Dams

Dams

We always visit a dam as a tourist place; now let's understand the proper functioning of the dam and its types.

The basic definition of dams is, it is a massive superstructure that is constructed along with the flow of a river in order to act as a barrier.

Based on the construction material, dams can be classified into two types :-

1. Gravity Dam

2. Earth/Rock Fill Dam

Gravity Dam : It is a massive structure having triangular cross-section. The weight of the dam (self-weight) and impounding water is directly transmitted to the ground surface strata. Therefore it requires a strong foundation and while constructing a gravity dam a lot of construction material is used.

Granite, gneiss, quartz can be used as a foundation for a gravity dam.

Further in gravity dams we have two categories:

1. Buttress Dam
2. Arch Dam

Buttress Dam : It is similar to a gravity dam, but here we have triangular sections with slope decreasing in downward direction called Buttress. These buttresses are further strengthened by walls called struts.

1. The space between two buttresses is hollow therefore less construction material is used.
2. There is no necessity of a strong foundation as in the case of Gravity Dams ( When compared to gravity dams a less strong foundation can be used).

Arch Dam : In this type of dam the amount of construction material required is less. The abutment rocks (called shoulders of the dam) need to be strong as the entire load is transmitted over there.

        Arch Dam is of two types based on the radii of the dam :

                1. Constant Radii Arch Dam 2. Variable Radii Arch Dam

Earth/Rock Fill Dam : These sorts of dams are trapezoidal in shape. In these dams the inner core is section is made up of clay (an impermeable layer) and the exterior is filled with rocks/stones.

            Length of these dams is less and in this a strong foundation is not required.

DID YOU KNOW ? 

1. Around the Globe,around 5% of dams are -> Gravity Dams

2. Other 5% of dams are -> (Gravity + Masonry) Dams

3. Rest all are Earth and Rock Fill Dams

4. In India we have only 1 Arch Dam -> Idukki Dam which is present in Kerala.

Idukki Dam