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The WIDTH of the river channel can be measured by taking a 30 metre tape measure and stretching it from bank to bank. It should be kept as taut as possible to be accurate. If the stream bank is sloping, keep the tape as near to the water surface as you can so that you can line it up with the bottom of the bank.
Possible problems: banks overgrown with vegetation may cause problems in terms of finding the exact edge of the stream.

Once the tape measure is stretched across the channel, it is easy to move along at regular intervals e.g. one metre, and measure the DEPTH of the stream using a metre rule. Measure depth in metres e.g. 0.25 for 25 cms. so that width and depth measurements are the same units. Regular, accurate readings will allow you to draw an accurate cross-section of the stream channel.
Possible problems: large boulders or debris may make the stream very shallow at a particular point - record the reason for this on your data sheet. If the stream bed is soft, the ruler may sink into the mud.

The speed or VELOCITY of the stream can be measured in two ways. If you have a flowmeter, this allows you to take accurate readings at different positions across the stream and also at different depths if you wish. Ideally, you should take at least three readings - in the centre, close to the left bank and close to the right bank. This will allow you to see the effects of meanders on the position of the fastest current. The flowmeter has a propeller which turns in the moving water. The number of turns is recorded on a digital counter.
If you do not have a flowmeter, you will need to play 'pooh sticks'. Measure out a length of stream, five or ten metres is ideal. Float a small stick, an orange or similar object along the stream and time how many seconds it takes to get from marker one to marker two. The velocity can be calculated using the formula: speed = distance/time. Ideally, do this two or three times to get an average.
Problems: Even expensive flowmeters break down! Floating an object gives surface velocity which is not usually the maximum velocity. It is difficult to get readings close to the banks using floating objects.