Hobbies And Interests
Pan Evaporation
Pan evaporation is a method of directly measuring evaporation in a particular location. A sample of water is kept open to the atmosphere in a pan with known dimensions. Scientists measure the change in water level over time to calculate a rate of evaporation. The rate of evaporation from a pan is recorded in units of depth per time, such as inches per day.
Water Budget Calculations to Determine Evaporation
For large regions where flow data is readily available, hydrologists use a water balance method. Evaporation is calculated by adding together water inputs to the basin and subtracting water outputs. Water inputs include precipitation and surface and groundwater inflow. Water outputs include soil water storage and surface and groundwater outflow.
Scintillometer Measurements of Evaporation
When hydrologic data is not available and pan evaporation methods are not suitable, scientists use a scintillometer to measure evaporation. The scintillometer takes readings of temperature and humidity, and the fluctuations in each are used to calculate the rate of evaporation.
Remote Sensing Techniques to Estimate Evaporation
Remote sensing is an expensive technique used to estimate evaporation over very large areas. Equipment is installed through the basin and continuous water-vapor measurements are transmitted via satellite to a central location. Remote sensing techniques provide detailed data, but do require advanced calibration and validation using pan evaporation techniques.