water resources environmental science spring 2011
TRANSCRIPT
Water Resources
Environmental Science Spring 2011
ObjectivesDescribe the distribution of Earth’s water
resources Explain why fresh water is one of Earth’s
limited resourcesDescribe the distribution of Earth’s surface
waterDescribe the relationship between
groundwater and surface water in a watershed
Water CycleFreshwater: water that people can drink,
contains little saltSalt water: contains higher concentrations
of dissolved salts, people cannot drink, in oceans
Water CycleWater is a renewable resource- circulated
through water cycleWater evaporates at earth’s surface and
leave behind salts and impuritiesWater vapor: gaseous water, rises in air Condensation: water vapor cools and turns
into a liquid, falls to earth’s surface
Water Cycle
Global Water DistributionFreshwater is a
limited resource
Surface WaterSurface Water: freshwater on Earth’s land
surface Lakes, rivers, streams, wetlands
Provide drinking water, water to grow crops, food such as shellfish and fish, power for industry, and means of transportation
River SystemsRiver systems: a flowing network of water
formed as streams and rivers move across the landAmazon largest river system
Streams form as water falling rain and melting snow drains from mountains, hills, plateaus, and plains
Streams combine with other streams to form rivers
River Systems
WatershedsWatershed:
area of land that is drained by a river
Pollution anywhere in watershed may pollute a river
Amount of water entering watershed varies throughout year
Ground Water and Water TableGroundwater: water beneath earth’s surface
in sediment and rock formation Water percolates through soil and down into
rocks underneath Water Table: level where rocks and soils are
saturated with water At different levels, can range from at earth’s
surface to 100’s of meters beneath the surface
Ground Water and Water Table
AquifersAquifer: underground formation that contains
groundwater Water table forms upper boundary of aquifer Most consist of rocks, sand, and gravel that have a lot of space where water can accumulate
Porosity and PermeabilityPorosity: percentage of total volume of a
rock that has spaces (pores)Water in aquifer is stored in pore spaces and
flows between pores More porous, more water rock can hold
Permeability: ability of rock or soil to allow water to flow through it Gravel is permeable; Clay, granite
impermeable Most productive aquifers usually form in
permeable materials (sandstone, limestone, layers of sand and gravel)
The Recharge ZoneRecharge Zone: area of the Earth’s surface
from which water percolates down into an aquifer Environmentally sensitive areas because pollution
can enter aquifer Size of recharge zone is affected by permeability of surface above aquifer
Surface water can take a very long time to refill an aquifer, buildings can prevent this
WellsWell: hole that is dug or drilled to reach
groundwaterCreate wells because groundwater may be a
more reliable source of water than surface water because water is filtered and purified as it travels underground
Review1. Which of the following processes is not a part of
the water cycle?A. Evaporation B. Condensation C. Biomagnification D. Precipitation
2. Most of the fresh water on Earth is:A. Located underground in aquifersB. Frozen in polar icecaps C. Located in rivers, lakes, streams, and wetlandsD. Found in Earth’s atmosphere
Ansers1. Which of the following processes is not a part of
the water cycle?A. Evaporation B. Condensation C. Biomagnification D. Precipitation
2. Most of the fresh water on Earth is:A. Located underground in aquifersB. Frozen in polar icecaps C. Located in rivers, lakes, streams, and wetlandsD. Found in Earth’s atmosphere