The thesis concludes with linked technical and economic findings which indicate a rich potential new area for research - “hydroeconomics”. The published literature shows few people have worked in this cross disciplinary area. The technical finding is that changes to land use, especially in agriculture, can increase the flood damages in downstream settlements or increase the cost of flood mitigation works significantly. From an economic point ofview, this is a unidirectional externality which should be considered in catchment and flood management. Possible solutions could include the control of land use and instruments such as separate waste water fees for rainwater and sewage or run-off certificates.

On-site sewage systems, such as septic tank-absorption trenches, are used by approximately 20 000 people who live within the catchments that supply Sydney??s drinking water. These systems discharge sewage, treated to varying degrees depending on the system type and level of maintenance, to the environment. This can result in contamination of drinking water supplies if systems are not designed or managed appropriately. The aim of the project was to develop a methodology to define appropriate buffer distances between on-site sewage systems and waterways in Sydney??s drinking water catchments, to ensure the protection of drinking water quality. Specific objectives included: identifying the current status of on-site sewage management; assessing the effluent quality and treatment performance of septic tanks, aerated wastewater treatment systems (AWTS) with disinfection and an amended material sand mound; and development of an appropriate methodology for delineating buffer distances and assessing development applications. Viruses were used as a focus for delineating the buffer distances due to their mobility and robustness in the environment, and the potential health consequences of their presence in drinking water. A Quantitative Microbial Risk Assessment (QMRA) model was developed to calculate the cumulative impact of the on-site sewage systems in the Warragamba catchment based on data from literature and experiments, with consideration of virus loads from sewage treatment plants within the catchments. The model enabled consideration of what was a tolerable impact in terms of the resulting infections within the community. The QMRA the tolerable loads of viruses from the Warragamba catchment were 108 viruses per year in raw water and 104 viruses per year in treated water. A log reduction method was developed to facilitate individual site development assessments. This method was compared to other management approaches to development assessment: fixed minimum buffer distances of 100m, reducing failure rates to zero, and the use of a preferred system. Each of these methods had a limit for how much they could reduce virus loads to the catchment due to either failure or short buffer distances at some sites. While the log reduction method is limited by the failure rates, the method provides a quantitative measure of risk by which maintenance inspections can be prioritised.

Spicers Creek catchment is located approximately 400 km west of Sydney in the Central West region of New South Wales, Australia. Dryland salinity has been recognised as a major environmental issue impacting soil and water resources in the Central West region of NSW for over 70 years. Due to the geological complexity of the catchment and the presence of high salt loads contained within the soils, groundwater and surface waters, the Spicers Creek catchment was identified as a large contributor of salinity to the Macquarie River catchment. Over fifty-two dryland salinity occurrences have been identified in the Spicers Creek catchment and it appears that dryland salinity is controlled by the presence of geological structures and permeability contrasts in the shallow aquifer system. Combinations of climatic, geological and agricultural factors are escalating salinity problems in the catchment. The main aim of this thesis was to identify the factors affecting salinisation processes in the Spicers Creek catchment. These include the role of geological structures, the source(s) of salts to the groundwater system and the geochemical processes influencing seepage zone development. To achieve these aims a multidisciplinary approach was untaken to understand the soils, geology, hydrogeology and hydrogeochemistry of the catchment. Investigative techniques employed in this project include the use of geophysics, soil chemistry, soil spectroscopy, hydrogeochemistry and environmental isotopes. Evaluation of high-resolution airborne magnetics data showed a major north-east to south-west trending shear zone. This structure dissects the catchment and several other minor faults were observed to be splays off this major structure. These structures were found to be conducive to groundwater flow and are influencing the groundwater chemistry in the fractured aquifer system. Two distinctive groundwater chemical types were identified in the catchment; the saline Na(Mg)-Cl-rich groundwaters associated with the fractured Oakdale Formation and the Na-HCO3-rich groundwaters associated with the intermediate groundwater system. The groundwater chemistry of other deep groundwaters in the catchment appears to be due to mixing between these end-member groundwaters within the fractured bedrock system. The spatial distribution of electrical conductivity, Cl-, Sr2+ and 87Sr/86Sr isotopic ratios showed the correlation between saline groundwaters and the location of faults. Elevated salinities were associated with the location of two crosscutting fault zones. The spatial distribution of HCO3-, K+, Li+ and ?????3CDIC highlighted the extent of Na-HCO3-rich groundwaters in the catchment and showed that these groundwaters are mixing further east than previously envisaged. These findings show that Na(Mg)-Cl-rich groundwaters are geochemically distinctive and have evolved due to extensive water-rock interaction processes within the fracture zones of the Oakdale Formation. These saline groundwaters contain elevated concentrations of trace elements such as As, V and Se, which pose a potential risk for water resources in the area. 87Sr/86Sr isotopic ratios indicated that the source of salinity to the Na(Mg)-Cl-rich groundwaters was not purely from marine or aerosol input. Salt is most likely contributed from various allochthonous and autochthonous sources. This research found that the main mechanism controlling the formation of dryland salinity seepage zones in the Spicers Creek catchment is due to the presence of geological structures. These groundwater seepage zones act as mixing zones for rainfall recharge and deeper groundwaters. The main sources of salt to the seepage zones are from deeper Na(Mg)-Cl-rich groundwaters and rainfall accession. The major importance of this research highlights the need for an integrated approach for the use of various geoscientific techniques in dryland salinity research within geologically complex environments.

