Stormwater Hold Volume Remainder Tool

Description

Compute endingStored = existingStored+inflowVolume-discharged, remainingCapacity = capacity-endingStored and overflow = max(0,endingStored-capacity).

A volume estimate connects an area and depth, a flow and time, or a storage balance. Coherent units and explicit reserves distinguish physical volume from usable capacity; a valid quantity balance does not establish water quality or structural adequacy.

Compute endingStored = existingStored+inflowVolume-discharged, remainingCapacity = capacity-endingStored and overflow = max(0,endingStored-capacity).

When to use this tool

Use Stormwater Hold Volume Remainder when checking a supplied volume conversion, reserve or storage balance.

How to use the tool and how it works

Enter inflowVolume, existingStored, discharged, capacity. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read endingStored, remainingCapacity, overflow. Use the output convention below.

Require nonnegative inflowVolume, existingStored, discharged and capacity, with discharged <= existingStored+inflowVolume. Compute endingStored = existingStored+inflowVolume-discharged, remainingCapacity = capacity-endingStored and overflow = max(0,endingStored-capacity).^[1]

Input field	Meaning and units	Accepted input
inflowVolume	Inflow Volume	Required. Finite number; minimum 0.
existingStored	Existing Stored	Required. Finite number; minimum 0.
discharged	Discharged	Required. Finite number; minimum 0.
capacity	Capacity	Required. Finite number; minimum 0.

Output field	Interpretation	Returned shape
endingStored	Uncapped opening-plus-inflow-minus-discharge balance, including any reported excess.	Required. Finite number.
remainingCapacity	Remaining Capacity	Required. Finite number.
overflow	Amount by which the uncapped balance exceeds capacity.	Required. Finite number.

json

{
  "input": {
    "inflowVolume": 100,
    "existingStored": 20,
    "discharged": 50,
    "capacity": 80
  },
  "output": {
    "endingStored": 70,
    "remainingCapacity": 10,
    "overflow": 0
  }
}

Limitations and assumptions

All inputs share a volume unit. endingStored is the uncapped balance, so overflow is reported alongside it rather than subtracted from it. No hydraulic hydrograph, spill routing or structural storage adequacy is modeled.
Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Use a hydraulic model, actual tank geometry and qualified design criteria when time-varying flow or practical capacity matters.

References

Calculation and input contract: environmental-engineering/stormwater-hold-volume-remainder — tool.io

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