SUSTAINABLE PLANET GLY OF NAT RESOURCES
SUSTAINABLE PLANET GLY OF NAT RESOURCES GLY 120
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This 7 page Class Notes was uploaded by Tomasa Abernathy on Friday October 23, 2015. The Class Notes belongs to GLY 120 at University of Kentucky taught by Stephanie Schwabe in Fall. Since its upload, it has received 18 views. For similar materials see /class/228191/gly-120-university-of-kentucky in Geology at University of Kentucky.
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Date Created: 10/23/15
GLY 120 111809 I Precipitation generally increases in temperate regions 3560 degrees north and south atitiude I Decreases to less than 20 cm in the polar regions I Highprecipitation equatorial zones 0 Result of warm damp air rising into the atmosphere where cooling reduces its capacity to hold water producing torrential rains I Arid regions that flank the equatorial zones 0 Result of cooler and drier air descending from the upper atmosphere 0 As the air descends it is warmed by the Earths surface I The ability of the sinking air to hold water increases I The warmer air absorbs water creating arid regions 0 Other factors affecting water resources 0 Increase in demand with growing population 0 lmproper use poor farming and irrigation 0 Access to potable watersafe drinking water 0 Hydrology 0 Study of movement and characteristics of water 0 Includes surface water and groundwater o The hydrologic cycle I Cycling of water through different surface processes 0 Different earth spheres atmosphere hydrosphere I Akin to the rock cycle 0 Hydrologic cycle 0 Actually starts with the sun than 0 With evaporation of water from the surface 0 Water vapor rises into the atmosphere condenses and eventually falls back to Earth as precipitation I Part of this precipitation runs off on the surface as streams or forms glaciers I Part infiltrates into the ground I Plants use some of this water I Large quantities evaporate and return to the atmosphere 0 Precipitation rain snow ice 0 Evapotranspiration transfer of water in the ground in the air 0 Evaporation liquid to vapor heating of a water body 0 Transpiration plant respiration o Runoff into surface reservoirs o Infiltration into subsurface reservoirs o In some parts of the hydrologic cycle the water moves very quickly 0 In other parts water moves very slowly stored in reservoirs 0 Annual quotwaterfluxquot is enormous Water is an important component of many Earth processes 0 Weathering o Moderates climate 0 Support of life forms How much water Where 0 Oceans 9741 salt water I Covers 71 of the earths surface 0 Glaciers and polar ice 198 I Largest reservoir of fresh water 0 Ground water 592 I Shallow groundwater 31 I Largest reservoir of usable fresh water I Depth of 8 km O Lakes Freshwater 007 Saline lakes and inland seas 008 Residence Time 0 Average length of time that water spends in a particular system 0 Long residence times I Long time for rock dissolution reactions I High contaminant accumulation I Slow turnover rate Typical residence time for natural waters 0 Atmosphere9 days 0 Ocean water 2500 years 0 Glaciers and ice caps 9700 years O Lakes 17 years 0 Rivers 16 days 0 Shallow ground water variable but closer to atmosphere times 0 Deep ground water 1400 years 0 Soil moisture 1 year Human activities can affect the hydrologic cycle residence time o 1 Overuse of groundwater o 2 Paving and increasing ru noff lowers infiltration and recharge o 3 Global warming and altering climate melting polar ice 0 4 Irrigation in dry areas increases evaporation o Dams and reservoirs decrease in wetlands marshes swamps o Channelization of a river removal of flood plains Water on land 0 What happens to water that falls in the form of precipitation I lnfiltration into the groundwater system I A portion of the precipitation that reaches the Earths surface seeps into the ground I The amount of water that infiltrates the soil varies with o The degree of land slope o The amount and type of vegetation 0 Soil type and rock type 0 And whether the soil is already saturated by water I Evaporation into the atmosphere 0 Water is transferred from the surface to the atmosphere through evaporation the process by which water changes from a liquid to a gas I Surface runoff into lakes rivers swamps oceans o Runoff is the movement of land water in to the oceans chiefly in the form of rivers lakes and streams o Runoff consists of precipitation that neither evaporates transpires nor penetrates the surface to become groundwater o What determines how much water becomes runoff 0 Duration and intensity of rainfall I Fast downpours vs prolonged drizzle infiltration 0 Frequency and pattern of rainfall I Is the ground already saturatedgt I Quick warming trend and rapid snow melt o Vegetation patterns I Dense canopy thick humus trees sow runoff I Sparse or no vegetation fast runoff 0 Human activity I Urbanization storm sewers deforestation 0 Surface runoff is highly variable for any storm 0 General principles for rivers and streams o A river or stream is I Flowing water I Confined to a channel 0 Source rain or melted snow 0 Path runoff or infiltration 0 Water flowing downhill erodes and transports soil and sediment 0 River base level flow ceases formation of river delta 113109 0 Mississippi River Delta 0 Load the amount of sediment carried by the river 0 Bed load hops or rolls along the river bottom larger grains 0 Suspended load suspended in the water finer grains 0 Dissolved load dissolved ions and salts not grains 0 Value of rivers 0 Water source for drinking irrigation etc 0 Cheap transportation eg river barges o Hydroelectricity 0 Rich soil for agriculture in flood plains 0 Different kinds of rivers o Valleys are Vshaped steep sides narrow channel 0 Channel