Elements of the Water Budget

P All the PRECIPITATION that falls in one month

Elements of the Water Budget

PEP

All the PRECIPITATION that falls in one month

The ENERGY available to evaporate water Potential Evapotranspiration

Elements of the Water Budget

PEP

P- EP

All the PRECIPITATION that falls in one month

The ENERGY available to evaporate water

If P-EP > 0, then.... If P-EP < 0, then....There’s water left over There’s energy that can still

evaporate more waterWhen water is left over after evaporation, it can do either of 2 things.....

Left over energy can “look” for more water.....(where?)Soak into the ground (“infiltrate”)

“Run off” in streamsIn the soil! (called “Storage”)

Elements of the Water Budget

PEP

P- EP

St

St

All the PRECIPITATION that falls in one month

The ENERGY available to evaporate water

If P-EP > 0, then.... If P-EP < 0, then....There’s water left over There’s energy that can still

evaporate more waterWhen water is left over after evaporation, it can do either of 2 things.....

Left over energy can “look” for more water.....(where?)Soak into the ground (“infiltrate”)

“Run off” in streamsIn the soil! (called “Storage”)

Water stored in the Soil (soil moisture)

When St is (+)... When St is (-)... St < maximum, and P>EP St >0 and P<EP

called “Recharge” called “Usage”

Elements of the Water Budget

PEP

P- EP

StSt

EA

All the PRECIPITATION that falls in one month

The ENERGY available to evaporate water

If P-EP > 0, then.... If P-EP < 0, then....There’s water left over There’s energy that can still

evaporate more waterWhen water is left over after evaporation, it can do either of 2 things.....

Left over energy can “look” for more water.....(where?)Soak into the ground (“infiltrate”)

“Run off” in streamsIn the soil! (called “Storage”)

Water stored in the Soil (soil moisture)

When St is (+)... When St is (-)... St < maximum, and P>EP St >0 and P<EP

called “Recharge” called “Usage”

Actual amount of water evaporated.

EA < EP when

EA > EP whenP+ St => EP

P + St < EP

NEVER!EA = EP when

Elements of the Water Budget

PEP

P- EP

StSt

EA

S D

All the PRECIPITATION that falls in one month

The ENERGY available to evaporate water

If P-EP > 0, then.... If P-EP < 0, then....There’s water left over There’s energy that can still

evaporate more waterWhen water is left over after evaporation, it can do either of 2 things.....

Left over energy can “look” for more water.....(where?)Soak into the ground (“infiltrate”)

“Run off” in streamsIn the soil! (called “Storage”)

Water stored in the Soil (soil moisture)

When St is (+)... When St is (-)... St < maximum, and P>EP St >0 and P<EP

called “Recharge” called “Usage”

Actual amount of water evaporated.

EA < EP when

EA > EP whenP+ St => EP

P + St < EP

NEVER!EA = EP when

When there’s energy that never finds water, we say we have a ....

DEFICIT

When there’s more water than energy at the end of the month, we say we have a

SURPLUS

Elements of the Water Budget

PEP

P- EP

St

St

EA

S D

All the PRECIPITATION that falls in one month

The ENERGY available to evaporate water

If P-EP > 0, then.... If P-EP < 0, then....There’s water left over There’s energy that can still

evaporate more waterWhen water is left over after evaporation, it can do either of 2 things.....

Left over energy can “look” for more water.....(where?)Soak into the ground (“infiltrate”)

“Run off” in streamsIn the soil! (called “Storage”)

Water stored in the Soil (soil moisture)

When St is (+)... When St is (-)... St < maximum, and P>EP St >0 and P<EP

called “Recharge” called “Usage”

Actual amount of water evaporated.

EA < EP when

EA > EP whenP+ St => EP

P + St < EP

NEVER!EA = EP when

When there’s energy that never finds water, we say we have a ....

DEFICIT

When there’s more water than energy at the end of the month, we say we have a

SURPLUS

INFILTRATION

Infiltration refers to water soaking into the ground:

Infiltration rate

Slope

Infiltration rate

Permeability

Infiltration rate

Porosity

Infiltration rate

Soil Storage Saturation

RUNOFF

Runoff refers to the water that is not evaporated, and that does not soak into the ground. It is the water we find in streams.

Runoff occurs during seasons of high and relatively low

In areas where there is a lot of runoff during one part of the year.....

and dry and warm during another part of the year.....

can be built to store (or reserve) the runoff for an “un-rainy day”

P EP

Rainy season, when there’s extra water

When there’s plenty of energy but not enough water to “satisfy” the energy...

RESERVOIRS

EvaporationEvaporation

Transpiration

Animal Respiration

runoff

runoffinfiltration

infiltration

infiltration

EVAPOTRANSPIRATION

The Water (Hydrologic) Cycle

-all the ways that water vapor enters the air

Condensation