Flood Hazard Assessments, Hydraulic Modelling, and Stormwater Engineering for Land Development Projects
Flood risk can have a major impact on subdivision, resource consent, building design, and long-term site feasibility. If your property is affected by flood hazard overlays, overland flow paths, stormwater constraints, low-lying ground, or nearby waterways, getting the right advice early can help reduce delays, avoid redesign, and support a smoother consent process.
At Infill, we provide practical flood risk assessment, hydraulic modelling, and stormwater engineering services for land development projects across Kāpiti, Horowhenua, Porirua, Wellington, and the wider region. Our advice is integrated with our civil engineering, planning, and land development expertise, helping you understand site constraints, respond to council requirements, and move your project forward with confidence.
Our Flood Risk and Stormwater Services
Flood Hazard Assessments
We assess how flood risk affects your site and what it means for development. This may include reviewing council flood hazard maps, overland flow paths, site levels, nearby waterways, drainage constraints, and existing stormwater infrastructure.
Our flood hazard assessments can support early due diligence, subdivision feasibility, resource consent applications, floor level advice, and responses to council requests for further information.
We focus on clear, practical reporting that explains the real development implications of flood risk, rather than technical assessment for its own sake.
Hydraulic and Hydrological Modelling
Where a desktop assessment is not enough, Infill can undertake hydraulic and hydrological modelling to better understand how water moves through, around, and beyond a development site.
Using 1D and 2D modelling approaches, we can assess flood depths, flow paths, stormwater catchments, runoff behaviour, and potential development effects. This provides a stronger technical basis for design decisions, council discussions, and consent documentation.
Depending on the project requirements, we use industry-recognised modelling and design platforms including 12d Model, HEC-HMS, HEC-RAS, Stormwater Studio, and TUFLOW. This allows us to tailor the modelling approach to the site, catchment, and level of detail required.
Urban Stormwater Modelling and Engineering
Flood risk is often closely linked to stormwater design. We provide stormwater engineering input for subdivision, infill housing, and wider land development projects to help manage runoff, reduce downstream effects, and support council requirements.
Our stormwater engineering services may include catchment analysis, detention and attenuation design, hydraulic neutrality assessments, infiltration and soakage advice, pipe and drainage design, overland flow path assessment, stormwater calculations, and treatment design.
Where appropriate, we can also consider water-sensitive design options such as swales, rain gardens, wetlands, and other stormwater treatment systems that help improve water quality and support better environmental outcomes.
Flood Mitigation Advice
If flood risk is affecting your project, we can help identify practical ways to respond. This may include site layout changes, minimum floor level advice, stormwater upgrades, flow path protection, detention solutions, or further technical modelling to support resource consent or engineering design.
Our focus is on practical mitigation options that are technically sound, realistic to build, and aligned with council expectations.
When This Service Is Useful
Flood risk assessment, hydraulic modelling, or stormwater engineering may be needed when:
- a property is affected by a flood hazard overlay
- council requests further flood or stormwater information during consent
- you are buying, subdividing, or developing a low-lying site
- a development is near a stream, wetland, pond, or overland flow path
- a subdivision needs stormwater neutrality or downstream effects assessment
- you need floor level, building platform, site layout, or stormwater design advice
Why Choose Infill?
- We Look at the Whole Project: Flood risk can affect site layout, subdivision design, building levels, stormwater requirements, and council approval. At Infill, our flood risk advice is connected with our planning, civil engineering, and land development services, so you get advice that considers the whole project.
- We Explain Things Clearly: Flood maps, modelling results, and council requirements can be hard to understand. We explain what they mean for your site, what the risks are, and what steps may be needed to keep your project moving.
- We Focus on Practical Solutions: We help identify realistic ways to respond to flood risk, such as layout changes, floor level advice, stormwater design, flow path protection, or detention solutions. Our focus is on practical outcomes, not technical outputs for their own sake.
- We Understand the Local Area: We work across Kāpiti, Horowhenua, Porirua, Wellington, and surrounding areas, and understand the local flood, stormwater, and consent issues that often affect development projects.
- We Have Specialist Modelling Capability: Flood modelling is a highly specialised technical service that requires advanced modelling knowledge, engineering judgement, and specialised software packages to assess complex flood and stormwater behaviour using 1D and 2D modelling where required. This capability is not widely available in the region, and Infill is one of the few specialists able to offer this expertise, helping clients better understand flood risk, support stronger design decisions, and respond confidently to council requirements.
Flood Risk Advice for Your Next Project
Whether you are assessing a site before purchase, responding to a council request, designing a subdivision, or trying to resolve flood and stormwater constraints, Infill can help you understand the risk and identify a practical path forward.
Contact Infill to discuss flood risk assessment, hydraulic modelling, or stormwater engineering support for your project.