Charlton Flood and Drainage Management Plan Charlton Town Hall 23 - PowerPoint PPT Presentation

Charlton Flood and Drainage Management Plan Charlton Town Hall 23 August 2011

Community Meeting Principles • Reflection on the past to better plan for the future • CMA and Shire is seeking to understand • Wanting to hear all views – allow others to contribute • All perspectives are valid

North Central CMA role • Emergency management support • Incident Control Room support • Predictions re flood behavior and impacts • Community meetings • Short term response • Priority Flood mitigation works i.e. debris removal etc • Flood pegging and mapping • Stream gauge reinstatement • Longer term recovery • Flood studies, Floodplain Plans etc

Buloke Shire Council role • Leads the development and implementation of local stormwater management plans • Manages local urban drainage systems • Responsible for incorporating best practice guidelines in local planning policies • Works with communities to ensuring adequate urban drainage systems are put in place

Overview • Charlton Flooding – Historic and Recent • Flood and Drainage Management Plan • Where to from here and meeting close • Community knowledge session

Charlton Flooding – Historic Flooding • Charlton has had a history of flooding, incl.1893, 1909, 1939, 1956, 1983, 1992

Charlton Flooding – 1973

Charlton Flooding – 1983

Recent Charlton Flooding September 2010 • Up to 100mm in Western/Central Victoria

Recent Charlton Flooding September 2010 • Up to 100mm in Western/Central Victoria October, November & December 2010 • Further rain events wetting catchments • Large scale rural inundation October, November & December 2010 • 100 – 300mm across two thirds of Victoria • Wettest start to a year since records began • Record river heights on Avoca, Loddon & Campaspe catchments

Summary of Rainfall

Avoca Catchment • ~ 3000 square kilometres upstream of Charlton

Avoca Gauging Stations • 4 flood warning gauging stations on Avoca River • Archdale Junction • Coonooer (Yawong Weir) • Charlton D/S • Quambatook

Charlton Flooding • Key issues to investigate (what we have heard so far) • Improved Flood warnings • Origin of flood flows – Yeungroon Creek/Avoca River • Limited capacity of opening through railway line • Obstructions to flood flows incl. roads/culverts

Response to Flooding • Flood mapping – pegging of flood extent, surveys undertaken • Immediate works (debris removal) • Charlton Flood and Drainage Management Plan commissioned

Plan for the Future • Charlton Flood and Drainage Management Plan • Aim - identify key flooding issues and assess and recommend flood mitigation and drainage improvement works • Steering Committee and Technical Working Group Established to Guide Plan development • Victorian Flood Review and ENRC – Separate process with focus on flood warning and short term response

BMT WBM • BMT WBM will be undertaking the Charlton Flood and Drainage Management Plan • Michael Turnley Project Director • Philip Pedruco Project Manager • Michael South Project Engineer • We have completed 100’s of flooding and drainage studies across Victoria, Australia and internationally

Development of the Plan • The Aim of the Plan – Identify key flooding issues and assess and recommend flood mitigation and drainage improvement works • Collect data and information – From agencies such as BoM and Council – From the community (Local knowledge and observations are essential to the development of the Plan) • Create a flood model – Calibrate the model so we have confidence in the results • Test mitigation options in the model • Make recommendations

Collect data and information • Data collection – Topographic data (digital elevation model) – Historical flow data and flood level data – Flood behaviour – Land uses, aerial photography, infrastructure data, flood photos and videos • Local information and input – Learn from local knowledge, e.g. where did water flow, how fast, how high etc – Invaluable information – Benefits » Community involvement » Confidence in modelling and study outcomes

Create a flood model • Whole of catchment model – Calculates how much water and the timing of flow • Detailed model – Calculates the extents and flood heights

Detailed model

Model calibration • Can a mathematical model really simulate a flood? • The software is well proven on hundreds of catchments both in Australia and overseas • IMPORTANTLY we will verify the model to local conditions – Model will be calibrated and validated against the recent events

Test mitigation options in the model • We can test options to manage flooding – Modify terrain data to include levees, embankments, etc – Modify drainage structures such as bridges and culverts – Run model with changes and compare flood heights to existing case – Adjust design if required

Outputs of the Plan • An improved understanding of flooding in Charlton – Return periods • Flood maps of Charlton – Flood depths, velocities and levels – Flood hazard • Recommendations on mitigation options – Structural and non-structural

Timing of the Plan • The Plan has commenced – We are collecting data and information (including tonight) – We have started building model • Flood model completed in November / December • Public Meeting in December to discuss flood mitigation options • Completion of options investigations February / March 2012 • Plan completion by June 2012

Charlton Flood and Drainage Management Plan Key Steps • Community Engagement (Through out Plan development) • Review flood information (Inc local community information) • Develop Models – represent flooding events • Assess effectiveness and feasibility of mitigation actions • Recommend mitigation actions in Plan • Seek community feedback on draft Plan & finalise Plan

Community Feedback • Local knowledge and observations important • Flood extent & behavior • Localised flooding issues • Local rainfall information • Historic flooding events • Local knowledge will provide a better understanding of flood behavior and lead to more accurate assessment of Mitigation options

Next Steps • Collate community information • Develop Flood Models • Keep community informed of progress • Develop Draft Plan & seek community feedback on Draft • Finalise Plan and seek funding to implement

Feedback Session • Documenting local knowledge important • Maps of Charlton – mark on flood information (extent, flood directions, major issues) • Questionnaire – Fill in tonight or Drop off to Council Flood Recovery Office (copies made available for other community members not at meeting)

Thank you • Reminder – to provide contact details so we can keep you informed of progress • Return Questionnaires