1. The Hydrologic Cycle and Groundwater
Understanding Earth
Fifth Edition
Chapter 17:
The Hydrologic Cycle and Groundwater
Copyright © 2007 by W. H. Freeman & Company

2. Hydrology-- is the study of movements and character of water on and under the Earth’s surface.
On the Earth, there is enough water to completely cover the United States with a 145 km-deep ocean.
Only 4% of global water is fresh

3. Concepts you should know well…
Reservoirs
Orographic Rainfall
Porosity and Groundwater
Groundwater Table- satureated and unsaturated zone
Recharge Zone
Aquifer// Confined
Conce of Depression
Overpumping
Karst Topography an Sinkholes

5. The total amount of water on Earth is relatively constant with time
The total amount of water on Earth is relatively constant with time. None is lost to outer space
Water is in constant motion between different reservoirs (“area of storage// storage tanks”)
The Amazon carries ___ the world’s run-off
The Mississippi carries ____ of the Amazon’s run-off
“Runoff” is water that does not inflitrate but moves mainly, to the ocean, along the surface of the earth.

7. In 3 hours, (10,800 seconds), we would get,
~3,717,000,000 m3, that is, 3.7 cubic kilometers!

8. Let us look at the different reservoirs on the earth, or temporary “storage tanks”
Since 434,000 cubic km evaporate from the sea each year and 398,000 cubic km rain over the ocean every year, the difference goes on land and runs to the ocean every year!
That is about 36,000 cubic km each year

9. Question: At current run-off rates how many years would it take to fill the oceans if we started with just empty oceans???
Question: How long would the oceans take to evaporate at current rates of evaporation and without any runoff?
The total ocean volume of water is 1.4 US billion cubic km

11. Main reservoirs in the world are---
oceans, lakes, glaciers and groundwater

12. Often, within a region, the areas in front of mountain ranges are wetter than the areas to the back of mountain ranges.

14. Why does this take place
Why does this take place? The rain that is dropped on the windward side of mountain ranges is know as orographic rain.

16. GROUNDWATER
--- Flows through connected pores
Shales can have a lot of space (porosity) to trap water but the water flows poorly through shale (very low permeability)

18. WHY DO WE BURY OUR DEAD ABOVE THE SOIL IN LOUSIANA?
The saturated zone is too shallow

20. Where does Baton Rouge get its water?
We get our water from aquifers (Chicot Aquifer, 600-foot sand) Our aquifers are recharged by rainfall in the hill country.
Would you approve a PVC plant in St Francisville?

22. Why do we have so many place names with the word Springs in them?
A cone of depression is the lowered water table surface that results from overpumping an aquifer, I.e. pumping an aquifer faster than it can naturally recharge.