Variables
Description
What is this formula?
Reservoir Storage Yield estimates the average water supply that can be delivered from the usable storage volume of a reservoir over a specified period.
It is commonly used during preliminary reservoir design, drought planning, emergency water supply studies, and long-term water resource management.
The formula provides a first-order estimate of the sustainable withdrawal rate that can be maintained from stored water.
When to use it
Use this formula when evaluating:
- Reservoir planning
- Drought management
- Municipal water supply projects
- Irrigation systems
- Emergency water storage
- Water security studies
Example
A reservoir contains 45 million cubic meters of usable storage.
Engineers want to determine the average supply that can be maintained during a 180-day drought.
Data:
S = 45,000,000 m³
T = 180 days
Formula:
Y = S / T
Substitution:
Y = 45,000,000 / 180
Result:
Y = 250,000 m³/day
The reservoir can provide approximately 250,000 m³/day during the drought period.
Applications
- Reservoir design
- Water resource planning
- Drought resilience studies
- Irrigation management
- Municipal water systems
- Strategic water storage analysis
Note
This simplified relationship assumes that inflows, evaporation losses, seepage losses, environmental releases, and operational constraints are negligible. Real reservoir yield analyses typically require hydrological simulation, storage-yield curves, reliability assessments, and long-term inflow records to obtain more accurate estimates.