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Midterm

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Department
Geography
Course
GGR100H1
Professor
Sarah Finkelstein
Semester
Fall

Description
Geography chapter 9 The hydrologic cycle Hydrosphere ● Over the ocean has majority of the waters, most of the hydrological action is over the water. ● 419 evaporation and 382 precipitation over water so its just staying over the water mostly ● Wind pushes cloud to over the land and eventually rains ● Some of land precipitation comes from ocean other is from evapotranspiration ● Transpiration comes from plants releasing water from photosynthesis ● 69 plus 37 = 106 which is the precipitation on land ● Precipitation some just runs off a stream or creek down back to the ocean ● Overland flow is where the water is simply going down the land not exactly a stream or river ● Soil is porous so it can take water and rainfall will penetrate and infiltrate then that will go to lakes rivers soils and even oceans ● Rain and vegetation interaction first is that ● 1) trees can intercept the tree and tree will retrain and that can be up to 50% of the rain ● 2) throughfall stemflow is part of throughfall ● 3) runoff to stream etc ● 4) infiltration --> soil water or groundwater ● Difference between soil water and groundwater, groundwater is completely saturated in groundwater there's no space in between ● Soil water there can be found air and spaces in the holes unsaturated ● In wetland dig just a bit to hit a groundwater and drier will be a lot further down south ● Ground water will also flow downhill but a lot slower, rock can contain water, some rocks are permeable and water can form in crystal lattices of rocks ● Soil water, absorbs light to moderate rain will infiltrate, it's also easily lost to evapotranspiration ● SOil WATER BUDGET --> (good for agriculture to know how much we need for irrigation) ● Precipitation is input then losses ● First loss is evapotranspiration which breaks down to potential evapotranspiration - the need ● Further explanation of that is potential need is how much water we need to keep the water at a constant level while it's evaporating ● It's demand - the shortage (how much you add) ● The second term of the budget is the overland flow plus the streamflow ● Third term is change in soil moisture? ● For us in toronto, in winter it snows but the demand isn't there so its a surplus and it's stored and only released in summer when its hot and the demand is there this is when the storage is released. ● Environment is not providing enough moisture and so water your garden in summer ● GROUNDWATER, it comes from soil water, water table is the boundary between soil and ground waters ● When you drill a well you get a cone of depression, and if you take it out too fast it'll take too long to refill ● Aquifer:are the rocks that permits the flow of water ● Aquiclude :the rocks that don't permit the flow of water (shale) ● Perched is when it's sandwiched between two surfaces etc ● Difficult to clean groundwater ● Ogallala Aquifer is the sand and gravel type, groundwater really close to land surface, It's a vital aquifer for agriculture -------------------------------------------------------------------------------------------------------------------------- Weathering and Mass wasting Chapter 13 Lithosphere ● chemical weathering happens when lithosphere come in contact with a liquid ● process of wearing down landscape is called denudation ● geomorphology study of what's happening on earths surface is ● endogenic processes is happening deep within the solid earth ● exogenic processes, outside of earth so on the surface of earth ● Processes that make land surfaces such as uplifting and volcano ● and processes that rid of land which are weathering ● Mineral is a material of elements crystal structure and chemical formula and they make up rocks ● granite is made up of number of different types of minerals ● igneous rocks crystallized directly from magma ● sedimentary rocks are made up of small rocks ● metamorphic rocks are exposed to high pressure and high temperature ● New mountains are jagged and spiked and big and then through weathering they turn into smaller ones ● 1)Weathering:attacks rocks through physical work \ regolith forms ● chemical weathering ● as they take place they form sediments and that is eroded transported by wind water or ice ● These form major landforms → drummlands ● biosphere atmosphere and hydrosphere attacks bedrock (gasses, water, etc) ● sedimentary rocks formed by layers of sediments ● Regolith is the process where big bed rocks are broken down to smaller rocks as they rise to top to form new landscapes ● size of sediment is useful for understanding geo ● physical weathering --> no chemical reactions ● water freezes it increases by 9% volume ● frost wedging is the process of water freezing and increasing in volume to break rocks ● salt wedging is a cave formation from salt ● pressure release jointing (unloading) is a physical weathering ● formed deep in earth then ● release of mass on top of rock then it expands up due to less mass ● so rock expands because