A levee is a system to control water levels. 堤是一种控制水位的系统。

　　When it rains a lot, floods can happen. 降雨很多时，就可能会发生洪水。

　　People build walls along rivers or coasts to prevent floods. 人们在河边或海岸边筑堤来防洪。

　　So, a levee is also called a flood bank. 因此，堤也被称为防洪堤。

　　People bulid levees with various things. 人们用各种材料来筑堤。

　　Such as stone, soil or cement. 比如石头、土块或水泥。

　　However, people sometimes pile sand bags in a flood emergency. 然而，发生洪灾时，人们有时会叠沙包来抗洪。

　　The parks near seas or rivers also act as levees. 近海或河的公园也起堤的作用。

　　How does it prevent flooding? 它是怎样防洪的呢？

　　When it rains a lot, the park is filled with water and this prevent flooding. 下很多雨时，公园里灌满了水，这样也能防洪。