ABSTRACT
O n small rivers it is often convenient to measure flow by m e a n s of a weir or f lume. Such structures have the advantage that they are less sensi t ive to the downs t ream condi t ions, the channel roughness and the influence of backwater than the ve loc i ty -a rea me thod for example . A good example o f the use of measur ing structures is to be found in the Uni ted K ingdom where , mainly because of the small rivers and the influence of backwater , the hydrometr ic ne twork of some 1400 streamflow stat ions contains about 750 measur ing structures. Practically all of these are of a type which has been precalibrated in the laboratory, some of wh ich have been check-calibrated in the field. In this chapter , those weirs and f lumes which have been precalibrated and standardized by the Internat ional Organizat ion for Standardizat ion or the Brit ish Standards Insti tution will be discussed with an additional sect ion on non-s tandard weirs .
