IGCSE Geography Paper 1 Notes PDF
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This document is a set of notes on river environments and the hydrological cycle. Topics covered include the importance of rivers, water usage (agriculture, industry, and domestic), water scarcity and surplus, and the elements of the hydrological cycle. It is suitable for IGCSE Geography students.
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River Environments - Syllabus Overview 4 Lesson 1: Is Water Really A Scarce Resource? Why are River Environments Important? Why do rivers need to be sustainable managed? ow much water is usable and easily accessible?...
River Environments - Syllabus Overview 4 Lesson 1: Is Water Really A Scarce Resource? Why are River Environments Important? Why do rivers need to be sustainable managed? ow much water is usable and easily accessible? H Despite water seeming to be an abundant resource, only 3% is freshwater - the rest is saltwater. Out of this, only 0.3% is easily accessible - on the surface of the earth. Most of this water is in rivers and lakes (see diagram). What are the uses of water? Agriculture: forirrigation(supplying water to land or crops to help them grow), drinking water for livestock Industry:generating electricity (eg: through Hydro-electric power [HEP]), as acoolant for industrial processes (eg: manufacturing steel) Human hygiene:bathing / showering, flushing toilets,drinking, cooking, washing clothes, washing dishes Leisure:sailing on lakes and ponds, watering golfcourses, sport fishing on rivers, watering gardens Global water use by sector is: ○ 70% agriculture - irrigation of crops and water for livestock ○ 20% industry - producing goods and generating energy ○ 10% domestic - toilets, cooking, cleaning, washing How does the use of water vary around the world? The use by sector varies across countries depending on whether they aredeveloped, emerging or developing(see class activity notes youmade below and the online powerpoint in class files for the maps; you should review the maps so that you can practise the skills stated in the syllabus). CONTINUES ON NEXT PAGE 5 Figure 1:Which countries use the most amount of water?Why? Examples of countries Reason Figure 1:Which countries use the least amount ofwater? Why? Examples of countries Reason Figure 2, 3 and 4:Which countries use water for thefollowing the most? Agriculture Industry omestic use D (leisure and human hygiene) Figure 5:Which countries havewater shortages? Why? Examples of countries Reason CONTINUES ON NEXT PAGE 6 Figure 5:Which countries may have awater surplus?Why? Examples of countries Reason Figure 6:How has the use of freshwater changed overtime? Why? Trend Reason Key Terms & Definitions: Water abstraction- water removed from any sources(commonly: lakes, rivers, aquifers and reservoirs). ○ Aquifersare rock and/or sediment that holds water.The water that is held in aquifers is known asgroundwater. ○ Areservoiris a large natural or artificial lakeused as a source of water supply. Water demand - this is the volume of waterrequestedby users to satisfy their needs. Water consumption- this is the amount of water thatis no longer available for use. Water supplyis theportion of abstracted water thatis delivered to users, excluding any losses that occur during storage, transport, or distribution. Water stressrefers to theamount of freshwater extractedas a percentage of available freshwater resources. Which section of the syllabus does this topic connect to? Section 1.3: River environments are of great importance to people and need to be sustainably managed Section 1.3 (a): Uses of water, including agriculture, industry, human hygiene and leisure, and the rising demand for and supply of water: areas of water shortage and water surplus. Skill: use different maps (paper or online) to investigate the impact of human intervention. 7 Lesson 2: Where Does Our Freshwater Really Come From In the Hydrological Cycle? Which section of the syllabus does this topic connect to? Section 1.1: The world’s water supply is contained in a closed system – the hydrological cycle. Section 1.1 (a): The hydrological cycle: characteristics, stores and transfers. ctivity 1:After we discuss this in class, (i) highlightstoresin one colour andtransfersin A another colour and (ii) label if water is stored as a solid, liquid or gas gas in every store. ctivity 2:How would the following affect the watercycle? A Draw a flowchart to show the changes, using as many key terms from the hydrological cycle as you can! A B uilding artificial reservoirs B D raining water from wetlands to build cities C U sing water from rivers, lakes and aquifers for homes D Deforestation E D ry season - lack of rainfall F elting glaciers M and ice sheets 8 heHydrological Cycle(also known as the water cycle)is a continuous movement and T circulation of water on Earth. Characteristics: It is aclosed system: this means that there is afixed amount of water within the system and water is recycled as it moves through it. This is because water does not enter or leave the atmosphere. It is aglobal circulationof water. Within this system, water changes its state and can be seen in solid (ice), liquid (water) and gaseous (water vapour) form. The hydrological cycle hastransfers / flowsandstores;it doesnotinclude inputs or outputs as it is a closed system. Storesare places where water is held for a periodof time. These include: ○ Atmosphere:clouds (water is as water vapour or liquidwater droplets) ○ Land:puddles, lakes, rivers,reservoirs, vegetation,soil, ice-sheets, glaciers, aquifers. Aquifersare rock and/or sediment that holds water.The water that is held in aquifers is known asgroundwater. Areservoiris a large natural or artificial lakeused as a source of water supply. Interceptionis how precipitation is prevented fromreaching the ground and hence is stored. This is usually by precipitation being caught on leaves or branches, or in puddles. ○ Sea: oceans and icebergs. ○ Note: whilst the amount of water in the hydrological cycle remains the same, the amount of water held in eachstorecan. Transfers / flowsare the ways in which water is movedaround the hydrological cycle. ctivity 3:(1) Label the types of transfers / flowsin the diagram below. (2) Which types of flows A are missing? Label these, using an arrow to show the direction of flow 9 Transfers / Flowsin the Hydrological Cycle Activity 4:match the key term with the correct definition. Transfer / Flow Definition A Evaporation lants take up liquid water from the soil and release this water as P water vapour from its leaves to the atmosphere.