Reservoir Storage Volume from Area and Depth
Reservoir Storage Volume from Area and Depth
A quick estimate of how much water a reservoir holds comes from multiplying its surface area by an average depth — a simplified prismatic approximation used in early-stage water supply and dam planning before a detailed bathymetric survey is available.This storage estimate feeds directly into water supply yield studies and flood storage calculations, so while it is a rough approximation, getting the average depth reasonably right matters because volume scales directly with it.
The storage volume is V = A·d, the reservoir surface area times its average depth. where A is the reservoir surface area and d is the average water depth.
Inputs
A_res := 50000 m^2=50000 m^2
d_avg := 6 m=6 m
Treating the reservoir as a simple prism, the surface area times the average depth gives an estimate of total stored volume.
V_res := A_res·d_avg=300000 m^3
Results
A result of 300,000 m³ is a modest but usable storage volume for a small community reservoir. Because real reservoirs are not perfect prisms, this estimate should be refined with a stage-storage curve from bathymetric survey data once the project moves past initial planning, since irregular bottom topography can shift the true volume meaningfully.
Assumptions & limitations
- Prismatic approximation (area × average depth), not a true stage-storage integration.
- Constant surface area assumed at the given depth.
- Sedimentation and dead storage not subtracted.