Many physically-based models of surface and groundwater hydrology are constructed without the possibility of multiple stable states. For such a conceptualisation, at the cessation of a transient hydrological disturbance of any magnitude, the model will return to the original stable state and therefore will have an infinite resilience. Ecosystem resilience science propose a very different dynamic where, if the system has a positive feedback, disturbances may shift the system over a threshold where, upon cessation of the disturbance, the system will move to a different steady state. This dissertation brings together concepts from hydrology and ecosystem resilience science to highlight this often implicit assumption within hydrology. It tests the assumption that dry land water-limited catchments always have only one steady state (henceforth referred to as 'attractor'). Following a discussion of this implicit assumption within hydrology, approaches for rigorous testing that could result in its falsification are considered and that of numerical modelling is adopted. The aims of the research were to test this assumption by proposing a biophysically plausible hydrological model; utilise it to investigate the catchment attributes likely to result in multiple attractors; and to assess the model's validity by way of implementation and calibration. (For complete abstract open document.)

This study investigated the catchment of an urban wetland on sandy soils in Perth, Western Australia. The wetland is of high conservation value but is currently used as a stormwater-compensating basin. The three main aims of this work were to: 1. determine the importance of stormwater drains in the water and pollutant balance of the lake; 2. evaluate pollutant retention rates by the wetland; and 3. identify current land uses in the catchment, determine their impacts on the wetland and identify tolerable levels of urbanisation for a wetland of this type. Stormwater flowing in and out of the lake subcatchments was monitored for two years for background flows and storm events. Water discharge, physical and chemical characteristics —including nutrients and heavy metals — were measured. Water and pollutant mass balances were determined. There was year-round flow at all sites, except from the smallest subcatchment. Flow characteristics differed between sites and were more influenced by catchment characteristics than rain intensity or duration. More water entered than left the lake in spring. In autumn more water left the lake via the overflow than entered. Due to poor maintenance, many drains overflowed during storm events. When compared to Australian and New Zealand Environment and Conservation Council (ANZECC) water quality guidelines for receiving waters, only pH and conductivity met the recommended criteria. The nutrient and heavy metal loads varied with rainfall during both years of study. Suspended solids, total nitrogen and total phosphorus concentrations were proportional to rainfall, while concentrations of dissolved forms of nutrients were not. Background flows contributed significantly to the pollutant load. More than 85% of total suspended solids, nutrients and heavy metals were retained by the wetland — the only exceptions being copper and some forms of dissolved nutrients. An evaluation of the performance of the lake as a pollutant sink, using published data from constructed wetlands, identified phosphorus as the pollutant that requires the largest area for treatment.

Thesis (Ph. D.)--University of Hong Kong, 1992.

