Hydrosphere: All the water at or near the surface of the earth Amount of water essentially constant and moves between different reservoirs 100 million billion gallons move through Hydrologic Cycle Oceans account for ~96%, Fresh water lakes and streams for only 0.016% of all water

1. TOPIC OF PRESENTATION
Distribution Of
Subsurface Water

2. Hydrosphere:Hydrosphere: All the water at or near theAll the water at or near the
surface of the earthsurface of the earth
Amount of water essentially constant andAmount of water essentially constant and
moves between different reservoirsmoves between different reservoirs
100 million billion gallons move through100 million billion gallons move through
Hydrologic CycleHydrologic Cycle
Oceans account for ~96%, Fresh water lakesOceans account for ~96%, Fresh water lakes
and streams for only 0.016% of all waterand streams for only 0.016% of all water
HYDROLOGIC CYCLE

3. DISTRIBUTION OF WATER

4. Thousands of km3
/yr
-
- - +
HYDROLOGIC CYCLE

5. GROUND WATER
• 22% of all fresh water occur underground
• Aquifer: Underground formation that holds and yields
water
• A good aquifer needs to be both porous and permeable

6. POROSITY AND
PERMEABILITY
• Porosity: Proportion of void space: pore space,
cracks, vesicles
• Gravel : 25-45% (1K - 10K), Clay: 45-55%(<.01)
• sandstone: 5-30% (0.3 - 3), Granite: <1 to 5%(.003 to .00003)
• higher porosity in well rounded, equigranular, coarse grained
rocks
• Permeability: Measure of how readily fluid
passes through a material
• Depends on the size of the pores and how well they
are interconnected
• Clay has high porosity but low permeabilty

7. Less porosity
porosity permeability
Clay 45-55% <0.01 m/day
sand 30-52% 0.01 - 10
gravel 25 - 45% 1000 to 10,000

8. SUBSURFACE
WATER
• Zone of Aeration or
Vadose Zone or
Unsaturated Zone:
Overlies Phreatic Zone.
Pore spaces partly filled
with water. Contains soil
moisture.
Saturated
Zone
Zone of Saturation or Phreatic Zone:Zone of Saturation or Phreatic Zone: saturatedsaturated
zone overlying impermeable bed rock. Water fillszone overlying impermeable bed rock. Water fills
all the available pore spacesall the available pore spaces
Water Table:Water Table: top of the zone of saturation wheretop of the zone of saturation where
not confined by impermeable rocknot confined by impermeable rock

9. • Water table follows the topography but more gently
• Intersection of water table and ground surface
produces lakes, streams, spring, wetlands…
• Ground water flows from higher elevation to lower, from
areas of lower use to higher use, from wet areas to dry
areas.

10. DARCY’S LAW
• Hydraulic Gradient: Slope of the ground water table
• Rate of flow is proportional to the hydraulic gradient

11. AQUIFER
• Recharge: Process of replenishment of Ground
Water by infiltration, migration and percolation
• Aquifer: A rock that holds enough water and
transmits it rapidly. Porous and Permeable.
Sandstone and Coarse Clastic Sedimentary rocks
make good aquifers
• Aquitard and Aquiclude: Rocks of low and very
low permeability e.g., shale, slate
• Perched water table: Local aquifer in Vadose
Zone

13. CONFINED AND UNCONFINED AQUIFER
• Unconfined Aquifer: open to
atmosphere e.g., overlain by permeable
rocks and soils
• Confined aquifer: sandwiched between
aquitards
• Artesian System: Water rises above the
level in aquifer because of hydrostatic
pressure
• Potentiometric surface: Height to which
water pressure would raise the water.

14. Artesian System: Water rises above the
level in aquifer because of hydrostatic
pressure
Potentiometric surface: Height to which
water pressure would raise the water.

15.  Lowering of Water Table
 Cone of depression: Circular lowering of water
immediately around a well
Consequences of Ground Water
Withdrawal

16. CONSEQUENCES OF GROUND WATER
WITHDRAWAL
–overlapping cones of depression causes loweringoverlapping cones of depression causes lowering
of regional water tableof regional water table
–Water mining: rate of recharge too slow forWater mining: rate of recharge too slow for
replenishment in human life timereplenishment in human life time

17. Compaction and Subsurface subsidence

18. CONSEQUENCES OF GROUND
WATER WITHDRAWAL….
• Compaction and Subsurface
subsidence
• Building damage, collapse
• flooding and coastal erosion e.g.,
Venice, Galveston/Houston (80 sq km
permanently flooded), San Joaquin
Valley (9m subsidence)
• Pumping in of water no solution

19. Land subsidence inLand subsidence in
San Joaquin Valley ,San Joaquin Valley ,
CaliforniaCalifornia

21. THE HIGH PLAINS AQUIFER
• 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.
• 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.
• Since early 1800s, irrigation water pumped from the aquifer
has made the High Plains one of the Nation’s most
important agricultural areas.
• the intense use of ground water for irrigation has caused
upto 100m decline in water-level in parts of Kansas, New
Mexico, Oklahoma, and Texas.

