TURNING INFORMATION INTO PROFITS
ET pan
|
Evaporation pans are giving the evaporation of an open water surface. The water evaporated can be converted into evapotranspiration. The following FAO document
IRRIGATION WATER MANAGEMENT
Part I Principles of irrigation water needs
a manual prepared jointly by C. Browser |
PAN COEFFICIENTS FOR CLASS A PAN
PAN COEFFICIENT (K pan) FOR CLASS A PAN FOR DIFFERENT GROUND COVER AND LEVELS OF MEAN RELATIVE HUMIDITY AND 24 HOUR WIND
Class A pan |
Case A: Pan placed in short green cropped area |
Case B1: Pan placed in fallow area |
||||||
RH mean % |
|
low |
medium 40-70 |
high > 70 |
|
low |
medium 40-70 |
high |
Wind |
Windward side distance of green crop |
|
|
|
Windward side distance of dry fallow |
|
|
|
Light |
1 |
.55 |
.65 |
.75 |
1 |
.7 |
.8 |
.85 |
< 175
|
10 |
.65 |
.75 |
.85 |
10 |
.6 |
.7 |
.8 |
100 |
.7 |
.8 |
.85 |
100 |
.55 |
.65 |
.75 |
|
1000 |
.75 |
.85 |
.85 |
1000 |
.5 |
.6 |
.7 |
|
Moderate |
1 |
.5 |
.6 |
.65 |
1 |
.65 |
.75 |
.8 |
175-425 |
10 |
.6 |
.7 |
.75 |
10 |
.55 |
.65 |
.7 |
100 |
.65 |
.75 |
.8 |
100 |
.5 |
.6 |
.65 |
|
1000 |
.7 |
.8 |
.8 |
1000 |
.45 |
.55 |
.6 |
|
Strong |
1 |
.45 |
.5 |
.6 |
1 |
.6 |
.65 |
.7 |
425-700 |
10 |
.55 |
.6 |
.65 |
10 |
.5 |
.55 |
.65 |
100 |
.6 |
.65 |
.7 |
100 |
.45 |
.5 |
.6 |
|
1000 |
.65 |
.7 |
.75 |
1000 |
.4 |
.45 |
.55 |
|
Very strong |
1 |
.4 |
.45 |
.5 |
1 |
.5 |
.6 |
.65 |
> 700 |
10 |
.45 |
.55 |
.6 |
10 |
.45 |
.5 |
.55 |
100 |
.5 |
.6 |
.65 |
100 |
.4 |
.45 |
.5 |
|
1000 |
.55 |
.6 |
.65 |
1000 |
.35 |
.4 |
.45 |
Created by system. Last Modification: Monday 21 of May, 2012 14:00:15 GMT by Lena.