The most suitable place is a (temporary) bridge. Always make the measurement at the upstream side of the bridge! If the bridge has pillars-r do not make your measurements close to these pillars. The man holding the meter should never be standing in the water. Build a- temporary bridge or use a boat or float instead. Measurements can also be taken upstream of a structure. In any case make sure there are no offtake between the structure and the measurement site. Close them, if another site is not available.