In an Expert Focus article for Waterbriefing, Marc Barone, Managing Director Water, UK & Ireland, AECOM discusses a range of projects in the UK and the USA to contain flooding – including multi-benefit integrated flood protection designs and ways to both store and transport floodwater.

Marc Barone: Extreme weather events are becoming increasingly frequent, meaning more and more communities are facing significant disruption due to storms and floods. Changes in land use, such as new development on flood plains, are exacerbating the problem – amplifying the cost of flood damage while reducing the capacity of the natural landscape to soak up or carry away heavy rainfall.

People affected by flooding naturally become vocal lobbyists, arguing that governments or local authorities must act promptly and decisively to prevent a recurrence. However, the dilemma for those in charge of flood defences can be acute. Traditional measures such as levees, drainage channels and tidal barriers are typically expensive and time consuming to construct, may not be practical given existing buildings and other infrastructure, and will still require back-up measures such as pumping stations to handle the potential for overflow. 

A group of communities in New Jersey are currently assessing the merits of mixing these traditional line-of-protection measures with more naturalistic approaches. The RBD Meadowlands project area that includes the Boroughs of Little Ferry, Moonachie, Carlstadt, and Teterboro, as well as the Township of South Hackensack, located across the Hudson River from New York City, is on average only six feet above sea level.

In October 2012, Hurricane Sandy revealed how vulnerable the area was to flooding. The storm overwhelmed defences and leftsome communities swamped by up to five feet of water. Even storms much smaller than Sandy can test the capacity of the local sewer system, leading to many smaller floods during heavy rainstorms.

AECOM has undertaken studies to assess different ways to alleviate these risks, including measures to improve the area’s natural capacity to store and carry away large volumes of water safely. 

RBDM project to develop multi-benefit integrated flood protection designs

The Rebuild by Design Meadowlands (RBDM) project, currently being undertaken by the New Jersey Department of the Environment and funded by the United States Department of Housing and Urban Development, draws on the expertise of a wide range of disciplines, including engineers, urban planners, landscape architects, ecologists, environmental scientists and economists. The aim is to develop multi-benefit integrated flood protection designs that will improve public spaces, reduce impacts to the natural environment and improve future resilience for social, environmental and economic systems.

The project is investigating three alternative concepts todevelop replicable and scalable approaches to inland and tidal surge flood management concepts that can be implemented separately, or together, to address a wide spectrum of risks while providing civic amenities and renewed investment.

The three alternative concepts vary by the type of infrastructure that is proposed. The first analyses various structural, infrastructure-based solutions that could be constructed to provide protection from both inland and tidal/storm surge flooding. The second will develop a system of improved storm water management that may include local drainage improvements along with green infrastructure techniques and potential wetlands restoration to protect communities located in the project area and address day-to-day water management challenges. The third will develop a strategic, synergistic blend of new infrastructure and local drainage improvements to reduce flood risk in the project area.

The goal is not simply to reduce the flood risk in the Meadowlands region but to provide a model for other affected communities to follow, delivering necessary flood prevention as part of renewal, development and redevelopment efforts.

Glasgow scheme to develop environmentally sensitive ways to store and transport stormwater

In the UK, a separate project is also pioneering a similar approach to storm water management that should also prove transferable to other communities.

Much like RDB Meadowlands, the North Glasgow Integrated Water Management System (NGIWMS) aims to develop environmentally sensitive ways to store and transport floodwater.

The Glasgow project aims to utilise the existing Forth &Clyde Canal, a 19th Century artificial waterway, as an alternative to a costly traditional solution that would require investment in a 2km drainage tunnel.

The canal offers attractive flood management potential due to its size. With a long, narrow profile the canal makes up a deceptively large body of water. The 19km section closest to North Glasgow, about a third of the canal’s overall length, has a total surface area of about 42 hectares. To raise the surface level in this section by just ten centimetres would require 4.2 million litres of water.

The NGIWMS concept was created in 2013 by AECOM to support the cost-effective development and regeneration of 260 hectares of land in the north of the city, which would otherwise have insufficient drainage capacity.

The approach is not, of course, to simply divert floodwater into the canal. The Forth & Clyde Canal is a protected Scheduled Monument, an important part of Scotland’s heritage and a thriving, diverse habitat. It has to be handled with care.

The NGIWMS concept includes a range of measures to safeguard the canal’s ecosystem, starting with intelligent control. A range of remote sensors will collect data to allow real-time operational management of the canal. For example, storm forecast data will be linked to water level controls, allowing the canal’s surface level to be pre-emptively lowered by up to 10cm in advance of incoming storms. This small change provides as much as 42,000 cubic metres of storage capacity.

The quality of water within the canal and surrounding watercourses will be closely monitored, while incoming stormwater will be actively treated to protect the canal environment.

Work on the new water management system is expected to begin in 2017, with the first connections likely to be made in 2018. Completion will be coordinated with the regeneration of North Glasgow, with the first phase expected to be in the Sighthill area where 1960s tower blocks have been demolished over the past few years. 

New ways to protect urban areas from flooding - an intelligent approach to natural landscape and existing infrastructure

The NGIWMS concept is also not limited to the canal system, but comprises an integrated plan that views water in the area as a community resource. The overall project is being developed with the involvement of Scottish Canals, Glasgow City Council and Scottish Water as key stakeholders in the Metropolitan Glasgow Strategic Drainage Partnership (MGSDP).

If realised, the NGIWMS approach would allow Glasgow to claim a place at the forefront of best practice in urban water management, providing an example for water engineers, infrastructure designers and city planners around the globe.

Scotland’s Centre of Expertise for Waters (CREW) recently carried out an in-depth review of the NGIWMS project and concluded that it will provide a significant number of direct and indirect benefits, including socio-economic improvements such as health, wellbeing and resilience, and that the canal should continue to underpin future development and regeneration activities.

In Glasgow as in New Jersey, we are seeing the development of new ways to protect urban areas from flooding, taking an intelligent, sympathetic approach to both the natural landscape and existing infrastructure. As climate change makes severe weather events more likely, any approach that can prepare for and store large volumes of floodwater – rather than attempting to hold back the inevitable – seems to be a wise course of action.

Waterbriefing is media partner with the Environment Agency’s major three-day conference and exhibition Flood and Coast 2017 which takes place from 28 to 30 March 2017 in Telford. Click here for more information