22. Changes in ground-
water levels in the High
Plains aquifer from
before ground-water
development to 1997.
(V.L. McGuire, U.S.
Geological Survey,
written commun.,
1998.)

23. • The Gulf Coastal Plain aquifer system 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.
The Gulf Coastal Plain Aquifer System

24. LAND SUBSIDENCE IN
HOUSTON

25. Flooding in coastal Galveston because of subsidence

26. Salt water
incursion
in caostal
aquifer
SaltwaterSaltwater
IntrusionIntrusion
–upconing below cone ofupconing below cone of
depressiondepression
–Aquifer below Brooklyn, NYAquifer below Brooklyn, NY
destroyeddestroyed
–Serious problem in Gulf Coast andSerious problem in Gulf Coast and
CaliforniaCalifornia

27. EXTENT OF
SALT WATER
INCURSION
IN MIAMI-
DADESalt water intrusion in
Miami-Dade

28. Sinkholes
• forms in areas with abundant water and soluble
bedrock (gypsum or limestone)
• collapse follows ground water withdrawal

29. Dripstones in a cavernDripstones in a cavern
Stalagmites
Stalagtites

30. URBANISATION AND GROUND WATER
• Loss of Recharge
• Impermeable cover retards recharge
• Filling of wetlands kills recharge area
• Well planned holding pond can help in recharging
ground water

31. WATER QUALITY
• Most freshwater contain dissolved substances
• concentrations are described in ppm or ppb
• TDS=Total Dissolved Solids
• 500 to 1000 ppm for drinking water
• 2000 ppm for livestock
• some solids (e.g., Iron, Sulfur) more harmful than others (e.g.
calcium)
• synthetic chemicals can be toxic at ppb level
• Radioactive elements pose special hazard
• Uranium, Radium, Radon

32. HARD WATER
• Hard Water:
• Common in limestone country
• contains dissolved Ca and Mg; problematic if
>100 ppm
• problem with soap
• leaves deposits in plumbing and in appliances
• can be cured with water softener typically ion
exchange through zeolites

33. WATER USE IN US
• 4200 billion gallons of precipitation
• 2750 billion gallons lost by evaporation
• 1400 billion gallons available for consumption
• Biological need : 1 gal/person/day
• US consumption: 1800 gal/person/day
= 400 billion gallons per day for the entire US

34. • Offstream Use: water diverted from source e.g.,for
irrigation or thermal power generation
• Consumptive: water used up
• For farming, drinking or lost by evaporation
• Instream: water returns to flow: e.g., for hydroelectric
power generation

35. WATER USE …
• Main Uses:
• Thermoelectric Power
• Surface: Ground water = 67:33
• Consumed 2%, Return Flow 98%
• Irrigation
• Surface: Ground water = 63:33
• Consumed 56%, Loss 20%, Return Flow 24%
• Industrial
• Surface 67% (saline 12%), Ground water 15% (1%
saline), Public Supply 19%
• Consumption 15%, Return Flow 85%
• Domestic
• Public Supply 86%, Ground Water 13%, Surface 1%
• Consumption 23%, Return Flow 77%

36. IRRIGATION AND
GROUND WATER
• Thus, irrigation is the major consumer of ground water
• Western states are the major drawers of ground water
causing serious environmental problems

37. Most of the precipitation is in the eastern states but…

38. Most of the water withdrawal is in the western states (see
also the next slide)

40. •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

41. WATER RIGHTS
• 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

42. 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

43. Colorado River basin
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.
Story of Colorado River

44. COLORADO RIVER
COMPACT
• 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.
• These apportions were decided during a particularly wet
climatic period. At present, the flow in Colorado does not add
up to all the apportionments

45. Within Colorado water
allocations are based on
the Doctrine of Prior
Appropriation or the
First-in-Time, First-in-
Right 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. But a large part of
the Colorado river water
is diverted to Los
Angeles on the basis of
this doctrine

46. CONSERVATION
• Shift water-hungry crops to regions with more rainfall
• Use drip irrigation to reduce evaporation loss
• Use pipes to reduce transport loss
• Water lawns in morning and evening or opt for no lawn
• Direct storm water in recharge basins

47. INTERBASINAL TRANSFER
• Transfer water from water-surplus regions
to water-deficient regions
• California : Los Angeles aqueduct moves 150
million gallons/ day from east of Sierra Nevada
to LA
• New York: Water supply to NYC from Finger
Lakes region
• political problems
• Desalination
• Filtration, distillation
• Expensive, limited

48. THANKS.