Dispersion of localised releases in a street network (DIPLOS)

The security threat level from international terrorism, introduced by the UK Security Service, has been classified as either "severe" or "critical" for much of its six-year history, and currently remains as "substantial" (source: MI5 web site). Part of the risk posed by terrorist threats involves potential releases of air-borne chemical, biological, radiological or nuclear (CBRN) material into highly populated urbanised areas. Smoke from industrial accidents within or in the vicinity of urban areas also pose risks to health and can cause widespread disruption to businesses, public services and residents. The Buncefield depot fire of 2005 resulted in the evacuation of hundreds of homes and closure of more than 200 schools and public buildings for two days; consequences would have been much more severe if prevailing meteorological conditions had promoted mixing or entrainment of the smoke plume into the urban canopy.

In both these scenarios it is crucial to be able to model, quickly and reliably, dispersion from localised sources through an urban street network in the short range, where the threat to human health is greatest. However, this is precisely where current operational models are least reliable because our understanding and ability to model short-range dispersion processes is limited. The contribution that DIPLOS will make is: (i) to fill in the gaps in fundamental knowledge and understanding of key dispersion processes, (ii) to enable those processes to be parametrized for use in operational models, and (iii) to implement them into an operational model, evaluate the improvement and apply the model to a case study in central London.

Most of the existing research on urban dispersion has focused on air quality aspects, with sources being extensive and distributed in space. Scientifically, the proposed research is novel in focusing on localized releases within urban areas, and on dispersion processes at short range. Through a combination of fundamental studies using wind tunnel experiments and high resolution supercomputer simulations, extensive data analysis and development of theoretical and numerical models, DIPLOS will contribute to addressing this difficult and important problem from both a scientific research and a practical, operational perspective.

Beneficiaries from this research:

(1) Developers of operational dispersion models in the commercial (e.g. ECL, CERC), public (e.g. Met Office) and security (e.g. DSTL) sectors.

(2) Model users, including emergency services and regulatory bodies (e.g. Met Office, DSTL, Local Authorities).

(3) The general public.


How they will benefit:

(1) Model developers: The immediate beneficiaries of the project will be developers of operational dispersion software in the commercial, public and security sectors. This includes direct collaborators in the project, namely the developers of the SIRANE model (Ecole Centrale de Lyon, ECL), the NAME model (UK Met Office) and the UDM model (Defence Science & Technology Laboratory, DSTL) - see their respective letters of support - but also developers of other software such as ADMS (Cambridge Environmental Research Consultants, CERC). They will benefit from the increased scientific understanding that DIPLOS will generate, the specific parametrizations that we will develop and the comprehensive datasets that we will make available, allowing them to improve their respective models.

(2) Model users, including emergency services and regulatory bodies: This includes the Met Office, DSTL and also other bodies such as Health Protection Agency, Environment Agency and Local Authorities. The results of DIPLOS will help to define a hazard area, allow a more precise definition of danger in a particular event, contribute to the reliability and quantify the uncertainty of models. These are key benefits from an operational point of view.

(3) The public: The public will benefit through better emergency preparedness, aided by more reliable modelling enabled by the advances made by DIPLOS.