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24 Cards in this Set
- Front
- Back
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What are the major uses for water?
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Agriculture, irrigation, industry, household uses.
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Where is most freshwater found?
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groundwater
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What are the major sources of water we use?
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seawater (can’t use), glacial ice caps, underground (too salty, too deep), lakes & streams
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What are the characteristics of a good aquifer?
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High porosity, high permeability
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What types of rocks make good aquifers?
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Sandstones and carbonates
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What is porosity?
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volume of a rock not occupied by solid, volume of empty space in a material
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What is permeability?
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solids ability to allow liquid to pass through it, ability of material to allow fluids to pass through an interconnected network of pores
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How do characteristics of the rock (grain size, sorting, grain shape, etc) affect porosity?
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Well sorted-high porosity, more rounded-high porosity, bigger size-more porosity
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What geologic processes affect porosity (fracture, cementation, etc.) and how do they affect it?
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Fracture and dissolution increase secondary porosity
Cementation, compaction, lithification decrease primary porosity |
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What is primary porosity? Secondary porosity?
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Primary-space that remains between solids grains or crystals immediately after a sediment accumulates or a rock forms
Secondary-new pore space in rocks created sometime after a rock first forms |
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How does pumping affect the water table?
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Lowers locally and creates cone shape
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Be able to speculate where springs might be located.
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-Where ground surface intersects the water table in a discharge area, such springs typically emit water upward into rivers, ponds, or valley floors
-where a perched water table intersects the surface of a hill -where downward-percolating water runs into a continuous impermeable layer and migrates along the top surface of the layer to a hillslope -where a particularly permeable layer or zone intersects the surface of a hill, water percolates down through the hill and then migrates along the permeable layer to the hill face -where a network of interconnected fractures channels groundwater to the surface of a hill -where flowing groundwater collides with a steep impermeable barrier, and pressure pushes it up to the ground along the barrier, faulting can create such barriers by juxtaposing impermeable rock against permeable rock -ARTESIAN SPRINGS form if the ground surface intersects a natural fracture (joint) that taps a confined aquifer in which the pressure is sufficient to drive the water to the surface |
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Know how vertical drop, distance of flow, hydraulic conductivity affect flow rate.
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Hydraulic gradient increases-rate increases. Steeper slope-faster flow. Vertical drop/flow distance = rate. Hydraluic conductivity (K) includes permeability and fluid viscosity and the higher the K, the faster the rate.
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What is a karst terrane? How does it form? What types of rocks? What types of land forms and geological features does it include?
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Landscape where caves develop. Made of limestone. Water table and limestone. Cave network forms. Water table drops. Sink hole roof collapses.
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hydraulic gradient
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slope of water table (change in H over d)
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Darcy’s law
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Equation that states the amount of water passing through an area depends on hydraulic conductivity and the gradient
Q=K*(H/D)* A Q=volume of water passing through area K=hydraulic conductivity, permeability and viscosity H/D=gradient A=cross sectional area |
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Perched
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quantity of ground water that lies above regular water table because lens under it is impermeable and prevents water from sinking down to water table
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Artesian
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well where water rises on its own
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Aquicludes
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sediment or rock that doesn’t transmit water
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Unconfined aquifers
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layer of water just below earth’s surface and below porous layers that rain water can seep into
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Aquifers
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sediment or rock that transmits water easily
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Cementation
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phase of lithification where cement which consists of mineral that precipitate from ground water fills space between clasts and attaches grains together, after this occurs, no longer porous
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groundwater table
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boundary between pores full of air and pores of water, approx. parallel to ground
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vadose
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word used to talk about water above level of ground water in unsaturated zone
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