EAD515 July 8th

HYDRAULIC STRUCTURES

Dr H Md AzamathullaLecturer,REDAC, USM

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INTRODUCTION

SPILLWAY

Dispose flood water in excess of reservoir capacity

Control of discharge over spillway by gate operation

Type of energy dissipator provided

Efficacy of Energy dissipator downstream of spillway

Ski-jump bucket , Stilling Basin, Roller bucket, Stepped Spillway,etc.

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Ski-jump bucket throws the jet away from lip depending on velocity & bucket lip angle

Scour occurs d/s of lip of bucket.

to prevent uncontrolled scour of river bed and banks

1. pre-excavated plunge pool is provided.

2. raising tail water level by constructing weir sufficiently d/s.

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Types of spillways

Vatnsfellsvirkjun hydroelectric scheme from above

The spillway at Vatnsfell – from below

The spillway at Vatnsfell – the crest

The splitter wall and cover from above

The chute cover from below

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SKI-JUMP BUCKET IN OPERATION

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SPILLWAY IN OPERATION Q = 1,50,000 CFS

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VIEW OF THE DAM, PLUNGE POOL AND SLIDE ON RIGHT BANK

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If neither splitter wall nor chute cover...

Vattenfall’s hydraulic model

• Recommended Text Book

• Hydraulic Structures by Novak, Nalluri & Narayan

• Hydraulics of Spillways and Energy Dissipators by R M Khatsuria