Calculate the values for ACTET, DEFIC, SURPL, ±ΔSTRGE, and STRGE. given 8” of PRECIP, 14” of POTET, 2” of soil moisture storage and a maximum of 4” soil moisture storage.

Question

Calculate the values for ACTET, DEFIC, SURPL, ±ΔSTRGE, and STRGE. given 8” of PRECIP, 14” of

POTET, 2” of soil moisture storage and a maximum of 4” soil moisture storage.

Answer 1

Calculate the water balance components

1. Water Need

POTET – PRECIP = 14" – 8" = 6" deficit to meet POTET

2. Soil Moisture Change (±ΔSTRGE)

We can supply some of the 6" deficit using the 2" of available soil moisture.

So, soil moisture is used up by 2", leaving:

1. ±ΔSTRGE = -2"
2. Soil storage is now: 4" – 2" = 2" → becomes 0"

3. Actual Evapotranspiration (ACTET)

This is the actual water that can evaporate/transpire =

PRECIP + soil moisture used = 8" + 2" = 10"

4. Deficit (DEFIC)

POTET – ACTET = 14" – 10" = 4"

5. Surplus (SURPL)

Since there is no excess PRECIP over POTET and soil is already dry, SURPL = 0"

6. Final Soil Moisture Storage (STRGE)

Initial: 2"

Used: 2"

→ Final storage: 0"

✅ Final Answer Summary:

ComponentValue
ACTET	10"
DEFIC	4"
SURPL	0"
±ΔSTRGE	-2"
STRGE (Final)	0"