Green field and river serves as a buffer zone when it rains in the city. Due to insufficient water storage space in urbanization, flooding is often caused by heavy rains. Excessive water leads to urban flooding which causes a lot of damage. We need to store it quickly, not only to reduce flooding, but also to make good use of the water. Like the city sponge, tower absorbs water to remove excess flood water, reduces water shortage during drought by storing water, and solves sanitation problems through purification.