Dam Storage & Yield Calculator

1. Mean annual inflow

Catchment area, CA (km²)

Mean annual runoff, MAR (mm)

MAI = CA × MAR × 1,000

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Conversion

1 km² × 1 mm = 1,000 m³

2. Live storage

Gross dam capacity, DC (m³)

Dead storage, DS (m³)Illustration assumes DS = 0 because it was not supplied.

Sediment allowance, SA (m³)

U = DC − DS − SA

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SRn = U / MAI

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3. Evaporation index

Net evaporation over dry months, E (m)

Full-supply reservoir surface area, A (ha)

EI = E × A × 10⁴ / U

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4. Optional yield estimate

Use the source table for the relevant coefficient of variation (CV), EI and SRn. Enter its yield fraction only when available.

Coefficient of variation (CV)For reference only; not used in any calculation (no source table is embedded).

10%-risk yield as fraction of UEnter a source-supported fraction from 0 to 1.

Yield at 10% risk

Not calculated

Q = fraction × U

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Engineering note: The example produces MAI = 59,20,000 m³/year. U = 13,15,200 m³ only if DS = 0 m³. The supplied information does not provide E, A, or the CV/EI/SRn-to-yield table; enter or verify these before interpreting EI or Q for design.