GEOGRAPHY NOTES OF 16/02/2016

 

TOPIC: |RIVER SYSTEM Sub topic: River profile What is a long profile? The long profile shows how a river’s gradient changes as it flow from its source to its mouth. A river changes shape as it flows from its source (where a river starts) to its mouth (where a river flows into a sea or lake). The shape of both the long profile (a slice through the river from source to mouth) and the cross profile (a slice across the river) changes.   The youthful or upper course of a river The upper part is steep and the river cuts a narrow and deep V-shaped channel. Further towards the sea, the slope is gentler and the river has a wider channel. In the youthful stage, a river is full of vigor and splash it forms interlocking spurs, Plunge pools, V-shaped valleys, Gorge, River canyon, water fall, rapids and potholes.                                                                                      The mature stage of a river In the mature stage, a river slows the speed of flowing and it forms the U-shaped valley, Bluffs, Cliffs. The middle course of a river has more energy and volume then in the upper course. The gradient is gentler and lateral (sideways) erosion has widened the channel. The river channel has also become deeper. Meanders are typical landforms found in this stage of the river        The lower course of a river Nearly all rivers have an upper, middle, and lower course. The beginning of a river, when it flows quickly with lots of energy, is called a young river. The river here is smaller and usually has a rapid, tumbling flow that cuts a narrow channel through rocky hills or mountains. In the old stage, a river is too slow in flowing and it forms the Flood plain, braided channel, meanders, ox-bow lakes, meander scars, Distributaries, Differed tributaries, Lagoons and Deltas. River profile summery                       Upper Course    Mid Course                          Lower Course Long Profile Steeply sloping towards the lower sections of the river. Shallow slopes towards the mouth of the river. Almost at sea level, very gently sloping towards its mouth. Cross Profile Steep sided v-shaped valley. Thin river channel, deep in places. V-shaped valley remains with a wider valley floor and the river begins to meander across it. The river channel begins to widen and become deeper. Wide, shallow valley, with large flood plains and meanders. The river channel is wide, deep and smooth sided. Exercise   What is a long profile?  Outline the stages of the river profile.  Outline three features formed in each stage.