(Hintto remember it: plants ‘breathe’ the water back into the atmosphere). B Infiltration ater vapour cools and changes into its liquid form (water). This W can happen in the atmosphere (eg: clouds are formed as a collection of water droplets) or at ground level (eg: dew). C Evapotranspiration ater is converted from liquid to a gas (water vapour) by the heat W of the sun. This takes place in areas such as the sea, lakes, rivers and soil. The water vapour is stored in the atmosphere. D Condensation orizontalmovement of water through rocks in theaquifer. The H water can eventually reach rivers, lakes and the sea. E Transpiration his is the combined transfer of water from the earth’s surface T (through evaporation) and plants (through transpiration). F Precipitation ater movesvertically into the surfaceof the land. W (Hint: it “infiltrates” the soil) G G roundwater flow ovement of watervertically through the soil itself.This can be, M / Base flow for example, through the soil and into the groundwater store / aquifers. H O verland flow / iquid or solid water that falls to Earth as a result of condensation L runoff in the atmosphere. This includes rain, snow, and hail. I Percolation here is more water than the soil can absorb so the water moves T over the surface of the soil(hint: “runs off”). Thiswater can move faster down slopes due to gravity and is eventually absorbed by nearby rivers, lakes or sea. J Throughflow ater enters ariver or streamand moves through this. W (Hint: the flow is confined within a channel). K Canopy drip recipitation (eg: rainfall) reaching the ground in a forest by P draining down the trunks of trees or stems of plants. L C hannel flow / recipitation drips off the leaves and branches of trees and plants P river flow onto the ground or plants below. M Stem flow orizontalmovement of waterthroughthe soil.Itcan eventually H reach a stream or river through the soil. 10 Lesson 3: How do the Drainage Basins Ignite Water Wars? Which section of the syllabus does this topic connect to? Section 1.1(b): Features of a drainage basin: source, watershed, channel network, mouth. drainage basinis an entire river A system and the surrounding land that influences the river system—it is the area drained by a river and its tributaries. It is also known as acatchment areaorriver basin. watershedis the high land that forms A the boundary of a river drainage basin. It usually separates two drainage basins, but there are exceptions. For example, the drainage basins of smaller tributaries are included within the drainage basins of larger rivers. hefeatures(which are the visible forms) T of a drainage basin, include: Source- where a river begins (eg: an upland lake,springorglacier). ○ Aspringis a point on land where groundwater fromaquifers rises up to the surface. Mouth- where a river meets a larger body of water(eg: a lake, sea, reservoir) Confluence- the point at which two streams or riversmeet. Tributary- a small river or stream that joins a largerriver. Channel- this is where the river flows. Drainage network: the pattern of tributaries and riverswithin a drainage basin. ○ Drainage density:this is the total number of channelsdivided by the total area of the drainage basin. Drainage basins with lots of channels have a high drainage density Drainage basins with few channels have a low drainage density ○ Drainage densities are affected by a number of factors: During times of drought, rainfall reduces and channel flow reduces. This reduces the drainage density. During summer, when snow melts, there is more channel flow, which increases the drainage density. Open system -this means that the drainage basin hasinputs(water coming in; for example: by precipitation)and outputs(water releasedout; for example: to the sea or atmosphere). As a result, the amount of water in a drainage basin would vary over time. ○ Avoid a common error:the hydrological system is aclosed system (no inputs and outputs). The drainage basin is an open system. Activity 1: Task 1: On Figure A, label: (i) mouth, (ii) confluence, (iii) tributary, and (iv) channel. Task 2: Figure A shows a drainage basin with labels of some processes that take place in this region. Highlight each of the following in different colours: (a) transfers, (b) stores, (c) inputs and (d) outputs. 11 T ask 3: Are there any stores, transfers, inputs or outputs that are not labelled? Label these as well! Figure A: Diagram of a drainage basin and the process that are happening within it 12 Lesson 4: Can you read a Storm Hydrograph? Which section of the syllabus does this topic connect to? Integrated Skills: Draw and interpret storm hydrographs using rainfall and discharge data. Recall Activity: Drainage Basins & Data Analysis Practice Figure A (i) On Figure A, mark the following: (a) Confluence that is closest to Bostcastle (b) Tributary of the River Valency that is closest to Bostcastle (c) Mouth of the River Valency (ii) Is Boscastle part of the drainage basin of the River Valency? Explain your choice. Yes it is as it makes up the mainstem drainage basin. Mainstem = valency -https://education.nationalgeographic.org/resource/tributary/ ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. Questions continue on next page 14 Figure B: Rainfall and River data collected at Boscastle (iii) According to Figure B: ( a) What is the rainfall at 13:30 hours?............................................................................................... (b) What is the amount of water flowing in the river at 13:30 hours?.................................................. (c) At what time is the rainfall the highest?......................................................................................... (d) When does the rainfall in Boscastle stop?.................................................................................... (e) How does the amount of water in the river at Boscastle change between 12:30 and 20:00? ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ( f) Why is there a gap in time between the rainfall at Boscastle and the amount of water flowing in the river at Boscastle? (Hint: steps in the water cycle…) ime for the water to flow (throughflow - takes time, runoff - fastest, groundwater flow - slowest). T Interception (puddles, vegetation, obstructions on the ground) End of Questions 15 nalysing a Storm Hydrograph A A river’sdischargerefers to the amount of waterthat passes a given point on a stream or river within a given period of time. It is measured in cubic metres a second (cumecs) storm hydrographshows the changes in river dischargebefore, during and after a storm event. A It is one graph with the variations in a river’s discharge (as a line graph) and rainfall (as a bar graph) over time shown on it. The time that it usually covers is just the time taken for a storm to pass (a few hours or days). An example is shown below: Base flow- this is the usual discharge of the river. ○ If there is no input to the drainage basin of a river, the water would be at base flow. Peak rainfall- highest rainfall during a storm. Rising limb- shows the rise in the discharge ofa river during a storm. The steepness of the rising limb indicates how quickly the discharge increases. Peak discharge- highest level of discharge. Lag time- the time difference between peak rainfalland peak discharge. There is a delay between these because it takes time for the water to find its way to the river. ○ A shorter time lag occurs when the water reaches the river more quickly. Recessional limb- the river discharge returns backto usual levels (base flow) as the extra water brought by the storm moves downstream or infiltrates the ground. A steep falling limb suggests that water is leaving the drainage basin quickly. ○ Note that the falling limb shows that water is still reaching the river but in decreasing amounts. Bankfull- The water level at a stream, river or lakeis at the top of its banks and any further rise would result in water moving over its banks onto the land around it Storm flow -the additional discharge of the riverdirectly related to the passing of the rainstorm. hydrograph shows you the ways in which a river is affected by a storm. This helps us to A understand discharge patterns of a particular drainage basin, which in turn helps to predict flooding and plan flood prevention measures. 