Year 10 Geography Notes: River Environments - PDF

Okay, here's the conversion of the provided text into a structured markdown format. I've focused on clarity and readability. ### YEAR 10 RIVER ENVIRONMENTS **Content** 1. Water cycle/hydrological cycle. 2. Drainage basin and their features. 3. Hydrographs/river regimes. 4. Weathering and mass...

Okay, here's the conversion of the provided text into a structured markdown format. I've focused on clarity and readability. ### YEAR 10 RIVER ENVIRONMENTS **Content** 1. Water cycle/hydrological cycle. 2. Drainage basin and their features. 3. Hydrographs/river regimes. 4. Weathering and mass movement. 5. River processes 6. River landforms 7. Flooding 8. Water uses, demand and supply. 9. Water quality/pollution 10. Managing the supply of clean water. #### 1. WATER CYCLE/HYDROLOGICAL CYCLE It is a natural recycling of water between the ocean, atmosphere, and land. It is a closed system because it has a fixed amount of water; therefore, no water is added or lost from the system. The diagram below shows the structure of a water cycle. *A hand-drawn diagram of the water cycle illustrates stores and flows, indicating the following elements:* * Solar energy driving evaporation from the sea and land features. * Evaporation leads to cloud formation, with condensation and subsequent precipitation (rain and snow). * Interception by vegetation. * Water flow from clouds as precipitation, glaciers and ice sheets. * Runoff into rivers and lakes/freshwater surface stores. * Infiltration into the soil, leading to percolation into groundwater flow, and surface runoff. * Evapotranspiration from vegetation back into the atmosphere. There are two processes in the water cycle: 1. Transfers/Flows. 2. Stores ##### 1. STORES These are places where water is held in the water cycle. There are a number of stores in the water cycle: 1. Waterbodies - In the form of oceans, seas, lakes, and rivers. 2. The atmosphere - Where the water exists as either water vapor or as minute droplets in clouds. 3. Vegetation (interception) - Water held by tree leaves after heavy rainfall. 4. Rocks - Water is stored below ground in the bedrock. This is known as the groundwater store (aquifer). ##### 2. TRANSFERS/FLOWS It is the movement of water that takes place between stores in the water cycle. There are a number of transfers/flows in the water cycle. 1. **Evaporation** - Water from water bodies is converted from a liquid into a gas (water vapor) due to the heat of the sun. 2. **Transpiration** - Plants/vegetation take up liquid water from the soil and breathe it into the atmosphere as water vapor due to the heat of the sun. 3. **Evapotranspiration** - Refers to the loss of moisture from the ground by direct evaporation from waterbodies or the soil, plus transpiration from the plants, due to the heat from the sun. 4. **Condensation** -The change in the atmosphere when water vapour cools and becomes liquid. The liquid takes the form of water droplets that appear in the atmosphere as clouds. 5. **Precipitation** - The transfer of water in any form (rain, hail, or snow) from the atmosphere to the land or sea surface. 6. **Overland flow/surface runoff** - It is the horizontal movement of water on top of the soil when the soil is saturated (air space within the soil is filled up with water) and eventually enters a stream, river, or lake. 7. **Infiltration** - It is the vertical transfer of water through the tiny pores in the soil from the earth's surface. 8. **Percolation** - It is the vertical transfer of water through the empty spaces in the rock into the aquifer or groundwater store. 9. **Throughflow** - It is the horizontal movement of water through the soil until it reaches a stream/river. 10. **Groundwater flow** - It is the horizontal movement of water in the rocks of the aquifer until it reaches a stream, river, or sea. #### 2. DRAINAGE BASIN AND THEIR FEATURES 1. **Drainage Basin/Catchment Area** - It is an area of land drained by a main river and its tributaries. 2. **Watershed/River Divide** - A dry ridge of land that separates adjacent drainage basins. 3. **Drainage/Channel Network** - A system of surface and underground channels that collects and transports the precipitation falling on the drainage basin. 4. **Drainage Density** - It is the total lengths of all streams and rivers in a drainage basin divided by the total area of the drainage base. *A hand-drawn diagram illustrates the structure of a drainage basin with the following features:* * Source * Tributaries * Confluence * Main River * Distributaries * Mouth * Ocean/sea *Definitions of components in the water drainage diagram:* 1. **Source** - A point where a river starts/begins. 2. **Tributaries** - Are small streams that flow into the main river. 3. **Confluence** - The point where tributaries join the main river. 4. **Mouth** - A point where a river enters an ocean/sea. *NB:* * A drainage basin is an open system because water is added from various sources and lost through various ways. The amount of water in the system varies over time. * A drainage basin has input and output. a) The inputs of a drainage basin are; 1. Energy from the sun. 2. Precipitation formed from moisture picked up outside the basin. 