Formula used
Evaporation depth: adjusted rate × days × exposure hours ÷ 24.
Gross loss: area in square metres × depth in millimetres ÷ 1,000.
Replacement water: net loss after rainfall and recovery × contingency factor.
Method equations provide planning estimates. Calibrate them with measured site data whenever possible. Concrete decisions must follow project specifications and professional guidance.
How to use this calculator
- Select the site operation and evaporation-rate method.
- Enter the exposed area using direct or geometric dimensions.
- Add weather, duration, rainfall, and adjustment information.
- Complete mode-specific, truck, and water-cost settings.
- Calculate, review warnings, then export the project summary.
Example construction-site data
| Scenario | Area | Typical inputs | Recommended review |
|---|---|---|---|
| Temporary pond | 1,000 m² | Penman method, seven days, no cover | Compare measured water levels |
| Concrete slab | 750 m² | Hot weather, low humidity, moderate wind | Check curing and cracking controls |
| Sand stockpile | 400 m² | Initial and target moisture contents | Check available material moisture |
| Haul road | 8,000 m² | Two applications daily, 2 mm depth | Check truck cycle and runoff |
Frequently asked questions
What does the evaporation rate represent?
It represents water depth lost from an exposed surface each day. The calculator converts that depth into a volume. Actual losses vary across the site.
Which method should I select?
Use measured station or pan data when reliable data exists. Use Penman-style inputs for detailed weather estimates. Direct rates suit approved project assumptions.
How does rainfall affect the result?
Rainfall volume offsets gross evaporation across the entered area. The calculator prevents rainfall from creating negative loss. Runoff effects require separate review.
Can this estimate concrete cracking risk?
It provides a screening warning from the calculated hourly rate. It cannot confirm cracking or curing adequacy. Follow project specifications and site observations.
How are covered surfaces compared?
Cover efficiency reduces the adjusted evaporation rate. The results show estimated saved water and cost. Enter realistic efficiency from supplier or site data.
How does soil moisture limiting work?
The calculator estimates removable water between initial and target moisture. Soil-mode loss cannot exceed that available quantity. Density and depth strongly affect results.
How are truckloads calculated?
Replacement volume is divided by entered truck capacity. Decimal loads show partial final loads. Operational planning may require rounding upward.
What costs are included?
Water, delivery, truck hire, labour, pumping, and treatment are included. Currency defaults to pounds sterling. Add only costs relevant to the project.
Are the results suitable for contracts?
Results are estimates based on entered assumptions. Contract quantities should use agreed measurement methods. Keep records supporting every selected factor.