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Description of the Water Cycle.
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Understanding EarthSixth EditionChapter 17:THE HYDROLOGIC CYCLEAND GROUNDWATER 2011 by W. H. Freeman and Company
Grotzinger Jordan
Chapter 17The HydrologicCycle and Groundwater
About the Hydrologic CycleHydrology is the study of movements and characteristics of groundwater.The hydrologic cycle has a profound effect upon climate prediction. Water is vital so we must understand where to find water and how water supplies cycle through the Earth.
Lecture Outline
The geologic cycling of water2. Hydrology and climate3. The hydrology of groundwater4. Erosion by groundwater5. Water quality6. Water deep in the crust
The Geologic Cycling of Water Flows into a reservoir include inflows and outflows, and inflow equals outflow.
Reservoirs include all the places that water is stored in and on the Earth.
The Geologic Cycling of Water
The hydrologic cycle
precipitation
infiltration and runoff
evaporation, transpiration, and sublimation
groundwater flow The Geologic Cycling of Water
The hydrologic cycle The Geologic Cycling of Water
Thought questions for this chapterIf global warming caused evaporation from the oceans to increase greatly, how would the hydrologic cycle of today be altered?
Key climatic factors
relative humidity
rainfall
landscape2. Hydrology and Climate
Key tectonic factors
ocean-land relationships
mountain rain shadows2. Hydrology and Climate
2. Hydrology and Climate:The Rain Shadow Effect
The runoff-precipitation relationship
stronger in local areas
less strong in regional areas2. Hydrology and Climate
2. Hydrology and Climate
2. Hydrology and Climate
Surface storage of water runoff
lakes and reservoirs
wetlands and swamps2. Hydrology and Climate
The Hydrology of Runoff:Similarityof aDammedLake anda NaturalLake
The Hydrology of Runoff:Similarityof aDammedLake anda NaturalLake
Thought questions for this chapterHow might the hydrologic cycle have been different 18,000 years ago, at the Wisconsin glacial maximum, when much of North America, Europe, and Asia were covered with ice?
Groundwater flow through soil and rock
porosity and permeability
groundwater table3. The Hydrology of Groundwater
Groundwater:Porosity andthe Amountof Open Spacein VariousMaterials
3. The Hydrology of Groundwater
Above and below the groundwater table
unsaturated (vadose) zone
saturated (phreatic) zone3. The Hydrology of Groundwater
Inflow and outflow of groundwater
recharge (influent streams)
discharge (effluent streams)3. The Hydrology of Groundwater
Groundwater:Effluent WaterHeaded for aStream
3. The Hydrology of Groundwater:Dynamics of the Groundwater Table
3. The Hydrology of Groundwater
Types of aquifers
unconfined has an aquiclude below
confined has aquiclude above and below3. The Hydrology of Groundwater
Characteristics of some confined aquifers
artesian (flowing) wells
artesian flow (under pressure)3. The Hydrology of Groundwater
3. The Hydrology of Groundwater
Complex geological environments
perched water tables
unpredictable flow conditions3. The Hydrology of Groundwater
Balancing recharge and discharge
balance = stable water table
excess recharge = rising water table
excess discharge = falling water table3. The Hydrology of Groundwater
Groundwater:ExcessDischargeand the Cone of Depression
Groundwater:ExcessDischargeand theMovement of SaltWater
Groundwater:ExcessDischargeand theMovement of Salt Water
Speed of groundwater flows
hydraulic gradient
Darcys law
Q = A (K h / l)3. The Hydrology of Groundwater
Groundwater: Darcys Law
Some major U.S. aquifers
U.S. Great Plains and midwestern states
Ogallala aquiferWater resources from major aquifers:
Water Resources: U.S. Withdrawal
WaterResources:The GreatOgallalaAquifer only a fewyears left
Thought questions for this chapterIf you lived near the seashore and started to notice that your well water had a slightly salty taste, how would you explain the change in water quality?
Why would you recommend against extensive development and urbanization of the recharge area of an aquifer that serves your community?
Your new house is built on soil-covered granitic bedrock. Although you think that prospects for drilling a successful water well are poor, a well driller who is familiar with the area says he has drilled many good water wells in this granite. What arguments might each offer to convince the other?
Features of groundwater erosion
caves and caverns
stalactites and stalagmites
karst features (karst topography)
sinkholes4. Erosion by Groundwater
Characteristics of areas with karst
high rainfall and abundant vegetation
limestone bedrock with joints
significant hydraulic gradient4. Erosion by Groundwater
4. Erosion by Groundwater: Karst
Erosion by Groundwater: CarlsbadCaverns, New Mexico
Erosion by Groundwater: Sinkhole in Winter Park, Florida
Thought questions for this chapterYou are exploring a cave and notice a small stream flowing on the cave floor. Where could the water be coming from?
Contamination of the water supply
lead pollution
radioactive wastes
microorganisms in water
other chemical contaminants 5. Water Quality
5. Water Quality: Human Contamination
Reversing contamination
easier if recharge rate is fast
usually costly and very slow
decontamination after pumping
in-ground water treatments 5. Water Quality
Dissolved materials in drinking water
potable water has 150 ppm
distilled water has < 1 ppm
some elements have their limits
example: arsenic, 0.05 ppm5. Water Quality
Thought questions for this chapterIf you discovered that radioactive waste had seeped into groundwater from a nuclear processing plant, what kind of information would you need to predict how long it would take for the radioactivity to appear in well water 10 km from the plant?
Why should communities ensure that septic tanks are maintained in good condition?
Why are more and more communities in cold climates restricting the use of salt to melt snow and ice on highways?
Types of deep crustal groundwater
meteoric water that seeps in
magmatic water
hydrothermal (hot spring) water6. Deep Water in the Crust
Water Deepin the Crust:The Originof Hot Springsand Geysers
Mammoth Hot Springs,Yellowstone National Park
Ancient microorganisms in deep aquifers
active colonies of microbes that may have been there for millions of years are found in deep crustal groundwater
they live by dissolving minerals6. Deep Water in the Crust
Thought questions for this chapterWhat geologic processes would you infer are taking place below the surface at Yellowstone National Park, which has many hot springs and geysers?
AquicludeAquiferArtesian flowDarcys lawDischargeDroughtGroundwaterGroundwater tableHydraulic gradientHydrologic cycleHydrologyHydrothermal waterInfiltrationKarst topographyMeteoric waterKey terms and concepts
PermeabilityPotablePrecipitationRain shadowRechargeRelative humidityRunoffSaturated zoneSinkholeUnsaturated zoneKey terms and concepts