V-Shape of River Derwent - Essay Example

THE RIVER DERWENT V-SHAPE By: Word count: 1565 Nature is often seen as quite interesting due to its tendency to portray varied features on several occasions especially in different seasons. Take, for instance, the happenings in different rivers where after at a particular time a river has a different shape. For many people not keen with understanding what goes on it might seem obvious. However, there are different reasons why rivers tend to flow in a certain way; there are processes that take place for a river to have a V-shape. One such an interesting river is Derwent in Yorkshire, England where it demonstrates various exciting features, which will form the basis of this paper. River Derwent is undoubtedly one place many people tend to flock but this paper will investigate and explain the reason this river has a V-shape in its Grange, Cumbria section. Background The River Derwent flows from North York heading to the southern part where it converges with River Hertford then heads westwards. At the Vale of York, River Derwent now joins with River Ouse. This river was at the centre of conflict in the past but now it proves to be essential to many people especially in the cities of Leeds, Hull, Scarborough, and York. Besides being used as a reserve for several natural features, the river is often used in sporting activities. Moreover, since it has been proved to have low Biochemical Oxygen Demand (BOD), its water is seen as of good quality (Carstairs 2007). River processes As stated above, there is hardly an explanation offer by observers who frequent a river to witness its magnificent features concerning its various appearances. Unknown to many is that a river undergoes various processes, which eventually lead to a particular appearance. This section will now focus on the processes that lead to the V-shape appearance specifically the one at River Derwent in the Cumbria part. Normally, there exist three major types of river processes including Deposition, Transportation, and Erosion. The intensity of each is largely dependent on the magnitude of the energy (Bellmore and Baxter 2013). That is to say, the effects of each of these will be seen mainly depending on the energy the river is able to exert. The amount of energy water has is dependent on three factors: the mass of water, channel-gradient and the river’s height above the sea level. Transportation Depending on the energy a river has, the transportation of any material cannot begin until friction is subdued where the loosened materials now are transported. Further, the turbulence energy is another determinant of transportation. In short, friction with the banks and the bed coupled with the velocity the river has will determine how well the river will transport the sediments. In the case of River Derwent, its energy is able to carry some materials due to its energy (Carstairs 2007). During the transportation stage, there are further four other processes which include the suspension, saltation, traction and solution. Suspension refers to the silting and subsequent lifting of light materials due to turbulence. Again, the amount of silt carried by the river depends on the turbulence, and at this stage, there is a tendency of the river to seem muddy. Saltation is used to refer to the bouncing off of the heavier materials, for instance the gravel and pebbles, by the velocity. Similarly, traction involves the pushing of larger materials by the river’s force. At some point, the materials transported may be left if the velocity of the water is negatively affected. According to Beechie et al. (2010), velocity is mainly dependent on the factors including slope of the channel, shape of the cross-section channel and the roughness in the channel’s banks and bed. Therefore, the higher the velocity the greater water turbulence hence the more sediment transportation. In Cumbria, the picture of River Derwent reveals some rocks appearing to be at the center of the river. This is a perfect case of transportation where the rocks were not originally there but rather were brought due to the aforementioned reasons. Actually, from this explanation, there is a possibility that the particles visible at River Derwent in Cumbria were originally huge rocks. Due to the process of breaking down as a result of turbulence, the once big rocks are now seen as mere particles. In essence, that is what transportation entails where the pressure of the water sees the rocks collide and break into smaller particles. As the process continues, the particles keep getting smaller due to colliding with other bigger rocks. Erosion The energy a river has that determines its behavior, and in this case, this includes erosion as well. If a river has more energy, it will cause erosion both on its banks and bed hence widening, deepening, and lengthening it. Worth noting here is that the term erosion is used to describe any impact of river extension irrespective of its direction. If an erosion occurs head-ward, the impact will see the river become longer; mostly this happens at the river’s source during the first phase. Any vertical erosion