Dam and Reservoir Design

What is a berm?

A berm is a man-made sediment barrier placed at the edge of a slope or a wall built adjacent to a ditch to guard against potential flooding.

Berms are placed in flood-prone areas to protect against erosion, run-off and high water. Berms typically are made of compost, mulch or gravel materials because their density enables them to slow down and retain floodwaters. 

Click here for more information on berms  

• Primarily made of soil or rock that is found locally.
• Erosion is a major concern for these dams; continuous maintenance (such as vegetation control) is required.
• A cross section will look like a bank or a hill.
• Most have a central section made of impermeable material to stop water from passing through.
• Embankment dams can be either “earthfill” or “rockfill”.
• Earthfill dams are the least expensive type of dam to build, are made of clay and compacted earth, and are relatively small and easily eroded.
• Rockfill dams are constructed from materials from the reservoir site and work well in cold or rainy conditions.

•  Made from concrete with steel support.
• Used for on-stream storage where water will flow over the top of the dam. 
• Resilient to erosion.
• Consequences of over-topping (when water runs over the top of the dam) can be potentially catastrophic depending on design. 
• Arch dams are supported by abutments, anchors and a solid geological foundation.
• Arch dams are used in narrow valleys with solid rock foundations. Typically arch dams are very tall. 

• Made from concrete with steel support.
• Used for on-stream storage where water will flow over the top of the dam.
• Resilient to erosion.
• Consequences of over-topping (when water runs over the top of the dam) can be potentially catastrophic depending on design. 
• Gravity dams are supported by abutments, anchors and a solid geological foundation.
• Gravity dams are very large. Most gravity dams constructed since 1980 used a specific method of building. These dams are called Roller Compacted Concrete dams (RCC dams) because the dam is built in thin layers and a roller compacts the concrete after each layer is added. 
• A cross section of a gravity dam will look triangular.

• Made from concrete.
• Must be constructed on sound rock.
• Buttress dams are supported by triangular shaped walls (“buttresses”).