Soil and the Hydrologic Cycle

Question 1

Explain the global hydrologic cycle

Answer 1

Water evaporates from open water sources. Radiative energy from the sun converts liquid water to water vapor. The water vapor travels in the atmosphere and it can condense and form precipitation. Condensation releases energy back into the atmosphere. This water falls onto the land surface can be intercepted by plants, or it can fall into the ground. And it makes its way slowly back to the ocean through rivers and lakes and some of it goes back into groundwater

Question 2

Evaporation (blue water)

Answer 2

Evaporation of water from the soil surface or within the soil surface but has connectivity to the surface

Question 3

Transpiration (green water)

Answer 3

A byproduct of photosynthesis. Water is transported from the soil into roots to the leaves and evaporates from inside the plant
*major returning flux of water from the land surface

Question 4

Discharge/runoff

Answer 4

From rain or within the layers of the soils. Water goes back very quickly into rivers and streams and makes its way back to the ocean

Question 5

Infiltration

Answer 5

Process of which water goes from the atmosphere or on top of the soil surface into the soil
-depends on the texture, structure, temperature, and initial water content
-amount and frequency of precipitation
-human impacts like compaction

Question 6

Percolation/drainage

Answer 6

water that infiltrates the soil and goes into the ground and can refill groundwater sources

Question 7

Vadose zone

Answer 7

The whole volume of the soil and underlying rock substrate above the groundwater table

Question 8

Irrigation

Answer 8

Irrigation ditches and canals used to move water around
-flood irrigation: you flood an area and water seeps in all at once
-sprinklers
-center pivot irrigation type
-drip irrigation

Question 9

Potential vs actual evapotranspiration

Answer 9

-Evaporation from the land surface is driven by solar radiation but it can be limited by the amount of water
-Can be really really dry and potentially support a lot of evaporation but if ground surface is not wet you have no evaporation
-If ground is wet but it is cloudy then there is less evaporation then there could have been

Question 10

Water budget equation/ the water balance equation

Answer 10

P=ET+SS+D
Precipitation=Evaporation & Transpiration+Soil Storage+ Discharge (runoff)
-tells you a lot about the actions on the land surface will do to water fluxes

Question 11

Explain the role soils play in the water budget of the land surface

Answer 11

If you go from an area of shallow soils to deep soils, you get more storage and you get less discharge and potentially less storage and less water available in transpiration
-less infiltration will mean less water available for evaporation and less water stored in soils

Question 12

How do soil properties affect (evapo-)transpiration and runoff (risk of flooding)

Answer 12

-In wet areas transpiration is a major flux of water from the land surface also more discharge