Our Services


With 25 years’ experience in urban flood hydrology, we provide a range of services to meet your needs. We use state of the art techniques and models to assess flood risk from UK and Ireland urban drainage networks and river catchments. Recently using our specialist experience as lead authors of CIWEM’s Integrated Urban Drainage Modelling Guide.

Our staff have a high level of experience in the use of specialist modelling packages and techniques, including in depth knowledge of the Flood Estimation Handbook (FEH) methodologies and Wallingford Hydro Solutions ReFH v2.3.  Our team are experienced in applying hydrological inflows in InfoWorks ICM for design events, calibration and validation.

We use our expert understanding of the integrated nature of hydrology to determine the appropriate tools to be used in each case. We can work at a catchment and/or sub catchment level to provide hydrological assessments for any flood problem.

We have an extensive knowledge of the accuracy and limitations associated with hydrometric data. This experience and understanding is essential when utilising hydrometric datasets for hydrological analysis and hydraulic model calibration and verification.

Our services include:

  • Assessment of design fluvial flood event flows applying the latest climate change allowances under the National Planning Policy Framework (July 2018)
  • Use of observed data for model calibration and verification
  • Return period analysis of observed events using WINFAP v4.0
  • Drainage analysis prepared in support of Flood Risk Assessments, Drainage & Wastewater Management Plans and Surface Water Management Plans
  • Uplifting of observed rainfall events testing climate change impacts using the latest allowances from UKCP18 (UK Climate Projections 2018). We keep up to date with the latest developments in Climate Change science through our professional networks including BHS, CIWEM and CEH.
  • Sizing of storage reservoirs for flood detention and drainage
  • Drainage and Rainfall Runoff
  • Review and Quality Assurance of existing hydrological studies
  • Assessment of design fluvial flood event flows applying the latest climate change allowances under the National Planning Policy Framework (July 2021)
  • Return period analysis of observed events using WINFAP v5.0

Urban Flood Forecasting

We are developing our hydrological services using our understanding of catchment processes to provide a range of inputs to create innovative, integrated water management and nature based solutions.

We are well placed to appraise Natural Flood Management options and support wider catchment plans to ensure the right measures in the right place, using best practice to deliver multiple socio-environmental benefits.

We are looking to engage with appropriate partners now including; Lead Local Flood Authorities, Local Resilience Forums, Community Groups, Catchment Partnerships, Utility Providers, Health Authorities, Emergency Planners, Statutory Environmental Bodies, Local Nature & Wildlife Partnerships and Climate Change Partnerships to identify relevant local approaches and help to strengthen our resilience to floods at different scales.

Our technical capability and experience sets us on par with larger organisations. Our size enables us to provide hydrological services at a competitive price and respond quickly. Richard Allitt Associates assure that you will have an experienced and skilled team dealing directly with your project from start to finish.