Post on 29-Mar-2015
Water Resources
• 1. Hydrologic Cycle and Water Reservoirs
• 2. Floods and Flood Control
• 3. Use of Water
• 4. Water Composition
• 5. Water Problems
Hydrologic Cycle
Distribution of Water(from “Resources of the Earth” 1972 data)
Type Location Volume (l) PercentSurface Lakes 1.25 x 1017 0.009
Saline lakes/seas 1.04 x 1017 0.008
Streams 1.00 x 1015 0.0001
Subsurface Vadose 6.7 x 1016 0.005
Groundwater (to 750 m) 4.17x 1018 0.31
Groundwater (below 750m) 4.17x 1018 0.31
Other Reservoirs Icecaps, glaciers 2.9 x 1019 2.15
Atmosphere 1.3 x 1016 0.001
Oceans 1.32 x 1021 97.2
Distribution of Waterhttp://ga.water.usgs.gov/edu/waterdistribution.html (1997 data)
Source Volume (km3) % Fresh % Total
Oceans 1338 x 106 96.5
Ice caps/glaciers 24 x 106 68.7 1.74
Groundwater 23.4 x 106
Fresh 10.53 x 106 30.1 0.76
Saline 12.87 x 106 0.94
Soil Moisture .0165 x 106 0.05 0.001
Permafrost 0.3 x 106 0.86 0.022
Lakes 0.1764 x 106 0.013
Fresh 0.091 x 106 0.26 0.007
Saline 0.0854 x 106 0.006
Atmosphere 0.0129 x 106 0.04 0.001
Swamp Water 0.0115 x 106 0.03 0.0008
Rivers 0.00212 x 106 0.006 0.0002
Biological Water 0.00112 x 106 0.003 0.0001
Bibliographical Acknowledgment referenced publication for content development
Peixoto and Kettani, 1973 The Control of the Water Cycle
Scientific American - Vol. 228 - pp. 46-6
Heat Capacity of Water
• This means that water has the ability to absorb and hold heat with a minimal change in temperature
• Why?• When water evaporates it takes 540 cal/gm.
This means that evaporation creates a cooling effect.
• Ice going to water releases 80 cal/gm, thus releasing heat
World water resources
http://www.worldmapper.org/
Evaporation (mean annual U.S.)
http://geochange.er.usgs.gov/sw/changes/natural/et/
http://ga.water.usgs.gov/edu/watercycleevapotranspiration.html
Evapotranspiration
Mean Annual Evapotranspiration
When ppt >>> e/t
• Then we get rivers and streams
• Eastern NA—water surplus
• Western US—water deficiency
• Plays a role in population density in U.S. and Canada
Freshwater Reservoirs
• Rivers and Streams
• Lakes
• Icecaps
• Groundwater
Groundwater
• Much greater in volume than either lakes or streams
• Non-renewable in our lifetime
Water Table
• Surface below which pores and fractures of rocks and overburden are water filled
What is an aquifer?
• Geologic formation that possesses porosity and permeability
Water Resources
• 1. Hydrologic Cycle and Water Reservoirs
• 2. Floods and Flood Control
• 3. Use of Water
• 4. Water Composition
• 5. Water Problems
Surface Water/Floods/Flood Control
• Surface water is water that flows off the land in streams and rivers
• What is it dependent upon??
• Amount of precipitation
• Slope and Length of drainage basin
• Rock and soil type of drainage basin
• Vegetation
• Extent of impermeable areas
Red River Discharge Hydrograph
When does flooding occur?
• When surface run-of exceeds a normal stream channel’s capacity and water spreads out onto the flood plain
• Is this a problem?
What do we do to minimize flooding?
• 1. build dams
• 2. build levees
• 3. create channels (channelization)
• 4. Moveable dams—Thames
Dams: pro
• 1. Do help with flood control• 2. Supply electricity• 3. Provide recreation• 4. Sources of water for irrigation• 5. Increases groundwater
• Does anyone see some inconsistency here?
Dams: con
• 1. Sediment catchment
• 2. Increased evaporation
• 3. Loss of land
• 4. Interruption of river transport and fish migration
• 5. Environmental alteration
Some Dams
• Aswan High Dam
Glen Canyon Dam
Hoover Dam
Three Gorges Damhttp://svs.gsfc.nasa.gov/vis/a000000/a003400/a003433/#topm
Levees
Channelization
• Replacement of a meandering stream by a deeper, straighter channel
Drawbacks
• Transfer of flooding
• Flood plain doesn’t get new sediment
Kissimmee river in Florida
Drawbacks of Channelization
• Increased erosion• Transfer of flooding downstream• Reduced natural filtering of water and drainage basin• Loss of wetlands• Reduction in available water for general use• Less evapotranspiration• Less infiltration• Lower ground water levels• Larger variations in flow rates• Reduction in wildlife