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

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

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

“Water, water, every where, And all the boards did shrink; Water, water, every where, Nor any drop to drink.” STC, 1798

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.

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

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

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

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

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

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

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)

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

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?

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.