16 Knowledge-Check igure B: Rainfall and River data collected at Boscastle F (iv) According to figure B above: (a) What is the peak rainfall?....................................................................................................... (b) What is the peak discharge?.................................................................................................. (c) How long is the lag time in Figure B? Show your working. ( d) Is the rising limb or the recessional limb steeper?.................................................................. (e) Using Figure A and B, explain why the discharge in the river decreases back to base flow. ………………………………………………………………………………………………………………….. …………………………………………………………………………………………………………………. (f) What is the percentage increase in water level from 12.30 to 18.00? Show your working. (g) What is the percentage decrease in water level from 18.0 to 20.00? Show your working. (v) Draw a storm hydrograph on graph paper to show the following data. 17 ctivity 1:Which river is more likely to flood duringa storm? A A river floods when it has too much water to hold, causing the water to overflow from itsbanks(a bank is the side of a river). ydrographs for different H he river that is most Explanation for your choice T scenarios.Peak rainfall likely to flood… occurs at the start of the (select the correct x-axis for all graphs. answer) as a large H large drainage basin is able to hold A drainage basin more water (greater channel flow). This Has a small increases the capacity of a river - so the drainage basin river would take a longer time to reach bankfull discharge. as a forested H egetated land increases interception - V vegetation in its which reduces overland flow and drainage basin throughflow. This in turn reduces storm Has bare land (no flow and the risk of bankfull discharge. vegetation) in its drainage basin as gentle valleys H teep valley sides increase overland S surrounding the flow and reduce infiltration - which river increases storm flow and the risk of Has steep valley bankfull discharge. slopes surrounding the river aspermeable H Impermeable rock prevents infiltration (allows liquids or and increases overland flow - which gases to pass increases storm flow and the risk of through)rock in its bankfull discharge. drainage basin Hasimpermeable (does not allow liquids or gases to pass through)rock in its drainage basin 18 Activity 2 Column 1 Column 2 Column 3 Factor an this increase C Explain your answer in column 2 the risk of a river flooding? (yes / no) ow drainage L his reduces channel flow and increases the risk T density of bankfull discharge. igh amount of H his increases overland flow and throughflow - T rainfall which contributes to storm flow and increases the risk of bankfull discharge. nowstorm (not a S ater is stored in its solid form on soil and W rainstorm) vegetation. This reduces channel flow and storm flow. rtificial drainage A rainage systems that connect to the soil D system in cities that increase infiltration and percolation - leading to connect to soil and storage of water as groundwater. This can also canals lead to throughflow - which increases the risk of storm flow. If the drains connect to canals, this can increase channel flow and increase the risk of bankfull discharge. iver is next to a R here is increased overland flow and less T road and pavement infiltration as the ground is impermeable. This increases storm flow and the risk of bankfull discharge. iver has many R ater can be stored in lakes and reservoirs. This W lakes and reservoirs reduces channel flow and storm flow. longated basin E hannel flow is faster and this reduces bankfull C shape (left on the discharge. diagram below) 19 Lesson 5: River Regimes: What Forces Control the Rise and Fall of a River's Waters? ast lesson, we looked at the variation in discharge due to a short-term cause such as a storm. This L lesson is focused on a river regime. riverregimeis the seasonal variation in the dischargein the river over the course of a year. It A takes into account factors such as precipitation, temperature, and the features of the surrounding landscape. River regimes can be shown on anannualhydrographor a map. Figure A: River in Turkey Figure B: River in England he area has hot, arid summers but there can T he drainage basin is flat (no steep slopes), T be intense downpours of rain during the winter. covered in vegetation and the rock underneath The rock underneath this drainage basin is the soil is permeable chalk. Adamis also in this impermeable chalk. area to control the flow of water - it stores water in areservoirduring droughts and lets it out during floods. igure C: River in Canada F Figure D: River in the Sahara desert The drainage basin contains glaciers and T he climate is very dry so river levels are very snowfields. Snow falls in the winter and melts in l ow or non-existent. It only rains occasionally, the summer. but when it does rain it rains a lot in a short period of time. Glossary Reservoir: a large natural or artificial lake usedas a source of water supply. 20 D am: a barrier constructed to hold back water andraise its level, forming a reservoir. Dams also have a gate which can control the amount of water in the reservoir by letting out excess water. Water abstraction: (taking water from rivers, lakes,and aquifers for various uses, such as drinking, irrigation, and industrial cooling) hy are the river regimes different for the locations shown in Figure A-D? Complete the table W below with your responses. One reason is completed for you as an example. Reason Explanation ater W he river regime for the river in the Sahara desert shows a sharp drop in discharge T bstraction every time it rises. This is because the water is scarce in a desert environment and a ence the people living there would extract any water available for their own use (eg: h rinking, washing clothes). Further, the overall discharge is low as groundwater is d xtracted for use, which reduces groundwater flow. e Climate 21 Figure E omework Question: H Using Figure E, analyse why the storm hydrographs of Clapham Beck and Austwick Beck are so different. Which section of the syllabus does this topic connect to? Section 1.1(c): Factors affecting river regimes: precipitation, including storm hydrographs, temperature, vegetation, land use, water abstraction, dams. Integrated Skills: Draw and interpret storm hydrographs using rainfall and discharge data. 22 Lesson 6: How Do Erosion, Transportation, and Deposition Transform Rivers? Which section of the syllabus does this topic connect to? Section 1.2(a): Fluvial processes involved in river valley and river channel formation: erosion (vertical and lateral), weathering and mass movement, transportation and deposition, and factors affecting these processes (climate, slope, geology, altitude and aspect). ivers