5.3 Definitions

Question 1

Field capacity

Answer 1

At this point the soil is full of water and cannot hold any more

Question 2

Soil moisture surplus

Answer 2

Precipitation is greater than potential evapotranspiration and the soil water store is full, so there is a surplus of soil moisture for plant use, runoff into streams and recharging groundwater supplies. the soil is said to be at field capacity

Question 3

Soil moisture recharge

Answer 3

This occurs when potential evapotranspiration decreases so that it is lower than precipitation, and the soil store starts to fill up again

Question 4

Maximum annual temperatures

Answer 4

High temperatures cause maximum evapotranspiration, precipitation is at a minimum and therefore plants use up the soil moisture store. River levels will fall and crops will need irrigation.

Question 5

Soil moisture utilisation

Answer 5

Potential evapotranspiration increases and exceeds precipitation, so there is more water evaporating from the ground surface and being transpired by plants than is falling as rain. Water is also drawn up from the soil by capillary action. the water is gradually used up.

Question 6

Soil moisture deficiency

Answer 6

The soil water store has been used up by high rates of evapotranspiration and low precipitation. Plants can only survive if they are adapted to periods of drought or are irrigated.