Simulating the impact of water infrastructure on groundwater and surface water within the Laurel Creek Watershed

Abstract

As the urbanization of the City of Waterloo, the infrastructure system expanded fast in the last couple decades. The increased population gave a higher load to the Laurel Creek Watershed. At the same time, the aged infrastructures have fractures and cracks, which result in the leakage of watermain and groundwater infiltration into the sewer pipelines. Those waste drinking water and additional sewer water increased the water bill of the citizens. Therefore, the City of Waterloo needs a municipal infrastructure asset management to keep the water supply and drainage system sustainable in the future. Part of the municipal infrastructure asset management is to establish an integrated natural water cycle model of the Laurel Creek Watershed. This surface water-ground water simulation model was built up using HydroGeoSphere (HGS). Then, insert the watermain, sewer pipeline, and the storm water pipeline (GIS data was from the City of Waterloo) into this natural water cycle model. The subsurface geology of the model is based on the multi-aquifer Waterloo Moraine system created by Martin and Frind (1998). The updated hydraulic conductivities, the land use condition, and the evapotranspiration pattern have been added into the Laurel Creek Watershed model. In the HGS model, there are a total of 46 layers. The 20 upper layers were generated based on the shape of the topography. The bottom 17 layers were created based on the bedrock layer. In between the upper layers and the bottom layers, there are 8 sublayers to refine the information of hydro-stratigraphic units. There is an additional layer for the municipal infrastructure to input the pipelines’ elevations. Due to the time limitation, only the sewer trunk lines have been inserted into the model. The Laurel Creek Watershed model was first run to steady state using only the nature water cycle system driven by rainfall and evapotranspiration. Next, the model was then to run steady state again but now containing the sewer drainage pattern. The stream flow in both models was measured to compare the difference between the model with the sewer drainage pattern and the model without the sewer system. Also, the stream flow simulated data is compared with the real word measurement data. This thesis concludes that the municipal infrastructure is possible to be simulated in the natural water cycle HGS model. The simulated results are reasonable matching the real hydraulic condition in the Laurel Creek Watershed.