Geography rivier

Topics: Slope, River, Velocity Pages: 10 (2098 words) Published: February 11, 2014


AS/Foundation geography Coursework

Investigating downstream changes on the Afon Caerfanell

INTRODUCTION

AIM: To investigate how selected parameters change downstream on the Afon Caerfanell.

Hypothesis:

1. The velocity of Afon Caerfanell increases downstream

2. The velocity of the river increases down the stream as the angle of the slope increases.

RIVER DEFINITION

A river is the natural course of the water, which goes from a higher point, to the lowest point, usually the sea, ocean, lake or another river. There are few cases where the river simply flows under the ground surface or dries completely before reaching a bigger body of water. The river is also freshwater; there are no rivers with sea water (salty water). Rivers are not always called rivers. Smaller rivers can also be called streams, rills, rivulets and tributaries. Rivers are part of the hydrological cycle. The water inside a river is mainly collected from precipitation (rain) from the drainage basin. The water is also collected from surface runoff, which is caused, by precipitation, groundwater, springs and the melting of natural land (glaciers) and snow. The water in a river is usually confined into a channel and there is usually only one single stream of water within the channel.

VELOCITY DEFINITION

The velocity of a river is t basically the rate of water movement measured in meters per second. In other words it is the speed at which water flows along it.

(Location of Afon Caerfanell)

(River Usk and its tributaries)

The Caerfanell River is a tributary of the river Usk .It rises from the eastern end Brecon Beacons National Park in Wales. The source of the river is on the Gwaun Cerrig Llwydion plateau. The river starts flowing southeastwards, then in turns the opposite direction, northeast and enters the Talybont reservoir, which is 3 kilometers long. It goes out of the reservoir generating electricity by passing to a turbine next to a village called Aber. Then the river meets its confluence, the river Usk next to the Aber village. The length of Afon Caerfanell is 7.5 km in a direct line from the source to Usk confluence but because the river follows a curving Zigzag shaped valley twice that length. (The Village of Aber on river Usk, South of Wales)

Theoretical Background

Bradshaw model

The Bradshaw model, which can be seen on the diagram is geographical model which describes how the characteristics of a river vary down the stream, from the upper and lower course of the river. The model suggests that velocity, discharge, Cross-sectional Area and the hydraulic radius, all increase with distance downstream. As a river travels down its path, from its source in the mountains to the low lying floodplains toward its mouth, the valley, the river channel, the flow of water and the sediment it transports change. The model is depicted as a series of triangles. If a triangle gets wider towards the downstream section, it means that on average the variable it represents also increases downstream. If the triangle decreases in size going to the downstream section, it means that the variable on average decreases as well. UPSTREAM DOWNSTREAM

Schumm’s model

Stanley Schumm created his model to show how a typical river should behave like. It represents how the different characteristics of the river change as the river progresses down the stream.

The model consists of an X axis and a Y axis.

The model shows how the river characteristics change from the source to the mouth....
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