The study investigated groundwater and surface water in an urban area to understand where the water comes from and how it moves through the ground. They found that different areas of the aquifer have different types of water, with some areas showing signs of wastewater. This suggests that water from streams can seep into the ground and recharge the aquifer. By analyzing certain chemicals, they could see how the water interacts between the surface and underground. The age of the groundwater was mostly less than 20 years, but some older water was also mixed in. The researchers suggest using more tracers to better understand how old and new water mix in the aquifer. This study helps us understand how water flows in complex urban areas.