study guide part 2
study guide part 2 Geol370
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Popular in Geology
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This 9 page Study Guide was uploaded by Monica Huang on Monday April 13, 2015. The Study Guide belongs to Geol370 at San Francisco State University taught by Dr.Sklar in Fall. Since its upload, it has received 184 views. For similar materials see Geology in Geology at San Francisco State University.
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Date Created: 04/13/15
Study guide exam 2 part 2 Weeks Drought Types of drought definitions Meteorological 0 based on the degree of dryness in comparison to some quotnormalquot or average and the duration of the dry period 0 is different for each region since it relates to atmospheric conditions that differ from place to place 0 Drought periods begin with a meteorological drought Agricultural 0 occurs when low precipitation and soil moisture affect crop yields 0 links meteorological drought to agricultural impacts focusing on precipitation shortages soil water de cits reduced groundwater or reservoir levels needed for irrigation etc 0 usually evolves slowly over time 0 economic losses can be signi cant tens of billions of each year in US Hydrological 0 occurs following periods of extended precipitation shortfalls that impact water supply ie stream ow reservoir and lake levels groundwater potentially resulting in signi cant societal impacts 0 Because regions are interconnected by hydrologic systems the impact of meteorological drought may extend beyond the borders of the precipitation de cient area Socioeconomic 0 occurs when reduced water supply causes the demand for goods or services to exceed the supply such as when hydroelectric power production declines with reservoir depletion 0 is a comprehensive de nition that considers water rationing wild re events loss of life and other widespread impacts of water shortfalls What is Drought Drought drier conditions over an extended period of time Which of 3 class themes Variability in time and space Six industries at big risk from CA drought 1 Organic dairies Why 0 rely on pasturegrazing the cattle 0 Drought prevents irrigating pasture lands 2 golf courses Why 0 drought prevents irrigating 0 many courses invested in water storage 0 some using smart39 irrigation technology to conserve water 3 Breweries Why 0 many breweries required to reduce water consumption by 20 0 lack of surface water forced to use groundwater different taste 0 conservation more ef cient cleaning amp bottling processes 0 further restrictions could mean less beer 4 Sushi rice Why 0 Most US sushi served uses California rice according to California Rice Commission 0 rice acreage down 25 this year 0 rice eld habitat for birds brings regulatory constraints 0 upside quotCA rice farming has survived last 100 yrsquot 5 Ski industry Why 0 20132014 ski season skier visits down 30 in CA Why 0 20142015 season even worse 6 Marijuana growers Why 0 Cannabis plants consumer huge quantities of water 0 Twice as much pot grown today as in 2008 0 Water illegally diverted from streams at detriment of Salmon 0 Con ict now between ecologists shers and cannabis growers How is Drought Monitored and Assessed US Drought Monitor provides a general summary of current drought conditions Created by USDA NCAA and UNLincoln 0 Based on many drought indicators various indices outlooks eld reports 0 has 4 categories of drought and abnormally dry close to drought conditions US Drought Monitor Palmer Drought Index PDI PDI attempts to measure the duration and intensity of the longterm droughtinducing circulation patterns and is based on recent precipitation and temperature What are the Causes of Drought 1 Ocean amp atmospheric circulation patterns 2 Land and ocean temperatures 3 Soil moisture content Less soil moisture translates to 0 Less ET 0 Less condensation to clouds 0 Less precipitation from clouds 0 Less soil moisture Primer on Climate Weather Climate Primer on Climate state of the atmosphere at any given time and location 0 includes individual storm events state of the weather that can be expected months years or longer into the future 0 climate is a function of the atmospheric circulation patterns topography solar radiation and ocean circulation patterns What is Climate Change Climate change refers to a statistically signi cant variation in either the mean state of the climate or in its variability persisting for an extended period typically decades or longer Climate change may be due to natural internal processes or external forcings or to persistent anthropogenic changes in the composition of the atmosphere or in land use Intergovernmental Panel on Climate Change IPCC Climate change may be due to natural internal processes or external forcings or to persistent anthropogenic changes in the composition of the atmosphere or in land use Intergovernmental Panel on Climate Change IPCC High Plains Land Use 0 Agriculture is the dominate land use Irrigation water 0 97 of total withdrawals Maupin and Barber 2005 0 Drinking water Provides water for gt80 of the people within aquifer boundary Dennehy et al 2002 Week 10 Urban Hydrology ampLakes Limnology the study of Lakes How lakes are formed Types Layers of water Structure It39s not just H20 Chemistry Limnology the study of lakes Considers several factors about lakes 0 how the lake was formed 0 size 0 shape 0 topography and local geology 0 chemistry 0 regional climate 0 local biological communities 0 and human activities 0 Lake type classi cation is determined by how it developed 0 Three general lake classi cation systems 1 Lakeforming geologic events 2 Hydrologydrainage characteristics 3 Trophic status O Lakes are formed by glacial activity 0 glacial melt water forms lakes Pleistocene 25 MYA to 12000 yr before present Laurentide Ice Sheet 95000 to 20000 yr before present oProglacial lake lake formed by the damming action of a moraine or ice dam during the retreat of a melting