What is Flood Impact Assessment and Management?
Flood impact assessment and risk management is required to assist developments that have waterways traversing through or located adjacent to a site. Customarily, local and state government provide the determination for the need of flood management and assessment based upon the following site conditions:
- Flooding is likely to significantly impact the site based upon existing catchment models, hydrologic studies and/ or observed flood characteristics
- The proposed development is likely to modify the characteristic of the existing waterway, E.g. altered hydraulic capacity, obstruction of flow, realignment of waterways
At Broadcrest our team of professionals are qualified to address a diverse range of flood management needs & services, from modelling, provision of flood mitigation measures, defensive structures, to procedures and advice on actions to be taken before and during a flood.
What site factors contribute to flooding?
For a given site a variety of climatic and landform features interact to produce the distinct hydrology of a catchment. During significant storm events surface water may converge at recognisable points of conveyance (e.g. rivers, creeks, streets), or may track in ways not perceptible during minor storm events (i.e. river overbanking, exceeding drainage/pit capacities). Broadcrest Engineers assess your development for multiple site and catchment variables including:
- Climate and Local Rainfall Characteristics
- Existing and Proposed Site Development / Land Use
- Catchment Area, Land Use and Built Features
- Soil Type and Existing Vegetation
- Downstream Water Levels
- Major and Minor Flow-paths
- Riparian Shape and Condition
- Site Specific and Local Flooding Issues
- Existing and Proposed Stormwater Drainage Systems
- Stormwater discharge Points from site
We offer our assessment and modelling capabilities over a wide range of services, tailored to your reporting requirements and project characteristics. To discuss a flood study or flood risk management assessment suitable for your project, contact Broadcrest to speak with one of our Engineers.
How are Flood Impact Assessments and Studies Prepared?
Broadcrest draws from a combination of geo-spatial and meteorological resources to inform our modelling and analysis methodology. Preparation of our flood studies & overland flow studies assess available data including:
- Mapping and topographic survey data (e.g. contour surveys, LiDAR data)
- Stream flow and tidal data
- Rainfall and soil data
- Catchment area, land-use and built features
- Vegetation coverage and waterways characteristics
- Historic flood heights and weir data
Dependent on product and site specifics, Broadcrest engineers provide the following process of analysis and investigation:
- Determine the catchment hydrology and evaluate the hydraulic characteristics of the impacting waterway for the pre- and post-development case
- Based upon topographic surveys and/or LiDAR Digital Elevation Models (DEMs) calculate the pre- and post-development flood storage
- Assess the result of flood modelling to determine the cumulative impact of the development upon neighbouring properties
- Where necessary design and model flood amelioration or defensive structures to mitigate the impact upon the development or neighbouring properties
- Determine the flood risks associated with the development, quantifying risk and the necessary flood management strategies
The outcome of this process is a report and associated computer model detailing flood impact, risks, flood planning levels and advice / procedures on the management of flood for the development. Broadcrest engineers also consult with clients and local government throughout the assessment process to ensure the best development outcome for our clients.
Follow the link below to see the full range of our flood management services: