This page used to contain links to reports for our clients.
We, however, now use Hightail (https://www.hightail.com) for this purpose. They're really great!
As an alternative, we will put some useful tools (at least useful to somebody!) on this page, such as the spreadsheets below:
When you want to calculate the flow through a pipe by gravity, then use this spreadsheet below. All you need to do is to fill in values in the 6 orange-coloured cells... There are two sheets, the one is intended for pipes flowing at less than half full, the other for pipes with flow greater than half full.
When you want to estimate the flow through a pipe (e.g. a pipe under a road) in the field without a proper flow metre, the you can use this spreadsheet below.
You need to measure the length of pipe (e.g. from one end of a culvert to the other), then you need to measure the pipe diameter and the depth of the water flowing in the pipe (there are several alternatives to do this, explained in the spreadsheet) and you need to measure the number of seconds it takes for a floating object dropped in the water at the one end of the pipe to reach the other end. The latter object must preferably "float" just below the water surface so that it actually indicates the water velocity and is not influenced by wind, etc. on surface. Then just enter the four values in the orange-coloured cells. There are two sheets, one for pipes with water flowing less than half the pipe diameter and another one for pipes flowing more than half full.
If you find any errors, please contact us at firstname.lastname@example.org