O-Level Geography Chapter 3 Water Resources Dams and Barrages

O-Level Geography Chapter 3 Water Resources River Systems of Pakistan

To view other notes Related to O-Level Geography of Pakistan. Click Here.

Dams

Mangla dam

Tarbela Dam

Pakistan has two large dams (Tarbela and Mangla), while all other dams are either small or medium sized. Tarbela and Mangla are multipurpose dams which store water not only for irrigation but also for generating power. These dams have reservoirs because the dam wall holds up the water. Spillways are gates through which the water is allowed to go downstream due to either deficiency of water downstream or flooding upstream. A dam may break if it is filled beyond its capacity.

Both Tarbela and Mangla store water during the main rainy season (monsoons), which accompanies the melting of snow and ice (due to high temperatures in summers) in the Northern Mountains. The rainwater and melted snow drains into the rivers and ultimately ends at the reservoir.

Barrages

1. Chashma barrage
2. Rasul Barrage
3. Marala barrage
4. Qadirabad Barrage

Barrages are long structures similar to a dam. They divert water that is in the river into the canals. They have many dozens of gates, which either can be closed to create a lake with the embankments of a river serving as a container wall.

Or the gates of a barrage can be opened and allow water to continue its course in the river. Barrages have been built to transfer water between rivers via link canals, like Rasul Qadirabad Link canal. Sukkur Barrage has 60 gates with total length of 4000 feet.