INSTRUCTOR

Dr. B. R. Chahar Professor Office: Block V 324 Phone: 1187 Email: Chahar@civil.iitd.ac.in Web: www.chahar.tk http://web.iitd.ac.in/~chahar

CEL351: Design of Hydraulic Structures

Contact Schedule LTP 2-0-2 3 Credit course Prerequisite – CEL251 Lect. 9 - 10 AM Venue IV Lt-2

Tuesday Wednesday Friday Design 2 - 4 PM Venue -V-317 Gr. I - Mon Gr. II - Tue Gr. III - Wed Gr. IV – Thu

Gr. V – Fri

CEL351: Design of Hydraulic Structures

Why study – Hydraulic Structures?

INTRODUCTION

Development of water resources of a region Requires Conception Planning Design Construction Operation

of various facilities to utilise and control water, and to maintain water quality.

INTRODUCTION

Utilize/Need water Domestic & Industrial uses Irrigation Power generation Navigation Other purposes

Water Resources Engineering Utilisation of water Control of water Water quality management

INTRODUCTION Water is controlled and regulated

Flood control Land drainage Sewerage Bridges

Not cause damage to property, inconvenience to the public, or loss of life

Water-quality management Required quality of water for different uses Preserve Ecological balance Contamination of Groundwater/Surface water

INTRODUCTION Water Resources development projects are planned to serve various purposes

Main Purposes Domestic & Industrial uses, Irrigation Power generation, Navigation, Flood control

Secondary Purposes Recreational, Fish and wild life, Drainage control, Watershed management, Sediment control, Salinity control, Pollution abatement

Miscellaneous Purposes Employment, Accelerate development etc

Single-purpose and Multi-purpose

INTRODUCTION

Main source of water is Precipitation

Precipitation is not uniform over space and time Monsoon, North East, Himalaya, W. Ghat

Store water at surplus location during surplus period – Storage structures – Reservoirs

Transport water – Demand Point - Gravity

INTRODUCTION

Water Resources projects – Two Main Steps

First step – How much water is available?

Knowledge of Hydrology

Precipitation – average Abstraction – Losses Runoff, Yield of basin Flood – Peak runoff Reservoir sizing – Mass curve

INTRODUCTION

Second step – How to utilise and control water?

Require various structure Hydraulic Structures

Types of Hydraulic Structures

Storage Diversion Transportation Regulation Control

COURSE Contents

1. Introduction 2. Gravity Dams – Site selection, Forces,

Stability analysis. 3. Diversion Works – Weirs and Barrages 4. Head Regulators and Cross regulators 5. Canals – Design and Canal Falls. 6. Cross Drainage Works

CEL351: Design of Hydraulic Structures

GRADING CRITERIA

The weightage likely to be as 20% Minor I 20% Minor II 40% Major 20% Quiz/ Assignment/ Design Class

Attendance

CEL351: Design of Hydraulic Structures

LESSON PLAN

Lecture 1,2 Gravity Dams: Introduction Lecture 3,4,5 Gravity Dams: Forces

MINOR I TEST Lecture 6,7,8 Gravity Dams: Stability Analysis Lecture 9,10 Gravity Dams: Elementary & Practical

Profile MINOR II TEST

Lecture 11-15 Diversion Works: Weir & Barrages

MAJOR TEST

CEL351: Design of Hydraulic Structures

Text Books 1.  Hydraulic Structures; P. Novak, AIB Moffat, C. Nalluri, and R.

Narayanan: Taylor & Francis, New York 2.  Engineering for Dams, Vol I & Vol II; Creager, Justin and Hinds; John

Wiley 3.  Water Resources Engineering; JB Franzini, DL Freyberg, G

Tchobanoglous; McGraw Hill 4.  Design Textbooks in Civil Engineering – Irrigation Engineering – Vol VI –

Dams; L Leliavsky; Chapman & Hall 5.  Design of Small Dams; USBR; Oxford & IBH. 6.  Fundamentals of Irrigation Engineering; Bharat Singh; Nem Chand. 7.  Irrigation and Water Power Engineering; BC Punmia, BBL Pande; Laxmi

Pub. 8.  Irrigation, Water Power and Water Resources Engineering; KR Arora;

Standard Pub. 9.  Theory and Design of Irrigation Structures; Varshney, Gupta, Gupta; Nem

Chand. 10.  Irrigation Engineering and Hydraulic Structures; SK Garg; Khanna Pub.

CEL351: Design of Hydraulic Structures

IS Codes IS Code 6512: Criteria for Design of Solid Gravity Dams

IS Code 1893: Criteria for Earthquake Resistant Design of Structures

IS Code 4410 : Part 22 : 1994 Glossary of terms relating to river valley projects: Part 22 Barrages & weirs

IS Code 6966 : Part 1 : 1989 Guidelines for hydraulic design of barrages and weirs: Part 1 Alluvial Reaches

IS Code 7349 : 1989 Guidelines for operation and maintenance of barrages and weirs

IS Code 7720 : 1991 Criteria for Investigation, Planning and Layout for Barrages and Weirs

IS Code 11130 : 1984 Criteria for Structural Design of Barrages and Weirs

IS Code 14955 : 2001 Guidelines for Hydraulic Model Studies of Barrages and Weirs

CEL351: Design of Hydraulic Structures

INTRODUCTION

Storage Structures

Store water at surplus location during surplus period – Storage structures – Reservoirs

