Final answer:
Preserving wetlands and other natural flood storages is a passive way to mitigate floods by absorbing excess water from heavy rainfall and slowly releasing it over time. Wetlands also provide a habitat for plants and animals and help remove excess nutrients from runoff.
Step-by-step explanation:
Preserving wetlands and other natural flood storages is considered a passive way of flood mitigation because it involves protecting and maintaining existing natural features that naturally reduce the impact of floods. Wetlands act as natural sponges, absorbing excess water from heavy rainfall and slowly releasing it over time, which helps to prevent flooding. They also provide a unique habitat for plants and animals and help remove excess nutrients from runoff before it enters rivers or lakes.