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River Studies

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Geography MYP Coursework River Studies Rio Lizandro is a river located in Portugal, near the district of Lisbon, and has an approximate length of 30km. In this coursework, we have to test the hypothesis related to the characteristics of the Rio Lizandro to discover if it is justified. In order to do so, we will have to draw, measure and calculate the data which we are give on four different sites along the river, and thus conclude with an analysis on the relationship between our results and the given hypothesis. Task 2: State the aim of the study. You need to explain the hypothesis and perhaps suggest what you expect to be the outcome referring to Bradshaw's Model River. The aim of this study is to use the given data on the four different sites along the Rio Lizandro to see how its river variables change and compare it to Bradshaw's model. By doing this, we will be able to test the hypothesis and conclude on whether or not it is correct. The Bradshaw Model is a geographical model which illustrates how a river's characteristics differ from the mouth to source, or lower course to upper course, of a river. According to Bradshaw's model, the hypothesis is that "Stream characteristics (i.e. cross-sectional area, discharge, velocity, efficiency, and gradient) ...read more.


Gradient: 1�. Dist. from Left bank (m) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 Depth (m) 0.0 0.32 0.20 0.16 0.16 0.22 0.27 0.38 0.25 0.20 0.13 0.05 0.23 0.25 0.21 0.12 0.07 0.02 0.0 Velocity measured over 10 metres in the centre of the river flow: Attempt Time in seconds 1st 10 2nd 12 3rd 14 Average time = 10+12+14 = 12 3 Average velocity: 10 / 12 = 0.83m/sec. - Wetted Perimeter: 9.5m - Cross sectional area: Width x Average depth Average depth: 0+0.32+0.20+0.16+0.16+0.22+0.27+0.38+0.25+0.20+0.13+0.05+0.23+0.25+0.21+0.12+0.07+0.02+0 19 = 0.17m 9 x 0.17 = 1.53m2 - Discharge: Cross sectional area x Velocity 1.53 x 0.83= 1.2852m 3/ sec - Hydraulic Radius: Cross sectional area Wetted Perimeter 1.53 / 9.5 = 0.161 = 0.16m Site 4: Foz de Lizandro Gradient: 0�. Distance from left bank (m) 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 11.76 Depth (m) 0.00 0.15 0.57 1.35 1.51 1.60 1.51 1.60 1.67 1.00 0.56 0.41 0.00 Time taken for float to travel 10 metres: Left bank 11 secs 10 secs 14 secs Middle 10 secs 10 secs 12 secs Right bank 12 secs 15 secs 13 secs Average time = 35/3 + 32/3 + 40/3 = 11.7 + 10.7 + 13.3 = 35.7 = 11.9 3 3 3 Average velocity: 10 / 11.9 = 0.84m ...read more.


It is for this reason that the halving pattern cannot be taken into consideration if we were predicting the gradient for other sites in other rivers. Nevertheless, the decrease in gradient along the river supports Bradshaw's theory. Essentially, the wetted perimeter means the perimeter of a cross sectional area that is covered with water. Although it is not included in the hypothesis, it however does not show to have any pattern at all. At first, the wetted perimeter shows a decreasing pattern along sites 1 to 2, as it decreases from 16.7 to 16.4 cm. But from sites 2 to 4, the wetted perimeter increases from 16.4cm to 950cm to 1425cm. It may be that the data for site 1 is incorrect and is supposed to be lower, in order to show an increasing pattern for the wetted perimeter from source to mouth. So, overall as stated in the hypothesis, the stream characteristics do change along the course of the river. It is also correct that they are all interconnected. As you can see from the results, the hypothesis stated in the beginning of the coursework is fully correct and the characteristics of Rio Lizandro meet accordingly with what Bradshaw's table shows, as seen in the results and calculations. Hence, stream characteristics all change along the course of the river and they are all interconnected in one way or another. ?? ?? ?? ?? 1 ...read more.

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