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. 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 In the worksheet activity students identify the same features on a simplified drawing of a river system. It is differentiated two ways:

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. 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 velocity of a river is the speed the water flows. The velocity will change along the course of a river. Which river channel characteristics you chose to measure will depend on the question you investigate.It is not possible to measure river discharge directly in the field. Instead take measurements which will allow us to calculate discharge.

The discharge of a river is the volume of water flowing through a river channel. It is usually measured in cubic metres per second. 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!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 type