Infrastructure Engineering - Theses
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ItemThe digital lodgement of cadastral survey data in Victoria( 1998-12)An integral part of the Victorian land registration system is the lodgement of cadastral data. Originally data was lodged to support the operation of the land market and the legal rights of the individual owner. The purpose for which it was designed, coupled with the technology that was available at the time, resulted in a paper based system of plans and indexes. Due to many external factors, the current land registration system has essentially remained the same for the past 130 years. However the need for cadastral information means that plan lodgement now serves a wider range of needs, and although changes have been made to the system, it would seem that document-based systems are reaching the limit of cost-effective improvement. A detailed study of the Victorian system of data lodgement has shown there to be several inefficiencies within the system, many of which would benefit by the shift to a digital environment. Research has also shown that the Victorian surveying profession is actually quite prepared to adapt to a digital environment, with many surveyors already preparing or submitting plans digitally. Other jurisdictions that are experiencing similar problems to Victoria have progressed substantially in this area and form ideal examples to learn from. The study of these jurisdictions has shown that although technically the process of lodging data in a digital format is quite straightforward, there are still many technical and legal problems that must be resolved. It is envisaged that in the future, data be lodged in a digital format, which would involve there-engineering of the Victorian land registration system as we know it. This thesis explores the concept of the lodgement of cadastral survey data in a digital format, the issues associated with such a change and the long term benefits it will provide to the surveying, mapping and land development industries.
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ItemThe behaviour of salinity and density stratified flows in the Wimmera River, Australia( 1994)A quantitative understanding of the behaviour of salinity and density stratification in the Wimmera River is developed using a combination of field, laboratory and numerical modelling techniques. The Wimmera River, which is located in north-western Victoria, Australia, is a saline stream with a seasonal and highly variable flow regime. Large salt fluxes enter the Wimmera River as a result of surface water inflows from the upper catchment and groundwater inflows in the upper and lower reaches of the stream. During periods of low and zero flow, a series of long deep pools exist along the river, particularly downstream of Horsham. Inflows of saline groundwater accumulate in scour depressions within these large pools and a series of density stratified or saline pools results. Small flows of saline and fresh water down the river can also lead to density stratification. Larger flow events lead to destruction of the density stratification. A model of flow and salinity in a 200 km reach of the Wimmera River is developed using the MIKE 11 model (DHI, 1992a; 1992b). MIKE 11 solves the St Venant equations for gradually varied, unsteady flow and the Advection-Dispersion equation for solute transport. A time-series data base of discharges and salinities for all surface water and groundwater inflows to the river is developed. This was an important step in the model development due to the existence of a significant number of ungauged tributaries and the importance of groundwater as a source of salt. Stream channels are specified in MIKE 11 by defining a channel network and specifying a series of cross-sections along each channel. The channel morphology of the Wimmera River is studied and a methodology for characterising channel variability is developed. It is shown that the Wimmera River channel can be divided into two statistically different channel types which are characterised by a typical length-scale of several kilometres. Using the above analysis as a basis, a stochastic model of stream channel cross-sections is developed for the Wimmera River and used to infill the existing cross-sectional data. The hydraulic implications of along-channel cross-sectional variation are investigated numerically. A one-dimensional model of the Wimmera River is calibrated and tested. This model is applicable to in-bank flows and their associated salinities. The model adequately simulates the routing of water and salt down the Wimmera River. Variations in salinity associated with flow events and the seasonal variation of salinity are reproduced. Field and laboratory investigations of density stratified pools are described. Density stratified pools form as a result of saline groundwater inflows when the stream discharge is less than 200 - 300 Ml/d. The rate at which the stratification develops is quantified for four field sites. Saline water is mixed from density stratified pools during flow events. The mechanism responsible for most of the mixing involves a thin outflow of saline water up the downstream slope of the scour depression. Turbulent entrainment is also responsible for some mixing. During the autumn, convection associated with surface cooling can also mix some density stratified pools. A model of individual density stratified pools, known as Salipool, is developed and tested. Salipool is applied to four density stratified pools in the Wimmera River. A generalised calibration of the mixing relationship incorporated in Salipool is suggested. This generalisation is based on bend sharpness. It is hypothesised that bends have a significant impact on mixing of density stratified pools due to their effect on the vertical velocity profile and the direction of nearbed currents. Salipool is used as a basis for modifying MIKE 11 to incorporate the effect of density stratification.
