Flood Damage Studies

Flood damage estimation assessments and studiesAn important consideration for floodplain managers and those managing flood risks is understanding the economic impacts of flood events. Molino Stewart is a leading authority in this field, researching and applying best practice in flood damage estimation, creating asset databases, estimating flood damage assessments, evaluating annual average damages and undertaking economic assessments of mitigation options.

Molino Stewart has assisted numerous clients, including local and state government and insurance companies with flood damage estimation and economic analysis. Our leading experts have conducted flood damage assessments for commercial, industrial and residential properties, developing databases of 20,000 to 30,000 properties for use on a number of occasions. We have developed a range of techniques for deriving the information required to populate these databases for the purpose of flood damage calculation and our staff has expertise in utilising a range of data sources efficiently in order to capture the appropriate data. Our experience also includes sourcing and collating infrastructure data from both public and private asset managers for all infrastructure asset types. We have developed a range of techniques for deriving the information required to populate these databases for the purpose of flood damage calculation.

 Hawkesbury-Nepean Flood Damages Assessment (Infrastructure NSW)

Hawkesbury-Nepean Flood Damages Assessment done for Infrastructure NSW

As part of the 20 Year Sydney Infrastructure Strategy, Infrastructure NSW investigated the flooding impacts in the Hawkesbury Nepean Valley and the potential for these to be reduced through construction of mitigation infrastructure.

Molino Stewart was engaged to determine the potential flood damages and the benefits of various mitigation options. This included significant updates to 20 year old residential, commercial and industrial property databases and liaison with infrastructure owners to obtain updates on previous work undertaken by Molino Stewart about how these would be affected by flooding.

Key Relevant Tasks Performed:

  • Developed methodology for updating the property database which now includes approximately 30,000 buildings, including key attributes such as building type, size, number of stories and floor levels.
  • Sourced infrastructure data from both public and private asset managers for all infrastructure asset types across the floodplain and collated this into a database.
  • Conducted international literature search into best practice methodologies for estimating flood damages for residential, commercial and industrial properties as well as a range of infrastructure asset types.
  • Estimated damages to future development using subdivision plans, planning schemes and release areas.
  • Mapped the direct and indirect impacts of infrastructure outages within and beyond the floodplain.
  • Compiled aggregated damages across 400km2 of floodplain, along 150km of river, for 13 asset classes for 11 flood frequencies for 13 different mitigation options for existing and future development scenarios.
  • Prepared standard economic analyses of mitigation options using AAD and NPV
    Prepared the Cabinet report and presented findings.

Moreton Bay Regional Flood Database and Floodplain Management Study (Moreton Bay Regional Council)

Flood Floodplain Management Study & Database prepared for Morton Bay Regional Council

Moreton Bay Regional Council embarked on an Australian first process of developing a comprehensive LGA-wide GIS database of topographic data and using that along with one hydrological modelling program, one hydraulic modelling program, and consistent assumptions across all catchments, to simultaneously produce flood models for 13 catchments covering 2,000km2. The outputs were then used to inform floodplain planning, emergency response and community education. Molino Stewart worked with Moreton Bay Regional Council and undertook the first stage of the floodplain risk management study. Steven Molino was a member of the Strategic Advisory Group guiding the project development and implementation and was the technical expert providing advice on landuse planning, emergency planning, warning and community education.

Molino Stewart undertook flood impact assessments across the entire 2,000km2 using a property database of more than 30,000 properties, identified the vulnerabilities of critical infrastructure and authored a floodplain management framework including a hierarchy of flood protection for critical infrastructure in proposed new urban release areas. We collected and collated of GIS layers for elevation, bathymetry, streams, land cover, floor levels, bridges and culverts, roads and critical infrastructure. Flood damage estimates were undertaken for each of 30,000 residential and commercial buildings and consistent mapping of flood vulnerability developed across 13 catchments. We developed a cutting edge web-based interface for communicating flood risk at a community wide and individual property level and a leading practice, risk-based floodplain planning framework.

Newcastle Floodplain Risk Management Plan (Newcastle City Council).

Newcastle Floodplain Risk Management Plan prepared for The City of Newcastle

Newcastle City Council prepared a floodplain risk management plan for ocean, river and flash flooding which affects more than a third of the City’s 60,000 properties. Many of the residents and businesses had strong expectations about improving the preparedness and response to the flooding in light of the devastating 2007 event. Molino Stewart was engaged to assess damages from three types of flooding under existing conditions and with the impacts of climate change.

Molino Stewart undertook a thorough and detailed estimate of tangible and intangible flood damages was undertaken across the City. Five models were integration, to allow data analysis between flood models, WaterRIDE, GIS and Excel. Structural and non structural floodplain management options were evaluated, and impacts, options and constraints were presented spatially. The economic assessment included a benefit cost analysis and detailed option evaluation. Stakeholders were consulted in an equitable, transparent and consistent manner and information was disseminated to the community through a range of media and stakeholder workshops were facilitated in several communities across the City.

Flood Planning Levels Overview (Major Insurer)

Molino Stewart provided an overview of the flood planning rules across Australia as they apply to flooding and floodplain management. The report was based on responses to a questionnaire prepared by Molino Stewart and forwarded to the relevant agency in each State/Territory, as well as a literature review of Government policies and practices for all States and Territories and the Commonwealth Government.

Blacktown City Council Eastern Creek Flood Damages (Blacktown City Council)

Eastern Creek Flood Damages Study prepared for Blacktown City Council Molino Stewart was engaged by Blacktown City Council to provide an estimate of the residential and commercial and industrial damages which would result from flooding of the Hawkesbury-Nepean Valley, for the Blacktown LGA across the Eastern Creek and South Creek floodplains.