occupies all of the valley bottom no flood plain o Follows a strait path no meanders due to the steep gradient 1040 mkm I Gradient the slope of a stream generally expressed as the vertical drop over a fixed distance I Gradient is steeper upstream and gentler downstream o Meandering rivers wander or meander back and fourth across a broad valley and a flat plain floodplain o Floodplain that part of a valley that is inundated during a flood I Consists of sediment deposited during flood stages I Natural levees form during periods of flooding I Located in the plains and near the mouth of the river I Gradient 1 mkm o Meanders path of least resistance Rivers change course with time due to constant erosion and deposition 0 Outer bend erosion 0 Inner bend deposition I Placer deposits golddiamonds o Abandoned meander oxbow lake Drainage basin watershed the area drained by a river and its tributaries o Tributaries and drainage ditches coalesce o Drainage divide ridges that separate the drainage basins Fundamental unit of surface runoff system 0 Problems in one segment affect the entire watershed o Basin boundaries do not always coincide with political boundaries More drainage in Atlantic than Pacific Canals use natural flow of water or pump water out to support irrigation and urban areas 0 Dams reservoirs store water for many uses 0 Downhill flow no pumping required Dec 3 Control floods Irrigation and drinking water Hydroelectric power Recreation Spillways overflow channels prevent overflow and dam failure OOOOOO Advantages I Control flooding I Electric power I Water source I Recreation 0 Disadvantages I Interference with 0 Wildlife 0 Natural river cycles I Dam failure 0 Flooding o Flooding occurs when a river overflows its channel due to high discharge levels 0 For an average river in a humid climate flooding occurs ever 12 years 0 Floods affect more people than all other geologic hazards I USA 20000 communities and 6 million homes 10 of the population are located on flood prone land I 4 billion in damage and 100 deaths per year I In Europe and Asia annual deaths exceed 8000 people 0 Floods are I Seasonal or cyclic I Infrequent and unpredictable I Caused or exacerbated by human activity Causes of Flooding 0 Heavy rain 0 Rapid snow melt heavy snowfall quick warming trend 0 Storm surge tropical storms and hurricanes o Dam failure Types of floods o Upstream flash floods brief but severe floods due to a sudden intense rainstorm floodwaters rise and fall rapidly I Typical for mountain rivers affect small areas but can be devastating I Water cant infiltrate the ground quickly enough goes directly into the river I Made worse by impermeable soils steep slopes and a lack of vegetation Downstream floods a large meandering river spreads over floodplain o Often due to prolonged rainfall and snow melt over a large region water levels rise and fall more slowly o The ground is saturated with water now here else to go 0 Examples of downstream floods I 1997 red river flood in NW minnesota and E north Dakota I 1993 Mississppi and Missouri Riverfloods 12 billion in damage stationary fron t that allowed for the convergence of warm 0 Hydrograph I A graph that depicts flood data discharge vs time 0 Recorded a river gauging station monitors stream velocity and stageheight I Lag time time between maximum rainfall and maximum flood stage peak discharge rate 0 Upstream floods short lag time short flood duration 0 Downstream floods longer lag time longer flood duration 0 Human influence on discharge levels 0 Urbanizationbuilding of cities sidewalks roads parking lots roofs guttersetc 0 Development of cities around rivers can intensify the effect of flooding increases flood size and decreases lag time I lmpermeable barriers prevent infiltration enhance runoff I Sewers send water directly into local rivers I Buildings take up space on the floodplain I Construction leads to sediment pollution higher flood levels 0 Lag time has increased since urbanization 0 Response to flood hazards o Historically the response has been to try to prevent the problem I To control the water by constructing dams I Modify the stream by building levees I Or even rebuild the entire stream so it will drain the land more efficiently 0 Flood control I US army corps of engineers USACE o The US has made a large investment into flood prone areas which are inhabited and developed and need protection 0 Problems with flood control I Can lure people to live in a certain region I Transferflooding problem I Make flooding problem worse 0 Transfer problem I Levees prevent flooding in the problem areas but cause flooding further downstream in areas not thought to be problems which sometimes do not have eeves 0 Make even worse I When people move onto the floodplain the result is a decrease in the size of the floodplain which results in greater flooding 0 Methods of flood control I Channelization straightening deepening lining with concrete or widening a channel 0 Flood control and erosion control discourages meanders o Allows for faster flow rate 0 Problems increased downstream erosion and flooding o Adverser effect the river ecosystem I Dams creates a reservoir that can be filled during periods of high rainfall 0 Benefits 0 O O Hydroelectricity Recreation lrrigation water 0 Problems sediment pollution and rapid filling of the reservoir 0 Increased downstream erosion 0 Possible dam failure I Artificial levees man made walls of san dirt and mud along the sides of a river channel 0 Problems 0 O O O O lncreases bank height higher discharge Flood walls concrete St louis New Orleans stronger but more expensive Levees can fail by overtopping Seepage flow through Seepage flow under 0 The Kissimmee river example of channelization
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