glacier 0 At the end of the last ice age 10000 yrs ago large proglacial lakes were widespread in the northern hemisphere O Lakes are formed by volcanic activity o volcanic calderas rimmed basins that form from volcanic collapse can ll with rainwater and form lakes oExample Crater Lake in Oregon Cascade Mountains O Lakes are formed by tectonic activity 0 movement of the Earth39s crust can create lakes by forming rift ssures in rocks that ll with water Lake Types Hydrologic Activity O Lakes are formed by rivers that forms an oxbow lake Oxbow Lakes when the former meander becomes isolated from the rest of the river Lake Types Hydrologic Activity O Lakes are formed by sinkholes called sinkhole lakes Lake Types Human Activity O Lakes are formed by humans are reservoirs 0 usually constructed with a dam 0 reservoir functions water storage ood control recreation Lake Types HydrologyDrainage Characteristics O Lakes can be described by their water source and out ow 0 seepage lakes have in ow but no out ow 0 drainage lakes have in ow and out ow Lake Types Trophic Status O Lakes are categorized based on their trophic status which the level of nutrients and subsequent growth of biological organisms o trophic status a measure of a lake s productivity 1Eutrophic lakes nutrientrich 20ligotrophic lakes nutrientpoor 3Mesotrophic lakes in between eutrophic and oligotrophic Lake Types Trophic Status 1 Eutrophic lakes nutrientrich Example Lake Merced 0 High algal production from excessive nutrients 0 Lake bottom is muck decomposing organic debris Lake Types Trophic Status 1 Oligotrophic lakes nutrientpoor Example high mountain lake 0 Few small sh 0 Low vegetation density Lake Types Trophic Status Nutrients 0 Nitrogen N and Phosphorus P 2 most important for water quality 0 Organisms need N amp P to create energy and grow 0 Excessive N amp P overstimulate aquatic plant growth and death which accelerates eutrophication Eutrophication Plant and algae growth and decay which consumes DO 0 lack of DO for sh and aquatic plants sh kills 0 blocks sunlight and prevents photosynthesis Lake Structure 0 Strati cation layers 0 Temperature pro le with depth Lake Structure O Lakes are highly structured bodies of water 0 Large lakes usually stratify vertically into 3 physical layers based on density which is in uenced by temperature 1 Epilimnion top layer shallow warm well mixed layer where light can penetrate and plants and phytoplankton thrive 2 Metalimnion 3 Hypolimnion Lake Zones 0 Lake zones biological communities linked to the physical structure of the lake Lake Shasta Littoral zone nearshore zone where sunlight reaches the bottom sediment and aquatic plants grow easily Has most abundant aquatic life Plants are food for other organisms and habitat for sh Euphotic zone depth to which light can penetrate Two most common waterquality issues in lakes 0 Dissolved oxygen DO 0 Nutrients nitrogen and phosphorus How does dissolved oxygen DO get into water Diffusion random motion of molecules from higher concentration to lower concentration Moves toward equilibrium How does dissolved oxygen DO get into water Hydrodynamic dispersion physical mixing from moving water 0 In ow streams wind and waves Lake Water Budgets INFLOW OUTLOW CHANGE IN STORAGE Water Budget 0 Can be calculated for any storage volume some are easier to calculate than others 0 atmosphere 0 ocean o continent 0 watershed 0 stream segment 0 lake bPRDGEChangeinV Types of dams Embankment Dams Earth and rock ll typically in wide valleys on 508 ll 80 of dams Types of dams Concrete Gravity Dams Thick straight wall across valley Types of dams Concrete Arch Dams Thin arched wall in narrow canyon in hard rocks 4 of dams Pumped Storage Dam A giant ba Hery to store energy Pump water up when excess power ava Coffer dams Temporary dam to dewater39 a dam construction site liable Let water ow through turbines when more power needed AnaSt Francis Dam Completed in May 1926 200 feet high concrete arch dam 2nd largest in US at Yme storage for water supplytomy of a HydroElectric Dam Efopstream effects of dams Submerged Land Displacement of people and submergence of towns and land Globally 80 million people have been displaced by dams ects of dams on river systems and people Upstream effects of dams Submerged Land Three Gorges Dam on Yangtze River displaced 15 to 20 Million people Upstream effects of dams Greenhouse gas emissions Due to plant decomposition in reservoir Methane released from anoxic deep water Upstream effects of dams Greenhouse gas emissions In tropics emissions per unit energy can be greater than burning coal Upstream effects of dams MethylMercury Reservoirs eventually ll with sediment Coarse sediment forms delta at entrance to reservoir Fine sediment settles to bottom throughout reservoir Trapping of sediment leads to downstream effects Downstream effects of dams Channel Incision Due to quothungry waterquot effect Downstream channels starved of sediment Sediments eroded away are not replaced by supply from upstream Downstream effects of dams Coastal Erosion Rivers supply sand to coastlines Waves and currents move sand along shore and to deep water Dams trap sand more moved to deep water than replaced by river Downstream effects of dams Loss of ow oods Effects of Dams on Salmon Salmon are a keystone39 species because they bring marinederived nutrients to terrestrial ecosystems Dams linked to salmon decline Shasta Dam California Impacts of dams on Salmon 0 Block migratory access to upstream habitat o Trap gravel starving downstream channels 0 Reduce ood ows and scouring of sand 0 Loss of spawning and rearing habitat Restorationquot of salmon spawning habitat downstream of dams Gravel Augmentation Why do we remove dams o Dam failed 0 Dam was unauthorized 0 Economics 0 Recreational bene ts 0 required by National Par Options for Reservoir Sediment 0 Allow River to Erode 0 Remove Mechanically 0 Stabilize in Reservoirs Service 0 Safety 0 Ecological bene ts
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