Edexcel GCSE geography Rivers Questions and Answers correct

Edexcel GCSE geography Rivers Questions and Answers correct Drainage basin Area of land drained by a river. Watershed Boundary of a drainage basin, usually high land such as hills or ridges. Source Starting point of a river. Mouth Where the river meets the sea. Upper Course Area of a river near its' source, often in upland areas and when discharge is smaller. Middle Course Area further downstream, typified by wider valley floors and less steep slopes. River begins to meander. Lower Course Area nearer the mouth, typified by very wide flat floodplains, meanders and oxbow lakes. Contour Lines Lines on maps which show the height of land. Erosion Wearing away of the land Hydraulic action The sheer power of the water forcing into cracks, compressing air and breaking the rocks apart. Abrasion The effect of rocks being flung at the bed and banks and rubbing the land away. solution The dissolving of rocks such as limestone and chalk. Attrition The knocking together of pebbles, making them gradually smaller and smoother. Vertical erosion When rivers erode down into the land, often in the upper course. Lateral erosion When rivers erode from side to side, often in middle and lower courses. Soil Creep Where individual particles of soil move slowly down a slope. Sliding / Slumping Saturated soils and weak rock flow down the slope, often it is rapid such as a landslide. In slumping material rotates as it flows down. Mass movement Movement of large amounts weakened rock / soil down a slope. Can be very slow of very sudden. Rock fall When rock from a weathered rock face falls down, often when rock at the base of a cliff has been eroded. Transportation Movement of material and sediment along the river. Traction Heavy particles rolled along the river bed. Solution The transport of dissolved chemicals. Saltation A hopping movement of pebbles along the river bed. Suspension Lighter particles carried (suspended) within the water. Deposition The dropping of transported sediment and material when river discharge and velocity decreases and lose energy. Heaviest materials are dumped first. Alluvium Name for fine sediments deposited in the lower course of a river. Geology The make up and type of rocks around the coast that influence landforms. faults Weaknesses or joints in the rock that make erosion more likely. More resistant rock Hard rock which take more time to erode. Often metamorphic or igneous rock types. Less resistant rock Softer rocks which are easier to erode, often sedimentary. Interlocking spurs When rivers flow around river valley side slopes as they do not have power to erode them into a straight line. V-shaped valley Shape created when rivers erode vertically down in the upper course. Waterfall Created when a river flows over areas where hard rock lies over a layer of softer rock which is more easily eroded. Plunge pool Deep pool at the base of waterfall created by erosion. Gorge Very steep or vertically sided valley caused when a waterfall retreats upstream. Meander Bends in a rivers course, created by lateral erosion in middle and lower course of a river. River Cliff Created by lateral erosion on the outside of a meander. Slip off slope Created by deposition on the inside of a meander. Point Bar Name for the material deposited on a slip off slope. Oxbow Lakes Formed when a meander neck becomes narrower and the bend is cut off and the river takes a straighter course. Flood plains Flat land either side of a river formed by erosion and deposition. Levees Natural embankments of sediment formed along the banks of a river. Long profile Shows the height of the land and the distance downstream from the rivers source to its mouth. Valley cross profile /cross section Shows the steepness of the valley sides River cross section Shows the shape of the river bed and banks. Reservoir Large human made lakes to store water for human use. Drought Periods of low rainfall which reduces river discharge and velocity. Flood Natural event when water levels exceed the bankfull level and water covers the surrounding land. Hydrograph Shows how a river responds to a storm, showing relationship between rainfall and river discharge. Rising limb How water levels rise in a river following rainfall. Lag time Difference between heaviest rainfall and highest discharge. Falling limb Shows how water levels fall in a river. Hard engineering Expensive techniques to stop flooding in certain areas. Try to overcome or control natural processes. Soft engineering More natural approach to managing flooding, using natural processes. Embankments Walls or banks built near river channels. Channelisation Involves deepening or straightening river channels. Flood Relief Channels Extra channels built next to or leading from rivers to take away excess water. Dam and reservoirs Built to store and control water levels in a river.