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Equation
A general water balance equation is:
- P = Q + E + ΔS
where
- P is precipitation
- Q is runoff
- E is evapotranspiration
- ΔS is the change in storage (in soil or the bedrock)
A water balance can be used to help manage water supply and predict where there may be water shortages. It is also used in irrigation, flood control and pollution control.
The water balance can be illustrated using a water balance graph which plots levels of precipitation and evapotranspiration often on a monthly scale.
Several monthly water balance models had been developed for several conditions and purposes. Monthly water balance models had been studied since the 1940s.[1]
Diagnosis of water balance models
Several diagnostic measures in hydrology can be used to select and evaluate the performance of water balance models
Applications
- Evaluate the components of the hydrologic cycle
- Snowmelt simulation
- Climate change impact assessment
- Flow forecasting and project design
- Assess agricultural water management
Types
- Models using precipitation (rainfall) as input
- Models using rainfall and temperature as input
- Models using rainfall and potential evaporation as input
- Models using daily input data
References
- ^ Xu, C.-Y.; V.P. Singh (1998). "A Review on Monthly Water Balance Models for Water Resources Investigations". Water Resources Management 12 (1): 31–50. doi:.
See also
External links
A paper on water and salt balances on the soil, in the rootzone, unsaturated zone, aquifer and their interactions can be found as reply nr. 4 to frequently asked questions on the FAQs page in www.waterlog.info.
On the software page of the same site : [1] one can find a conceptual model (RainOff) using a nonlinear reservoir applicable to (small) watersheds. Free download.
