Hard at work now. No pretty pictures.

I Wonder What Flow Moves This?

In Norrish Creek. Think it ever moves?

Seasonal Variation

So if a stream fines after a big flood and then coarsens again over time as it winnows... what is the appropriate stage to use to represent it for effective discharge calculations?

The fine stage may represent the Qe in terms of maximum sediment transported, but the coarse stage undoubtedly represents the channel forming discharge as it is this being moved that will reshape the channel itself instead of moving sediment through it.

Photo: channel of Ambusten Creek - large immobile clasts not well represented in the sediment photos.

Playing Catchup

Reworking and rethinking a lot of this stuff in an attempt to get the papers written and out the door. Nash (1994) paper is very useful on second read-through as here is someone who has considered many of the same issues as I am confronting albeit with simpler computational tools from 15 years ago.

An Important Question

1) Norrish Creek
2) Illecillewaet River
3) South fork of Thor Creek



How often do some of the visible clasts in these streams move? Yearly? Once a decade?
If they are largely immobile, and hard to measure using the photogrammetric method, then is the channel-forming discharge the discharge at which they move and not the effective discharge that moves finer sediment through without moving these large clasts?

Slow Time

I'm taking time off school to do work!

It's financially rewarding but I'm getting ready to come back to academia and finish this thing off.

One sentence synopsis of results to date: Most BC headwater streams have infrequent bankfull discharge but frequent effective discharge, and hence may be classed as degradational systems rather than equilibrium systems.

First Update In A While

I haven't posted in a while because I have been too busy with last minute calculations, not to mention writing articles!

The image above is an example of a sediment transport calculation and a flow frequency analysis combined to evaluate effective discharge. The sediment transport relation is from the surveyed channel cross-section (via WinXSpro and HEC-GEORAS), sediment photoanalyzed with Digital Gravelometer, and the Wilcock and Kenworthy (2002) transport equations, using a two-fraction method with the fine "sand" fraction <8.5mm, assumed Dsand of 2mm.

The flow frequency analysis is from WSC daily data, and divided into 25, 50 and 100 arithmetic flow classes.

The Qeff is c. 6.9 cms, from this and other cross-sections (peak in the blue line). Interestingly the Qbf is 27.6 cms and the Q2, 22.5. So this is a watershed where the Qe << Qbf. It didn't look unstable, and it seems that a lot of sediment is moving through but not spilling over the banks.