The aim of this paper is to describe and compare various methods of runoff separation. Therefore it is necessary to explain basic hydrological terms that are important for understanding the water regime of landscape. Long-term monitoring of the water regime of the whole catchment area can provide successful detection of hydrological extremes such as droughts or devastating floods. The paper is divided in two parts. The theoretical part includes the literature rerview explaining basic hydrological terms and individual components of water cycle in nature, summary of methods usually used for runoff separation, and the description of the applied methods. The practical part specifies the locality of Jenínský stream, located in the Český Krumlov district. This part further reflects separation of runoff based on the daily runoffs. Methods GROUND, MPGM and Chapman digital filter have been chosen to compare primary runoff and direct runoff. We have also considered the method of separation of minimal monthly runoff according to Kille for seven-year period in relation to the methods mentioned above. Finally, we have chosen several discharge waves for the method of recession curve analysis. The paper compares direct and primary runoff separated by individual methods in the catchment area of our interest.

Submitted by Jean Medeiros (jeanletras@uepb.edu.br) on 2017-03-03T12:17:51Z No. of bitstreams: 1 PDF - Ozéas Jordão da Silva.pdf: 3415187 bytes, checksum: a9e7a199f5e77be9726af8db8b2cdcd6 (MD5) / Approved for entry into archive by Luciana Medeiros (luciana@uepb.edu.br) on 2017-03-03T15:47:01Z (GMT) No. of bitstreams: 1 PDF - Ozéas Jordão da Silva.pdf: 3415187 bytes, checksum: a9e7a199f5e77be9726af8db8b2cdcd6 (MD5) / Made available in DSpace on 2017-03-03T15:47:02Z (GMT). No. of bitstreams: 1 PDF - Ozéas Jordão da Silva.pdf: 3415187 bytes, checksum: a9e7a199f5e77be9726af8db8b2cdcd6 (MD5) Previous issue date: 2003-05-29 / This is work present the proposal that the pluvial water catchment in the Campina Grande’s public schools is an politics for confrontation of the problem of water scarcity in the city. Stating fron the discussion on the phenomenon of the drought in the region of the Brazilian Semi-arid, this work concentrates its focus on the specific problem of Campina Grande’s analyzing 39 of its schools. The result of research show: that the schools make exclusive use of system of supply of state Company – CACEPA – and that her terms infrastructures conditions are precarious, especialy, in the periods water rationing in the city; that the steps by the directors of the schools in the attempt to fight the serious damages of the complex system educational caused by water scarcity are inefficient; that the schools buildings roofs posse such of the a great capacity of rain water catchment that by adopting the system of rain water catchment out of the schools, 15 would be super-suficients, 15 almost-coefficients and 9 insufficient, with respect to relation of water catchment versus water demand, that the student community knows buildings. Hence, it is concluded, that the system of pluvial water catchment present a helpful, viable, efficient and economic alternative for combating the scarcity in the Campina Grande’s public schools. / Este trabalho apresenta a proposta de que o sistema de captação de águas pluviais nas escolas públicas de Campina Grande é alternativa para uma política de enfrentamento do problema de escassez de água na cidade. Partindo da discussão sobre o fenômeno da seca na região do Semiárido Brasileiro, concentra o foco da pesquisa na problemática especifica de Campina Grande, analisando 39 escolas. O resultado da pesquisa mostra que: as escolas dispõem exclusivamente do sistema de abastecimento de água da Companhia Estadual – CAGEPA – e que suas condições infraestruturais se apresentam precárias, sobretudo, em períodos de racionamento de água na cidade; as providências tomadas pelos diretores das escolas na tentativa de combater os sérios prejuízos do complexo sistema educacional causados pela escassez de água são insuficientes; que os telhados dos prédios das escolas possuem capacidade de captação de água de chuva tamanha, que adotado o sistema nas escolas e considerada a relação captação X demanda, das 39 escolas pesquisadas, 15 seriam supra-suficientes, 15 quase-suficientes e 9 insuficientes, sendo a contribuição destas bastante significativa; que a comunidade estudantil conhece e concorda com a utilização do sistema de captação de águas de pluviais na escola. Conclui-se, a partir deste resultado, que o sistema de captação de águas pluviais se apresenta como alternativa auxiliar, viável, eficiente e econômica de combate à escassez de água nas escolas públicas de Campina Grande.