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