change the shape of drainage basins, primarily through thefluvial processes:erosion, R transportation, deposition,weatheringandmass movement. Glossary Fluvial- relating to rivers ○ River bed- bottom of the river ○ River bank- sides of the river Erosionis the process in which earthen materialsare worn away and transported by natural forces such as water. ○ Erosion can occur as a result of wind and ice as well; you will learn about this later. Weatheringis the breaking down or dissolving of rocksand minerals on the surface of Earth. The broken down segments remain where they are. Mass Movement - movement of material down a slope. Transportationis the way in which rivers carry material(known asload)from one place to another Depositionis the process in which earthen materialsare left behind, or built up, on a landform. Load- includes: (1) material that has fallen intothe river and (2) material which has been eroded by the river from its banks and bed. ○ Bedload: material at the bed of a river ○ Alluvium: this is a loose, fertile soil or sedimentmade up of sand, silt, clay, and gravel. It is formed due to erosion at the upper course of rivers and is deposited by rivers and river floods in other landscapes (eg: a floodplain). Aspect- this refers to the direction in which a slopefaces. It can also refer to the physical features of a river (eg: a waterfall, the bends in a river) etc. ○ Meander- this is a bend in a river. How does Erosion Happen in Rivers? There are four main types of erosion: Hydraulic actionis the wearing away of rocks intwo ways: (1) As the water rushes along, it slams against the river’s banks and bed, constantly hitting and grinding against the rocks and soil. This force alone can wear the land down over time. (2) River rocks often have cracks in them. As the river water flows, it pushes air and some water into these cracks. When this happens, the air and water trapped inside the cracks get compressed, which puts pressure on the rock. Over time, this pressure can cause the rock to crack 23 A brasion- when rocks and other materials carried by the water scrape against a surface (such as thebedor thebanksof a river), wearingit down over time. Attrition- when rocks that the river is carryingknock against each other. They break apart to become smaller and more rounded. Solution / Corrosion- when the flowing water dissolvescertain types of rocks, eg limestone. The four types of erosion above can erode a drainage basin either vertically or laterally: Vertical erosionincreases the depth of the riveras the river erodes downwards Lateral erosionincreases the width of the river asit erodes sideways ow is this Eroded Material Transported in Rivers? H There are four types of transportation that happen in rivers: Traction- large, heavy pebbles are rolled along the river bed. This is most common near the source of a river, as here the load is larger. Note that traction in the dictionary means: the action of pulling something over a surface. Saltation- pebbles are bounced along the river bed, most commonly near the source. Note that saltation in the dictionary means the action of leaping or jumping. Suspension- lighter sediment is carried (suspended) within the water, most commonly near the mouth of the river. Solution- the transport of dissolved minerals andchemicals. 24 How Does Deposition Happen? When a river does not have enough energy to carry materials it drops them; in other words, deposition occurs. The heaviest material is deposited first, this is known as thebedload.The lighter materials (eg:alluvium) are carried further downstream to bedeposited. The dissolved materials are carried out to sea. hy does deposition occur? W Complete the table below to show how deposition occurs at various places and times: At certain locations such as… t the inner bend of a river A here T is a narrow space for the water to flow at the bend → less (eg:meander) ater w flows at the bend → so the river has less energy → river water drops material (deposition) At the mouth of the river River bed and banks Friction entle sloping river cross G profiles at the lower course Reduces speed of flow During certain times such as… Lack of precipitation Abstraction upstream 25 Debate Preparation: CLIMATE SLOPE Erosion Erosion Transportation Transportation Deposition Deposition GEOLOGY ASPECT Erosion Erosion Transportation Transportation Deposition Deposition ALTITUDE A reason of your choice: Erosion Erosion Transportation Transportation Deposition Deposition 26 Lesson 7: How Do Weathering and Mass Movement Sculpt Rivers? Which section of the syllabus does this topic connect to? Section 1.2(a): Fluvial processes involved in river valley and river channel formation: erosion (vertical and lateral), weathering and mass movement, transportation and deposition, and factors affecting these processes (climate, slope, geology, altitude and aspect). Recall: What is the difference between weathering and erosion? eathering W There are three types of weathering: Physical weathering- rocks are broken down into smallerpieces without any changes to its chemical composition. Rocks are broken down by rain, wind and other atmospheric processes. xample of E Explanation of Process Physical Weathering Freeze-thaw In a cold climate, liquid water seeps into cracks in a rock and freezes into ice. When water freezes as ice, it expands, which slowly widens the cracks and splits the rock. As the temperature increases (eg: during daytime), the ice melts into liquid water, which can seep through the cracks in rocks again for the process to start again. Exfoliation he outer layers of rock expands when exposed to high temperatures during T the day and contracts when exposed to low temperatures at night. As this happens over and over again, the structure of the rock weakens. Over time, the outer layers flake off. C hemical weathering- rocks are weakened and brokendown due to chemical reactions that change the molecular structure of rocks. ○ For example:carbonation.This is when carbon dioxidefrom the air or soil combines with water to produce a weak acid, calledcarbonic acid, that can dissolve rock. Carbonic acid is especially effective at dissolvinglimestone. Biological weathering- rocks are weakened and brokendown by living organisms and their processes. gent of A Explanation of Process Biological Weathering 27 Plant he seed of a tree may sprout in soil that has collected in a cracked rock. As the T roots grow, they widen the cracks, eventually breaking the rock into pieces. Over time, trees can break apart even large rocks. Animals nimals, such as moles, dig underground and trample rock aboveground, A causing rock to slowly crumble. ass Movement M There are a number of types of mass movement, but in river valleys there are two main types: Type Slumping (Rotational Slide) Soil Creep Definition lumpingis when ahuge sectionof S S oil Creepis theslowandsteady the river bank or valleyslides rapidly downward movementof theupper along acurvedslope. layersof the soil on a slope. Causes here are two main causes that T his happens because the material is T occur together or at different times: constantly under a small amount of (1) The bottom of a valley or the river stress that causes it to slowly change bank is eroded by the water shape over time, without breaking flowing against it. This makes the apart. slope unstable and the overlying material slides down. or instance, when soil is saturated F (2) Heavy rain on the slope: with water, it expands outward and (a) makes the soil on top heavier becomes more compact. When the soil so that it slides down dries, it contracts and loosens, causing (b) makes it easier for the soil to the material to be pulled down the slide by acting as a lubricant slope slightly under the influence of gravity. Over many wetting-drying cycles, the soil moves slowly down the slope. Diagram 28 Picture oil creep is the slowest of all mass S movements, with movement less than a centimetre per year. However, there are signs of soil creep over time: as the soil creeps downward, it can tilt trees and poles and bend straight fences. 