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ItemModelling hydrologic and climatic controls of closed lakes, western Victoria( 1995)To quantify changes in water level and climate, a water balance model, calibrated using historical climate and lake levels, is used to construct a detailed 16,000 year record of precipitation/evaporation (P/E) ratio for three closed lakes in western Victoria. Lakes Keilambete, Gnotuk and Bullenmerri are maar lakes situated in western Victoria, 200 km W of Melbourne. With high lake/catchment ratios, these lakes are sensitive to atmospheric conditions affecting water balance. Their levels are controlled by direct precipitation and evaporation; groundwater (baseflow) is a minor contributor to the water budget. Previous studies have constructed detailed records of lake levels and palaeosalinities, providing a continuous hydrologic record from 16,000 years ybp to the present. The lakes were observed at high levels by early European settlers but since 1841, waterlevel has undergone the most rapid and sustained decline recorded for the Holocene. Regional meteorological records are used to construct climate series representative of the study area from 1859-1990. Regional homogeneity is demonstrated between the study area and climate stations elsewhere in southern Victoria, South Australia and Tasmania. Climate change recorded at the lakes is therefore indicative of regional climate. No evidence of climate change is found early in the instrumental record, but a statistically significant increase in of 0.3 °C in temperature occurs after 1960. Evaporation is calculated using Morton's Complementary Relationship Lake Evaporation model, utilising long records of air and dewpoint temperature and sunshine ratio. The model calculates water budgets from rainfall, evaporation and baseflow. Baseflow is calculated from the infiltration rate which is derived from modelled soil moisture. Baseflow is optimised for each lake to reproduce the historical fall in lake level. The equilibrium climate for the pre-European lake level is modelled as a P/E ratio of 0.94-0.96, compared to the current ratio of 0.79-0.80. The historical fall in all three lakes preceded the period of instrumental climate measurement and major land-use changes. It is therefore ascribed to a natural climate change. Equilibrium and non-equilibrium modelling of lake water levels have produced detailed estimates of P/E ratios, demonstrating wide climatic fluctuations during the Late Pleistocene and Holocene. Holocene P/E ratios vary from 0.77-0.80 in the early and late Holocene to > 1.10-1.20 from 7,000-5,500 ybp. Late Pleistocene P/E ratio varied between 0.70-0.80. The resultant record enables precise estimates of P and E to be determined if independent estimates of either variable can be supplied. It provides a detailed view of climate throughout the Holocene and is of special relevance to continental and hemispherical climate records. Further information on palaeolake levels from the study lakes and other related maar lakes will permit the construction of an even more detailed record of P/E ratio for the Holocene. With other long records from the region, it will provide a highly detailed record of climate change in south-eastern Australia, dating from the late glacial period. The study lakes also show great potential for monitoring future changes in P/E ratios, particularly precipitation change.
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ItemMeasurement and modelling of irrigation channel seepage in northern Victoria( 1993)The earthen irrigation channel network in northern Victoria is operated and maintained by the Rural Water Corporation of Victoria. Water tables are now within 2 m of the surface throughout a large part of the irrigated area in northern Victoria. Groundwater accessions from seepage losses from earthen irrigation channels contribute to these high water tables and the associated problems of salinisation and water logging. Seepage tests using a pondage method were performed on two irrigation channels near Tatura (36° 26’ S, 145° 16’E) in north-central Victoria. Testing took place over two irrigation seasons (1989-90 and 1990-91) at both channel sites (Tatura East and Dhurringile). Testing also took place during a third irrigation season (1991-92) at the Tatura East site. This study is the most extensive of its kind ever completed within an Australian irrigation system. Seepage rates were calculated for all seepage tests performed (11 at the Tatura East site; 8 at the Dhurringile site). Seepage losses in the upstream pond of the Tatura East channel varied between 20 and 34 mm d-1. In the downstream pond this variation was 14 to 19 mm d-1 under normal pondage conditions. The difference between channel water level and aquifer head was the most significant factor in determining the seepage loss rate from the channel. The related problem of leakage (loss from the channel through holes in the channel bank) was highlighted in this study. Measurements of leakage losses were made in 5 of the 8 tests at the Dhurringile site and estimates of the relative magnitude of seepage and leakage losses were made. The average seepage loss (not including leakage ) during these five tests varied between 5 and 9 mm d-1. The data collected from the Tatura East site included channel water elevation and groundwater elevation in three piezometer transects perpendicular to the channel. Using these data, an existing computer model employing the boundary integral equation numerical method was modified to simulate the seepage processes occurring at this channel site. Physically based algorithms of deep seepage and net evaporation from the water table were added to the model during this study. Through calibration and validation of the model results to the field observations, the aquifer parameters were determined and the processes involved in the transmission of seepage away from the channel were identified.
