The Grand Challengers Podcast Episode #70

The permeable engineer, saving a stream with its catchment and tanks for platypus

Guest: Tim D. Fletcher

September 8th, 2026

Overview

Tim D. Fletcher did not plan to work on cities. He studied forest science, worked as a commercial tree faller and then a firefighting tree faller, did a PhD in rural hydrology, and took a stormwater job at Melbourne Water that felt on the first morning like a serious mistake. What changed his mind was a single idea: that you could use nature to protect nature, and do it in the least likely place.

Three decades later he is Professor of Urban Ecohydrology at the University of Melbourne, running a research group whose work reaches from laboratory columns to whole catchments. This conversation follows that arc through three chapters. At Monash he helped build MUSIC, the model that replaced back-of-the-envelope stormwater design across Australia, and along the way stumbled on the moment two colleagues realised at a shared office printer that they had independently drawn the same decay curve. At Melbourne he joined Chris Walsh on Little Stringybark Creek, retrofitting nearly three hundred stormwater control measures into an existing catchment and measuring what happened, with a reverse auction that asked residents to name the price they would accept for hosting one. And now, under an Australian Research Council Industry Laureate Fellowship, he is networking smart rainwater tanks across a catchment east of Melbourne so a stream can hold its flow for a species that cannot survive without it.

The technical work is only half of it. Tim is unusually direct about what does not work, including his own most-cited paper, which he calls a blah-blah paper, and a council stormwater strategy he wrote that sat on a shelf until he had to teach its own authors their policy to get a permit for his firewood shed. Underneath everything sits a straightforward moral claim about research funding, and a quieter one about how he would like to be remembered.

Episode Teaser

Teaser caption…

Biography

“… The idea that you could use nature to protect nature, being inspired by nature to protect nature, it really fascinates me….”

Tim D. Fletcher is Professor of Urban Ecohydrology at the University of Melbourne, where he heads the Waterway Ecosystem Research Group at the Burnley campus and co-leads the Melbourne Waterway Research-Practice Partnership with Melbourne Water. He came to water through forest science rather than engineering, working first as a commercial and then a firefighting tree faller before a PhD in hydrology took him towards catchments and streams. A post-doctoral position with Tony Wong at Monash University put him on the team that developed MUSIC, the Model for Urban Stormwater Improvement Conceptualisation, which became the national reference tool for demonstrating stormwater compliance in Australia. He later served as Director of the Institute for Sustainable Water Resources at Monash and was an invited professor at INSA Lyon in France. He is lead author of the 2015 paper on urban drainage terminology, the most-cited paper in the field, and holds an Australian Research Council Industry Laureate Fellowship.

His research runs from laboratory testing of biofiltration media through to catchment-scale field experiments, and it consistently ends up somewhere ecological. With Chris Walsh he co-led Little Stringybark Creek, a two-decade attempt to retrofit an entire urban catchment with stormwater control measures and measure whether the stream downstream recovered. That work now feeds directly into Tanks for Platypus, a project networking smart rainwater tanks and urban lakes across the Monbulk Creek catchment east of Melbourne so that stored water can be released before storms and returned to the creek in dry weather, timed around what a platypus needs to feed and stay hidden from predators. He describes his own discipline as permeable, full of holes he fills by working with economists, ecologists, chemists and sociologists, and he is candid that the remaining obstacles to this kind of work are governance and politics rather than hydraulics. He also helps organise Novatech in Lyon, the long-running international conference on sustainable urban water management, and is happiest, by his own account, with a chainsaw or an excavator in his hands.

Quick Summary & Highlights

  • There is no correct word for water sensitive urban design: His most-cited paper concluded that terminology is local rather than universal. Each region builds its own language around whoever championed the idea there. A term’s job is to persuade planners and architects, not to satisfy a dictionary.
  • The barrier to scaling this work is governance, not technology: Conservative cost-benefit work for the Victorian government returns marginal ratios of fifteen to twenty dollars of benefit per dollar spent. Governments still hesitate. Election cycles make long-term decisions structurally difficult, whoever happens to be in office.
  • A rainwater tank can work the way a solar battery works: Networked tanks release water ahead of a forecast storm and top up the creek in dry weather. The household keeps its supply, the stream gets its flow, and modelled flood damage in one precinct falls by around two million dollars a year.
  • Bigger stormwater projects were not cheaper, they were dearer: Problems at the household scale cost an extra five hundred or eight hundred dollars to solve. One large public system needed screw pylons under the tanks and cost three hundred thousand. The economy of scale ran backwards, an argument for measuring rather than assuming.

Resources Related to the Episode

Key research and publications

Tools, methods and context

Projects, groups and places

Cultural, natural and fun references

Episode Chapters

(Chapters are embedded in the episode for quick access, click this to expand and view all chapters and time stamps)
  • 0:00 Intro
  • 1:59 Guest Intro & Remembering our first encounter
  • 6:42 Reminiscing about undergraduate times and education
  • 10:39 How would Tim describe himself?
  • 13:10 The WSUD Terminology Debate
  • 21:28 The key barrier to scaling up WSUD
  • 27:09 Tim’s Monash Era
  • 31:33 The MUSIC Model
  • 40:40 A 101 on Ecohydrology & the Urban Stream Syndrome
  • 43:32 The Little Stringybark Ck Living Lab
  • 1:03:57 Tim’s Tanks for Platypus Project & Real-time Control
  • 1:22:21 What is Tim’s biggest lessons learnt so far?
  • 1:25:04 Q&A Start
  • 1:25:12 What does innovation mean to you?
  • 1:28:02 Key moment, book, person, event
  • 1:31:52 If you had a magic wand?
  • 1:33:34 Time Management
  • 1:36:10 Favourite childhood memory
  • 1:38:13 Biggest challenge to date?
  • 1:43:04 Advice for young professionals
  • 1:46:34 What is something you’ll regret not doing?
  • 1:47:50 What would you most like to be remembered for?
  • 1:49:57 Where can people find you?
  • 1:52:48 Final Message
  • 1:53:23 Outro

Connect with Tim D. Fletcher

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Credits