Australian Rainfall and Runoff 2016 provides guidance on assessing the impact of blockage of culverts and bridges as part of flood modelling. Details are in Book 6 Chapter 6.
The need to assess blockage represents a change to hydraulic modelling practice. In the past, industry-wide guidance was lacking and the effect of blockage was often not considered. The new guidelines provide a standard procedure but, as yet, there is limited experience in their application. Part of the process is to complete a blockage assessment form which is linked from ARR. Unfortunately the link no longer works but the form is on the internet here.
The guidelines are being incorporated into hydraulic modelling software with a recent paper outlining the procedures that have been included in TUFLOW and an assessment of how they have performed in three case studies of recent flood modelling projects (Ollett, et al., 2017).
It is likely that future flood modelling briefs will require assessment of blockage so flood consultants will need to learn about, and be able to apply, the procedures and explain the significance of results to clients. Some resources are listed blow.
References – articles
Ollett, P., Syme, B. and Ryan, P. (2017) Australian Rainfall and Runoff guidance on blockage of hydraulic structures: numerical implementation and three case studies. Journal of Hydrology (NZ) 56(2) 109-122. (link)
Ollett, P. and Syme, B. (2016) ARR blockage: numerical implementation and three case studies. 37th Hydrology and Water Resources Symposium 2016: Water, Infrastructure and the Environment. Queenstown, NZ. pp. 346-359 (link)
Ribgy, E. and Weeks, W. (2015) Evolving an Australian design procedure for structure blockages. 36th Hydrology and Water Resources Symposium: The art and science of water. Hobart, Tas. pp. 154-161. (link)
Suitability of ARR guidelines as an alternative blockage policy for Wollongong. 36th Hydrology and Water Resources Symposium: The art and science of water. Hobart, Tas. pp. 370-377. (link)
References – ARR2016 project reports
Project 11 (Blockage of Hydraulic Structures) Stage 2 Report (2013) (link at arr-software.org)