The purpose of this research was to investigate the feasibility of a passenger rail service operating on a current rail line in Canterbury, known as the Main North Line, which connects the Waimakariri District to Christchurch. The Main North Line runs through the two main urban areas of the Waimakariri District: Rangiora and Kaiapoi. The need for research into the potential use of the Main North Line for passenger services has arisen due to increasing car congestion on arterial roads between the Waimakariri District and Christchurch. All traffic coming from the Waimakariri District into Christchurch must cross the Waimakariri River, creating a transport bottleneck. An assessment of the location of the Main North Line was conducted with respect to the travel needs of Waimakariri District residents using Geographic Information Systems (GIS) to investigate how far residents live and work from the line and resident surveys to determine whether people would use rail as their main mode of travel into Christchurch. Assessment of the infrastructure was with regard to the locations of potential railways stations and the capabilities of the infrastructure for supporting different levels of passenger service. National and regional transport strategies are placing more importance on the transportation of people and freight by way of rail. A potential rail service for Canterbury will therefore likely include national and regional stakeholders in co-operation with a private service operator, as currently occurs in Wellington and Auckland. An average of 71% of Waimakariri District residents stated they would switch to rail as their main mode of transport for the journey into Christchurch. GIS analysis found that the number of journeys which start in the Waimakariri District and terminate within 1km of Christchurch stations is around 610 which increases to around 4,300 if connecting bus services were utilised in Christchurch.

The purpose of this research was to investigate the feasibility of a passenger rail service operating on a current rail line in Canterbury, known as the Main North Line, which connects the Waimakariri District to Christchurch. The Main North Line runs through the two main urban areas of the Waimakariri District: Rangiora and Kaiapoi. The need for research into the potential use of the Main North Line for passenger services has arisen due to increasing car congestion on arterial roads between the Waimakariri District and Christchurch. All traffic coming from the Waimakariri District into Christchurch must cross the Waimakariri River, creating a transport bottleneck. An assessment of the location of the Main North Line was conducted with respect to the travel needs of Waimakariri District residents using Geographic Information Systems (GIS) to investigate how far residents live and work from the line and resident surveys to determine whether people would use rail as their main mode of travel into Christchurch. Assessment of the infrastructure was with regard to the locations of potential railways stations and the capabilities of the infrastructure for supporting different levels of passenger service. National and regional transport strategies are placing more importance on the transportation of people and freight by way of rail. A potential rail service for Canterbury will therefore likely include national and regional stakeholders in co-operation with a private service operator, as currently occurs in Wellington and Auckland. An average of 71% of Waimakariri District residents stated they would switch to rail as their main mode of transport for the journey into Christchurch. GIS analysis found that the number of journeys which start in the Waimakariri District and terminate within 1km of Christchurch stations is around 610 which increases to around 4,300 if connecting bus services were utilised in Christchurch.