3. Water from tributary drainage basins. b) The outputs are! 1. The river's discharge. 2. The water in its basin from which evaporation and transpiration take place; this water eventually falls as precipitation in another drainage basin. #### RIVER REGIMES/HYDROGRAPHS 1. **River Regime** - It is the seasonal variations in the discharge of a river. 2. **River Discharge** - It is the amount of water carried by a river at any one time, measured in cumecs (cubic meters per second). 3. **Hydrographs** - It is a graph showing the discharge of a river over a given period of time. **Factors Affecting River Regime:** 1. **Rock Type/Geology** - The type of rock which makes up individual river basins has a major influence on its discharge, e.g., impermeable rocks reduces percolation and increases the rate of surface runoff; therefore, water reaches the river faster, leading to a high river discharge, while permeable rocks increase percolation and reduce the rate of surface runoff. This delays water reaching the river, leading to a low river discharge. 2. **Relief/Slope** - Areas with steep slopes increase the rate of surface runoff and reduce infiltration. Therefore, water reaches the river faster, leading to a high river discharge. While gentle slopes reduce the rate of surface runoff and increase infiltration, this delays water reaching the river, leading to a low river discharge. 3. **Urbanization/Land Use** - Areas covered by tarmac and concrete surfaces in urban areas reduce percolation and increase the rate of surface runoff. Therefore, water reaches the river faster, leading to a high river discharge. 4. **Vegetation (Interception)** - Forested areas increase interception and reduce the rate of surface runoff; this delays water reaching the river, leading to a low river discharge. 5. **Dams/Reservoirs** - They regulate the discharge of a river by holding back water; this leads to a low river discharge and reduces the risk of flooding downstream. 6. **Climate** a) High Rainfall reduces infiltration because the soil is saturated, which increases the rate of surface runoff; therefore, water reaches the river faster, leading to a high river discharge. b) Temperature - High temperatures increase the melting of ice in the Arctic regions; therefore, the melted ice water reaches the river faster, leading to a high river discharge. ##### 3 HYDROGRAPHS It records the changing discharge of a river after a passing rainstorm, therefore a hydrograph displays data on a river regime. *A hand-drawn diagram depicts a storm hydrograph with these features:* * Peak discharge * Level of water discharge above which the river will flood * Storm flow * Rising limb * Falling limb * Lag time * Rainstorm * Rainfall * Base flow * Time * High river discharge * Low river discharge 1. **Limb** - The rising limb shows the rise in discharge of a river after a heavy rainfall leading to flooding, while the falling limb shows the decrease in discharge of a river after the subsidence of the rainstorm. 2. **Lag Time** - It is the difference in time between peak discharge and peak rainfall of a river. E.g., a river with a shorter lag time has high discharge because the water reaches the river faster, while a river with a longer lag time has a low discharge because there is a delay in the water reaching the river. 3. **Flows** - The storm hydrograph shows the discharge of the river as being made up of two flows: a) **Base flow** - Normal discharge of a river. b) **Storm flow** - Additional discharge of a river as a result of the rainstorm. *Question:* Describe six factors that affect the critical lag time of a storm hydrograph. 1. **Rock Type/Geology** - The type of rock which makes up individual river basins has a major influence on its discharge, e.g., impermeable rocks reduce percolation and increase the rate of surface runoff; therefore, water reaches the river faster, leading to a high river discharge, hence a shorter lag time, while permeable rocks increase percolation and reduce the rate of surface runoff; this delays water reaching the river, leading to a low discharge, hence a longer lag time. 2. **Relief/Slope** - Areas with steep slopes increase the rate of surface runoff and reduce infiltration. Therefore, the water reaches the river faster, leading to high river discharge, hence a shorter lag time, while gentle slopes reduce the rate of surface runoff and increase the rate of infiltration; this delays water reaching the river leading to low river discharge, hence longer lag time. 3. **Urbanization/Land Use** - Areas covered by tarmac and concrete surfaces in urban areas reduce percolation and increase the rate of surface runoff. Therefore, water reaches the river faster, leading to high discharge, hence a shorter lag time. 4. **Vegetation (Interception)** - Forested areas increase interception and reduce the rate of surface runoff; this delays water reaching the river, leading to low river discharge, hence a longer lag time. 5. **Dams/Reservoirs** - They regulate the discharge of a river by holding back water; this leads to a low river discharge, hence a longer lag time, and reduces the risk of flooding downstream. 