With an increase in world population and recent global climate changes causing increasingly unpredictable and extreme weather patterns, the reliance on groundwater is and will continue to be increasing. As a result, there has been an increase in research efforts to better understand groundwater processes, in particular how these interact with surface water systems and how groundwater abstraction affects this interaction. The aim of this thesis is to create an understanding of these processes through the use of a generic numerical model of river, aquifer and abstraction bore.A numerical model domain was defined for an aquifer-river system based on the general aquifer geometry and aquifer parameters at Elfin Crossing in Maules Creek. Model parameters such as hydraulic conductivity and gradient, distance of pumping bore from the river, pumping rate and a streambed clogging layer were varied within reasonable bounds for the field site. The aim was to quantify the influence each parameter has in terms of stream depletion and the time for the river water to reach the pumping bore. From these parameters values were selected to create a base case model. In addition realistic upper and lower values of each parameter were combined to make worst and best case scenarios. Then through a sensitivity analysis these scenarios were compared to observe the combined effects of these parameters on the system response and the stream flow depletion.Results of the sensitivity analysis found that the greatest effect was the distance that the abstraction bore was placed from the river followed by the pumping rate, then the hydraulic conductivity and the streambed clogging layer. It was also found that pumping induced by parameters when applied to historical flow data from Maules Creek caused extremely low flow values which could decrease water quality and deny downstream users of valuable irrigation water.