SuDS with Steve Burton of Steintec and Bioengineering with Alex Clark / Mike Yates of Salix River and Wetland Services

Designing with Water: Sustainable Drainage Systems (SuDS) and Nature-Based Solutions for Resilient Landscapes

As climate change continues to amplify the frequency and intensity of extreme weather events, cities and communities face growing challenges with surface water management, flooding, and water quality degradation. Traditional ‘grey infrastructure’ — concrete channels, pipes, and culverts — is increasingly seen as unsustainable, ecologically damaging, and expensive to maintain.

Enter Sustainable Drainage Systems (SuDS) and Nature-Based Solutions (NbS) — modern, environmentally-friendly approaches that mimic natural processes to manage water sustainably, enhance biodiversity, and create healthier, more attractive places for people and wildlife.

In this blog, we’ll unpack the fundamentals of SuDS, explore innovative permeable paving technologies, and look at nature-based engineering techniques that are transforming how we work with water in both urban and rural landscapes.

What Are Sustainable Drainage Systems (SuDS)?

SuDS manage surface water runoff by mimicking natural drainage processes — slowing water down, holding it temporarily, filtering out pollutants, and releasing it gradually into the environment.

Key SuDS Components

• Source control: Managing water where it falls (e.g., green roofs, rain gardens)

• Conveyance features: Moving water safely (e.g., swales, rills, tree pits)

• Storage features: Holding water temporarily (e.g., ponds, wetlands, detention basins)

• Treatment features: Improving water quality (e.g., wetlands, reed beds)

Benefits of SuDS include:

• Reducing flood risk

• Improving water quality

• Enhancing urban biodiversity and habitat creation

• Mitigating urban heat island effects through urban cooling

• Providing recreational, educational, and aesthetic value

• Examples include rain gardens, permeable paving, green roofs, swales, ponds, wetlands, detention basins, and rills — each tailored to site conditions and community needs

Permeable Modular Pavements: Steintec Lecture

Permeable modular pavements aren’t about the material itself, but about how paving units — slabs, setts, blocks — are arranged with gaps, voids, or open joints to allow water to infiltrate through the surface and into the ground.

Key Concepts:

1. Permeability: How easily water moves through a material (m/s)

2. Infiltration rate: Volume of water passing through a given area (mm/hr)

3. Construction types:

4. Unbound: No cement or concrete, allowing full infiltration

5. Bound: Stabilised structures with drainage capacity

6. Permeable paving reduces surface runoff, improves water quality by filtering pollutants, and helps manage stormwater sustainably

Design considerations:

• Urban vs. rural context

• Expected traffic loads and hydraulic capacity

• Longevity of infiltration performance and maintenance planning

• Compliance with standards like CIRIA SuDS Manual C753 and CB Interpave Permeable Pavement Design Guide

Nature-Based Solutions: Salix Lecture Insights

Nature-Based Solutions (NbS) embrace soil, water, and vegetation as active infrastructure. By working with natural processes, they offer lower carbon, cost-effective, and ecologically valuable alternatives to hard engineering.

NbS Applications:

• Soil erosion control

• River restoration and re-naturalisation

• Carbon sequestration through wetland creation

• Natural flood management

• Water quality improvement via wetlands and green channels

• Biodiversity habitat enhancement

Key NbS Techniques:

Hydroseeding: Spraying seed mixes for rapid vegetation establishment

Brushwood fascines: Bundles of twigs to slow water flow and trap sediment

Pre-established coir rolls/pallets: Vegetated natural barriers

Floating wetlands: Plant habitats in deeper water areas

Intertidal terraces and saltmarsh creation: Boosting biodiversity in urban tidal zones

Wetland planting requires stress-tolerant, brackish, and deep-rooting species for resilience against fluctuating water levels and salinity

Case Studies:

• River Elwy: Hard bank engineering replaced with bioengineering, allowing natural processes and vegetation to stabilise the river.

• Wandsworth Terraces, River Wandle: Plug planting and softening of urban riverbanks

• London Olympic Wetlands: Pre-established coir rolls and floating wetlands for urban biodiversity

• Cleddau River: Terra-lock and Rock-lock as carbon-saving alternatives to heavy stone gabions

Why This Matters

Modern water management isn’t just about avoiding floods. It’s about designing multifunctional spaces that:

• Connect people with nature

• Support urban biodiversity

• Reduce embodied carbon

• Improve water quality

• Create healthier, cooler, and more liveable urban environments

• Rivers, wetlands, and green infrastructure aren’t static features — they’re dynamic, evolving systems. With the climate emergency accelerating, integrating SuDS and NbS is no longer optional, but essential