29 Final Debate Preparation: CLIMATE SLOPE Weathering Weathering Mass Movement Mass Movement GEOLOGY ASPECT Weathering Weathering Mass Movement Mass Movement ALTITUDE A reason of your choice: Weathering Weathering Mass Movement Mass Movement 30 Lesson 8: What Processes Carve Out Upland Landforms Such as V-shaped Valleys, Interlocking Spurs and Waterfalls? s rivers begin high up in the mountains, waterflowsquickly downhillin the upper course, A resulting invertical erosion(this is when theriverbedis eroded). This results inupland landforms(landforms found in the upper course ofa river) such as Waterfalls, V-shaped Valleys and Interlocking Spurs. river can flow over different rocks - A some are hard and some are softer. As water flows, it erodes the rocks. However, it erodes layers of softer rock more quickly and easily than the layers (orstrata) of harder rock. hat are Waterfalls? W Awaterfallis whenwater flows steeply downwardover alargedrop in a riverbed. How are Waterfalls Formed? (1) There is a layer of hard rock overthe soft rock at the riverbed. The water that flows over the hard rock, into the soft rock, will erode the soft rock throughabrasionandhydraulic action. This is known as differential erosion. (2) At the base of a waterfall, a plunge poolis created by the flowing water and fluvial erosion (hydraulic action and abrasion). This deepens the waterfall. (3) Splashbackfrom the falling waterundercutsthe hard rock further. Thus, thehard rock will beundercutuntilit creates anoverhang. (4) Over time, theoverhang will collapse into the river below because there is no support to hold it. It can break up into smaller rocks as it collapses, which can result in more abrasion,making the waterfall deeper. he process of how a waterfall forms T continues, with soft rock eroding and hard rock collapsing. This results in the waterfall retreating upstream, carving a steepgorge into the landscape as it does. 31 Glossary Stratameans layers Differential erosionis when softer rocks in the streambedwear away (or erode) faster than harder rocks. Aplunge poolis a deep basin at the base of a waterfallwith turbulent water. Splashbackin a waterfall refers to the process wherethe water, after plunging down the waterfall, hits the plunge pool at the base and splashes back towards the rock face behind the waterfall. Undercutmeans to wear away (or cut) the part belowor under something. Anoverhangis a part of something that extends (orhangs) over something else. Agorgeis a narrow valley between hills or mountains,with almost-straight rocky walls and a stream running through it. Label the features of a waterfall you can observe in the pictures above. Draw and annotate the diagram below to show how a waterfall forms. 32 V-shaped Valleys hat are V-shaped Valleys? W This is a valley whose typical cross section is shaped like a 'v'. These valleys have steep sloping sides and a narrow gap in between. How are V-shaped Valleys formed? (1) Rivers begin high up in the mountains so the waterflows quickly downhillin the upper course, resulting invertical erosion(this is when the riverbed is eroded). (2) The river cuts a deep notch down into the landscape usinghydraulic action, abrasion and corrosion / solution. (3) As the river erodes vertically, the sides of the valley are exposed toweatheringwhich loosens the rocks. (4) Some of the weathered material will fall into the river throughmass movementand this will steepen the sides of the valley. Over time, the channel becomes wider and deeper, creating aV-shaped valley. (a) The rocks which have fallen into the river assist the process of abrasion and this leads to further erosion. They can also be transported downstream. nowledge-Check: K What are the differences between a gorge and a v-shaped valley? Interlocking Spurs hat are Interlocking Spurs? W Interlocking spurs are ridges of land that jut out into a river valley. As the river winds around these harder rocks in the upper course, it creates a zigzag pattern, making the spurs appear to "interlock" from the sides of the valley. How are Interlocking Spurs formed? (1) Rivers begin high up in the mountains so the water flows quickly downhill in the upper course, resulting invertical erosion(this is when the riverbed is eroded). 33 (2) As the river flows, it encounters areas of harder rock that are more resistant to erosion. The river can't easily erode these hard rock sections, so it has towind around them. (3) The river bends around these hard rock obstacles,eroding the softer rock on either side. Over time,this creates a series of ridges that jutout into the valley:these are calledspurs. (4) As the river continues to wind through the valley, it createsmore spurs on alternating sides, which appear to"interlock" with each otherwhen viewedfrom above or along the valley. These are calledinterlocking spurs. What features do you observe in the picture below? Label these! Which section of the syllabus does this topic connect to? Section 1.2(c): How river landscapes change over the course of a river, with distinctive upland and lowland landforms, including the formation of valleys, interlocking spurs, waterfalls, meanders, oxbow lakes, floodplains and levees. Integrated Skills: Use GIS to map river systems. 34 Lesson 9: How Do Meanders, Oxbow Lakes, Floodplains and Levees Form in Lowland Areas? s the river makes its way to the middle course, it gains more water and therefore more energy. A As a result,lateral erosion(erosion of the banksof the river) starts to widen the river. owever,vertical erosion is still present in themiddle courseas the river is still flowing from higher H altitudes to the sea which is at a lower altitude. t the same time, deposition of material also increases in the middle course, as the river loses A velocity(speed) at certain sections of the river:the river does not have the energy to carry its load so it deposits these. combination of increased deposition and increased lateral erosion formsdistinctivelowland A landforms(landforms found in the middle and lowercourse)such as meanders and oxbow lakes at the middle courseandfloodplains and levees inthe lower course. Meanders hat are Meanders? W Ameanderis a large, looping bend or curve in a river, typically found in the middle and lower courses. It is alowland landform. How are Meanders Formed? (1) As the river flows over a relatively flat landscape, small bends or curves begin to formdue to variations in the riverbed, obstacles, or differences in the river's velocity. (2) As a river goes around a bend, most of the water is pushed towards the outside. This causesincreased speedand thereforeincreasedlateral erosion (through hydraulic action and abrasion) on the outside bend. Theundercutting of the river bank forms ariver cliff. (3) Water on theinner bend is slower, causing the water to slow down and depositmaterial, creating a gentle slope of sand and shingle known as aslip-off slope. (4) Over time, the continuous erosion on the outer banks and deposition on the inner banks cause the bends tobecome more exaggerated, leading to the formation of distinct, snake-like curves known asmeanders. Knowledge-Check: How is a Meander Different from Interlocking Spurs? 