We carried out our investigation on the River Harbourne in the south west of England in the county of Devon. The river is approximately 18km long which runs south easterly. It is situated amongst a rural catchment area with small settlements. Our investigation was looking into the downstream changes of the River Harbourne.
Investigating how the width of the channel will increase we will use linear and stratified sampling. To collect this data, we used a tape measure to show the change in lateral erosion and how increasing lateral erosion is due to a decreasing gradient which therefore makes the sediment and river flow cut into the river side's widening the river. We measured this data in metres. We measured, using the tape measure, across the surface of the river from bank to bank. We found that this chosen method was simple to use and, the data we collected from it was easy to record. Although this proved to provide us with the width data, we found that the tape measure results could not be deemed as accurate as it had many limitations; the tape measure was not always torte therefore, not providing us with reliable data. Further, we did not always take the measurements exactly from bank to bank providing us with unreliable data. Lastly, we found that external disturbances, such as people measuring knocking into it disrupted readings and therefore again providing us with unreliable data. Although, we did try to ensure that we had some data accuracy and reliability by having the same investigator take the same measurement at each site of investigation. This allowed us to maintain the same type of data collection throughout the chosen sites of study.
Investigating how the velocity of the river increases as we move downstream was measured in m/s by an electric hydroprop. We used the hydroprop at three points across the river with an equal distance of every third across the river. These points will be systematically sampled placing it just under the water level for thirty seconds for us to collect the data needed. We found that these results were easy to read and with it being electrical, there is no room for biased results to be read from the machine. Although this proved to provide us with the velocity, the results could not be deemed as accurate as there were several limitations. Such as, obstacles in front of the measurement disturbing the true velocity of the rivers natural course providing us with unreliable results. Also there were external disturbances such as people walking in front of the hydroprop therefore making the data collected unreliable as the velocity would be untrue. Further, the depth of the propeller into the water was not set; therefore at each reading this may have varied giving results of velocity at different depths of the river. There was also the human error that the hydroprop was not always kept still whilst conducting a reading providing us with unreliable results. Although, we did try to ensure that we had some data accuracy and reliability by having the same investigator take the same measurement at each site of investigation. This allowed us to maintain the same type of data collection throughout the chosen sites of study.
Investigating the gradient of the river we used a dumpy level. This proved more effective than using other instruments to measure gradients such as Clinometers, as we're measuring to the specific cm giving us less room for errors improving the level of accuracy of our results. Although this proved to provide us with the data for the gradient of the river, the results could not be deemed as accurate as there were several limitations. Such as, the measurement between where the dumpy level was placed and the staff was not always exactly five metres due to incorrect measurements of the topography of the chosen study site. Furthermore, the staffs were not consistently placed just on top of the water providing us with the unreliable results. Although, we did try to ensure that we had some data accuracy and reliability by having the same investigator take the same measurement at each site of investigation. This allowed us to maintain the same type of data collection throughout the chosen sites of study.
Although we found that all of our chosen methods of investigation provided us with the data for our hypotheses, the data we collected was not reliable due to several limitations which were mainly down to human errors. With more planning into each chosen site of study the reliability of our data may be found to increase.