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Services

Flood Risk

RPS is at the forefront of Flood Risk Management and offers the full range of technical services in the assessment and management of Coastal, Fluvial and Pluvial flooding.

RPS offers a range of bespoke services to meet our client’s needs, from simple site specific flood risk assessments to national or catchment wide flood strategies which inform central government decision making or provide sustainable engineering solutions to complex flooding problems.

Our multi-disciplinary nature allows findings to be linked from other associated disciplines, such as hydrogeology, ecology and engineering.

In addition, we support clients across development sectors including industrial, energy, commercial and residential developers for individual sites and master planning schemes and operational risk assessments for retail, industrial and energy sectors.

Our range of services includes:

Hydrological analysis and rainfall run off modelling.

1D/2D River and Estuarine Modelling

2D/3D Coastal Process Modelling

Surface Water/Network/Pluvial Modelling

Integrated Catchment Modelling

Reservoir Inundation Mapping

Storm Surge Analysis

Flood Forecasting and Warning

Flood Risk and Hazard Mapping

Strategic Flood Risk Assessment and Management Plans

Feasibility Studies incorporating Social, Economic and Environmental Impact Assessment

Flood Alleviation scheme design and validation

Asset condition assessment and management

Flood Emergency Response and Planning

Pre-purchase site appraisals to assist with land negotiations

Due diligence assessments for corporate acquisition and asset management

Flood risk/consequences assessments including sequential/exception tests for planning applications

Drainage assessments for surface water attenuation

Sustainable Drainage schemes (SuDS)

Case Studies

Dodder Catchment Flood Risk Assessment and Management Study

Dodder Catchment Flood Risk Assessment and Management Study (CFRAMS)

Dublin City Council

The River Dodder CFRAMS is a catchment wide flood study undertaken by RPS in South Dublin for Dublin City Council to assist with Ireland’s implementation of the EU Floods Directive.

RPS undertook all aspects of this study which incorporated a significant data collection exercise for use in both the hydrological and hydraulic analysis.

This included topographical surveys (land and hydrographic), LiDAR, CCTV, meteorological, hydrometric, coastal, historical flooding and climate change information.

The hydrological analysis was based on the standard statistical approach to estimating river flows used FSR and FEH methodologies but also incorporated the development of a wide range of rainfall run-off models using MIKE NAM. Using this input data, coupled hydrodynamic models were established in MIKE Flood.

A suite of flood risk and hazard maps were presented for consultation with key stakeholders and members of the public. Over 30 different flood risk management options were considered for the catchment each of which was designed, costed and assessed against a wide range of criteria including a detailed cost benefit analysis and assessment against both social and environmental criteria. The environmental assessment integrated the project with the statutory Strategic Environment Assessment process and ensured compliance with that particular EU directive.

The preferred flood risk management options were included within a FRM Plan for consultation before adoption by the Local Authorities.

Eastern, South Eastern and North West Neagh Catchment Flood Risk Assessment and Management Studies

Eastern, South Eastern and North West Neagh Catchment Flood Risk Assessment and Management Studies

Office of Public Works

RPS is currently engaged in 3 major flood studies for the Office of Public Works in Ireland.

The combined study area covers three River Basin Districts (approximately one third of Ireland) and requires the detailed assessment of areas of significant flood risk and the proposal of flood risk management options in accordance with the requirements Directive 2007/60/EC of the European Union. RPS is providing the full range of services including:

Data collection

Survey specification and management

Defence asset condition assessment

Flood event response

Hydrological analysis and rainfall run-off modelling,

Detailed 1D/2D hydrodynamic modelling for 120 areas of significant risk totalling over 2,400km of river channel using MIKE Flood.

Coastal inundation modelling

Stakeholder consultation and engagement

Development and assessment of flood risk management solutions using a Multi Criteria Analysis

Strategic Environmental Assessment

Preparation of a Flood Risk Management Plan

Flood Resilience Assessments

Flood Resilience Assessments

Western Power Distribution

RPS has carried out river and tidal flood resilience assessments at over 150 electricity substations for Western Power Distribution.

