Transcript Water Resource

Water Resource
Total Withdrawal: 134,000 Mgal/day
Surface water : 63%
Groundwater: 37%
Irrigation Use: 39% of all freshwater
withdrawal
•Total withdrawal increased
from 1950 to 1980 and has
held steady since then
although population has
increased by 16%
•Withdrawal for
thermoelectric power
generation 190,000 Mgal/day:
largest of any other category
•Higher water price, more
public awareness,
conservation, better farming
and industrial techniques will
keep water demand in check
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Hydroelectric water use 3,160,000 Mgals/day
2.6 times annual run-off
Same water is used several times by a series
of dam on the same river
Instream use: water is returned to the stream
Almost all withdrawal is from fresh surface
water
The High Plains Aquifer
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The High Plains is a 174,000-square-mile area of flat to gently
rolling terrain that includes parts of eight States from South
Dakota to Texas. The area is characterized by moderate
precipitation but in general has a low natural-recharge rate to
the ground-water system. Unconsolidated alluvial deposits that
form a water-table aquifer called the High Plains aquifer underlie
the region. During the late 1800’s, settlers and speculators
moved to the plains, and farming became the major land-use
activity in the area. Since that time, irrigation water pumped from
the aquifer has made the High Plains one of the Nation’s most
important agricultural areas.
Over the years, the intense use of ground water for irrigation in
the High Plains has caused major water-level declines and
decreased the saturated thickness of the aquifer significantly in
some areas. For example, in parts of Kansas, New Mexico,
Oklahoma, and Texas, ground-water levels have declined more
than 100 feet
Changes in groundwater levels in the High
Plains aquifer from
before ground-water
development to 1997.
(V.L. McGuire, U.S.
Geological Survey,
written commun.,
1998.)
The Gulf Coastal Plain Aquifer System
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The Gulf Coastal Plain aquifer system consists of a large
and complex system of aquifers and confining units that
underlie about 290,000 square miles extending from
Texas to westernmost Florida, including offshore areas to
the edge of the Continental Shelf.
Water withdrawals from the aquifer system have caused
– lowering of hydraulic heads at and near pumping
centers;
– reduced discharges to streams, lakes, and wetlands;
– induced movement of saltwater into parts of aquifers
that previously contained freshwater;
– and caused land subsidence in some areas as a result
of the compaction of interbedded clays within aquifers.
Land subsidence in Houston
The Colorado River flows through
Utah to Lake Powell, thence
through the northwest corner of
Arizona to Lake Mead. From
Hoover Dam it flows southward to
Mexico forming the border
between Nevada, California and
Arizona, and yielding major
diversions to central Arizona and
southern California. The river is
the lifeblood of the southwestern
US and its development and
management have been the focus
of attention by the member states
for more than a century. Waters of
the Colorado River System have
been apportioned by a treaty with
Mexico, compacts, and a Supreme
Court decree to the seven basin
states.
Colorado River basin
Colorado River Compact
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The Colorado River Compact of 1922 divided the use of waters
of the Colorado River System between the Upper and Lower
Colorado River Basin.
It apportioned in perpetuity to the Upper and Lower Basin,
respectively, the beneficial consumptive use of 7.5 million acre
feet (maf) of water per annum.
It also provided that the Upper Basin will not cause the flow of
the river at Lee Ferry to be depleted below an aggregate of 75
maf for any period of ten consecutive years.
The Mexican Treaty of 1944 allotted to Mexico a guaranteed
annual quantity of 1.5 maf. These amounts, when combined,
exceed the river's long-term average annual flow.
Within Colorado water
allocations are based on
the Doctrine of Prior
Appropriation or the
First-in-Time, First-inRight Doctrine. This
doctrine is found in most
arid states because
when there is too little
water to satisfy all
users, sharing of the
remaining water would
be of little value to any
user
Water Rights
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Riparian Rights (Eastern USA):
– Every landowner can make reasonable use of lake
or stream or water flowing through or bordering his
property
– Municipalities have the right of eminent domain: at
times of scarcity, cities get their requirement first
– Sale of riparian rights allowed in some states
– Practical in regions of plentiful water
Law of Prior Appropiation
– First come, first served
– Settlers can lay claim to certain amount of water
which will be honored for perpetuity
– The oldest claim are honored first and any left
over goes to the next claimant and so on..
– Los Angeles bought up water rights in 1900 from
areas far and wide, some even from Arizona. Now
people in those areas are very unhappy about the
arrangement