3.5 A TMOSPHERIC P RESSURE ...................................................................................................... 4
3.6 Q UALITY OF W ATER .............................................................................................................. 5
4.0 METHODS OF DETERMINING EVAPORATION ............................................................ 6 4.1 W ATER B UDGET / S TORAGE E QUATION M ETHOD ................................................................ 6
4.2 M EASUREMENT IN AN A UXILIARY P AN ................................................................................. 9
4.3 E MPIRICAL F ORMULAE ........................................................................................................ 10
4.4 M ASS T RANSFER OR H UMIDITY AND W IND V ELOCITY G RADIENT M ETHOD .................... 12
4.5 E NERGY B UDGET / I NSOLATION M ETHOD .......................................................................... 12
5.0 MONTHLY AND ANNUAL EVAPORATION ................................................................... 13