I am surprised by your call for information in an international mailing list like River-List (IAHR). There are a lot of works and studies available in Australia. I am concerned by a process suggesting that overseas experience is better than local expertise.

In Australia, Professor Colin APELT did a lot of research works on the hydrodynamic of submerged bridges, including debris loads on bridges. I recommend you to contact him directly :

Professor Colin J. APELT
Dept. of Civil Eng., University of Queensland
Brisbane QLD 4072, Australia
Fax: (61 7) 33 65 45 99
Email: c.apelt@mailbox.uq.edu.au

For culverts, I believe that a major issue is the blockage/obstruction of the barrel by large debris. Traditionally, wide barrel culverts are designed with a multicell arrangement, each cell being 1 to 2 m wide. (For example, "The Hydraulics of Open Channel Flow: an Introduction", Butterworth-Heinemann, 1999).

During the 1974 flood of the Brisbane river, Brisbane QLD, timber houses were seen floating on the river. In one case, a bridge located upstream of the city centre was partially blocked by debris (trees, cars). It had to be cleaned during the flood to prevent bridge failure and subsequent damage. That particular bridge is seen in the video-documentary :
    "The river's rage [video recording]: Queensland 1974"
    Channel 7, 24 April 2000
    UQ Library link

I have myself research interests in debris load on spillways and dams. Debris impact is not often taken into account and the impact process is still poorly understood. Nevertheless
the impact of debris can be significant. In one case (Ngalimbiu bridge, Solomon islands), substantial damage to concrete bridge piers was reported with plastic hinges in the pier portals. The equivalent static force at headstock level was estimated in excess of 3,000 kN, and it is believed that debris impacts contributed to the bridge failure (BOYCE 1987).

BOYCE, W.H. (1987). "Cyclone Namu and the Ngalimbiu Bridge - Did it fall or was it pushed ?"
Queensland Div. Tech. Paper, IEAust., Vol. 28, No. 20, pp. 13-18.

I hope that the above information will assist you. I genuinely feel that we can learn a lot from local expertise.

Sincerely Yours,

Hubert Chanson

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Hubert CHANSON
Dept. of Civil Eng., University of Queensland
Brisbane QLD 4072, Australia
Ph.: (61 7) 33 65 35 16 - Fax: (61 7) 33 65 45 99
Email: h.chanson@mailbox.uq.edu.au
Internet : http://www.uq.edu.au/~e2hchans
 

Habib Rehman wrote:

Many Australian rivers/creeks carry a substantial load of debris during floods. The debris results in blocking of culverts and bridges. The situation becomes critical in an urban setting where additional aflux across the structures due to blockage can exacerbate flooding in the floodplain. Some efforts have been made to provide some sort of debris control structures but so far the impact of such devices is not very well known.

I would appreciate a response from anybody who has information on strategies/devices for debris control.

Thanks

Habib Rehman
Senior Project Engineer
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