Presentation on theme: "BY, M.MANIVANNAN BTE-06-017. CLASS A EVAPORATION PAN."— Presentation transcript:
BY, M.MANIVANNAN BTE
CLASS A EVAPORATION PAN
SUNKEN COLORADO PAN
Installed in the field Filled with a known quantity of water (the surface area of the pan is known and the water depth is measured) allowed to evaporate during a certain period of time (usually 24 hours). After 24 hours, the remaining quantity of water (i.e. water depth) is measured The amount of evaporation per time unit (the difference between the two measured water depths) is calculated; this is the pan evaporation: E pan (in mm/24 hours) The E pan is multiplied by a crop coefficient, K c, to obtain the ETo.
ET o = K C × E pan ET o : reference crop evapotranspiration K C : crop coefficient E pan : pan evaporation
Month'sMean Monthly Pan Evaporation (in mm/day) January February March April May June6.74 July August September October November December1.8097
MonthMean Monthly Pan Evaporation (in mm/day) E pan KcKc Mean Monthly Crop Evaporation (in mm/day) E c Evapotranspirati on for month ( in mm) January February March April May June July August September October November December =