Dams of India

• Dams of India have been pivotal in India’s development, providing crucial agricultural irrigation, clean hydroelectric power, and flood control. According to the 7th Schedule of the Indian Constitution, water management falls under state jurisdiction. India’s water infrastructure is extensive, with 5,334 dams, including 447 significant ones.

• However, a recent study by the United Nations University- Institute on Water, Environment and Health (UNU-INWEH), raises concerns about sediment accumulation, predicting a 26% loss in storage capacity for around 3,700 Indian dams by 2050.

Major Dams in India

• Dams are massive structures used for reservoirs, water supply, and flood control. They are gravity-based, earth-fill dams, and arch dams, which are curved structures that transfer water force horizontally. They are critical components of a country’s water management infrastructure.

– The table below shows some of India’s major dams, their connected rivers, and the states where they are located:

Types of Dams

Based on the structure, the types of dams are as mentioned below:

1. Arch Dam: An arch dam is a concrete dam that is curved upstream in the plan. It is designed so that the hydrostatic pressure (force of the water against it) presses against the arch, causing the arch to straighten slightly and strengthening the structure as it pushes into its foundation or abutments. An arch dam is most suitable for narrow canyons or gorges with steep walls of stable rock to support the structure and stresses.
2. Gravity Dam: Dams constructed from concrete or stone masonry are Gravity dams. They are designed to hold back water by using only the weight of the material and its resistance against the foundation to oppose the horizontal pressure of water pushing against it. These are designed in such a way that each section of the dam is stable and independent of other section.
3. Arch-Gravity Dam: This dam has the characteristics of both an arch dam and a gravity dam. It is a dam that curves upstream in a narrowing curve that directs most of the water pressure against the canyon rock walls. The inward compression of the dam by the water reduces the lateral (horizontal) force acting on the dam.
4. Barrages: A barrage is a type of low-head, diversion dam which consists of a number of large gates that can be opened or closed to control the amount of water passing through. This allows the structure to regulate and stabilize river water elevation upstream for use in irrigation and other systems.
5. Embankment Dams: An embankment dam is a large artificial dam. It is typically created by the placement and compaction of a complex semi-plastic mound of various compositions of soil, sand, clay, or rock. It has a semi-pervious waterproof natural covering for its surface and a dense, impervious core.
6. Rock-Fills Dams: Rock-fill dams are embankments of compacted free-draining granular earth with an impervious zone. The earth utilized often contains a high percentage of large particles, hence the term “rock-fill”.
7. Concrete-face rock-fill dams: A concrete-face rock-fill dam (CFRD) is a rock-fill dam with concrete slabs on its upstream face. This design provides the concrete slab as an impervious wall to prevent leakage and also a structure without concern for uplift pressure.
8. Earth-fill dams: Earth-fill dams, also called earthen dams, rolled-earth dams or simply earth dams, are constructed as a simple embankment of well-compacted earth. A homogeneous rolled-earth dam is entirely constructed of one type of material but may contain a drain layer to collect seep water.