Spillway Design - Step by Step

1 Introduction 
1.1 Initial considerations 
1.2 Phases of studies of the basin. The cases of Banqiao (China), Mascarenhas de Moraes and Itá (Brazil) 
1.3 Spillway and design flood 
The case of the Mascarenhas de Moraes HPP 
1.4 Layout and choice of spillway 
1.5 Two notable cases: Theodore Roosevelt (USA) and Orós (Brazil) 
1.6 Ruptures of dams due to insufficient discharge capacity of the spillway 
1.7 Risks of dam ruptures – submersion waves 
1.8 Case of rupture by earthquake 
1.9 Operation and maintenance 
2 Types of spillways 
2.1 Classification of the spillways 
2.2 Ogee spillway 
2.3 Side spillway 
2.4 Morning glory spillway 
2.5 Tunnel spillway 
2.6 Chute spillway 
Barra Grande HPP, Pelotas river (Rio Grande do Sul/Santa
Catarina States, Brazil) 
Campos Novos HPP, Canoas river (Santa Catarina State, Brazil) 
Corumbá HPP, Corumbá river (GO, Brazil) 
Serra da Mesa HPP, Tocantins river (GO, Brazil) 
2.7 Culvert spillway (bottom outlet) 
2.8 Orifice spillway 
2.9 Labyrinth spillway 
2.10 Siphon spillway 
2.11 Stepped spillway 
2.12 Horizontal apron spillway (spillway without ogee) 
3 Spillway design 
3.1 Initial considerations 
3.2 Ogee shape 
3.3 Hydraulic design 
3.4 Practical rules for defining the type of spillway 
3.5 Hydraulic design of the ogee spillway – example of Tucuruí 
3.6 Hydraulic design of other types of spillway – notes 
4 Hydrodynamics pressures 
4.1 Initial considerations 
4.2 Average pressures 
4.3 Instant pressures – Shin-Nariwa (Japan) 
Forces acting in the chute/powerhouse roof slab 
Powerhouse roof slab oscillations 
Variation of Ćp 
4.4 Instant pressures – Karakaya 
4.5 Instant pressures – Tucuruí (Brazil) 
5 Energy dissipation 
5.1 Classification of the dissipators 
5.2 Ski jump dissipators 
5.3 Hydraulic jump dissipators 
5.4 Cases 
6 Pressure forces downstream of dissipators 
6.1 Hydrodynamics pressures downstream of ski jumps 
6.2 Example: pressure bulb in the pre-excavation downstream of the Tucurui spillway 
6.3 Example: pressure bulb in the pre-excavation downstream of the Jaguara spillway 
6.4 Hydrodynamics pressures downstream of stilling basins 
6.5 Hydrodynamics pressures downstream Canoas I HPP
spillway stilling basin 
7 Evaluation of the scour 
7.1 Scour holes in hydraulic models 
7.2 Estimate of scour holes depths; Veronese equation 
7.3 Yuditskii iterative method 
Conditions for pulling off the block from the rocky bed of the river 
7.4 Comprehensive scour model 
8 Cavitation 
8.1 Conceptualization and characteristic parameters 
8.2 Cavitation caused by irregularities 
8.3 Protective measures – surface finish specifications 
8.4 Cavitation cases 
8.5 Cavitation cases in culvert (bottom outlets) 
8.6 Aeration 
9 Gates and valves 
9.1 Types and components of the gates 
9.2 Classification of the gates 
9.3 Selecting the type of gate 
9.4 Limits of use 
9.5 Flow coefficients of outletworks 
9.6 Discharge coefficients of spillways radial gates 
9.7 Risks of the gates 
9.8 Rupture of radial gate of the Folsom dam spillway 
9.9 Valves 
10 Hydraulic models 
10.1 Summary of theory 
10.2 Definition of the model and laws governing the models 
10.3 Types of models 
10.4 Materials and methods of construction. Equipment 
10.5 Hydraulic models of the Tucuruí spillway 
Approach of the flow to spillway – abutments 343
11 Specific constructive aspects of hydraulic surfaces 
11.1 Tucuruí spillway 
11.2 Jaguara spillway 
11.3 Mascarenhas de Moraes spillway 
11.4 Heart Butte spillway 
11.5 El Guapo spillway 
11.6 Belo Monte spillway 
11.7 Colíder spillway 
11.8 São Manoel spillway 
11.9 Santo Antônio spillway 
11.10 Mauá spillway 
References 361
Appendix 1 Spillways deterioration and rehabilitation 
Operation and maintenance 
Australia (Eildon dam) 
South Korea (Imha dam) 
India (Hirakud dam; Narayanapur dam) 
México (La Villita dam; Malpaso dam; Peñitas dam; Infernillo dam) 
Appendix 2 Overflow dams 
Rockfill overflow dams 
Overflow dams with the downstream face lined 
Overflow dams with stepped spillway