GEOS 1004 Lecture Notes - Lecture 25: Transpiration, Igneous Rock, Saltwater Intrusion
8 Mar 2018
School
Department
Course
Professor
Document Summary
Hydrologic cycle: exchange (not creation and destruction) of water between (cid:498)reservoirs(cid:499) (cid:523)ocean, atmosphere, lakes, rivers, groundwater, glaciers, biosphere(cid:524). evaporation precipitation transpiration run-off infiltration groundwater flow ice flow. Dryland systems cover 40% of the earth and 1/3 of the population; where do these people get their water? groundwater = water stored underground in pore spaces and cracks in rock. ~1% of total water (100x more than lakes and rivers). Aquifer = layer of rock with usable water. Fractures are very important for low-porosity or low-permeability rock; igneous, metamorphic (e. g. the blue ridge). The shape and structure are also important; juxtaposition of (cid:498)confined(cid:499) aquifers against impermeable layers (aquicludes). Pressure; groundwater flows horizontally or upwards because it is under hydraulic pressure from elevation change (high to low) in the aquifer. Flows to position of equal height (potentiometric surface). One other major aspect of groundwater is important for water resources. Rate of groundwater flow; in most rocks, very slow; inches per day.
