What is Evapotranspiration (ET)...
And What Does it Have to Do with My Sprinkler System...
And Getting Back More of My Summer Leisure Time?
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Water cycle of the earth's surface, showing the individual components of transpiration and evaporation that make up evapotranspiration (ET). Other closely related processes shown are runoff and groundwater recharge.
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The process of evapotranspiration (ET) is, in fact, the combination of two separate processes…
1. water that evaporates from the soil surface (i.e.
intercepted water or dew)
2. and water that is transpired to the atmosphere from
plants (the actual site of evaporation occurs inside
the leaf substomatal cavity).
This process involves a change in the state of water from a liquid to a vapor requiring an input of energy.
The energy is derived from…
• radiant energy transfer from the sun through the
solar irradiance
• convective heat transfer from the air to the soil
• conductive heat transfer from the soil.
Wind (and wind speed gradients) as well as atmospheric gradients of both temperature and humidity affect the rate of evapotranspiration through the sensible heat transfer.
ET information is critical for effective sprinkler system design (application rate, flow rate) and for water management (irrigation scheduling, salinity control, etc.). But historically it's been difficult for consumers to get local ET information.
Now, with Toro's Intelli-Sense Controllers, all that has changed...
