ANUSPLIN surfaces have been fitted to australian network of 'class a pan data thereby enabling gridded estimates of potential evaporation to be generated. Therefore, can calculate(P-Eor(P: 3) But PE*actual evaporation(AE) AE is limited by soil moisture Therefore need to factor in soil water availability and calculate a moisture index as a function of 1. Precipitation 2. PE 3. Soil water status• ANUSPLIN surfaces have been fitted to Australian network of ‘class A’ pan data thereby enabling gridded estimates of potential evaporation to be generated. Therefore, can calculate (P-E) or (P:E) • But PE  actual evaporation (AE) • AE is limited by soil moisture Therefore need to factor in soil water availability and calculate a moisture index as a function of 1. Precipitation 2. P.E. 3. Soil water status