will see the river channel become deeper, and this is occurs mainly in the upper stage of the river. It is here that the V-shape mostly occurs (Bellmore and Baxter 2013). In light of this, it is imperative to understand that river Derwent in Cumbria has a V-shape where some small rocks can be seen. Interestingly, the small particles are assembled at the center of the river yet before them is much water. The reason for this feature is an occurrence of the vertical erosion where the river creates spaces downwards hence increasing the water. In rivers, erosion occurs mostly in four processes: hydraulic action, attrition, corrosion, and abrasion. In the hydraulic action process, the pressure in the water breaks the rock particles in the bed and banks then there is increase in water pressure as a result of water pushing into the cracks on banks hence the erosion. Often, depending on the velocity, there is a collapse of riverbanks as well as undercutting. It is here then that transportation becomes easier since the levels of velocity are pretty high. Once hydraulic action takes place, there is often another inevitable occurrence: abrasion (Booker 2010). In addition, called corrosion, this process sees the carried sediment have a scouring effect on the banks and the bed of the river. When depression is present, there is a possibility of emergence of potholes as a result of pebbles that are being spun around (Nicholas, 2013). Whereas River Derwent in the Cumbria section may seem not to have abrasion effect on the sides, its other stages would prove otherwise. In the attrition stage, the rocks that have since been eroded experience a collision leading to the breaking into yet other smaller particles. If analysed carefully, the edges in these rocks appear quite smooth and rounded. In River Derwent this is evident in the Port Castle bay where the smooth stones are seen albeit with little understanding of the process by the tourists. Normally, this stage does not see further erosion of either the bed or the bank, and instead the smoothening and rounding the smaller stones is evident here. Nonetheless, these stones may not be clearly visible until the final river process called deposition. Still in the erosion process, another occurrence is normal where formation of acid because of dissolution of Carbon Dioxide is experienced in the water. This process sees the dissolution of rock through a chemical process, and the end-result is seen in form of appearance of chalk and limestone (Booker 2010). Deposition At this point it is vital to understand that the river does not retain energy all through; it loses it at some point. When the energy is lost, the water can no longer carry the eroded materials, and instead has to drop them. Some of the reasons a river loses its energy include a reduction in the rainfall and increased evaporation. Furthermore, when friction exists near the riverbanks or shallow areas this leads to a reduction in the speed thus a reduced capability to transport the eroded materials; additionally, whenever a river encounters a sea the speed is significantly reduced (Booker 2010). Evidently, the above explanation perfectly explains the features and the habit exhibited by River Derwent. When the river starts its journey, the transportation takes place courtesy of hydraulic action, which sees head-ward erosion thus lengthening the river. Upon joining other rivers like River Ouse, Derwent’s pressure increases, and the rest of the process takes place. Erosion is not exceptional at River Derwent, though there have been efforts by the relevant bodies to lower erosion levels (Castairs 2007). As seen in the Cumbria picture, the river experiences vertical erosion here thus the deepening. Here the river loses the energy and all the eroded materials are deposed here. In conclusion, river Derwent, like many others, experience some processes, which have impact on other areas as clearly explained above. Forming a V-shape at the Cumbria section, river Derwent undergoes various stages including transportation, erosion, and deposition. Each of these is influenced by other factors where transportation is mainly dependent on the river’s velocity. The hydraulic action sees the increase of pressure, which then increases erosion until the river, loses ability to transport the materials. In the end, the materials are separated and this is evident in River Derwent’s Cumbria section. Bibliography Bellmore, J. and Baxter, C. (2013). Effects of Geomorphic Process Domains On River Ecosystems: A Comparison Of Floodplain And Confined Valley Segments. River Res. Applic., 30(5), pp.617. Beechie, T., Sear, D., Olden, J., Pess, G., Buffington, J., Moir, H., Roni, P. and Pollock, M. (2010). Process-based Principles for Restoring River Ecosystems. BioScience, 60(3), pp.209-11. Booker, D. (2010). Predicting wetted width in any river at any discharge. Earth Surf. Process. Landforms 19 (2) pp.200-03 Carstairs, Ian (2007). The Yorkshire River Derwent. Wellington, Somerset, England: Halsgrove. Nicholas, A. (2013). Modelling the continuum of river channel patterns. Earth Surf. Process. Landforms, 38(10), pp.1187. Read More