WATER RESOURCES

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WATER RESOURCES
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Case History Long Island

• GW pollution 1900 from agriculture
• GW decline
• Salt water intrusion
• Urbanization triggered more serious water
  pollution

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Management options
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Reduce urban runoff?
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Global Water Cycle

• Cyclic nature
• Global movementof water between different water
  reservoirs
• Global distribution
• Abundance not a problem
• Distribution in space and over time a problem
• Supply vs. use a problem

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Global Water Cycle

• Waters vertical movement
• Upflow Evaporation, transpiration
• Downflow Precipitation and infiltration
• Waters horizontal movement
• Surface runoff
• Shallow subsurface flow
• Groundwater flow

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Water, water, everywhere

• Mostly (97) seawater salty
• Remainder mostly (75) ice solid
• Remainder mostly (67) groundwater-hidden

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The Hydrologic Cycle

• Reservoirs and fluxes (as )

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Surface Water

• Surface runoff
• Drainage network
• Drainage basin or watershed
• Drainage divide
• Stream order and size of drainage basin
• Sediment pollution(?)

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Groundwater Layers

• Groundwater (GW) profile
• Vadose zone (unsaturated zone, zone of aeration)
• Phreatic zone (zone of saturation)
• Water table The boundary of the above two zones

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Groundwater definitions
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Groundwater recharge and discharge

• Recharge zone Area where water infiltrates
  downward from surface to GW
• Discharge zone Area where GW is removed from an
  aquifer, such as spring, well, river, etc.
• Influent stream above the water table, recharge
  water to GW, may be intermittent Losing
• Effluent stream perennial stream with the
  addition of GW when precipitation is low Gaining

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Visualizing Groundwater

• Aquifer
• Aquitard/ aquiclude
• Confined/ unconfined aquifer
• Water table
• Perched aquifer

Layer-cake
Sponge
Losing
Gaining
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Groundwater (5)

• GW pressure surface/water table
• Generally declining from source along the flow
  from recharge area to discharge area
• True for unconfined (water table) and confined
  aquifers
• Artesian well Water self-rising above the land
  surface(?) from a confined aquifer punctured by
  a well
• Cone of depression Drawdown cone of GW in a well

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Artesian wells

• Wells in which water rises without pumping are
  artesian
• Those that flow are called flowing artesian
• Requires confined aquifer
• Water rises towards potentiometric surface

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Water Table Issues

• Drawdown
• Vertical
• Cone of Depression
• 3-D
• Dewatering
• Overlap
• Pollution
• Change of gradient

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Groundwater Movement (1)

• Hydraulic gradient The gradient of water table,
  generally following the topographic gradient
• The water table is subparallel to the ground
  surface.
• Hydraulic conductivity Ability of rock materials
  to allow water to move through (m3/day/m2)
• Porosity Percentage of void (empty) space in
  sediment or rock to store water
• Permeability Measuring the interconnection of
  pores in a rock material

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Groundwater

• Aquifers
• Porosity
• f(size, sorting)
• Permeability
• f(sorting, cement)

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Groundwater Movement (2)
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Groundwater Use and Supply (1)

• Available GW estimated above the total flow of
  the Mississippi during the last 200 years
• GW is primary drinking water source for 50 of
  the U.S. population

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(No Transcript)
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Groundwater Use and Supply (2)

• Problems
• Overdrafts
• Pollution (later)

Figure 12.13
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Water Uses (1)

• Offstream use Removal or diversion from its SW
  or GW sources temporarily, e.g., irrigation,
  thermoelectric, industrial use
• Consumptive use Type of offstream use of water
  without intermediate return to the SW or GW, such
  as transpiration and human use
• Instream use Navigation, fish and wildlife,
  recreational uses
• Water law
• Riparian (you touch it, you use it)
• Appropriation (first in time first in right)

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Water Use (2)

• In major urban areas
• Overwithdrawal of groundwater
• Overuse of local surface water
• Threats of local urban landfills to the water
  supply, e.g., Long Island, NY
• Water import issues and problems
• What is distance to transport?
• How much water available?
• From where? Conflicts with other areas,
  litigations, and long-range planning

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Trends in Water Use (2)

• So what do we do about it?
• Environmentalism
• Reduce
• Reuse
• Recycle
• New Environmentalism (Andy Posner, Huffington
  Post, 8/03/08)
• Invent
• Invest
• Implement

Figure 12.20
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Water Management (1)

• Challenges for water management
• Increasing demand for water use (population and
  economic development)
• Water supply problems in semiarid and arid
  regions
• Water supply problems in megacities of humid
  regions
• Water traded as a commodity Capital, market, and
  regulations?

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Management of the Colorado River (1)
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Significance of water

• Hoover Dam/Lake Mead
• Water to ImperialValley, LA
• Power to CA, AZ, NV

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http//www.hcn.org/
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Multipurpose Dam(n)s

• Irrigation 48
• Electricity generation 36
• Water supply 36

• Flood control 39
• Recreation/fisheries 29
• Inland navigation 5

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Management of the Colorado River (2)
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Water and Ecosystems
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Emerging Global Water Shortage
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Applied and Critical Thinking Topics