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The formula \( Q = I - \frac{dS}{dt} \) calculates the outflow rate from a catchment area by subtracting the rate of change of storage from the inflow rate. This equation is fundamental in hydrology for water balance calculations.
The calculator uses the formula:
Where:
Explanation: This equation represents the water balance principle where outflow equals inflow minus the change in storage over time.
Details: Accurate outflow rate calculation is crucial for water resource management, flood forecasting, reservoir operation, and environmental impact assessments.
Tips: Enter inflow rate and rate of change of storage in Cubic Meter per Second. Both values can be positive or negative depending on the direction of flow and storage change.
Q1: What does a negative outflow rate indicate?
A: A negative outflow rate typically indicates that water is entering the system rather than leaving, which might occur during flooding or when storage is decreasing.
Q2: How is the rate of change of storage measured?
A: The rate of change of storage is typically calculated from water level measurements in reservoirs or groundwater monitoring wells over time.
Q3: Can this formula be used for groundwater systems?
A: Yes, this water balance equation applies to both surface water and groundwater systems, though additional factors may need consideration for complex aquifer systems.
Q4: What time interval should be used for these measurements?
A: The time interval should be consistent for all parameters. Common intervals include hourly, daily, or monthly depending on the application and data availability.
Q5: How does evaporation affect this calculation?
A: Evaporation is typically accounted for in the storage change term or may require additional terms in more comprehensive water balance equations.