9

							Water Moving Underground
Chapter 9

The World’s Water
• 97% Salt Water • 2.5 % Frozen Fresh Water • .5% Usable Fresh Water

Water Cycle
• Hydrosphere- water of Earth’s surface

• Water Cyclemovement of water in the hydrosphere, driven by sunlight

Water Cycle

Water Cycle

Recharge
• Rains more than plants use • Extra water stored in soil

Surplus
Rain Continues Soil becomes full Extra water runs off Water Table raises

Usage
• Plants use more water than it rains • Plants Draw from soil supply

Deficit
• Need for moisture continues • Soil Storage runs out

Water Budget Graphs
• Water budgets describe how much water is received and used in a region • Graphs show the moisture supply versus the moisture need for a region

Can Rocks Hold Water?
• Porosity- percentage of a volume that is pore space • Shape- more round increases porosity • Sorting- poorly sorted reduce porosity • Cement filling reduces porosity

Permeability
• Rate that liquids go through pore spaces • Increases with porosity (NOT ALWAYS TRUE)
– Holes must connect

• IMPERMEABLEliquid can’t get through

Capillary Water
• Water that sticks to grains • Only evapotranspiration can remove it

Water Table

Water Table
• Depth depends on rainfall, season, soil thickness, climate • Water Table is at the surface at swamps, lakes, rivers etc. • Hundreds of meters below surface in deserts • Few meters below surface in forests, farms

Wells
• Ordinary Wells- holes dug down to the water table to bring groundwater up • Wells must be dug below the lowest level the water table could fall to during dry seasons

Aquifers
Aquiferspermeable materials that carry groundwater

Artesian Formations
Artesian Formationaquifer under nonporous layers holds groundwater Artesian Wellsrelease water from Artesian formations

Groundwater Pollution
• Fertilizers, Toxic chemicals and even salt can get into groundwater as it moves through the soil • Restricting use of these pollutants can help clean up water

Conserving Groundwater
• Excess use of groundwater can lower the water table • Artificial methods of groundwater recharge can help refill the water table

Water Temperatures
• Water below the surface (up to 20m) remains the average temperature for that region • If average temp is below freezing water is permanently frozen PERMAFROST

Water Temps
• Below 20m temps rise 1°C for every 40m • Deep wells or springs may have warm water

Paint Pots
• Volcanic activity can also heat water to boiling temps • Paint Pot- hot water comes up through thick clays

Geysers
• Boiling hot springs that gush hot water and steam periodically • Blockages or constrictions in the waters path to the surface put it under pressure

Fumaroles
• Hot gas and steam escape from cracks in the ground

Minerals in Groundwater
• As water goes through the soil it dissolves minerals • Type of soil, temperature and length of passage determines mineral content • Hard water contains many ions, especially calcium • Artesian water is harder than groundwater • Groundwater is harder than river water

Mineral Springs
• Contain to many minerals to drink • Caused by
– easy dissolved rock – acids in water – Water is hot, minerals dissolve easier

Caverns
• CO2 in the air dissolves into rain • Carbonic Acid is created • Limestone underground is dissolved by carbonic acid in water

Sinkholes
• If the cave roof dissolves or falls in a sinkhole forms

Karst
• Regions with lots of sinkholes, sink ponds, caves and lost rivers. • Lost rivers form when streams flow underground and resurface kilometers away • Major areas MI, S. Indiana, Kentucky, Tenn, Florida

Dripstones
• Calcite deposit from dripping water • Stalactites- hang from ceiling • Stalagmites- come up from the ground • Pillars- form when the two meet

Travertine
• Calcite deposit around a mineral spring

Geyserite
• Silica deposit formed from the hot igneous rocks the water passed through

Petrified Wood
• Minerals dissolved in water replace the decaying wood of buried trees

The End