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Water cycle and urbanization

Track storage and movement of rainwater by changing precipitation, imperviousness, evaporation, and soil conditions.

    E18 · Water cycle and urbanizationReady
    You can also experiment with the numbers and controls below the scene.

    Earth Science · Ocean · Climate · Water Cycle / Principles and Exploration

    Water cycle and urbanization — principles and investigation

    Even if the same rain falls, the path through which the water stays or flows varies depending on the ratio of soil and pavement. Compare surface runoff and soil and groundwater storage by varying precipitation intensity, impervious area, evaporation conditions, and infiltration capacity. Observe how the stored water continues to move even after the rain stops.

    How does it work?

    As the impervious area increases, the space for water to seep into the soil decreases and the amount of water flowing into rivers increases. Even when the rain stops, water moves from the reservoir.

    Key relationship

    P = R + I + E + ΔS

    Try this investigation

    1. After it rains for 4 hours, we observe drainage for 20 hours. An imperviousness ratio of less than 0.5 is indicated as a forest, and above 0.5 is indicated as an urban scene. Take a look at the blue storage and flow.
    2. Precipitation, evaporation, and soil are kept the same, and cumulative runoff, soil infiltration, and deep infiltration from forests and cities are recorded.
    3. We change the soil infiltration capacity and evaporation conditions one by one in the forest standard. Check whether the water balance residual at each calculation step is close to 0.

    Interpreting your results

    What is the difference between I in water balance and surface → soil infiltration?

    Since soil and groundwater are also included in the storage, if internal infiltration is added to external outflow, it is counted twice. R is the stream outlet discharge, and I is the water that passed the boundary below the model.

    Assumptions and limitations

    It is a concentrated storage model of surface, soil, groundwater, and rivers calculated in mm of depth per uniform basin area. The soil volume is 70 mm and a virtual displacement coefficient is used. R is river discharge outside the basin, I is deep infiltration outside the model, E is evapotranspiration, and ΔS is the sum of the four reservoirs. Surface → soil infiltration is recorded separately as internal movement. We do not predict actual floods or flooding.