3Common River Terms Source – The place where a river begins. Course – The route the river takes to the seaTributary – A small river that joins a larger river.Confluence – The point where the tributary joins the river.
4Common River Terms Mouth – The point where the river enters the sea. Estuary – The part of the mouth that is tidal.Basin – The area of land drained by a river.Watershed – The high ground separating one river basin from another.
5The River’s Journey Rivers usually begin in the mountains. They flow downhill onto flat land and into the sea.
6The Shannon’s Journey The River Shannon is Ireland’s longest river. It flows from the Cuilcagh Mountains in Co. Leitrim to the Atlantic Ocean on the west coast of Ireland.
8The Stages of a River’s Journey As the river flows from it’s source to the sea it goes through 3 stages. These are,The Upper or Youthful StageThe Middle or Mature StageThe Lower or Old Stage
9The Youthful RiverThe youthful river has a small amount of water but it travels very quickly down the steep mountain slope.Most of its energy is used to erode (wear away) the landscape.This erosion (wearing away) occurs in 4 ways.
104 Processes of River Erosion Hydraulic Action – The force of the moving water wears away the banks and bed of the river.Abrasion – Small stones carried by the river wear away at the the banks and bed of the river.
114 Processes of River Erosion Attrition – The small stones in the river are worn down and broken up as they hit off each other.Solution – Rocks and soil are dissolved by acids in the water.
12Landforms of the Youthful Stage All of the erosion by the river creates features or landforms on the landscape.Three features created in the youthful stage are,V-shaped ValleysInterlocking SpursWaterfalls
13V-Shaped ValleysV-shaped valleys get their name from their shape. The river erodes the landscape and creates a valley in the shape of a V.This occurs because of Vertical Erosion. The river cuts down into the river bed, making it deeper. It creates a narrow deep valley. Mechanical weathering and mass movement create the V shape. See Diagram.
17WaterfallsWaterfalls are formed when rivers flow over areas of hard and soft rock.The river erodes the soft rock but cannot erode the hard rock. This creates a step which the water starts to fall over.The falling water erodes deeper into the bed. The rivers load creates a Plunge Pool as it falls. See Diagram.
20The Mature StageWe now know that during the youthful stage the river is mainly eroding the landscape.Erosion breaks off particles of rock and soil from the bed and banks of the river. They are carried along by the river and are known as the Load.The load is carried from upland to lowland areas. This process is called River Transportation.
21River TransportationAll rivers carry material in them. This material is carried bythe river as it flows along.Rivers can carry large stones, small stones, sand, andother dissolved minerals.All of this material in the river is called the river’s LoadWhen the river moves its load we call this River Transportation
22River Transportation Transportation occurs in 4 ways. 1. Rolling 2. Bouncing3. Suspension4. Solution
24RollingRolling – The large stones are rolled along the bed of the river.Rolling
25Bouncing Bouncing – The smaller pebbles are bounced along the bed of the river.Bouncing
26Suspension Suspension – Light material like sand and silt are carried along (floating) in the water.
27Solution4. Solution – Dissolved materials are carried along by the river.Solution
28Landforms of the Mature Stage In the Mature Stage the river begins to slow down,and so it begins to deposit some of its load. Itcreates the following features.Wide river valleyMeandersFlood plain
29Landforms of the Mature Stage Wider River ValleyIn the mature stage the river moves fromside to side and the valley becomes wideand flat. Weathering and Mass Movementcontinue to wear away at the sides of thevalley. See diagram.
31Landforms of the Mature Stage MeandersMeanders are bends or curves along the river. They are formed by erosion anddeposition. Erosion occurs on one side of the river while deposition occurs onthe opposite side. This continues, making the bends sharper. See diagrams.
34Landforms of the Mature Stage Flood PlainA flood plain is the flat area of land on either sideof the river. After heavy rain the river sometimesfloods. The water spreads out over the land oneither side of the river. When the river retreats itleaves behind a thin layer of alluvium. After manyfloods a thick layer of alluvium is created. This isvery fertile soil.
35The Old StageIn the Old Stage the river is carrying lots of sand and silt. It is now flowing over flat land and so it is moving slowly. Therefore it begins to drop off its load. This is called deposition. Like erosion in the Youthful Stage, deposition also creates many features or landforms.
36Landforms of the Old Stage The following features or landforms arecreated by river deposition in the Old Stage.Ox-Bow LakesLeveesDelta
37Landforms of the Old Stage Ox-Bow LakesAn ox-bow lake is a horseshoeshaped lake found beside ariver. Ox-bow lakes are formedwhen continued erosion anddeposition create verypronounced meanders.Eventually the river cuts throughthe neck of the meander.Deposition then occurs whichleaves the ox-bow lakeseparated from the river.
39Landforms of the Old Stage LeveesLevees are raised banks of deposited materialfound along the banks of the river. When the riverfloods and spreads out over the floodplain, theheaviest material is deposited close to the river.Over time and after many periods of flooding thisdeposited material forms levees along the banks ofthe river.
41Landforms of the Old Stage DeltaA Delta is a triangular shaped piece of landwhich is formed at the mouth of the river. Asthe river enters the sea it drops off all theremaining material it is carrying. Thismaterial builds up to form new land. The river isforced to break up into smaller channels calleddistributaries.
43Rivers and People Rivers have always been important for people. In the past, people settled near ariver as it provided them with food, water,defence, and an easy method of transport.Nowadays, people try to control rivers toprevent flooding, for irrigation, to create electricity(HEP), and to create improved transport links.Rivers are also important for tourism and leisure.
44Hydro-Electric Power (HEP) Engineers build dams acrossthe river.They can then control theflow of water in the river.They release the water anduse it’s power to turn largeturbines.Turning these turbinescreates power which is used togenerate electricity.