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Environmental Science Exam 2 Week 8 - Flood plains- level areas adjacent to rivers - Lots of floods in China - US Floods- 70% of disasters each year - Flood waters contain sewage, drowned livestock, pollutants - Runoff- water flow when soil is full of water and there is excess water from rain- Stream- in channel confined in bed and banks - River- freshwater flowing towards ocean - Watershed- region drained by single river or river system - Amazon River Watershed  Amazon & water from Andes Mountains flow east to Atlantic Ocean Covers 40% of South America  1/5 of all freshwater comes from Amazon - Deltas: Fan shaped deposits- streams at base level  Rivers deposit sediment in deltas  Sediment causes branching channels  Amazon- no delta due to strong tidal bore - Bedload- coarse material moving on river bottom- Suspended load- fine material carried along in water column - Dissolved load- dissolved minerals in water - Meandering Rivers- low lying flat areas, S-shaped curves, contain large floodplains - Worlds Muddiest river- Chinas Haung Ho (Yellow River) - Floodplain- flat surface adjacent to river channel - Flood stage- overtopping of banks by water- Flood crest- highest level above flood stage river reaches during flood - Great 1993 Mississippi and Missouri River Floods - 2008 Great Midwest flood- Levee failure in Illinois- 2009- Red River Flood- lack of slope, becomes shallow lake, flat lake plain - Hydrograph- graph of river’s discharge or stage (height) vs. time - Discharge- (Q)= W x D x V , volume of water flowing past point of river in certain amountof time  D= height or stage W= width V= velocity - Flash floods- Riverine Floods- larger volumes of water than flash floods , rainstorms and spring runoff from melting snow- Delaware River Flooding April 2005- major snow cover in Pocono and Catskill mountainsand heavy spring rains - Flood forecasting- past events, ranking them, future possibilities - Recurrence Interval- average time between floods of a given size, return time- Artificial leeves- clay, sand, soil- Flood walls- concrete - Channelization- straightening, deepening, widening, clearing - Hurricane Floyd- (1999) costliest disaster in NJ history - Dams- hydroelectric power, irrigation, flood control, creation of lakes, drinking water- Three Gorges Dam- worlds largest hydroelectric dam 1) What is a river and its floodplain?River- body of flowing waterFloodplain- Level area adjacent to river 2) What part of the water cycle isG runoff?GWater flow when soil is full and there is excess water from rain end- then evaporates 3) What is a watershed?Drainage basin 4) What is a hydrograph? What is the definition of stage?Hydrograph- graph of rivers discharge Stage- Hieght vs time 5) What is the 100 year flood? What data is used in graphing a recurrence interval for a specific river?1% probability of occurring in any given year Hydrographs, flood recurrence interval 6) How affects does urbanization have on flooding?% of impervious cover (roofs, cement, asphalt) % of area served by storm sewers Alters natural surface runoff patterns Increases size and frequency of floods Less water goes into ground- more runoffReduces lag time- amount 7) What are some basic flood prevention methods (levees, flood walls, storm retention basins, channelization)? What are some pros and cons with them.Leeves- clay, sand, soilFlood walls- concrete Storm retention basins- holds water until flood subsidesChannelization- straightening, deepening, widening 8) How does land use affect flooding?Eliminates habitats and vegetation9) How do we assign flood insurance?Producing flood hazard maps which satisfies minimum standards of land use regulation within 100 year flood plain 10) Why are dams constructed? What are some adverse environmental effects from dams?hydroelectric power, irrigation, flood control, creation of lakes, drinking waterloss of land, habitat destruction, change in water quality, flow reduction and disease 11) What is a drought? Where do they usually occur?No water, deserts Week 8- Water Resources - Hydrosphere- 97.2% is ocean , 2.8% is freshwater - Infiltration- water soaks into ground - 100 gallons per person per day - Colorado River- used for water supply, among 7 states  Increased water demand: irrigation, requirements to meet energy development  States fought over legal entitlements  Dams- water storage and power generation have tamed river - Los angeles water shortages - Groundwater- water beneath earth’s surface, water beneath water table in zone of saturation, water filling pre space in soil and rock - Water table- - Spring- water table intersects ground surface, ground water discharge - Porosity- portion of material that contains open spaces - Permeability- connection between pore spaces - Aquifer- rock brings water to wells and springs, high porosity and high permeability (sand) - Confining bed- impermeable rock that doesn’t transmit water freely (clay, igneous, sedimentary, metamorphic rock - Confined aquifers- below and above confining beds, internal pressure- Artesian water- rises above level in aquifer - Potentiometric surface- elevation water in well- Over pumping effects Pumping too much water- lowers water tables  Pulling salt water into fresh water aquifers  Desalinization  Subsidence- sinking, settling, lowering parts of the crust of the earth- High Plains Aquifier- groundwater mining- water gulping corn, lowered water tables1) What is Infiltration?- Water soaks in ground 2) What is the definition of groundwater.- Water beneath earth surface 3) What are some characteristics of the water table? What is a spring?Spring- water table intersects land4) What is porosity? permeability?-Porosity- open spaces - Permeability- connection between pore spaces 5) What is the definition of an aquifer? confining bed? What are the basic characteristics of each? What are some examples of each (rock types)?G-Aquifier- rock brings water to well and streams, porosity & permeability, sand -Confining bed- all rock types- not porosity or permeability 6) What is the difference between a water table and a confined aquifer?-Water table- - Confined aquifer- below and above confining bed 7) Understand some of the basic effects of overpumping including groundwater mining (High Plains or Ogallala Aquifer), saltwater intrusion (and desalinization), and subsidence.- Overpumping- lowers tables - Desalinization- salt water combines with fresh- hard to

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