The diagram highlights the difference between of the water cycle’s efficiency between a natural zone and metropolitan setting.
Overall, the water cycle appear to have more difficulties to fully perform in a urbanized space compared to a forested and natural one.
To be more precise, the permeable layer of the soil is thinning out in urban areas, causing significant disruption in the way water flows underground. Indeed, due to the reduced permeable topsoil, the less permeable subsoil underneath expands, therefore reducing baseflow. Subsequently, that water is being trapped under a harder layer, making it difficult for the transpiration and evaporation parts of the water cycle, but also increases erosion which considerably pollutes runoffs. Polluted runoffs infiltrate the topsoil, wich inevitably worsens the state of the permeable layer of the ground. In opposition, the water cycle is carried out way more smoothly in forested zones, since it is less exposed to pollution and urbanization. Water easily infiltrates the ground to the water table and evaporate again.
To conclude, urbanization dirsupts the process of the water cycle, which will inevitably result in a dangerous state of the soils.