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Lecture-19-F10 - EAS 111 General Announcements EAS 111...

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Unformatted text preview: EAS 111 General Announcements 11/15/10 EAS 111: Happy Hollow Park EAS 111: Happy Hollow Park What to expect: • Transportation to the field and back to campus on a Purdue bus – gather in lab • Flat, easy hike along paved roads and easy packed dirt trails. Two tiny hills to climb • About 1.5 hours outside What to bring? • Comfortable, walkable shoes + appropriate gear for weather • Something to write on and with – can leave other gear in bus • Your immense powers of observation, reasoning and thought Earth and Atmospheric Sciences 111 Fall 2010 Distribution of Water Distribution 17.01.a2 Lake Superior Superior Lake Lake Huron Huron Lake Lake Michigan Michigan Lake Lake Erie Erie Lake Lake Ontario Ontario Water Use in U.S. 17.02.a How Does Water Move? How Observe how water moves between settings Precipitation (rain, snow, (rain, hail) hail) Infiltration: Infiltration: water seeps into ground ground Groundwater Groundwater flows flows Groundwater flows Groundwater onto surface onto Condensation Air currents Runoff Evaporation (oceans, lakes, (oceans, rivers,…) rivers,…) Most precipitation Transpiration Transpiration iinto ocean; some nto evaporates on way from plants from down down 17.01.b1 What Influences Infiltration? Porosity: Proportion of Open Space Porosity: Which of the following have lower porosity and which Which have higher porosity? have High porosity Poorly Poorly packed packed clay particles which do not fit tightly tightly Crystals in Crystals granite which fit tightly tightly Rounded, sorted clasts do not Rounded, fit tightly fit High High porosity porosity Low Low porosity porosity Low porosity Poorly sorted clasts fit more Poorly tightly tightly 17.03.c Permeability: Pores Connected So Fluids Flow Which of the following have lower permeability and which have higher permeability? which High permeability Granite with many with connected fractures fractures High permeability Loosely cemented cemented gravels gravels 17.03.c Compacte Porous volcanic d clay clay rock with (shale) (shale) separate pores pores Low permeability Low permeability CPS: The best water-bearing body of rock or sediment (aquifer) would have the following properties: A. B. C. D. low porosity and high permeability low porosity and low permeability high porosity and low permeability high porosity and high permeability Groundwater Between Clasts Groundwater Most groundwater Most in pore spaces pore between clasts between Pores in upper Pores parts generally unsaturated unsaturated Below, pores Below, saturated with groundwater groundwater Top of saturated Top zone is water table water 17.03.a1 Groundwater in Fractures Fractures can contain Fractures groundwater May be the only pathways for water, if interconnected if More fractures = more water 17.03.a2 Groundwater in Cavities Some rocks, especially limestone, have cavities cavities Cavities can contain groundwater groundwater NOT where most NOT groundwater occurs groundwater 17.03.a3 Types of Aquifers Types Unconfined aquifer open to Earth’s surface and to infiltration infiltration Confined aquifer overlain by less permeable materials materials 17.04.c Perched aquifer underlain by low-permeability unit by Artesian aquifer: water rises in pipe (maybe to surface) in How Does Groundwater Accumulate? Rain or snowmelt can evaporate or used by plants evaporate Rain or Rain snow snow Seep Seep into ground ground Surface Surface runoff runoff Observe this figure and Observe note all the places where water could go water Wetlands and lakes Reach water table Reach and saturated zone and Below water table, Below groundwater may flow groundwater 17.03.b1 How Does Water Move Between the Surface and Subsurface? Surface Water can soak into Water subsurface and become groundwater groundwater 17.05.a1 Water table generally Water below surface, so water can seep in water Where water table intersects Where surface, water can flow out surface, What is the Geometry of the Water Table? Observe how the water table interacts with topography Similar to land surface, but more subdued 17.04.a1 Groundwater flows down slope of water table Water table cuts across rock units How Do Rivers Interact with Water Table? with Lower than water table: gain Lower water Observe how each Observe river relates to water table and flow of groundwater groundwater 17.05.d Higher than water Higher table: lose water table: Mound of groundwater below river below How Are Lakes and Wetlands Related to Groundwater? Groundwater? Perched above Perched water table water Observe the settings of Observe lakes compared to the water table water Water table Water intersects surface intersects Wetlands at Wetlands water table or perched 17.05.c1 On topographic bench On Valley bottom Effects of Pumping Groundwater Effects If the owner of Well A dramatically increased the rate of water withdrawal, what might happen to Well B? Before Before A. Well pumping B might start to interfere with the bigger well at A pumping B. Well B might run dry C. Nothing would likely happen at Well B B A 17.08.a After pumping: After cone of depression depression How Do We Study Groundwater? How Field studies: Field sequence and character of rocks rocks Measure discharge, Measure losses/gains, and water quality water Geophysical Geophysical surveys: depth to bedrock and water bedrock 17.07.a1 Drilling: verify geology, depth to water Drilling: table, provide samples, pump tests table, How Can Water Become Identify possible sources of surface water and Contaminated? Contaminated? groundwater contamination Factory wells, Factory spills, emissions spills, Fuel Fuel storage tanks tanks Dry cleaner Brought Brought by river by Brought from outside area by groundwater Households 17.09.a1 Mining and naturally Mining mineralized rock mineralized Landfill Farm Septic Septic tank tank Leaking Leaking tank in gas station station Truck Truck fuel spill spill EAS 111: Assignment for Wednesday 11/17/10 • Exploring Geology • Ground collapse from groundwater – 17.6, 17.8 section B • Slope failure, mass wasting – 15.7, 15.8, 15.9, 15.10, 15.11, 15.12 ...
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