In the past two years we have hosted students from Aylsham High School, Reepham High School, Sparsholt College, Exeter University and King’s College London, and we are keen to continue support students from local schools who may be interested in careers in conservation or river management. The tasks the students undertake are varied. Below is an assignment produced by Toby from Aylsham High School at the end of his ten days, sharing some of what he learned about rivers.
In the picture shown below two very different rivers are represented. Many factors contribute to a river becoming a river such as the one on the right, and not the one of the left. These factors can be controlled and managed in many different ways, and in relation to the picture shown below, I will try to explore some of these factors.
One key difference between the two rivers is the amount of silt and bacterial waste that enters the river via sources such as run off from fields and places such as pig farms, as shown in the above picture. Often the problem here is the silt cannot exit the river effectively. One reason for this is the fact that the river does not meander. Meanders allow for riffles and pools within the river, and ensures that the bacterial waste, such as the manure and waste from pig farms on the left river, can be deposited in the pools. This would assure that waste does not get carried downstream to the mouth of the river, where it could affect human activity and carry disease, which could in turn affect wildlife living there. If the silt could not exit the river then the water quality would decrease and only organisms and invertebrates tolerant to silt would be able to live in the river.
The high embankment further makes the lack of meanders in the left river worse. This would not allow the silt to exit onto the floodplain even at high flows. However with sufficient floodplain the silt and bacterial waste could exit the river and stimulate the growth of vegetation as well as depositing the silt it may have been carrying. This is an example of what has happened to river on the right. The growth of vegetation on the embankment would have allowed the wildlife seen in the picture to thrive in the area and surrounding embankment. Measures such as putting in place meanders and removing silt and other materials such as manure from the pig farms, could help with the clarity of the river and allow for a better habitat for wildlife there. High embankments such as the one on the left are often a result of dredging. Dredging often occurs when farmers and landowners want to protect their land flooding.
High levels of nitrate and phosphate are also very likely to be found in the river on the left and as a result some of the life that could be living in the river would be able to live there. Nitrates and phosphates can enter the river from areas such as pig farms and livestock waste, as shown in the picture. Upstream sewage works are also a common way for nitrates and phosphates to enter the river. The process of eutrophication causes a decrease of life in the river as well. This can happen because sunlight could not reach the riverbed due to and excess of plant growth. The aquatic plants would then die because they cannot photosynthesize and oxygen levels would decrease once these plants die, meaning life in the river would be at a minimum or not at all. The fertilizers and sewage that are likely to run into the left river from fields and sewage works are likely to cause eutrophication, most likely by increased growth of plants such as toxic algae blooms.
Although there are many other factors that would also affect the difference between the left river and the right river, these are some of the key ones. If these factors can be controlled and managed then our rivers are more likely to look like the right river than our other choice the left river.
The Norfolk Rivers Trust see the role that local communities play in securing their rivers future as a vital part of our work. We have funding to work with local communities to learn more about their rivers through guided walks, events, volunteering activities and school sessions.
These events are free and aim to educate people as to how important their rivers are and how we can all play our part in keeping our rivers healthy for people and for the wildlife that use them.
The Norfolk Rivers Trust has set up a scheme called River Guardians and this enables individuals, groups and schools to sign up to become involved in the future of their rivers through volunteering opportunities and events tailored to improve peoples knowledge of their local river. You can commit however much time is available to you and whether you choose to just keep an eye on your river and report anything that concerns you or get more involved with practical restoration work is entirely up to you.
To find out more about the scheme or about how we can help your school or community please contact Gemma Clark the Community Involvement officer at firstname.lastname@example.org also keep up to date with events near you through the Norfolk Rivers Trust website. If you would also like to be added to our email distribution list so that you get sent details on new events and the 9 Chalk Rivers Project newsletter then please let Gemma know at the above email address.