36 Oxbow Lakes hat are Oxbow Lakes? W This is a U-shaped body of water (lake) formed from an abandoned bend in a river. It is alowland landform. How are Oxbow Lakes Formed? (1) Due toerosion on the outside of a bend and deposition on the inside, the shape of a meander will change over a period of time. (2) Lateral erosion narrows the neck of the land within the meanderand as the process continues, the meanders move closer together. (3) When there is avery high discharge (usually during a flood), the rivercuts across the neck,taking anew, straighter and shorter route. (4) Depositionwill occur tocut off the original meander, leaving a U-shapedoxbow lake. nowledge-Check: What features do you observe in the K picture below? Label these! 37 Floodplains hat are Floodplains? W A floodplain is an area of land which is covered in water when a river bursts its banks. It is usually found in the lower course of a river (it is a lowland landform) and stretches from the banks of the river to the outer edges of the valley. ow are Floodplains Formed? H Floodplains form due to both erosion and deposition. (1) In thelower courseof a river,lateral erosion on the outer edge of a meander can wear down the valley slopes, making the valleywider and flatter,with no interlocking spurs. (2) During a flood, water overflows from its banks andinfiltrates the soilsurrounding the river on either side. (3) The water that infiltrates the soil,depositsa layerof sediment and material (rich in minerals). (4) Over time, theheight of the floodplain increasesas material is depositedon either side of the river and becomesa marshy land that is rich invegetation. hy are Floodplains Important? W Floodplains are often agricultural land, as the area is very fertile because it's made up ofalluvium (deposited silt from a river flood). Use a highlighter to mark the floodplain of theMississippiRiver (USA). 38 Levees hat are Levees? W These are mounds ofalluviumalong the bank of a river, at the floodplain - so it is a landform usually found at the lower course of a river. It is alowland landform. How are Levees Formed? (1) Sediment that has been eroded further upstream is transported downstream.When the river floods, the sediment spreads out across the floodplain. (2) When a flood occurs, the river loses energy. (3) Thelargest material is deposited first on the sides of the river banks and smaller material further away. (4) After many floods,the sediment builds up to increasethe height of the river banks. This means that the channel can carry more water (a greater discharge) and flooding is less likely to occur in the future. What features do you observe in the picture below? Label these! 39 Lesson 10: Can You Read a Map? Recall Task:Match the contour lines with the shapeof the hill. ontour linesare lines on a map that C connect points of equal elevation (heights) in metres above sea level.They show the topography(the height and shape of the land). ontour lines are drawn for certain elevations C (heights) only so that the map is not too crowded. These lines are evenly spaced apart. ometimes not every contour line has a S number of metres written on it for the height of the land. If this is the case,you need to look at the height ofthe lines around it to work out what each line represents. In the picture on the right, the two missing heights would be 20m and 40m. What can contours tell you about the shape of the land? If the contours are close together, you’re looking at a steep slope. If the contours have wide spaces in between — you are looking at a gentle slope. If there are no contours at all– the land is flat. It also tells you where hills and valleys are located (see picture) 42 Excerpt of Key: Figure A: Map of the Lower course of River Kingsbridge Use Figure A to answer the questions below: (i) Which direction is the River Kingsbridge flowing?......................................................................... Questions continue on next page 43 ow Do You Calculate Distances On a Map? H Most maps have a scale so that we can calculate distances on maps. This is given by the scale statement (eg: 1:50,000) and/or by showing a scale line (pictured below). he scale statement shows how much bigger the real world is than the map. If the scale is T 1:50,000 it means that every 1 cm on the map represents 50,000 cm in the real world. he easiest way to work out astraight line distanceon the map is to use the scale line and a T ruler: (1) Hold the ruler between two points on the map that you want to know the distance between. In this case the distance shown on the ruler between then two points in 4 cm (2) Bring the ruler down to the scale line and hold it against it. In this case the 4cm on the ruler represents 4km on the map. So the real life distance between the two places is 4km. (ii) What is the distance from A to B in kilometres?............................................................................. (iii) What is the distance from A to B in miles?.................................................................................... Questions continue on next page 44 hat if you need to measure a curved distance ? W (e.g. a river or road) ( 1) Divide up the curved line (eg: road or river) into small straight sections. (2) Then, use a piece of paper and pivot the paper alongside the curved line, marking off straight sections on the paper’s edge. (3) When you have finished step (2) above, you do the same as before, and hold the whole distance up against the scale line. (iv) What is the distance of the river shown in Box C?....................................................................... How Can You Tell The Height Of the Land on a Map? You have to either: Use the contour lines:they have a number attached to them. This is the height in metres above sea level. For example, Point D on the figure on the right is at 200 metres above sea level and Point C is at 130 metres above sea level. Usespot heights:these are exactly the same as they sound. They give height (in metres above sea level) for one particular spot on the map. For example, the highest point of the mountain in the figure above is labelled with a spot height of 325 metres above sea level. (v) What is the height of the following locations: (a) Rickham.....................................................110-130m (b) The Parking spot at Soar.....................................................13 3 -Figure Grid References 4 A map often has grid squares over the top of it. These grid lines are to help you pinpoint a particular location. On most maps, each grid square represents 1km by 1km in real life. o give the grid reference, use the coordinates in thebottom-leftof the T square. Thevertical numbers (x-axis) always come first; then the orizontal numbers (y-axis).The grid reference for the h is therefore 0113. -Figure Grid References 6 Sometimes on a map we need to pinpoint a location within a 1 km square and need to be more precise. In this case we use 6 figure grid references. 