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ItemThe evaluation of surge flow in border irrigation (with special reference to cracking soils)( 1993)Surge flow was identified as a potential method of improving farm water management to both reduce water use and minimise accessions to water table, and therefore to help address the salinity and water-logging problems facing the irrigated areas of the Murray-Darling Basin. Surge flow has been intensively researched in furrow irrigation in the USA, but border strips (which are the dominant application method in south-eastern Australia) and cracking soils have received minimal attention. This study investigated surge response in border irrigation with particular reference to cracking clay soils. Two years' field work resulted in a substantial data set covering four soil types and a range of management options. Surge flow reduces water use on cracking clays by 15-40% compared with continuous irrigation under similar conditions and given the same level of management. A negative response was observed on homogenous fine sandy loams, with up to 30% more water applied in surge flow. The positive response was obtained over a range of cycle ratios from 0.2-0.5 and with off-times from 30-300 minutes. Measured soil moisture distributions in the second season showed that application uniformity was better using long offtimes of around 300 minutes. Calculations of the water balance indicate that a greater proportion of applied water is retained in the root zone in surge flow and accessions are a small proportion of those in conventional irrigation. The strong field response was not supported by infiltration test data which recorded greater water intake in surge flow than in continuous tests. The recirculating infiltrometer over-estimated cumulative infiltration for both surge and continuous application, in both seasons. It was later observed that water advances in subsurface cracks in the off-time, up to 70 m ahead of the surface stream. Additional analysis indicates that the surge response is largely due to a mechanism connected with this phenomenon, which helps reconcile the disagreement between field and infiltration test data. Surges overlapped in every test and this phenomenon cannot be simulated by existing hydraulic models of surge flow and substantial revisions are needed before meaningful calibration can be undertaken. The field work provided a clear statement of the difficulty of obtaining infiltration data on cracking soils, and highlights the need for effective real-time estimation of infiltration parameters to overcome severe temporal and spatial variability in infiltration conditions. An inverse solution of the Zero Inertia model was developed, using a constrained Simplex optimisation algorithm to determine infiltration and roughness parameters from advance and depth profile data plus a compound objective function of the two. Global parameters, with reasonably effective predictive performance, were obtained using a compound objective function with continuous flow data sets and, more tentatively, for surge flow. This work provides practical possibilities for automation of border irrigation, using as little as two sensors to determine one roughness and one infiltration parameter from advance data, providing the Kostiakov exponent can be reliably classified. A minimum offour sensors are needed to identify two Simple Kostiakov infiltration parameters and one roughness value. Longer term, farm-scale trials are now required.
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ItemCatchment management for the control of sediment delivery: the case of the Eppalock Catchment, Victoria( 1996)This thesis investigates sediment delivery from large catchments, with regard to determining the benefits of whole-of-catchment management for controlling sediment delivery. This work was based on a case study from Victoria, and was supplemented by an analysis of data from other reservoir catchments in Victoria and around the world. The Lake Eppalock catchment, in central Victoria, was the case study considered in this investigation, and was examined in two steps. In the first pan of the analysis the original justification for the whole-of-catchment soil conservation project at Lake Eppalock, was investigated. In the second pan a field-based study of the catchment was implemented.. These analyses suggested that sediment delivered to Lake Eppalock was, and is, derived primarily from the channel network, and sediment delivery from the hillslopes is of minor significance. The investigation also indicated that the low hillslope yields may be attributed to the de-coupling of the hillslopes and drainage lines by broad footslopes. Examination of global sediment yield trends supported this hypothesis and thus a simple conceptual model was developed to explain variations in sediment delivery and long-term sediment yields between large catchments. The model was supported by thirteen of the sixteen case studies used in the validation process. On the basis of the conceptual model, it was concluded that whole-of-catchment management schemes may only be appropriate for controlling sediment delivery in steep catchments. In most flatter catchments, management techniques will have measurable impact in the channel areas only.