less mass on top of it now it forms dome shape, domes ● chemical weathering ● reaction!! ● increase temperature increase the rate of the reaction ● also precipitation increases the chemical weathering ● rainwater is naturally acidic ● co2 in air plus water makes carbonic acid so this is natural ● natural pH of water is acidic because of weak acid ● plus human activity ● mildly corrosive dissolves rock ● limestone --> carbonation because its very susceptible to chemical weathering so it has its own name carbonation ● granite is very resistant to weathering and peridotite is very not resistant to weathering ● H+ ions goes into rock since its porous and interacts chemically with rock ● H+ replaces K+ so its breaking it down ● feldspar minus potassium is just clay ● Oxidation --> such as rust ● sandstone has iron and through oxidation has adopted red colour which is iron oxide and makes red soils as well ● carbonation ● caco3 by carbonic acid and everything goes to solution ● sources of acid is is rain soils etc ● sinkholes --> holes opening in ground suddenly, they are results of chemical weathering of limestone bearing rocks, ● florida has many limestone so it happens a lot in florida ● development of karst --> ● in order to get karst you need limestone with many joints so water can get through, also ground water is weakly acid and promotes disintegration of rock ● vegetation also promotes fumic acid to break down ● no karst in arctic despite limestone because water is frozen ● formation of caves because of water under the ground ● water may get a river stream that falls down there ● dry climates more physical, more wet more chemical ● more cold more physical more hot more chemical -------------------------------------------------------------------------------------------------------------------- ● how quickly a slope will waste away? ● slope angle, steeper the slope the faster until waste away ● the materials the slope is made of, size / coherence / hydration / weight ● moisture content how sticky it is etc mobility ● tectonics movement of substrate creates instability on substance ● geomorphic threshold is the point where the slope falls down stable to unstable = point ● angle of repose is the angle where the slope won't get higher, dry sand will have a small angle of repose ● saturated sand is better at holding its angle through cohesion, moisture increases the angle of repose. ● Too wet, when complete saturation then moves downslope, angle decreases ● categories of mass wasting ● 1) Fall + avalanche ● occurs fast. ● They are associated with snow or water, create large piles of rocks at the base of slope ● talus cone is the term for rock waste, which have fallen off of slope. ● avalanche tracks are where there are no trees, it removes all the vegetation on its way down (geomorphic events) ● 2) Slides ● sudden movement of unsaturated regolith ● moves as a unit, not small units ● plate tectonics leave rocks on top unstable so higher risk of mass wasting ● 3) Flows ● high moisture dependant, mud: soil and very fine rock material and water ● 4) Creep is a slow process of persistent deformation of a slope. ● Freeze thaw , wet dry materials pushing slow ● slope is slowly creeping down hill, over long time periods ● Solifluction is a perma frost. ● summertime top part of soil will have unthawed, the moisture in top layer of soil then it'll be like gel and can creep slowly ● st lawrence valley there was water during ice age that came, and that frozen ice deposited clay and these are prone to land wasting ---------------------------------------------------------------------------------------------------------------------- ● chapter 14 geomorphology: river systems and fluvial landforms ● endogenic -->geology ● exogenic processes --> geomorphology ● erosion --> transport of surface material (sediments, regolith) ● wind (eolian processes) ● a lot of sediments and a lot of wind ● where there is vegetation then wind is less important ● whereas deserts wind is more important since there’s more open area for wind to act ● ice (ontario is primarily shaped by ice) ● water ● 1) Coastal areas (waves) ● 2) streamflow --> dominant process, it's everywhere ● a lot of words --> creek, stream, river ● rivers exist because landscape has to drain, so precipitation goes back to ocean essentially ● precipitation falls on stream ● overland flow --> falls on land then goes to stream ● base flow --> even when no rain water still flows, groundwater to stream channels ● those 3 add up to stream flow ● watershed --> area that is collecting water and is separated by a drainage divide = easily understandable with map ● ● gravity gives structure of network ● insolation --> provides rain to form network ● infiltration --> baseflow ● stream discharge = flow --> m^3/s^-1 = Q the letter ● Q=wdv ● wd=A area ● area times velocity ● (really basic math) ● Q= volume flowing per unit time ● rapid --> area decreases so velocity goes up so stream flows fast ● pool --> area increases velocity slows down ● volume generally stays the same ● Q goes up means more water added ● Q goes down means water removed ● HYDROGRAPH ● when