Western Power Distribution (WPD) is the electricity distribution network operator for the Midlands, South Wales and the South West, serving 7.7 million customers from a network of 216,000 kilometres of overhead lines and underground cables and 184,000 substations. In response to the summer floods of 2007 and the Pitt Review, WPD engaged RPS to carry out a systematic review of the risk of flooding to their primary and grid substation assets.

At sites where no flood level information exists but where older Environment Agency models indicate there is a risk of flooding, RPS undertakes 1D/2D computer based modelling carried out in accordance with UK best practice to generate flood levels against which improved flood resilience measures for each site can be designed. Our flood modelling work is cost effective, as a number of formerly at risk sites have been found either not to flood or to flood to lower levels or extents than previously indicated.

Langholm Flood Risk Assessment

Langholm Flood Risk Assessment

Dumfries and Galloway Council

RPS was appointed by Dumfries and Galloway Council to undertake a flood risk assessment of the river and its tributaries and develop a range of flood risk management solutions.

Langholm is located along the River Esk at the confluence of two of its tributaries and has flooded historically.

RPS specified and procured a detailed topographical survey of the river channel and utilised LiDAR data to define the floodplain. A detailed hydrological analysis was undertaken using local gaugings and FEH analysis and a hydrodynamic model was created in InfoWorks ICM using a fully integrated 1D in bank 2D out of bank flood model. The model was used to provide flood extents for a wide range of flood events including 50%, 20%, 10%, 5%, 2%, 1%, 0.5% and 0.5% AEP + Climate Change events.

RPS subsequently developed a range of measures which addressed the flood risk to the town from the 0.5% AEP + climate change events. These measures, which included a series of earth embankments, reinforced concrete walls and demountable defences, were then costed. A full cost benefit analysis was undertaken in accordance with the requirements of the Multi Coloured Manual from the University of Middlesex and the SEPA document "Flood Protection Schemes – Guidance for Local Authorities".

Reservoir Inundation Mapping

Reservoir Inundation Mapping

SEPA

RPS is currently undertaking Reservoir Inundation Mapping across Scotland for SEPA.

The Reservoirs (Scotland) Act 2011 was introduced to the Scottish Parliament on 6 October 2010 and gained Royal Assent in April 2011. This new legislation is intended to provide greater security for people, property and critical infrastructure from the risk of flooding from reservoirs by moving from the current capacity based regime to a risk based regime. The aim of project was:

To include in the Register of Controlled Reservoirs a map showing the area of land which, in the event of an uncontrolled release of water from the reservoir would likely to be flooded (section 9 (2) of the Act).

To assign a provisional risk designation to all controlled reservoirs in the register.


RPS is using InfoWorks RS 2D to produce Reservoir Inundation Mapping for over one hundred reservoirs of varying size and complexity across Scotland.

Vectis Wind Farm

Vectis Wind Farm

Infinergy

Flood Risk Assessment and Environmental Statement chapter to support proposed development of an on-shore wind farm.

RPS prepared a Hydrology, Flood Risk and Water Quality Environmental Statement chapter and Flood Risk Assessment to support the development of an on-shore wind farm. The development consisted of access tracks, crane pads, a control building and electrical substation, and a temporary construction compound.

The Environmental Statement identified that the site was located in a sensitive hydrological setting due to the presence of surface watercourses on-site. Impacts on hydrology, drainage and water quality during construction were considered to be adequately mitigated by the measures within the CEMP. For the operational phase, the increase in hardstanding areas was considered to have the potential to result in a significant increase in flood risk unless suitable mitigation measures were proposed. The Flood Risk Assessment included a conceptual drainage design, which proposed disposal of surface water via soakaways, with additional attenuation of surface water within drainage ditches/swales. Peak runoff rates were restricted to pre-development rates, thus mitigating against any potential increase in flood risk.