Dam and Reservoir coexist Dam – solid barrier across river Reservoir – artificial lake u/s of dam

Reservoir

Dam

Reservoir

Dam Spillway

RESERVOIRS

Types of Reservoirs – Single-purpose and Multi-purpose

Storage (or conservation) reservoirs Flood control reservoirs Multipurpose reservoir Distribution reservoirs Balancing reservoirs

Flood Control – runoff exceeding safe capacity of river is stored in the reservoir. Stored water is released in controlled manner

Detention and Retarding

RESERVOIRS Detention Reservoirs – regulated by GATES

Adv: More flexibility of operation and better control of outflow; Discharge from various reservoirs can be adjusted

Disadv: More expensive; Possibility of human error

RESERVOIRS Retarding Reservoirs – UNGATES

Adv: Less expensive; Outflow is automatic so possibility of human error

Disadv: No flexibility of operation; Discharge from various reservoirs may coincide – heavy flood

RESERVOIRS Multipurpose Reservoirs Serve two or more purposes. In India, most of the reservoirs

are designed as multipurpose reservoirs to store water for irrigation and hydropower, and also to effect flood control

Distribution Reservoirs Small storage reservoirs to tide over the peak demand of

water. The distribution reservoir is helpful in permitting the pumps to work at a uniform rate. It stores water during the period of lean demand and supplies the same during the period of high demand. As the storage is limited, it merely helps in distribution of water as per demand for a day or so and not for storing it for a long period. Distribution reservoirs are mainly used for municipal water supply but rarely used for the supply of water for irrigation.

RESERVOIRS

Balancing Reservoirs A balancing reservoir is a small reservoir constructed d/s of

the main reservoir for holding water released from the main reservoir.

RESERVOIRS

Storage Capacity of Reservoirs Storage capacity of a reservoir depends upon the topography of

the site and the height of dam. Engineering surveys The storage capacity and the water spread area at different

elevations can be determined from the contour map. In addition to finding out the capacity of a reservoir, the

contour map of the reservoir can also be used to determine the land and property which would be submerged when the reservoir is filled upto various elevations.

To estimate the compensation to be paid to the owners of the submerged property and land. The time schedule, according to which the areas should be evacuated, as the reservoir is gradually filled, can also be drawn..

RESERVOIRS Storage Capacity of a Reservoir

Both the elevation-area curve and the elevation- storage curve on the same paper. Abscissa - areas and volumes - opposite directions

Area-Elevation Curve – from contour map An elevation-area curve is then drawn between the surface area as abscissa and the elevation as ordinate. Elevation-Capacity Curve: is determined from elevation-area curve using diff formulae.

RESERVOIRS

Storage Capacity calculation formulae 1. Trapezoidal formula 2. Cone formula 3. Prismoidal formula 4. Storage Volume from cross-sectional areas

RESERVOIRS Basic Terms and Definitions 1. Full reservoir level (FRL): is the highest water level to which

the water surface will rise during normal operating conditions. Also called the full tank level (FTL) or the normal pool level (NPL).

2. Maximum water level (MWL): is the maximum level to which the water surface will rise when the design flood passes over the spillway. Also called the maximum pool level (MPL) or maximum flood level (MFL).

3. Minimum pool level: is the lowest level up to which the water is withdrawn from the reservoir under ordinary conditions. It corresponds to the elevation of the lowest outlet (or sluiceway) of the dam. However, in the case of a reservoir for hydroelectric power; the minimum pool level is fixed after considering the minimum working head required for the efficient working of turbines.

RESERVOIRS Basic Terms and Definitions

RESERVOIRS Basic Terms and Definitions 4. Useful storage: volume of water stored between the full

reservoir level and the minimum pool level. Also known as the live storage.

5. Surcharge storage: is the volume of water stored above the full reservoir level upto the maximum water level. The surcharge storage is an uncontrolled storage which exists only when the river is in flood and the flood water is passing over the spillway. This storage is available only for the absorption of flood and it cannot be used for other purposes.

6. Dead storage: volume of water held below the minimum pool level. The dead storage is not useful, as it cannot be used for any purpose under ordinary operating conditions.

RESERVOIRS Basic Terms and Definitions

RESERVOIRS Basic Terms and Definitions 7. Bank storage: If the banks of the reservoir are porous, some

water is temporarily stored by them when the reservoir is full.

8. Valley storage: The volume of water held by the natural river channel in its valley upto the top of its banks before the construction of a reservoir is called the valley storage. May be important in flood control reservoirs.

9. Yield from a reservoir: Yield is the volume of water which can be withdrawn from a reservoir in a specified period of time. The yield is determined from the storage capacity of the reservoir and the mass inflow curve.

10 Safe yield (Firm yield): is the maximum quantity of water which can be supplied from a reservoir in a specified period of time during a critical dry year. Lowest recorded natural flow of the river for a number of years is taken as the critical dry period for determining the safe yield.

RESERVOIRS Basic Terms and Definitions 11. Secondary yield: is the quantity of water which is available

during the period of high flow in the rivers when the yield is more than the safe yield. It is supplied on as and when basis at the lower rates. The hydropower developed from secondary yield is sold to industries at cheaper rates.

12. Average yield: is the arithmetic average of the firm yield and the secondary yield over a long period of time.

13. Design yield: is the yield adopted in the design of a reservoir. Fixed after considering the urgency of the water needs and the amount of risk involved. The design yield should be such that the demands of the consumers are reasonably met with, and at the same time, the storage required is not unduly large.