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There are two methods of recording the amount of VEGETATION in the stream. You can simply record the presence or absence of vegetation at each individual site or you can use a quadrat divided into 25 or 100 squares. The quadrat is placed over the stream at regular intervals and the number of squares with vegetation in them is counted.

Possible problems: It is not easy to measure vegetation! Plants growing on the bank may hang in the water - do you count these? In some places the vegetation may be dense and will have a strong effect on flow and velocity. In other places, the vegetation may cover an equal area but be very sparse and will only have a minimal effect on flow and velocity. How much of the square in the quadrat must be filled with vegetation before it is counted?

Unless the stream bed is muddy or sandy, it is useful to take samples of the BEDLOAD. This can be measured to look for any differences across the stream and downstream from site to site. There are two useful measurements to take. The first, the long axis of the pebble is shown in the photo on the left. It is being recorded using callipers but can be just as easily recorded with a 30 cm ruler.
The second measurement is the angularity of the pebbles. This can be recorded by observation using Powers' Angularity Chart (see picture on the left) which uses a set of six pictures to help you make your judgement.

Possible problems: You could measure the width as well as (or instead of) the length of the pebbles. The sample size is very important - most students don't measure enough pebbles because it is tedious and time-consuming. The angularity index is subjective and different people might give different answers.

In mountain areas the GRADIENT of the stream bed is an important factor to measure. In lowland streams, such as the River Darent, gradient is less significant as it is very gentle (between 1-3 degrees) along most of the stream's length. Only close to the source does it rise to between 3-10 degrees. In order to measure gradient, you need two ranging poles and a clinometer. The two ranging poles are held vertically, about 10 metres apart (further if possible). The person with the clinometer holds it level with the bottom of the red stripe and looks through the sight to the same position on the other pole. On a gun clinometer, the angle is recorded when the lever is released. On other types the angle can be read as the clinometer is being sighted.

Possible problems: If the stream bed is uneven and the distance between the ranging poles is small, it is not unusual to find that the stream is going uphill! The accuracy of the clinometers is not good and differences may show up even where they don't exist.