Visualizing Environmental Science

Unconfined aquifer

recharge area

Confined

aquifer

recharge area

Unconfined

aquifer

Water

table

Water

table

well

Confined

aquifer Artesian

well

Precipitation

Runoff

Stream

Lake

Infiltration

Impermeable

rock or clay

246 CHAPTER 10 Freshwater Resources and Water Pollution

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Excess surface water seeps downward through soil and porous rock layers until it reaches
impermeable rock or clay. An unconfined aquifer holds groundwater recharged by surface
water directly above it. A confined aquifer stores groundwater between impermeable layers.

1. Relate some of the problems caused by
   aquifer depletion, overdrawing of surface
   waters, and salinization of irrigated soil.


2. Contrast the water problems associated with
   the Ogallala Aquifer and the Colorado River
   Basin.


3. Describe the role of international cooperation
   in managing shared water resources.

Water Resource Problems

LEARNING OBJECTIVES

W

ater resource problems fall into three catego-

ries: too much water, too little water, and poor-

quality water. Flooding occurs when a river’s

discharge cannot be contained within its nor-

mal channel. Today’s floods are more disastrous in terms of

property loss than those of the past because humans often

remove water-absorbing plant cover from the soil and con-

struct buildings on floodplains. (A floodplain is the area

and groundwater are interrelated parts of the hydro-
logic cycle. Aquifers are underground reservoirs in
which groundwater is stored (ˆ}ÕÀiÊ£ä°{).
Most groundwater is considered a nonrenewable
resource because it has taken hundreds or even thousands
of years to accumulate, and usually only a small portion of
it is replaced each year by seepage of surface water.

1. How do hydrogen bonds form between
   adjacent water molecules?


2. What are two unique properties of water?


3. How do processes in the hydrologic cycle affect
   the accumulation of groundwater?