RG2 – By looking at the depth graph I can pick out that site 1 is deeper than site 2. The graph then shows that from site 2 to about site 8 the general trend of the graph shows that the river is getting deeper. Generally I can say that apart from site 1 which looks to be an anomaly compared to the general trend of the river shape I can say that the river stream is getting deeper as you go downstream.
I now that the river is getting wider as you downstream because many different types of erosion are occurring such as attrition, corrosion and carrasion is happening. Carrasion, also known as solution, is the process by which the river water reacts chemically with soluble minerals in the rocks and dissolves them. This process is very likely to be happening at site 5 and onwards. This is because the water in the river must be travelling at high speeds in order to break down such tough bedload. Hydraulic action is also likely to be happening downstream of the river as this is where the river velocity is fast and has got the energy to break down rocks and drag them away from the bed and banks by its force. The energy in the river is dispersed which means that it is spread out along the river and whenever it hits rocks it will have the strength to break them.
RG3 – Based on the data mentioned above I can say that the average depths of the river at each site indicate that the trend of the river is getting deeper as you go downstream. Processes such as lateral erosion are occurring downstream and the processes mentioned in the previous graph are also happening.
RG4 – From looking at this graph on the velocity of the river, I can say that at site 1 the velocity was 1m/s. At site 2 the velocity was 2.25m/s and at site 3 the velocity was 4m/s. Between sites 1 and 4 I can say that the velocity was not too fast this is because the orange which was dropped in the river drifted towards the inside bend of the river – at the inside bend of a river the velocity is at its slowest and on the outside it is at its fastest as there is a larger surface area for the river flow to travel so it has time to speed up. From site 5 to site 8 the river starts to pick up some speed and there is an increase in velocity but the velocity is increasing steadily. From site 5 to site 8 the river velocity increases greatly by 7m/s to 19m/s. The general trend of the river is that the velocity increases as you go downstream. Based on my findings, I can say that river velocity is influenced by three main things:
- River Gradient
- Channel Roughness
- Channel Shape
River Gradient – I can say that based on my results for the river Dove is not travelling down a steep slope because its velocity would increase rapidly. I can now say that a river flowing down a steep slope or gradient has higher velocity than one which flows down a gentler gradient. For example, the speed of flow in a river that plunges down in the form of a waterfall is much higher than the speed of flow in a river that winds a gentler slope.
Channel Roughness – In figure A, of the river dove the channel is smooth – site 1 or 2 while figure B it is rough or uneven – site 7 or 8 with boulders on the river bed as well as rocks that protrude out from the bank. At site 7 or 8 the river will have to overcome such obstacles and therefore there will be more friction and the velocity is reduced.
Channel Shape – The greater the wetted perimeter, the greater the friction between the water and the banks and the bed of the channel, and the slower the flow of the river.
RG5 – By looking at the discharge graph, I can say that from site 1 to 2 there is a stable or steady increase of about 500 cumecs. The amount of water at site 3in the river or discharge then increases stably to about 2000 cumecs. I can also say that between sites 3 and 5 there is a steady increase in discharge of about 100 cumecs. Then from this point onwards to site 6 the discharge increases rapidly by over 5000 cumecs suggesting that the river might be deeper at this point due to vertical and lateral erosion taking place. Overall I can say that the trend or pattern of the river is that the river’s discharge is increasing from site to site as you go downstream. It is steady up until the point of site 5 where then it shoots up rapidly to around 29,000 cumecs.
RG6 – From looking at this graph I can say that the efficiency of the river channel steadily increased with the exception of site 5 where it plunged. From site 1 to site 3 the efficiency of the river - the hydraulic radius increased from 20 to 40. From site 3 to site 4 the hydraulic radius had decreased by 3. The hydraulic radius then dropped by about 18 at site 5 and then increased by about 58 from site 5 to site 8. The general trend of the graph shows that the hydraulic radius is increasing at a stable rate.
RG7 - This graph, the river cross section at site 1 shows that at site 1 the river depth was not too deep. The graph shows that the depth of the river fluctuates a lot in terms of the depth is not going up only or is going down only but is instead showing signs of fluctuation. At 1 metre the depth of the river was 88cm and the width was 1 metre, then at the second metre interval the depth was 92cm. The width of the river stream was 2m at this point. I can state that the relationship between the width and the depth based on my graph is that as the width of the river gets wider then so the depth of the river gets deeper.
RG8 – By looking at this cross section showing the efficiency of the river channel at site 5 it shows that as the depth of the river gets deeper then the width of the river gets deeper. My graph’s trend shows that at the first metre interval the width was 1 metre and depth was 26cm and at the eighth metre interval the width of the river the depth was 57cm. The trend shows that the river is getting deeper as you go past each metre interval. The volume of water content in a river depends on four things in general:
- The Presence of vegetation – the presence of vegetation affects the rate at which water is intercepted and is able to infiltrate into the ground. If an area is covered with vegetation, then the vegetation will intercept the rain and will allow some of it to infiltrate into the ground. As a result of this, there will be less water as the surface run – off goes off and so the volume of water in the river will be lowered.
- The Permeability of rocks – the permeability of rocks is determined by the size of the pores between the rock particles. If the rock has small pores, water cannot easily infiltrate into the ground and this means that the rock is impermeable. On the other hand if the rock has large pores, water can easily infiltrate and thus the rock is permeable. When water flows through an area of impermeable rock, little water infiltrates into the ground and as a result of this there will be a high surface run – off and this will lead to a high volume in the flow of water.
- The size of the drainage basin – a larger drainage basin will have more water content in the river because there is a greater amount of tributaries bringing water to the river resulting to a high surface run – off
- And the climate of the area
RG9 – My star graph shows that 4 out of 6 rocks picked out of the river were sub angular at site 1 and 2 were angular.
RG10 – This star graph shows that 3 of the bedload picked up were sub angular. It also shows that one rock was angular and 2 of the rocks were rounded.
RG11 – My radar graph shows that an angular type of rock was picked up 2 times, a sub angular type of rock picked up twice, a rounded rock was picked up once and a very rounded type of rock was also picked up once.
RG12 – This graph shows 6 angular were picked up, 1 very angular type of rock was picked up and 1 rounded rock was picked up.
RG13 – This radar graph shows that 2 very angular rocks were picked up, 3 angular rocks, 2 sub angular and 1 rounded type of rock was picked up.
RG14 – From looking at this graph I can say that I picked up 1 very rounded type of rock, 2 rounded rocks, 3 sub rounded rocks, 3 angular rocks and one sub angular rock.
RG15 – This graph shows that I picked up 2 angular rocks, 1 sub angular, 6 rounded and 1 very rounded type of rock.
RG16 – By looking at this graph I can say that I picked up 4 very rounded types of rocks, 3 rounded rocks, 2 sub rounded rocks, and 1 angular type of rock.
From looking at graphs 9 to 16 I can say that you are most likely to find rounded typed of rocks downstream and angular types upstream.