Water Supply and Management

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Water Supply and Management
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Discussion Objectives

• Important Properties of Water
• Distribution of Water
• The Water Cycle
• Major Uses of Water
• Human Impacts on the Water Cycle

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Properties of Water

• Hydrogen bonding

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Properties of Water

• Hydrogen bonding leads to the important
  characteristic of high specific heat.
• Takes a lot of energy to melt or vaporize water
• Implications
• Does not change temperature rapidly
• Influences climates
• Organisms can regulate temperature.

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Climate Effects Near Large Bodies of Water
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Properties of Water

• Water is the universal solvent
• Dissolves some materials rapidly (salts) and some
  materials very slowly (granite).
• Major transport mechanism in plants and animals
  nutrients and pollutants.
• Major transport mechanism of Non-Point Source
  Pollutants locally and regionally.

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Properties of Water
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Properties of Water

• Water has a high surface tension
• Implications
• Facilitates movement through membranes and
  vascular tissues
• Water surface is a habitat to organisms.

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Properties of Water

• The solid form of water is less dense that it
  liquid form.
• Implications
• Global temperature
• Ice floatsimportant characteristic for fish?

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Properties of Water

• Water is transparent, therefore light can
  penetrate the surface and allow photosynthesis to
  occur.
• Implications
• Oligotrophic systems vs. Eutrophic systems

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Groundwater and Streams

• Groundwater
• Water found below the Earths surface, within the
  zone of saturation, below the water table
• Water table, recharge zones, discharge zones,
  aquifer, cone of depression
• Effluent Stream
• A type of stream where flow is maintained during
  the dry season by groundwater seepage into the
  channel
• Influent Stream
• A type of stream that is everywhere above the
  groundwater table and flows in direct response to
  precipitation

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How Much Water is There?

• Approximately 97 of the Earths water is in the
  oceans.
• About 2 is in the polar ice caps (freshwater).
• The remaining 1 is freshwater found in rivers,
  streams, lakes, groundwater and atmospheric water
  vapor.

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Global Water Supply
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Global Distribution of Water

• Is the global distribution of water uniform?

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Water Usage

• Do All Nations Use Water the Same?
• Developed nations that have high industrial
  and/or agricultural output consume large
  quantities of water.
• Global per capita water usage is approaching 200
  gallons/day.

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Major Water Use Categories

• Off-stream use
• Uses that temporarily or permanently remove water
  from its source (e.g., irrigation or cooling
  waters).
• If not returned, it called consumptive use.
• In-stream use
• Uses that do not remove water from its source
  (e.g., hydroelectric power or recreation).
• Multiple uses can cause conflict between users.

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In Stream Water Use
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Water Use Trends In The U.S.

• Water for irrigation and and the thermoelectric
  industry have been the largest water users since
  the 1950s.
• Water usage for domestic consumption has
  increased with the population increase, but
  industrial consumption has decreased.

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Water Use Trends in The U.S.

• From 1950-1975, water use steadily increased with
  the population increase.
• From 1975 to the present, water use has remained
  constant although the population has grown.
• This trend suggests that water conservation and
  management techniques have been mildly successful.

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Water Budget for the U.S.
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Factors Influencing Water Distribution

• Global Air Flow Patterns

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Factors Influencing Water Distribution

• Local Air Flow Patterns

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Factors Influencing Water Distribution

• Evaporation
• Precipitation
• Run-off
• Infiltration
• Percolation

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Evaporation

• Approximately 66 of total precipitation is lost
  through evaporation or evapotranspiration
  processes.
• Evaporation and transpiration rates vary
  depending on season, vegetation, soils, land use
  and local climatic conditions.

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Precipitation

• Precipitation rates are a function of relative
  humidity.
• Approximately 34 of the total precipitation
  enters groundwater or surface water supplies.
• Is this enough to compensate for current water
  usage patterns?

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Precipitation as a function of relative humidity
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Mean Annual Precipitation
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Water Run-Off

• Water stays on the land surface.
• Influenced by local topography.

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Percolation
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Sources of Our Water Supply

• Drinking water supplies come from surface water
  bodies and groundwater aquifers.
• Approximately 51 of the U.S. population gets
  drinking water from underground wells.
• A higher percentage in Southeast Missouri gets
  its water from private wells.
• Are these private wells required to be tested to
  determine if the water is free of biological or
  chemical contamination?

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What is an Aquifer?

• Aquifer
• Underground soil or rock formations that contain
  pore space or fractures that may become filled
  with water.
• Aquifers near the ground surface are called
  surficial or unconfined aquifers (any potential
  problems with this type?).
• Aquifers separated from surficial aquifers by an
  impermeable layer are called confined aquifers.

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Aquifer Recharge and Discharge

• Aquifers can be recharged by surface infiltration
  and by streams.
• This is a long-term processtakes years to
  replace lost water.
• Groundwater moves very slowly.
• Aquifers can recharge surface water bodies.

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Groundwater Overdraft

• The total groundwater supply in the U.S. is
  large, however, it is unevenly distributed and
  withdrawals exceed recharge in some areas (e.g.,
  Ogallala Aquifer).
• The excessive removal of groundwater is called
  overdraft.

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Human Impacts on the Water Cycle

• Physical Impacts
• Deforestation
• Dams/Flow Diversion/Channelization
• Creating Impervious Surfaces.

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Impacts of Deforestation
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Damming of Rivers
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Effects of Stream Channelization

• Stream channelization is the widening, deepening,
  clearing or lining of existing streams.
• Positive effects
• Improve drainage
• Flood control
• Erosion control
• Improve navigation.

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Effects of Stream Channelization

• Environmental effects
• Alteration of stream habitat
• Alteration or removal of streamside vegetation
  and habitat
• Removal of water storage capacity in wetlands
• Removal of wetlands
• Loss of aesthetic quality of the stream.

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Impervious Surfaces

• Increased runoff.
• Source of pollutants.
• Reduction in groundwater recharge.
• Ex. 5 cm rain
• ¼ acre wood 6 mm runoff
• ¼ acre housing project 18 mm runoff

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Overdrawing of Water Supplies

• Overdrawing from surface sources causes a drop in
  water levels that may affect habitat and
  organisms occupying the reservoir or lake.
• Groundwater
• Lowering of the water table
• Land subsidence
• Saltwater intrusion.

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Overdrawing of Groundwater
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Overdrawing of Groundwater
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Land Subsidence
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Land Subsidence
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Saltwater Intrusion
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Saltwater Intrusion
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Sustainable Water Use

• Sustainable water use
• The use of water resources by people that allows
  society to develop and grow into an indefinite
  future without causing the degradation of the
  components of the water cycle or the ecological
  systems that depend on it.

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Sustainable Water Use Planning

• Sustainable use criteria
• Sufficient water volume to maintain human health
• Sufficient water volume to maintain ecosystems
• Maintaining water quality standards
• Providing for the renewal of water resources
• Promoting water-efficient technology and
  practice
• Appropriate pricing of water resources.

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