6. **Climate** a) Heavy rainfall reduces infiltration because the soil is saturated, this increases the rate of surface runoff therefore water reaches the river faster leading re a high discharge nence shorter lag time. b) Temperature - High temperatures increase the melting of ice in the Arctic regions, therefore the ice water reaches the river faster leading to high river discharge hence shorter lag time #### 4. WEATHERING AND MASS MOVEMENT \* Weathering - It is the breakdown of rocks on the Earth's surface by natural processes (in situ/without movement). \* Mass Movement - It's the movement of weathered materials down the slope due to the influence of gravity. **Types of Weathering** There are three types of weathering: 1. Physical Weathering (Exfoliation, Freeze-thaw). 2. Biological Weathering (Plant action, Human activities). 3. Chemical Weathering (Oxidation, carbonation). **Physical Weathering** It is the breakdown of rocks into smaller particles by changes in temperature and rainfall (climatic factors. Physical weathering occurs in two ways: 1. **Exfoliation** - It occurs in warm climates when rocks are exposed to repeated heating and cooling. During the daytime, the surface layer of rocks is heated by the sun (expanding), and during night time, the surface layer of rocks is cooled (contracting) due to low temperatures. The repeated expansion & contraction over a long time causes. 2. **Freeze-Thaw** - It occurs in mountainous regions when water (rainfall) enters the crack during warm and freezes during the cold night The water turns into ice expands and exerts pressure on the surrounding crack leading to me breakdown of rocks into smaller particles. **Biological Weathering** →It is the breakdown of rocks into smaller particles by action of living organisms. It occurs in 2 ways: 1. **Plant Action** - The roots of plants, especially trees, growing into cracks in the rocks gradually split the rock apart. 2. **Human Activities** - The use of explosives in mining areas has led to the breakdown of rocks into smaller particles. **Chemical Weathering** →It is the breakdown of rocks into smaller particles by chemical reaction within the rock. Occurs in two ways. 1. **Oxidation** - It is the process in which rocks rich in Iron (Fe) combine with oxygen in the presence of moisture. The rocks become oxidized; therefore, breakdown occurs in the process. 2. **Carbonation** - It occurs in limestone rocks when they react with weak carbonic acid rainfall, and in the process the rocks breakdown into small particles. **Mass Movement** There are two types of mass movement: 1. **Soil Creep** - Refers to the movement of weathered materials slowly down a gentle slope under the influence of gravity. It collects at the bottom of the valley site and is eroded by the river. 2. **Slumping** - This occurs when the bottom of a valley-side slope is cut away by the river flowing at its base. The river makes the slope unstable, and weathered material slumps down towards the river. #### 5. RIVER PROCESSES A river works in 3 different ways. 1. River erosion 2. River transport 3. River deposition. **1. River Erosion** - It is the wearing away of the river bed and river bank by the force of water. *There are 3 types of river erosion:* 1. **Vertical Erosion** - The increase in depth of a river bed due to the force of water. 2. **Lateral Erosion** - It is the increase in the width of a river bank due to the increase in the discharge of a river. 3. **Headward Erosion** - The increase in the length of a river due to continuous erosion by the river on a softer rock. *There are four processes of river erosion.* 1. **Hydraulic Action** - It is the sheer force of water that dislodges material from the river bank and river bed and carries it away. It is common during high discharge of a river. 2. **Abrasion** - The material (load) being carried by a river is wrapped against the river bed and bank of the channel. This sandpaper action widens and deepens the channel. 3. **Corrosion (Solution)** - Minerals in the rocks (soluble) forming the sides of the river channel are dissolved by the water flowing past them, e.g., limestone rock 4. **Attrition** - It involves particles of material being carried by a river, becoming rounder and smaller as they collide with each other. This process does not cause erosion of the river channels and valleys. **2. River Transport** - Movement of material (load) by the river. The load is made up of material that has been warned or fallen into the river: i.e., boulders, pebbles, wood, etc. *There are different ways a river transports its load.* 1. **Traction** - It is the process of river transport where large boulders are rolled on the river bed. 2. **Saltation** - Process of river transport where small boulders bounce along the river bed. 3. **Suspension** - Process of river transport where lighter material is carried along by the river flow. 4. **Solution** - It is a process of river transport where soluble material is dissolved in the water and carried by the river. *** Pg.9 The diagram below shows the process of river transport *A hand-drawn diagram of a river with its corresponding means of transport* * *Solution indicates dissolved material in water* * *Traction indicates the large bouiders that rolled on the bed* * * Saltation indicates the small bouiders that bounced along the bed* * *Suspension indicates the movement of lighter materials that are carried by the river flow* **3. River Deposition** - The laying down of material (load) transported by the river. It is common in the lower course/old stage of a river when a river enters a lake or sea. *River deposition is influenced by the following factors:* 1. Decrease in river gradient. 