It is not possible to measure river discharge directly in the field. Instead take measurements which will allow us to calculate discharge.

Which river channel characteristics you chose to measure will depend on the question you investigate. In the worksheet activity students identify the same features on a simplified drawing of a river system. It is differentiated two ways:Extend a tape measure from the point where the dry bank meets the water on one side of the river to the same point on the other side (hold it taut about 20cm above water level). Record the length, viewing the reading from directly above the tape measure. The velocity of a river is the speed the water flows. The velocity will change along the course of a river. According to the Bradshaw model as you move downstream river discharge should increase. This is because tributaries will feed the river leading to an increase in discharge. Measuring the velocity of a river Students are challenged to match eight features of river systems to photos, satellite images and maps. This activity can easily be differentiated by giving groups different numbers of cards. River depth is how deep a river is. Depth changes across a river channel due to material on the river bed. Therefore, it is useful to calculate the mean depth.

It is not possible to measure river discharge directly in the field. Instead, you need to take measurements that allow you to calculate discharge. For the collection of your qualitative data it is not necessary (or practical!) to measure all parts of the river – you will need to take a sample. If you have a flow meter it is very easy to measure the velocity of a river in the field. If you don’t have a flow meter you can take measurements in the field using a float, stopwatch and tape measure. Once you have recorded the appropriate data you can use the formula below to calculate the velocity. The Bradshaw Model suggests that certain changes occur along the long profile of a typical river. For example, discharge increases as you move downstream of a river or bedload (material on the river bed) particle size decreases along the river channel.Tip: If the bed is rough and bumpy, you will need more measurements at closer intervals to get an accurate result. The discharge of a river is the volume of water flowing through a river channel. It is usually measured in cubic metres per second.

According to the Bradshaw Model, the wetted perimeter of a river should increase along its course. Measuring the cross profile of ariver River cross profiles show you a cross-section of a river’s channel and valley at certain points in the river’s course. Measuring the width of the river channel enables you to calculate the cross-sectional area. Also, according to the Bradshaw Model, channel width increases downstream. Measuring the wetter perimeter of a river In justifying your choice of the variables you have measured it can be helpful to consider the linkages between the different river variables. Measuring river discharge In situations where access is more limited you may have to take a more opportunistic approach to sampling – however in this case it is sensible to get as close as possible to a systematic sample as possible.Place a metre ruler into the river until it touches the river bed. Record the distance between the river bed and the surface of the water. You should do this at regular intervals between the banks of the river. Add the depths together and divide by the number of recordings you took to calculate the mean depth. Coastal Environments CPD – Erosional Erosion, Coastal Management, Deposition and Fieldwork on the Holderness Coast

There is a range of things you can use for a float including an orange. We recommend dog biscuits because they break down in water if swept away! To calculate the cross-sectional area you will need to know the mean depth. According to the Bradshaw Model depth increases from the source to the mouth of a river. Measuring river width It introduces many key river concepts and a wide range of related vocabulary. First the presentation recaps the main processes of the water cycle. It then introduces some of the well known features of river systems (e.g. waterfalls and lakes). There are two activities: Questions that focus on changes along the long profile or downstream changes support in developing a hypothesis. A hypothesis is astatement, usually an educated guess, that you will either prove or disprove through the data you collect as part of your investigation. Primary Field Work Techniques The cross profile of a river changes as it moves from the upper to lower course as a result of changes in the river’s energy and the processes that the river carries out. Measuring sediment size and typeTo gather your data you need to measure a distance of 5 metres downstream. Place your float in the water upstream at 0m. Record the time it takes for the float to travel 5m. Repeat this three times and calculate the mean. Next, use the above formula to calculate the velocity. Coastal Environments CPD – Erosional Landforms, Coastal Management and Fieldwork on the Holderness Coast mathsf{Discharge \;(m