Hydraulic Structures: Fourth Edition

Table 4.1 Flood, wind and wave standards by dam category (ICE, 1996)

Reservoir design flood inflow

Initial reservoir

Minimum standard

Concurrent wind speed

Dam

Potential effect of

condition

General

if overtopping is

and minimum wave

category

a dam breach

standard

tolerable

surcharge allowance

a

Where a breach could

Spilling long-term

Probable maximum

10 000-year flood

Mean annual maximum

endanger lives in a community

average inflow

flood (PMF)

hourly wind speed

b

Where a breach

Just full

10 000-year flood

1000-year flood

Wave surcharge

(i) could endanger lives not

(i.e. no spill)

allowance not less

in a community or

than 0.6 m

(ii) could result in extensive

damage

c

Where a breach would pose

Just full

1000-year flood

150-year flood

Mean annual maximum

negligible risk to life and

(i.e. no spill)

hourly wind speed

cause limited damage

Wave surchargeallowance not lessthan 0.4 m

d

Special cases where no loss

Spilling long-term

150-year flood

Not applicable

Mean annual maximum

of life can be foreseen as a

average inflow

hourly wind speed

result of a breach and verylimited additional flood damage

Wave surchargeallowance not less

would be caused

than 0.3 m