Investigating the river Caerfanell

Have a little read: ... INTRODUCTION I am going to be investigating the river Caerfanell. This river is a right-bank tributary of the River Usk of whose source is in the eastern end of the Brecon Beacons national park in South Wales, and joins the main river further downstream of Brecon. The catchment area is 32.4 km^2 and is an area of high precipitation, with 1800- 2000mm/year on average falling near the source and 1100mm/year near the confluence with the Usk. The valley of the Caerfanell lies within the Brecon Beacons national park and is relatively untouched except in more recent years where the river has attracted many holiday homes to situate nearby having an impact on surface runoff. The surrounding forest trees are coniferous and mostly evergreen, which also have an impact on runoff through interception and evapo-transpiration. A reservoir (the Talybont reservoir) was built in 1937 to store water, and now is being used as a drinking water supply for surrounding areas. The river has a built a delta, where it enters the reservoir, and just above the delta, the river has a strong tendency to meander eroding the farmland either side, although the farmer has attempted several times to straighten the river to protect his livestock. The Caerfanell valley has been carved into sedimentary rocks of the Devonian age (about 360 million years ago). These are known as the old red sandstone, which consists of a thick sequence of relatively resistant sandstones with easily friable and erodable mudstones. Also the acidity of water caused by the coniferous trees helps erode the mudstone. This modification of the sand and mudstones has made a series of attractive waterfalls in areas such as Blaen y Glynn. During the Pleistocene there was an ice cap on the Brecon Beacons with valley glaciers descending from it along the Caerfanell. The ice left behind glacial troughs (steep sided U-shaped valleys). Within the ten thousand years since the ice melted, the Caerfanell and its tributaries have begun to alter the glacial landscape, creating in places steep v-shaped valleys and re-worked glacial deposits with some sediments still carrying its glacial origin. I chose three sites on the river Caerfanell, to perform my methods. Site 1 à Blaen - y- Glynn Site 2 à Pont blaen y Glyn - The Valley Site 3 àBy the Talybont reservoir. These sites are situated on the location maps later in my project. My main focus of these coursework is to answer the following question... "Is there a correlation between velocity, gradient, and channel shape?" I intend to answer this question through a series of key questions. 1) How does velocity change downstream? 2) How does channel shape change downstream? 3) How does the channel shape affect velocity? 4) Does gradient affect velocity? 5) Does gradient affect channel shape or roughness? My hypothesis' are: * Velocity increases downstream * Channel shape increases in both width and depth downstream * As channel size increases, velocity will increase * As gradient increases, velocity will increase * Gradient will have no affect channel shape or roughness METHODOLOGY The three sites we choose from this river to assemble and gather results from are... Site 1 - Blaen y Glyn is a section of this river very close to the source, 400m above sea level. Site 2 - Pont blaen y Glyn is an area further down the valley, near the middle of the river, 260m above sea level. Site 3 - Talybont reservoir delta is a section, which is near to the mouth of the river, 190m above sea level. We choose to perform the experiments and gather evidence from these 3 contrasting areas of the river moving downstream to gather a holistic view of the rivers characteristics. This increases the accuracy of my results, as they are not bias whilst trying to represent the whole river. Also by choosing 3 different areas, I will be able to analysis the different processes and features that a river can present downstream therefore gathering a background of the rivers history. TYPE OF DATA NEEDED EQUIPMENT NEEDED METHOD LIMITATIONS PICTURE CROSS REFERENCE How I could use this data. THE GRADIENT OF THE SITE OVER 10 METRES * 2 Ranging poles * A Clinometers * Tape measure - Lay the tape measure with a measurement of 10 m down along the side of the bank of the river - 2 people take a pole each and stand at their two designated points, 0m and 10m in the river. The person marked at 0m should have the clinometer. - The 2 people should then find a rock tipping the surface of the water and place the pin of the pole on top the rock pointing up straight. - The person marked at 0m should then place the clinometer two-thirds up the pole at the colour change and aim at the exact same point on the other pole. - Wait for the movement of the meter to relax and note down the degree angle of the site. - At the designated points 0m and 10m, there may not be a rock for the pole to lean on which therefore leaves it up to the person carrying the pole to estimate where they may think the tip of the water is. This can lead to inaccurate of gradient as this turns the method into a subjective perception. - The people holding the two poles have to make sure that their poles are pointing straight into the air as any tiling will cause inaccuracy of degrees and therefore wrong results - When the person using the clinometer, is aiming at the other pole, make sure they are tilting the clinometer to measure the angle and not moving the clinometer itself. This is a common mistake that leads to the wrong degree angle being taken and therefore wrong results. This data can be used to evaluate the effect of gradient of velocity. WETTED PERIMETER OF RIVER BED * Tape measure * Metal pin - Mark half way - 5m, on the laid tape measure along the river bank - Take the beginning tape measure and nail it down with the metal pin at 5m where the water has started to touch the