45 ook at the grid on the right. We could easily give the four figure grid reference for the square L with the orange and blue balls as 1201 using the method explained above. o give a more exact 6 figure grid reference, you T must imagine that the grid square is divided into 100 little squares: e number the new imaginary squares from 0-9 W going up and across the square. To give the 6 figure grid reference for the blue ball , we insert numbers in between the 4-figure grid reference. So: 1201 would be 121011. The orange circle would be: 126017 (vii) What is the Grid Reference for: (a) Snapes Manor?..................................................... (b) Public Telephone at East Portlemouth?..................................................... (viii) What do the following grid references show: (a) 765356..................................................... (b) 696391..................................................... 46 Practice Questions Grid squares represent 1 km by 1 km Figure X Figure Y ( a) What is the grid reference of: (i) Cross Fell (Point A)? …………………………………….. (ii) High Force? …………………………………….. (iii) Cow Green Reservoir? …………………………………….. ( b) What is the height above sea level of: (i) Cross Fell? …………………………………….. (ii) The Source of River Tees? …………………………………….. (c) Which direction is the River Tees flowing? …………………………………….. ( d) What is the distance between (i) Cross Fell and the Source of River Tees? …………………………………….. (ii) Cross Fell and High Force? …………………………………….. Questions continue on next page (e) Describe the topography near the Source of River Tees using Figure Y. 47 ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. Skills: Can You Find River Landforms on a Map? 48 49 50 Figure B: Changes in Landscape Along a Long Profile Practice: Reading an OS Map to Identify Landforms on a Long Profile The following series of maps shows different sections of the River Tees in the UK. Complete the table below. You can use Figure B above to help you as well. hich section of the river W is this? Upper course Middle course Lower course tate three reasons for S your choice: (1) (2) (3) Figure C 51 hich section of the river W is this? Upper course Middle course Lower course tate three reasons for S your choice: (1) (2) (3) Figure D hich section of the river W is this? Upper course Middle course Lower course tate three reasons for S your choice: (1) (2) (3) Figure E 52 hich section of the river W is this? Upper course Middle course Lower course tate three reasons for S your choice: (1) (2) (3) Figure F hich section of the river W is this? Upper course Middle course Lower course tate three reasons for S your choice: (1) (2) (3) Figure G 53 Lesson 11: How Does a River Change Along its Course? Case Study: River Tees Figure A: Drainage Basin of the River Tees Figure B: High Force Waterfall ecall Task:Complete row 1 and 2 in the table below.Figure A and B above and Figures C-G in R Lesson 10 will help you identify the river landforms. pper course of River M U iddle course of River L ower course of River Tees Tees Tees 1 River Landforms 2 ain river M processes ( Hint: v-shaped valleys are because of vertical erosion, weathering and mass movement…) 54 3 Channel width 4 Channel depth 5 Discharge 6 elocity(speed V of water flowing) 7 Sediment size 8 Sediment shape 9 radient G (steepness) 10 Land Use heBradshaw Modelis a theoretical model that describeshow a river's characteristics change T from its source to its mouth. Does the River Tees fit the model? Figure C: Bradshaw Model Take notes and label Figure C during the class discussion! ll rivers have a long profile and cross profiles.Each river's long and cross profiles are unique but A they do have some characteristics in common. ong Profile L The course of a river drawn from source to mouth is known as along profile. It shows the changes inaltitude(height above sea level)andgradient(the steepness) of a river. he long profile is divided into three stages. The upper course, the middle course and the lower T course, each of which have distinctive characteristics. 55 Figure D: Long Profile of a River How does the altitude of the river change along its long profile? ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… How does the gradient of the river change along its long profile? ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… What factors affect the long profile of a river? 56 Choose any three factors from the debate and explain these in the table below: Factor Explanation Rank Which section of the syllabus does this topic connect to? Section 1.2(b): How channel shape (width, depth), valley profile (long and cross profiles), gradient, velocity, discharge, and sediment size and shape change along the course of a named river. Integrated Skills: Use geology maps (paper or online) to link river long profiles to geology. Case Study: River Tees (UK) 57 Lesson 12: What Causes Shifts in a River's Cross Profile? Recall Activity: How does the rock type affect the long profile of the River Tees? ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. ………………………………………………………………………………………………………………….. 58 Why does the cross profile of a river change from the upper course to the lower course? Note that the depth of the water increases from the upper to lower course. How would the long and cross profile of a river change if: eforestation occurred D on the slopes of the hill and valley next to the river griculture occurred on A the floodplains eanders were M straightened near the mouth to create a port dam and reservoir A were added at the upper course of a river 59 kills: Drawing a Cross Profile S Thecross profilesof a river are cross-sections fromone bank to another. an You Draw A Cross Profile of a River? C (1) Take a piece of paper and place it across the section you are studying. Mark each contour and the height of each contour. (2) On a graph, put a scale on the Y axis according to the height above sea level. (3) Place the piece of paper along the X axis, where each contour line is marked on the height. Join the lines together to create the shape of the valley. igure A below shows a close-up of the Source of River Tees. Use the information in it to draw a F cross profile of the river. Figure A 60 hat does the cross profile you drew above tell you about the river and its features at this W location? ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… ……………………………………………………………………………………………………………… Which section of the syllabus does this topic connect to? Section 1.2(b): How channel shape (width, depth), valley profile (long and cross profiles), gradient, velocity, discharge, and sediment size and shape change along the course of a named river. Integrated Skills: Use geology maps (paper or online) to link river long profiles to geology. Case Study:any one of -River Tay, Yangtze River,Nile River and Ebro River 61 Lesson 13: Who Has Access to Clean Water? ater qualityrefers to the chemical, physical, andbiological characteristics of water, which W determine its suitability for various uses like drinking, agriculture, and supporting ecosystems. igh water qualitymeans water is free from pollutants,safe for consumption, and capable of H sustaining healthy ecosystems. Contaminated water can cause health issues, harm wildlife, disrupt agriculture, and lead to costly water treatment. hat Affects the Quality of Water? W The following human activities affect the quality of water. Categorise them into: (1) agricultural, (2) industrial and (3) domestic activities. ntreated or partially treated U Industries often discharge oil erosion due to S sewage introduces pathogens chemicals and heavy metals deforestation introduces (bacteria, viruses, and (such as mercury, lead, and sediment into waterways. This parasites) and organic matter cadmium) into water bodies, can negatively affect into water systems. which are toxic to life. photosynthetic aquatic plants and habitats. esticides and weedicides P mall plastic particles come S ivestock farms can contribute L leach into water sources from synthetic fibres, personal organic waste (manure) and through surface runoff, care products, and household pathogens to water sources, introducing toxins into water items. This introduces increasing bacteria and leading bodies. microplastics to water. to waterborne diseases. xcess fertilisers containing E ater used in industrial W ertain industrial processes, C nitrogen and phosphorus can cooling is often released at like mining, can release acidic wash into nearby water bodies, higher temperatures, causing compounds (such as sulfuric promoting rapid algal growth. thermal pollution, which acid) into water, which lowers Algae deplete oxygen when affects temperature-sensitive pH levels and makes toxic they decompose, creating species. metals more soluble. "dead zones" where most aquatic life struggles to survive. This is known as eutrophication. What are some other ways that domestic use of water pollutes water bodies? What are the impacts of pollution above for: Humans Environment (Plants and Animals) 65 ho Has Access to Clean Water? W Almost three-quarters of the world's population uses a safely managed water source, but why do some areas of the world have easier access to water than others? hich regions of the W Reason: world have access to basic drinking water? hich regions of the W Reason: world do not have access to safe water (through an improved water source)? hich rivers in the W Reason: world are most polluted? Which ones are the least polluted? Glossary Basic Drinking Water iswater from protected wellsor springs in less than 30 minutes distance Improved watersourcesare those that have thepotentialto deliver safe water and include: piped water, boreholes or tubewells, protected dug wells, protected springs, rainwater, and packaged or delivered water. How does access to clean water differ between developing and developed countries? 66 How Can We Get Clean Water? ollectionof water is from rivers, dams/reservoirs,lakes, aquifers (especially in dry climates) and C wells. In developing economies and villages, untreated water is often collected in buckets from wellsfor homes. Buckets and plastic containers canfurther contaminate the water as they may be dirty, and open buckets of water can be contaminated by dust, insects and animals. A lot of time is also spent in collecting water. Water is alsocollected and deliveredinplastic bottlesfilled at asource, such as a spring. This is a very expensive way to deliver water (cost of plastic containers, filling and transporting to the point of sale). However, it is used frequently by those who are worried about the quality of water treatment of piped water ater that is collected may also undergo W treatment, whichremoves pollutants from the collected water. This occurs in a series of stages: 1. Coagulation: Chemicals are added to the water so that small particles in the water stick together, forminglarger particles calledflocs. This makes it easier to remove these materials. 2. Sedimentation: the water sits in large tanks where gravity helps theflocs settle to the bottom. This forms a sludge layer, which is removed. The remaining clear water moves to the next stage. 3. Filtration: water is passed through filters (layersof sand and gravel or a screen) to remove very small particles that could not be removed through sedimentation. 4. Disinfection: water is disinfected to kill remainingbacteria, viruses, and parasites using chlorine or UV light. 5. Additional treatment: Aeration: exposing water toair (by using air bubbles in tanks). This helps to remove dissolved gases (eg: carbon dioxide) and excess minerals (eg: iron, manganese) by reacting with these elements. This also improves the water's oxygen content. Delivery of treated water: In developed economies and urban areas, water is delivered from treatment plants bypipes. However,the cost of installing and maintaining pipe networks is high, and if not maintained, the cost of leaks can be very high. In developing economies and / or villages, water can also be collected from astandpipe(see picture on right),which is a vertical pipe connected to a water supply and residents from around the area can collect water for themselves through this. It is used in areas without direct water connections to individual homes or buildings. Which section of the syllabus does this topic connect to? Section 1.3(b): Reasons for variations in water quality, including pollution (sewage, industrial waste, agriculture) and the storage and supply of clean water (dams and reservoirs, pipelines, treatment works). Integrated Skills: Use different maps (paper or online) to investigate the impact of human intervention. 67 Figures Figure A: Share of People in the World Without Access to Basic Drinking Water (2020) Figure B: People not using an improved water source (2022). Figure C: Municipal solid waste (MSW) leakage in rivers in 2020. 68 Lesson 15: Case Studies Questions on case studies for the IGCSE exam can be: 4-mark questions on a situation happening in a developed or emerging / developing country.For these, you must be able to summarisewhat is happening about water supply, water demand, water quality, water storage or flood risk in two points (each of these should be explained for one more mark in the answer). 8-mark questions- here, you will be given a new casestudy which you may not have learnt. You must be able to apply your knowledge to this new situation - in other words, when you get the question, think about: can anything in the case studies we learnt in class apply to this new case study? How to use the notes for case studies: Memorise TWO key facts foreachcase study. Thesemust be specific to the case study(eg: (1) GERD is creating conflict over waterin Sudan, Ethiopia and Egypt, (2) the reservoir Lake Mead is decreasing in size). Know the significance of each case study and the main impacts.You should be able to correctly explain the situation in each case study to a friend. You do NOT need to remember every single detail / fact / statistic provided on these notes. Th
