There are a myriad of ways to prevent floods. The creation of flood plains and winding streams are two of the best ways to hinder the accumulation of water by providing a route for the drainage of water. Also, the protection of wetlands helps to maintain a natural drainage system to provide a place for the excess water to gather. Such devices allow the water to evaporate before it can accumulate, creating flooding conditions.
Levees also impede the collecting of water. Levees are embankments composed of soil and earthen material that are used to prevent annual flooding in many areas. With a levee, a huge amount of rain water is required before flooding occurs. However, one drawback to their use is that if water is able to get past the levees, then the flooding is significantly worse and causes several times more damage.
Above, levees prevent possible flooding
Other ways of preventing floods include placing sandbags along the riverbank to serve as levees and placing large rocks on banks to prevent erosion, which prevents riverbanks from deteriorating, remaining high enough so that flooding will not occur as frequently.