Understanding Earth Sixth Edition Chapter 17: THE HYDROLOGIC CYCLE AND GROUNDWATER © 2011 by W. H. Freeman and Company Grotzinger Jordan

Chapter 17 The Hydrologic Cycle and Groundwater

About the Hydrologic Cycle Hydrology is the study of movements and characteristics of groundwater.Hydrology is the study of movements and characteristics of groundwater. The hydrologic cycle has a profound effect upon climate prediction.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.Water is vital so we must understand where to find water and how water supplies cycle through the Earth.

Lecture Outline 1. The geologic cycling of water 2. Hydrology and climate 3. The hydrology of groundwater 4. Erosion by groundwater 5. Water quality 6. Water deep in the crust

1. 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.

1. The Geologic Cycling of Water

● The hydrologic cycle ● precipitation ● infiltration and runoff ●evaporation, transpiration, ● evaporation, transpiration, and sublimation and sublimation ●groundwater flow ● groundwater flow 1. The Geologic Cycling of Water

The hydrologic cycle 1. The Geologic Cycling of Water

Thought questions for this chapter If 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 ●landscape ● landscape 2. Hydrology and Climate

● Key tectonic factors ● ocean-land relationships ● mountain rain shadows 2. Hydrology and Climate

2. Hydrology and Climate: The Rain Shadow Effect

● The runoff-precipitation relationship ● stronger in local areas ● less strong in regional areas 2. Hydrology and Climate

● Surface storage of water runoff ● lakes and reservoirs ● wetlands and swamps 2. Hydrology and Climate

TheHydrology of Runoff: Similarity of a Dammed Lake and a Natural Lake

TheHydrology of Runoff: Similarity of a Dammed Lake and a Natural Lake

Thought questions for this chapter How 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 and rock ● porosity and permeability ● groundwater table 3. The Hydrology of Groundwater

Groundwater: Porosity and the Amount of Open Space in Various Materials

3. The Hydrology of Groundwater

● Above and below the groundwater table table ● unsaturated (vadose) zone ● saturated (phreatic) zone 3. The Hydrology of Groundwater

● Inflow and outflow of groundwater ● recharge (influent streams) ● discharge (effluent streams) 3. The Hydrology of Groundwater

Groundwater: Effluent Water Headed for a Stream

3. The Hydrology of Groundwater: Dynamics of the Groundwater Table

3. The Hydrology of Groundwater

● Types of aquifers ● unconfined – has an aquiclude below below ● confined – has aquiclude above and below above and below 3. The Hydrology of Groundwater

● Characteristics of some confined aquifers aquifers ● artesian (flowing) wells ● artesian flow (under pressure) 3. The Hydrology of Groundwater

● Complex geological environments ● perched water tables ● unpredictable flow conditions 3. The Hydrology of Groundwater

● Balancing recharge and discharge ● balance = stable water table ● excess recharge = rising water table table ●excess discharge = falling ● excess discharge = falling water table water table 3. The Hydrology of Groundwater

Groundwater:ExcessDischarge and the Cone of Depression

Groundwater:ExcessDischarge and the Movement of Salt Water

Groundwater:ExcessDischarge and the Movement of Salt Water

● Speed of groundwater flows ● hydraulic gradient ● Darcy’s law ● Q = A (K  h / l) 3. The Hydrology of Groundwater

Groundwater: Darcy’s Law

● Some major U.S. aquifers ● U.S. Great Plains and midwestern states midwestern states ● Ogallala aquifer Water resources from major aquifers:

Water Resources: U.S. Withdrawal

WaterResources: The Great Ogallala Aquifer – only a few years left

Thought questions for this chapter If 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) ● karst features (karst topography) ●sinkholes ● sinkholes 4. Erosion by Groundwater

● Characteristics of areas with karst ● high rainfall and abundant vegetation vegetation ● limestone bedrock with joints ●significant hydraulic gradient ● significant hydraulic gradient 4. Erosion by Groundwater

4. Erosion by Groundwater: Karst

Erosion by Groundwater: Carlsbad Caverns, New Mexico

Erosion by Groundwater: Sinkhole in Winter Park, Florida in Winter Park, Florida

Thought questions for this chapter You 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 ● microorganisms in water ●other chemical contaminants ● 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 ppm 5. Water Quality

Thought questions for this chapter If 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) water ● hydrothermal (hot spring) water 6. Deep Water in the Crust

Water Deep in the Crust: The Origin of Hot Springs and Geysers

Mammoth Hot Springs, Yellowstone National Park

● Ancient microorganisms in deep aquifers aquifers ● active colonies of microbes that may have been there for millions of years are found in deep crustal groundwater may have been there for millions of years are found in deep crustal groundwater ● they live by dissolving minerals 6. Deep Water in the Crust

Thought questions for this chapter What geologic processes would you infer are taking place below the surface at Yellowstone National Park, which has many hot springs and geysers?

AquicludeAquifer Artesian flow Darcy’s law DischargeDroughtGroundwater Groundwater table Hydraulic gradient Hydrologic cycle Hydrology Hydrothermal water Infiltration Karst topography Meteoric water Key terms and concepts

PermeabilityPotablePrecipitation Rain shadow Recharge Relative humidity Runoff Saturated zone Sinkhole Unsaturated zone Key terms and concepts