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) TypeLocationVolume (l)Percent SurfaceLakes1.25 x Saline lakes/seas1.04 x Streams1.00 x SubsurfaceVadose6.7 x Groundwater (to 750 m)4.17x Groundwater (below 750m)4.17x Other ReservoirsIcecaps, glaciers2.9 x Atmosphere1.3 x Oceans1.32 x

Distribution of Water h ttp://ga.water.usgs.gov/edu/waterdistribution.html (1997 data) h ttp://ga.water.usgs.gov/edu/waterdistribution.html SourceVolume (km 3 )% Fresh% Total Oceans1338 x Ice caps/glaciers24 x Groundwater23.4 x 10 6 Fresh10.53 x Saline12.87 x Soil Moisture.0165 x Permafrost0.3 x Lakes x Fresh0.091 x Saline x Atmosphere x Swamp Water x Rivers x Biological Water x

Bibliographical Acknowledgment referenced publication for content development Peixoto and Kettani, 1973 The Control of the Water Cycle Scientific American - Vol 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

Evaporation (mean annual U.S.)

Evapotranspiration

Mean Annual Evapotranspiration

When ppt >>> e/t Then we get rivers and streams Eastern NAwater surplus Western USwater deficiency Plays a role in population density in U.S. and Canada

Freshwater Reservoirs Rivers and Streams Lakes Icecaps 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 channels 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 damsThames

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 Dam

Levees

Channelization Replacement of a meandering stream by a deeper, straighter channel

Drawbacks Transfer of flooding Flood plain doesnt 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