it rains there's a lag period because it takes time for the water to get into the stream ● during the rain fall the increase is mostly overland flow just a bit and direct water onto st ream ● but over time the water from drainage really piles up and then the Q really increases then as it is decreasing base flow starts and it has the greatest lag time ● differences in land cover effects hydrograph ● duffins creek --> more vegetation ● highland creek --> more housing ● pavement has higher run off compared to vegetation that infiltrates ● urban area has higher risk of flooding ● duffins creek has a higher base flow since there are vegetation for infiltration ● river flood ● stream charge cannot be withheld by the channel ● so basically water goes on land ● floodplain --> flat ground that receives water from channel ● floodplain gets built up with sediments in the form of alluvium ● flood frequency ● high magnitude happens rarely ● low magnitude happens more frequently ● large rocks in stream means that in the past there were large flows of water ● rocks have to somehow move and its by large streams ● friction will keep water up top ● energy is dissipated when water moves and work is done ● it is done to erode and transport sediment ● stream capacity --> what size of sediment or rocks or boulders can the stream transport ● base level is point on landscape where stream is going, either lake or ocean ● ground zero --> destination of water ● ultimate base level is sea level ● decrease sea level then streams gets more potential energy and greater entrenchment -- > steeper ● lower base level --> more work done by stream essentially ● rise up level of sea or any base level --> then gradient is reduced, less potential energy less gradient, reduced sediment transportation, sediments fill valleys, so valleys lift ● fluvial processes ● running water flattens hills and mountains ● what kind of landforms we get? ● 1) flood plain (flat) ● 2) ravines (valleys carved) ● 3) Fan ● how does river erode? ● 1) overland flow ● 2) vegetation (defends sediments) ● 3) rain splash loosens sediments ● 4) erosion of channel running ---------------------------------------------------------------------------------------------------------------------------- Still lecture 14 ● abraison → impact of particles on bed of banks ● corrosion → chemical weatherng ● ● landforms are classified into to two broad catogories ● 1) erosional ● 2) depositional landforms ● erosional landform → Ravines form from flowing water ● depositional landform → the floodplain where the sediments go to / fan is also depositional land form ● rivers powerful forms of erosion ● within channels there is erosion, water breaks down rocks that its flowing by ● it also chemical breaks down materials ● boulder>cobble>pebble>granule>sand>silt>clay ● in solution sediments can be transported in stream channels ● water is a good dissolver ● turbulent flow (suspension load) ● sands are kept up top since there small in size ● and pebble and boulders are toward the bottom of the stream ● saltation is another word for bouncing boulders bottom of river ● larger the velocity, larger the boulders ● flotation --> vegetation can fall on top and get transported ● st lawrence --> is our drainage basin ● geometry of drainage basin \ drainage basins, what are they made of? ● structure --> important ● substrate --> important ● igneous rocks are resistant and shale easily broken down ● radial drainage → normally a mountain ● annular --> going parallel to mountain ● parallel --> steep slope ● trellis --> folded bed rocks due to tectonic plates therefore water flows through these folds ● reach is term we use for a section of stream channel ● usually uniform characteristics ● reaches --> 3 categories ● 1)straight channel, not curving and not bending just straight so very strong bedrock control and contained ● 2) meandering rivers --> stream wanders in S shaped patterns these make landforms such as point bars, cutbanks, pools and riffles and floodplains ● 3) braided reaches ● water slows down at curves in meandering rivers ● also at the undercut bank is where the water erodes that part since the water is curving down ● also at the point bar there is deposition because water isn't fast enough to keep material going ● where do we get these? slope is less gradual in the mountains, there is more flatness ● also softer materials then it is easier to erode ● alluvium on top of bedrock, river deposited ● meander neck is where the water decides to take faster path the it cuts off the other part of the water then it forms a ox-bow lake because the water stopped flowing that way and goes down, path of least resistance ● floodplains are relatively flat ● relief component is the edges of the stream ● we call this accretion --> floodplain development by vertical accretion ● cut off bank --> erosional ● meander scar are easy to spot ● nickpoints in stream ● 2 type of bed rocks --> shale ● and more resistant rock ● shale layer gets eroded away ● so therefore creates a ledge --> a nickpoint thus theres a waterfall ● niagara falls --> goo
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