The problems to the pebble collection are that we may have been unsuccessful with the pebbles which we collected as these may have possibly been not the average pebble for that site. This might be because someone’s desire is often to select pebbles, most of the times they go for the big and smooth ones. The fact that we only took 15 pebbles from each site most probably was not enough and also maybe the fact that I only did the graph for the means which doesn’t show the individual outliers for the pebble size.
Some of my data agrees with my hypothesis very strongly, some goes with my hypothesis very weakly and others don’t fit my hypothesis at all. The width of the river is weakly proving my hypothesis, I think this is slight reliable because even though there is a weak trend line, it is still getting wider downstream and there aren’t any real big outliers. However in the velocity against distance downstream graph, I can’t see any real trend at all. My reason for this I think is because the orange we used may not have been floating when the clock was started. I think the data that is most reliable and useful is the width, bank height and water depth. I have chosen these as the most important because these are very simple to record, and usually it is very hard to make an error when measuring. These also give us a lot more information than the recording of pebbles and velocity, such as it shows the river’s shape, and the way it changes downstream, the hydraulic radius, which can give us a hint to how the velocity changes downstream. The pebble size is useful in the way that it shows us how the river manages with friction and the affect it has on things like velocity.
It would have been useful if there was the average rainfall in recent months and years to find the river’s discharge and also it would be useful if we had information on how often the river floods usually. This information would have helped me explain the outliers in the pebble size because the load gets increased in floods as the banks get worn away and eroded. It would have been useful if we could take some readings more nearer to the source as in the general river the upper stage of a river have V shaped sides, which are different to the middle and lower stages of a river.
I think that taking into account the outlier results, my data in general fits the general theory of river processes and features. The main results recorded that fit the general theory of a river are the velocity, width and depth. It does these because in the middle stages, rivers have meanders, so lateral erosion takes place eroding the river banks and making the river wider. Velocity increases due to the fact that towards the source of the river, there area in general greater pebble sizes, so the river’s energy is going into carrying the pebbles and pushing through them, so there is less energy on the velocity of it. Whereas towards the ending stages of a river, the pebble sizes is usually small which allows the river to put less energy into the transportation of the pebbles and more into the velocity.
I could have improved my investigation in many ways for example to measure the velocity, it would have been sensible to take more oranges to measure velocity, and then we may not have had many differences due to the orange. Also in the timing, it would have been better if every time that we were measuring the velocity that we made sure that the stopwatch was not started until the orange was fully floating. Some things such as velocity can be measured by computer devices, so if I had the chance I would have got information from a computer that would measure the velocity of the river a number of times, over a long period of time. These can help us as unlike humans, computers don’t get tired and they are very accurate in there results. I would have carried out the trial a lot more times if I had the chance again. The collection of pebbles could have been done a lot better in the way that people should not have picked the best looking pebble but looked away and picked a pebble at random. If I could, I would collect more many more pebbles and measured them and then the accuracy of my results would be increased.
