ISSUE 2, 2021 WATER LINES flood preparednessThere is an enormous body of work now available showing that investing in resilience yields a double dividend. This is achieved, as described in Deloitte Access Economics Report Building our Nation’s Resilience to Natural Disasters, through firstly reducing the cost of natural disasters and secondly driving social and economic ‘co-benefits’ that arise even in the absence of a disaster. The report goes on to detail that Current Australian and State Government spending on direct recovery from disasters is around $2.75 billion per year, compared to funding directly for natural disaster resilience of approximately $100 million per year. Our Water Technology team are passionate about leading and contributing to the development of resilience in the floodplain management space. Over the course of the following pages, you'll also get the chance to read through and experience several accounts of our talented team's expertise in action, including studies, detailed analysis, real-world operations, and formulation of action plans for mitigating flooding and its damages – in addition to meeting some of our early-career professionals, Cheryl, Michael, and Tahlia, who each come from unique backgrounds and share a powerful drive and vision for the future of the industry, and the world at large. I really can't wait for you to get to know them! STEVE CLARK Managing Director Welcome to our latest issue of Waterlines In this edition of Waterlines, we showcase several flood preparedness and response projects that we have recently completed, including: •A large-scale flood investigation of the Mary River (of personal interest to me as it was experiencing Mary River flooding as a kid that sparked my interest in flooding in general and set the direction for my future career).; •How community engagement supports better flood study outcomes Real-world flood events honing the skills of floodplain managers; and •A large-scale flood investigation of the Mary River. Thank you for taking the time to read Waterlines. Please do not hesitate to contact me or any of the Water Technology team at any stage if we can be of assistance. 2 WATER LINES : ISSUE 2, 2021Neerim South, Victoria, is a vibrant township of approximately 1,300 residents known for its rural lifestyle and nature-based tourism. Its unique position on the top of a ridgeline, located east of the Bunyip State Forest, marks the boundary between catchments managed by the West Gippsland Catchment Management Authority and Melbourne Water, with the local drainage on both sides being managed by Baw Baw Shire Council. Despite no catchment-scale flood study results or mapping information being available, the community regularly experiences flooding, forming an acute awareness for the location and magnitude of the flooding issues in the township. These flooding hotspots are known to be the result of legacy overland flow paths where development and infrastructure have since occurred, causing diversions of the overland flow paths towards residential developments and infrastructure. With the township predicted to experience moderate population growth in the future, it is critical for the Council to map out land to be set aside for drainage, reduce The Power of Community Engagement NEERIM SOUTH FLOOD STUDY For more information, contact +61 3 8526 0800, Belinda T am (belinda.tam@watertech.com.au) Celine Marchenay ( celine.marchenay@watertech.com.au ) existing flood risk to the community and guide future land use development. The Neerim South Flood Study, completed by Water Technology, aimed to build a flood model capable of replicating issues experienced by residents while investigating drainage solutions to reduce flood risk to the community. Two opportunities to engage with the community were planned during the study. The first was a face-to-face drop-in session at a local community hall. Residents were encouraged to share supporting photos, videos, and stories of historical flooding events. During the 2020 Victorian COVID lockdown, the second workshop was held online; the aim was to validate preliminary flood modelling results by sharing an interactive online map with all participants. This second session of community collaboration highlighted some discrepancies between the flood modelling results and what the community had experienced and recorded, thus leading improvements in the modelling investigations. Model calibration to historical events is often constrained due to a lack of gauge data, which can lead to inaccuracy, misrepresenting the scale of flooding, or error. This study emphasised the importance and crucial need for engagement with the local community, listening to their lived experience of flood events in order to provide a collective (technical and community) understanding of flood impacts and their risks. Council flood reporting and complaint registers are valuable sources of information that should be supplemented by listening, emphasising, and actively engaging with the local community on any flood study. Working closely with councils and communities to better understand historical flood events is critical to delivering the highest value technical outputs for mitigating risk and supporting community resilience. WATER LINES : ISSUE 2, 2021 3In March 2020, Water Technology was commissioned by Gympie Regional Council (GRC) to undertake a major flood study for the Mary River in order to better understand flood behaviour and inform land- use planning. Flooding in the Mary River catchment has occurred on numerous occasions, extending back to 1841, when flood records were first documented. The Mary River is a critical waterway within the Gympie Local Government Area, and historic flooding in the catchment has resulted in extensive community impacts. The project involved detailed hydrological and hydraulic modelling and joint calibration for a large catchment and is the most comprehensive and detailed study of the catchment undertaken to date. The URBS hydrology model developed for the study is the largest ever constructed. The hydraulic model is likely one of the largest and most detailed TUFLOW models that employ the latest Quadtree and Sub-Grid Sampling enhancements to more accurately represent the topography and improve model accuracy. Large-Scale Flood Investigation to inform Land-Use Planning informing catchment flood risk 4 WATER LINES : ISSUE 2, 2021The assessment included flood frequency analyses on several stream gauges, including consideration of paleo flood events. Monte Carlo analysis using URBS was undertaken to justify the use of ARR2019 ensembles for design event modelling. The hydrological and hydraulic