geographical investigation - River Holford

• title: 'how does the channel cross profile and velocity on the river holford change with distance downstream?'
• justification of question: this question was chosen as we are studying theoretical channel cross profiles and what happens to velocity in rivers, so it is sensible to see if it is true in real life
• we have to also consider where there is an interrelationship between the physical and human, we are therefore also going to ask: 'what is the impact on channel cross profile and velocity where human intervention has taken place?'
• aim: the purpose of the investigation is to determine how the channel cross profile and velocity of the velocity of the River Holford changes with distance downstream and if any of these changes are as a result of human intervention
• location: the source is in a wooded, steep valley and stays steep for some time. its source is at lady's fountain
• location: the river then works its way into a flatter area where flooding is a risk, for this reason, straighter drainage channels have been built
• location: the geology of the river consists of three different rock types, at the source there is Devonian Quartzite - metamorphic, in the middle course there is Permo Marl - sedimentary and in the lower course - Jurassic Limestone - sedimentary
• location: the first 2 rock types are impermeable, which means that it is a fast reacting river to rainfall events, but the third is permeable and so will lead to more infiltration lower down the river
• feasibility: the investigation was carried out on the river holford, at 10 different sites from source to mouth and the entire length is only 7.2 kms long
• feasibility: because the river is short, samples will be able to be taken along the length of the river over the course of the day
• feasibility: the river is a suitable study area as the gradient generally decreases with distance downstream, whilst also having a variety of land uses and changes in the valley shape, including geology
• feasibility: it was only 1 hour and 30 minutes from school and is a public right of way