Background

Unlike flooding problems, water quality failures are often unseen and therefore unreported.

Models that take into account solute mixing processes are vital to predict the concentration and distribution of potentially harmful chemicals and organisms in water networks.

One current example of the relevance of mixing is Metaldehyde, a pesticide applied to protect crops from slugs. During storm events it is washed off as a soluble material and travels via surface water systems into rivers. As a result, short duration spikes of low concentrations have been detected in drinking water supplies (Water UK, 2013).

In addition to the chemical reactions and biological degradation, the timing, concentration and duration of these spikes are governed by the physical mixing mechanisms, with spatial and temporal distributions controlled by physical flow and mixing processes.

The management of water quality in rivers, urban drainage and water supply networks is essential for ecological and human well‐being.

Professor Ian Guymer

The University of Sheffield

Predicting the effects of management strategies requires knowledge of the hydrodynamic processes covering spatial scales of a few millimetres (turbulence) to several hundred kilometres (catchments), with a similarly large range of timescales from milliseconds to weeks.

Predicting underlying water quality processes and their human and ecological impact is complicated as they are dependent on contaminant concentration. Current water quality modelling methods range from complex three dimensional computational fluid dynamics (3D CFD) models, for short time and small spatial scales, to one-dimensional (1D) time dependent models, critical for economic, fast, easy‐to‐use applications within highly complex situations in river catchments, water supply and urban drainage systems.

Relevant articles

• Water UK (2013). Briefing paper on metaldehyde.
• Eurobarometer (2014). Attitudes of European citizens towards the environment. (Special Eurobarometer 416).