models were also used to assess temporal pattern variability, focal point sensitivity, and potential impacts of climate change. Flood mapping for the entire Gympie Local Government Area was developed as part of the study, and included the full extent of events up to the PMF. Flood results and mapping produced by Water Technology have allowed the Council to progress detailed planning in priority development precincts, such as at Kybong. Study outcomes have significant consequences for other flood studies in the area and for future development control. The study outputs will be used to reliably inform catchment flood risk, which will enable the Council to proactively manage all aspects of the floodplain well into the future. For more information, contact +61 7 3105 1460 James Weidmann (james.weidmann@watertech.com.au) The project was completed in January 2021. We are incredibly proud of the quality of the study findings and outputs. Special thanks to Don Carroll for providing technical review and advice, and to Carlos Gonzalez at the Department of Transport and Main Roads for facilitating the sharing of the Cooroy to Curra upgrade designs, which added considerable value to the project. WATER LINES : ISSUE 2, 2021 5Burdekin and Haughton Audit Analysis QUEENSLAND RESILIENCE PROGRAM The Queensland Reconstruction Authority (QRA) recently provided the final project briefing for the Burdekin and Haughton Flood Resilience Strategy to partner councils, which will guide the way in which eight councils (Barcaldine Regional Council, Burdekin Shire Council, Charters Towers Regional Council, Isaac Regional Council, Mackay Regional Council, Tablelands Regional Council, Townsville Regional Council, and Whitsunday Regional Council) within the Burdekin and Haughton catchments will proactively work together to reduce flood risk and increase resilience. Water Technology was delighted to be one of the key project partners and contributors to the deliverables of this project. Water Technology provided key data analysis to assist the completion of the Flood Warning Infrastructure Network Project within the context of building a regional flood resilience action plan in the Burdekin and Haughton catchments. This included a desktop analysis of gauge coverage, asset types, the level of service, identification of gaps in the network, and a review of the flood classification levels following QRA guidelines. Water Technology carried out an assessment of situational awareness in the catchment to determine gaps in the network, identify opportunities for network optimisation, common asset management, strategic partnerships, and key transport links which may be able to benefit from flood warning infrastructure. Commentary and recommendations were provided for the future management of flood warning infrastructure assets in the catchment. The Audit and Analysis adopted a four-stage assessment involving a comprehensive data review, which provided baseline data towards flood classification levels to determine minor, moderate, and major flood levels for flood forecasting gauge locations. These gauges provide a critical element of planning and flood response for multiple agencies. The review was limited by using available flood information and data but provided a foundation for Councils to proactively engage with their respective communities in regard to flood warning, and links predicted flood levels with real-world impacts. The review also enabled recommendations to be made for new flood studies as part of maturing investments into a warning service. We are extremely excited to follow the delivery of the Flood Resilience Strategy across the Burdekin and Haughton catchments, and greatly look forward to seeing it being implemented over time. 6 WATER LINES : ISSUE 2, 2021For more information, contact +61 7 3105 1460 Richard Sharp (richard.sharp@watertech.com.au) WATER LINES : ISSUE 2, 2021 7Real-World Flood Events Honing the Skills of Floodplain Managers Floodplain managers have a wide variety of tools at their disposal which allow for a largely technical and meticulous assessment of flood events. Flood modelling is typically a quantitative process involving technical analyses of flooding behaviour to replicate historic events and characterise design flood events. What is often overlooked is the assessment of flooding behaviour in a real-world environment. Core Water Technology business is providing assistance to various insurance agencies following devastating flood events. This assistance usually takes the form of providing site-specific hydrology reports to assist in determining insurance claims. This work requires a sensitive approach due to the often tragic nature of circumstances and requires the involvement of senior staff in applying learned floodplain knowledge and an understanding of catchment hydrology in a real-world setting. Floodplain engineers use computers and flood models to attempt to replicate flood events, but there is no substitute for actually getting on the ground and analysing a flood event in person. The impacts and magnitude of a flood event is something that cannot be grasped by solely using computer models. Water Technology has recently been assisting several insurance companies in undertaking assessments in the Central Coast of NSW and Newcastle district following the severe flood events of Late March 2021. In many areas, recorded rainfall was more than a 1% Annual Exceedance Probability (AEP), with flood events in regional river systems hitting record levels in the Manning, Hastings, and Myall River catchments — resulting in widespread and extensive damage. A critical task for Water Technology hydrologists was observing catchment conditions and associated damage, 8 WATER LINES : ISSUE 2, 2021assessing rainfall and water level data and conducting comprehensive interviews with residents and property owners. This third task is particularly critical, given the sensitive nature of the events and the often overwhelming extent of the damage. Water Technology hydrologists are highly skilled in communicating complex, technical information in a format suitable for public discussions in trying times. In these cases, the critical deliverable is usually is a concise technical report compiled to allow readers of varying technical backgrounds to become familiar with the inundation mechanisms at the specific properties during the event. This work – which can be sporadic, frenetic and unfortunately traumatic – is a vital part of disaster response and recovery following a flood event. For more information, contact +61 7 3105 1460 Andrew Thompson (andrew.thompson@watertech.com.au) WATER LINES : ISSUE 2, 2021 9Next >