Edit: 11 Nov 2016. The final version of the paper is here.
I’ve put together a conference that provides a summary of current hydrologic practice in Victoria based on a review of 20 recent flood studies.
- The RORB hydrologic model was used in 17 of the 20 studies. Clearly RORB is popular and useful even though much of the core capability dates from the 1970s.
- Climate change impacts on flooding were only considered in half the studies. There has been other work that suggests Australian hydrologists and their clients lag behind their international counterparts in considering climate change (e.g. this study by Caroline Wenger and others). This is surprising given that Engineers Australia issued climate change guidelines in 2003. The latest guidelines are available here.
- The number of sub-catchments used in RORB models has increased greatly with the use of tools such as ArcHydro and CatchmentSim. There was an average of 92 sub-catchments in the studies I looked at. RORB models from 1970 to the mid 1990s generally used 10 and 20 sub-catchments.
- No one used Monte Carlo or ensemble approaches to hydrologic flood modelling despite these features being available in RORB (For a summary of RORB’s capability see this conference paper from 2006).
- Rainfall temporal patterns were taken from the 1987 version of Australian Rainfall and Runoff. RORB provides a tool to extract temporal patterns from local pluviographs but this was not used.
- Most studies used uniform spatial patterns for design rainfalls. The new recommendations from Australian Rainfall and Runoff are that spatial patterns should reflect variations in rainfall across catchments (ARR Book 2, Chapter 6). Clearly this will require a change in practice.
- The baseflow contribution to design flood hydrographs was generally not considered. Again there is increased emphasis on this in the new ARR.
Ladson, A. R. (2016) The State of Hydrologic Practice in Victoria, Australia. Hydrology and Water Resources Symposium. 28 Nov – 2 Dec 2016, Queenstown, NZ.