The Waimakariri-Avon River system is an important component of the Christchurch aquifer system and has been identified as one of, if not the, primary groundwater flow path. The Waimakariri-Avon River system is ideally suited to geochemical tracing of surface water- groundwater interaction and while many past studies have been undertaken to characterise this system, in terms of its geochemistry and physical hydrogeological components, there is still a large amount of uncertainty as to how long it takes for groundwater to flow from the Waimakariri River, through the Waimakariri-Avon River groundwater system, to the springs that feed the Avon River. The primary goals of this thesis were to; 1) Constrain the residence time of groundwater connecting the Waimakariri-Avon River groundwater system using stable oxygen and hydrogen isotopes and analysis of anionic concentrations of: chloride, fluoride, nitrate, nitrite, bromide and sulfate, 2) Provide additional evidence of a hydrological connection between the Waimakariri River and the Avon River systems, 3) Present observations of the stable isotopic and anionic response of surface water to rainfall events, 4) Identify stable isotopic and anionic surface water variation along the Waimakariri-Avon River system, and establish the reasons for these. This study presents the use of natural isotopic and anionic tracers to characterise the residence time of the groundwater that flows between the Waimakariri and Avon Rivers, by sampling surface water and meteoric water at sites that are part of the Waimakariri-Avon River system. 375 samples were collected from 10 surface water and 4 rainwater sites distributed across the Waimakariri-Avon River surface water-groundwater flow path between March 5th and August, 2014. Additionally the study provides further stable isotopic evidence of the connection between the Waimakariri and Avon Rivers, as well as presents the variability of surface water chemistry in response to rainfall events. Identification of isotopic and anionic variation along the Waimakariri-Avon River system, by surface water sampling, was also conducted to establish the probable causes of observed variations. This study found that the use of large rainfall events, as natural tracers, was not conclusive in establishing the groundwater residence time of the Waimakariri-Avon River system within the 4.5 month sampling period available. Surface water sampling provided further evidence in support of past studies that have determined an isotopic connection between the Waimakariri River and the Avon River with mean stable isotopic values for the Waimakariri River (-8.85‰ δ18O and-60.65 δD) and Avon River (-8.53‰ δ18O and -58.72 δD) being more similar than those of locally derived meteoric water (-5.48‰ δ18O and -35.13 δD). Observations of surface water chemistry variations thorough time determined and identified clear responses to rainfall events as deviations from baseline values, coinciding with rainfall events. Isotopic variation along the Waimakariri-Avon River system was shown to reflect Waimakariri River derived shallow groundwater with the contributions from rainwater increasing with increased proximity to the Avon River mouth. Anionic profiling of the Waimakariri-Avon River system identified increasing concentrations of chloride, nitrate, sulfate, nitrite and bromide, relative to the Waimakariri River, with increased proximity to the Avon River mouth. Fluoride concentrations were identified in lower concentration, relative to the Waimakariri River, with increased proximity to the Avon River mouth. Fluoride and nitrite concentrations were attributed predominantly, if not entirely, to an atmospheric source as mean concentrations were greater in meteoric waters by a factor of at least 2, compared to surface water samples. Chloride and bromide have been attributed to possible salt water mixing as a result of the interaction of upwelling deeper groundwater with the marine and estuarine sands beneath the upper unconfined aquifer, that act as a confining layer within the Christchurch aquifer system. Nitrate and sulfate concentrations have been attributed to potential fertilizer usage and past land-use impacts. A significant step-change increase in chloride, bromide, nitrate and sulfate concentrations was observed between the surface water sample sites at Avonhead Park and the University of Canterbury. The step-change coincides with the boundary of the upper confining layer within the Christchurch aquifer system, and explains the increases in chloride and bromide concentrations. It also suggests a widely distributed source area as concentrations do not become diluted at the Avon River site, at Hagley Park, , which would be expected from the addition of other tributaries, if they did not have similarly high chloride and bromide concentrations. The area between these two sites has also been identified by Environment Canterbury as potentially impacted by past agricultural land-use practices and may explain the increases in nitrate and sulfate concentrations.

ModClark and Clark’s Unit Hydrograph (Clark’s UH) within HEC-HMS software are distributed and lumped models, respectively. Clark’s UH simulates the transformation and attenuation of excess precipitation, and requires time of concentration (Tc) and Storage Coefficient (R) parameters. ModClark transformation accounts for variations in travel time to catchment outlet from all regions of a catchment, and it additionally requires gridded representation of a catchment and Gridded cell-based input files. Four cases (three from observed rain, and one from radar reflectivity) of three chosen events were specifically chosen and examined for the comparison of simulation results with the same estimated initial parameters apart from different rainfall inputs. The Upper Waimakariri River Catchment was divided into ten subcatchments, and the HEC-HMS basin model parameters were estimated by using the physical/hydrological characteristics. However, ModClark transformation was unavailable because of an output error from converting ASCII to gridded Soil Conservation Service Curve Number (SCS CN) format by the conversion tool – ai2dssgrid.exe. Therefore, Mean Aerial Precipitation (MAP) for each subcatchment was calculated by Thiessen polygon method combined with an overlay analysis for grid-cell-based rainfall estimation from radar with geographic information system (GIS) tools. The automated calibration/optimisation procedure included in HEC-HMS package was applied to the cases which showed a deviation between simulation and observed flows. The purpose is to ‘optimise’ the initial estimates of parameters only in a mathematical-fit manner based on the observed flows from the only discharge gauge at Old Highway Bridge (OHB). The TC values calculated from the five equations vary in a relatively narrow range apart from the one from Bransby-Williams equation. Therefore, the values from all the other four equations were averaged and used as the initial TC input. The simulation results showed that there was a notable difference between observed and simulated hydrographs for some case studies even though TC, R, CN, and lag time were calibrated/optimised separately. Also, radar estimated rainfall and grid-based data storage system (DSS) need more investigations.