Geo_notes-test2_spring_09.2

Geo_notes-test2_spring_09.2 - Geology Lecture Notes: Test #...

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Unformatted text preview: Geology Lecture Notes: Test # 2 2-12-09 Hydrologic Cycle: All water is trying to flow downhill to make it back to the ocean. Groundwater does the same They are in constant motion and exchange with each other 1. Ocean is the largest water reservoir 2. Ice comes in second 3. Ground Water- ice (glaciers and permafrost) 4. There is very little surface water compared to ground, ice, and, oceans. Surface water is the most highly depended on! Evaporation >Condensation >Precipitation Water can be taken out of this cycle for periods of time. ***Primary Source of water comes from the precipitation in the region. Annual Precipitation is based on an average --- rainfall is not consistent year to year. Georgia receives on average 43-58in but it may deviate from high-low Periodic-pattern that is seen regularly (deviations) Episodic-does not follow a specific pattern of time (unpredictable) Cyclical- (aka periodic) follows a certain pattern of time Shifts in climate (over larger time scale) Distribution of Earths Water: More than 97% of available fresh water is ground water, which far exceeds the volume of surface. Aquifer, Confined Aquifer, Unconfined Aquifer, Water Table --- terms to define (in the slide)------------ Without being confined the water table will rise or fall based on the rain level Discharge, Drawdown, Hydraulic Conductivity, Hydrostatic Pressure, Porosity, Permeability---terms to define (in slide)------------------ Good aquifers are porous and permeable ex.} Loose course grain rocks---sandstone, limestone, etc. Unconfined Aquifers-water continuously refills Confined Aquifers-must have a way to be recharged, or they become in a sense a non-renewable resource. Potentiometric Surfaces- (piezometric surface) the 2-D surface that represents the level to which water will rise in a tightly cased well. (see slide for diagram) Pumping Cone- the area around a discharging well where the hydraulic head in the aquifer has been lowered (aka Cone of Depression) Consequences:- Subsidence- a dropping of the land surface as a result of pumping---IRREVERSIBLE- Salt-Water Intrusion- the movement of saline groundwater into an aquifer formerly occupied by freshwater---ocean water intrudes ***Significant subsidence in California---bread basket area for farming Can cause large fractures and faults due to the lowering of the land level ---can happen overnight Large Salt-Water Intrusion in SE Virginia---due to large culminated cone of depression ***large meteor strike has a major affect on the intrusion 2-17-09...
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Geo_notes-test2_spring_09.2 - Geology Lecture Notes: Test #...

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