The Research Investigation focuses on the research aspect of a project undertaken as part of the requirements for an Honours Project. The research component of the project was divided up into three sections: meteorological and hydrological data analysis, the field investigation and saltwater intrusion modelling. Although the Literature Review included meteorological and hydrological data analysis, additional research and analysis of the meteorological and hydrological conditions was initiated after experiencing uncharacteristic weather conditions while on site. The further investigation into the site conditions identified that more accurate data could be sourced from the NASA Atmospheric Science Data Centre. These data provided a more representative depiction of the meteorological and hydrological conditions of the site by using regional averages for the coordinates 19˚S, 169˚E of Port Resolution.
A range of field tests and observations enabled information to be acquired regarding the required design parameters for the design of the potable water supply and wastewater disposal and treatment system. Well dipping was achieved with the assistance of the locals and information was gathered about the properties of the freshwater aquifer. Differential levelling methods and the use of a Trimble Pathfinder ProXRT GPS system enabled the site topography and layout to be mapped. Discussions with the locals and noted observations of existing practises at Port Resolution aided the knowledge of the cultural traditions and the expectations of the community. The field investigation significantly assisted in the detailed design of the integrated water system.
The hydrological data and information obtained from the site investigation were then incorporated into the analysis of saltwater intrusion and the environmental impact of extracting additional volumes of freshwater from the underground aquifer. A theoretical, conservative model based on the
Ghyben-Herzberg principle was developed using Microsoft Excel. The model was able to quantify the risk of saltwater intrusion and estimate the time for the treated effluent from the wastewater disposal system to percolate to the aquifer and reach the ocean. Conclusions were drawn by altering the values of the unknown parameters, soil hydraulic conductivity and the recharge, to determine if up-coning of the saltwater interface occurred. The saltwater intrusion modelling results will assist in the development of an environmental risk assessment that will be required as part of the Port Resolution Community Project (PRCP).
The following methodologies are a combination of the field investigation, theoretical modelling and engineering design undertaken as part of the research component of the project.
Meteorological and Hydrological Data Analysis
Upon returning from Vanuatu, site observations prompted further investigation into meteorological and hydrological conditions. The...