2. Decrease in river volume. 3. Decrease in river speed/discharge. 4. Overloading of the river channel by the load. #### 6. RIVER LANDFORMS Changes in the river landforms are associated with changes in the long and cross profile of a river. a) **Long profile** - Runs from the source to the point where the river enters a sea/ocean (mouth). b) **Cross profile** - Changes that occur in a river from one bank to another bank (cross-section of a river). The upstream and downstream changes in a river channel are associated with changes in river landforms and landscape. River landforms formed in the upper course of a river (upland landforms) and lower course of a river (lowland landforms). **1. UPLAND LANDFORMS** *These occur in the upper source of a river and are formed by erosion processes, ice, V-shaped valley, interlocking, water-foll Gorge.* 1. **V-shaped Valley** - Are formed when a river erodes its valley downwards through vertical erosion. Vertical erosion leads to the development of steep-sided, narrow-shaped valleys. The process of abrasion and hydraulic action erodes the rock, making the valley deeper. *A hand-drawn diagram illustrates how the river has cut down the valley through vertical erosion, resulting in a steep slope and narrower base*. 2. **Interlocking Spurs** These are formed when River moves from side to side Vertical erosion Leads to deepening the river bed therefore the river runs down, to flow between spurs Of higher alternating sides of the valley *interlocking spurs sketched* *A sketch shows: alternating spurs and a river cutting down* 4). **Waterfall** Waterfalls are formed where a band of hard rocks occurs. The harder rock is much more resistant to erosion softer rocks below it by the force of falling water over the hard caps *hydraulic action*. Plunge pool form after the softer rock erode to a force of water like Iguacu falls *A hand-drawn diagram depicts the structure of a waterfall, the softer rock are easier to erode and the harder caps difficult-to-erode. Gorge* **ADVANTAGES OF WATERFALL** a. Production of hydroelectric power b. Acts as tourist attraction **DISADVANTAGES OF WATERFALL** a. Hinders visibility b. Affects navigation for ships c. Prone to accidents **Lower Landform**. These features are common in low course when the river decrease by a. Gradient b. Volume c. Discharge d. Loading The following are low-land features a. Flood plain b. Levees c. Meanders **Floodplain**. Area of that land formed with a river buster during flooding Alluvium is deposited across floor Valley which builds a flatland after that largest amount of deposition is always on the bank on the channel to build it at greater height forms levee: Flood plane always at risk of flooding river flows The hand sketch illustrates the process of alluvium deposition and the shape of the plain after the flood #### 7. Flooding It is a period of a high discharge of a river when it bursts its banks and spills across the flood plain. * The causes are: 1. Physical Factors are: (Rock type, relief, vegatation,soil, weather and drainage desity. 2. Human factors * Factors Deforestation Urbanization Agriculture fuel fossil Rock- it will reduce Percolation, high run off so more water to river so high banks Relief- steep decrease rate and less infiltration but gentle the opposite River banks- reduces infiltration and increases runoff Climare *Rain will lower it because the soil is saturated *Temps higher will raise the Polar river Human factors (cutting of less vegetation and deforestation more increase un roof) Urban will increase of high rainfall So less filtration more rate by farm Causes- 1. Loss of life by water 2. Destructive materials 3. The risk of water 4. Injure by water food effect. Managing and adjustment to help to protect a water damage by flooding *improve floods water *afford *management by government *alter by rapid surge. #### 8. WATER USES, DEMAND AND SUPPLY a) Water used because Its essential with life with an easy one some one it is it is uneven River needed domestic such as -water -toilets Industrial -steel _Agriculture -irr. croping and stocking. b) Demand for water in uses: it is known is Consumption Factors are -in industrial (machan,cool electricity) _ agricutural (use for irrigation) (rise is stand living such as wash etc C)supply of water: involve Demand from the most part of world it is needed and come from River reservoir, and auq NB Creaghipals with show different patterne. that where water are positive and supply exceed and its same to all is equal Water qaility with sustain us for Industrial -domesic ect .water are place by place #### 9. 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