Operation of Dams and Barrages

Abstract

This chapter covers reservoir water balance and operation of gates of dam and barrage for canal water supply and for the safety of structures. The components of the dam structure and surface reservoir are explained. Reservoir operation is based on the concept of water balance, which accounts for various inflows, outflows, and resulting changes in water storage. A reservoir operation study is carried out to plan seasonal water allocations for irrigation and other purposes. Parameters to evaluate the reservoir performance in meeting irrigation demand are discussed and illustrated with an example. The procedure for the operation of a dam covers (a) regulation of gates as per requirements, (b) keeping records and online transmission, and (c) ensuring the safety of the dam and the public. Guidelines for normal and emergency operations are explained. The concept of still pond regulation and semi-still pond regulation to avoid sediment entry into the canal is explained. The operation of silt excluders and silt ejectors is described. Shoal formation near the barrage structure, both upstream and downstream, needs to be avoided. River surveys should be conducted regularly to keep a watch on river behavior. The operation and Maintenance (O&M) Manual for Bhoothathankettu Barrage in Kerala state of India is reviewed. The manual includes operation, inspection, maintenance, and repair of barrage components, and replacement of equipment and appurtenant structures, as required. A brief description of some important items is given in the chapter to illustrate the procedure for operating a barrage.

Questions

• 1. Explain the difference in the following terms

  • (i) Valley storage, surcharge storage, bank storage

  • (ii) Dead storage level, sill level, minimum operating level

  • (iii) Full reservoir level, spillway crest level, maximum water level.

• 2. How long term simulation would provide more reliable estimate of storage or yield to meet seasonal irrigation water demand

• 3. Discuss various indices of reliability for an irrigation reservoir.

• 4. How the sediment entry into canal can be avoided or reduced

• 5. Why the shoal formation in the vicinity of barrage should be avoided

• 6. Describe purpose of various gates in a dam and in a barrage.

• 7. What aspects of operation need to be covered in preparation of O&M manual of a barrage