Estuarine morphology : Understanding atypical behaviour and evaluating flood management scenarios

Tidal flooding in estuaries is a major challenge globally, and will worsen as sea level rises. The Humber is a strategically important region that is vulnerable to such flooding, but whose morphology does not behave as theory suggests. This project will work with the Environment Agency to build the first high resolution 3D numerical hydro-morphodynamic model of the Humber estuary and use it to investigate this behaviour and evaluate potential water management interventions.

Mud flats in the Humber estuary View of the Humber Bridge

Background

The Humber estuary and surrounds are home to 500,000 people, 120,000 ha of agricultural land, and industries worth over £17.5bn GVA. These include the second largest chemical cluster in the UK, two of the country’s six oil refineries, and five power stations. More than 25% of the UK’s primary energy flows through the region, and its ports handle 14% of UK trade. As such, it is of national strategic importance.

The wide, shallow, estuary provides extensive wildlife habitat in its large intertidal zones, including multiple designated conservation areas, but due to this same geography it is the second most flood-prone region in the UK, with over one third of properties at risk. This risk will be exacerbated by sea level rise. Following a storm surge in 2013 the Environment Agency (EA) reviewed its flood management strategy, leading to the “Humber 2100+” project to explore longer-term, systems-based solutions for water management.

However, the morphology of the Humber estuary has not responded in textbook fashion to long-term changes such as lunar nodal tidal cycles or increases in mean sea level over the last 80 years. This makes it difficult to predict its response to management interventions. Understanding this divergence from accepted theory is scientifically significant, as it may apply to other estuaries worldwide. It is also of practical importance to the stakeholders who depend upon long-term predictions of morphological behaviour.

Aims

Firstly, to understand the factors that lead to unexplained morphodynamic behaviour. It is hypothesised that this may result from one or a combination of,

  1. punctuated forcing (strong flows from rivers or storm surges)
  2. anthropogenic activity (dredging)
  3. sub-decadal to decadal changes in wind-driven waves
  4. inherent positional instability of tidal channels

Secondly, to evaluate the effectiveness and environmental impacts of water and sediment management scenarios developed by the EA as part of Humber 2100+.

Method

The first high-resolution, regional scale, 3D numerical model of the Humber will be built that incorporates the effects of meteorological and tidal boundary forcing, variable river inputs, and sediment transport.

To identify the parameterisation that best reflects the real behaviour of the estuary, hindcasts of morphological development will be compared to historical bathymetric records. This will give insight into the importance of the factors mentioned above.

The model will then be used to predict how the estuary will change under sea level rise scenarios, with and without interventions under consideration by the EA.

Benefits

Improved understanding of the morphodynamic processes of the Humber will be valuable as scientific knowledge, as the findings are likely to apply to other estuaries globally.

Predictions of how the estuary will respond to climate change and other long-term stressors will be valuable to a range of stakeholders:

  • The EA for flooding, water, and sediment management purposes
  • ABP, the port operator, for navigation
  • Yorkshire Wildlife Trust and other environmental organisations, for conservation purposes

The availability of a validated 3D hydromorphodynamic model of the Humber will be a strategic asset for marine management in the region. Through further development it could provide additional capabilities such as tidal energy resource assessment, optimisation of dredging operations, or modelling of oil or chemical spill behaviour.

Benefits to student

In addition to the training provided by the DTP, the student will learn from experts in the fields of coastal and estuarine processes, numerical modelling, high performance computing, and water management. Through conference attendance they will gain contacts in the academic community and through placements with the EA and Jacobs they will make connections in the public and commercial sectors.

Partners

Environment Agency: CASE partner. The EA will contribute towards the student’s training grant, host the student during placements, and be closely involved with the project.

Jacobs Engineering are technical consultants to the EA on the Humber 2100+ project. Jacobs have indicated support, including possibly co-hosting the student.

Associated British Ports operate the Humber ports, and will provide historical survey data.

Who we’re looking for

Essential

  • Highly numerate, with either
    • a physical science, engineering or applied mathematics degree (2:i or equivalent) with an interest in environmental problems, or
    • an environmental science degree (2:i or equivalent) with an interest in numerical modelling
  • High level of IT aptitude

Desirable

  • Existing background knowledge in relevant physical processes (ideally a relevant masters degree).
  • Experience with CFD or other numerical modelling.
  • Experience handling large datasets using a programmatic approach, for example MATLAB, Python or R.

The successful applicant must satisfy the university’s requirements on English language ability.