A device for recording fluctuating water levels

Abstract An operational device is described which is capable of recording fluctuations in a water level by graphical and data log methods. By altering the construction details it can be used to record small fluctuations such as those found behind a “V” notch weir in open channel flow measurements or large fluctuations as found in a watertable. The design of the device makes it cheap, accurate and reliable. Of those currently in use over a 300 mm range behind “V” notch weirs, an accuracy of ±0·83 mm is achieved, while a 1500 mm version for recording watertables achieves an accuracy of ±8·3 mm over the range. Changes in the water level are recorded on a 7-day revolving clock drum and chart by means of a pen and on the cassette tape of a data logger by means of a rotary potentiometer which works in sympathy with the movements of the float.