Terms Used In Water Balance

TERMS (WATER BALANCE) Definitely

Really

ACTUAL 1. Actual evapotranspiration (AET): the loss of moisture to the atmosphere by the processes of evapotration and transpiration which actually takes place. Possible

likely

POTENTIAL

maybe

2. Potential evapotranspiration (PET): the maximum amount of evapotranspiration which occur if an adequate supply of water were continuously available. (In Desert PET >AET amount of water is limited)

SURPLUS Extra

Excess

3. Soil moisture surplus: occurs when the soil water store is full and thus there is surplus of water for plants, runoff and groundwater recharge. (PP>PET) used

UTILISE 4. Soil moisture utilisation: Plants (and people) use moisture stored in the soil, leaving it depleted. (AET >PP) shortage

Scare

Lack

deficit

DEFICIENCY 5. Soil moisture deficiency: Equivalent to the extra water which would be needed to maintain maximum plant growth. There is little or no water available for plant growth

(irrigation could make good this deficit) (PET > AET) Fill up again

RECHARGED 6. Soil moisture recharge: The soil water store starts to fill again after a period of deficiency Ability

CAPACITY 7. Field capacity: The moisture a freely drained soil can hold after all free or gravity water has drained away. Such moisture is held by tension around soil particles, mainly as capillary water.