Thanks for the links, both of above will be useful. Particular pice of kit I was looking for however looked like it was made of moulded aluminium and included not only the v-notch itself but also small upstream section to allow small pool to form..... maybe I dreamt it!
I am looking for the details of a portable v notch weir that can be carried to site and used to monitor small streams of flow upto 0.5 cumecs.
I have seen these in a paper brochure but have lost, and now can't find anything similar on the net. Any leads?