Imperial College London


Faculty of Natural SciencesCentre for Environmental Policy

Research Fellow



+44 (0)1557 331 337a.w.leach




Silwood ParkSilwood Park





My main research interests lie in the development of decision support and evaluation tools for people making practical policy decisions with regard to economic and environmental processes.  This has included projects associated with tropical, sub-tropical and temperate agriculture, fisheries, the energy industry, pharmaceutical development and biological invasions of non-native species.  Much of my work involves the moneterization of environmental and human health impacts to greater rationalise, clarify and prioirtize policy considerations.  For example, John Mumford (Imperial), Hermann Waibel (Hannover University) and Wim Mullié (consultant) and I have recently completed a preliminary assessment of the economic impact of pesticide control of desert locust controls in West Africa.  The assessment of human health costs, livestock impacts and environmental damage were integrated with a decision tool (Pesticide Environmental Accounting model (Leach and Mumford, 2008)) which uses a logical, consistent and transparent method to convert these costs into €/hectare for individual pesticides based on their eco-toxicological behaviour and human health impact (Leach, Mullié, Mumford and Waibel, 2009).


Pesticides have non target impacts, we have developed a method for quantifying these for individual pesticides so that donors and government policy makers can make better choices when protecting societies from locust outbreaks (Leach, Mullié, Mumford and Waibel, 2009).  PEA report image, copyright W.C. Mullié, 2009.

Increasingly, we are including uncertainty in the models we develop to capture various aspects of risk and how new policy tools and options could be developed to mitigate risks.  For example John Mumford, Polina Levontin (Imperial) and Laurie Kell (ICCAT) and I have been considering how insurance models from agriculture could be applied to demersal fisheries.  A stochastic time based model was used to design and evaluate the structure, cost and system dynamics of such as scheme on a virtual fish stock (Mumford, Leach, Levontin and Kell, 2009).  Another aspect of risk and uncertainty has been encapsulated in the Invasive  Risk Impact Simulator (IRIS) (Mumford and Leach, unpublished) which is used to monetize the impact (£/year) of the non-native invasive species into the UK for the NNRAP project.  The model shows the full cumulative risk profile of each evaluated species rather than the just the extreme but low probability cases that can become the focus of policy makers attention.  This model is also closely linked to an EU Framework 7 project (PRATIQUE) in which I am currently involved. The remit of PRATIQUE is to imrpove pest risk assessment (PRA) processes in the EU.

 Cumulative distribution graph

Impact risk profile for a nominal invasive frog species (Mumford and Leach, unpublished)

Less recently, I have been involved in variety of projects ranging from protein marketing in Bangladesh, to coffee pests in Colombia, India and Mexico, cocoa pests and diseases in Indonesia and Costa Rica, and fruit flies around the Mediterranean basin, Cotton in Egypt, and provided consultancy services to both private and public organisations.  My PhD was in Environmental Technology with John Mumford, developing computer and policy tools to improve pest management in Egyptian cotton.


Screenshot of a Moniliophthora management model, developed in Costa Rica, to help identify combinations of practices to maximise net profits under a variety of economic constraints (price of cocoa, price of labour, labour requirement etc.) (Leach, Krauss and  Mumford, 2002).


In the near future, I am looking forward to starting to work on Malaria and Dengue control projects based in Africa, South America and South East Asia.

Currently funded by EC Framework 7 contract for PRATIQUE project.  Previous funding has included EC Framework 6 and 7 funds for Cleanfruit and PRONE respectively.  Common Fund for Commodities, CABI and NRInt have extensively funded the commodities research.



Dr Laurie Kell, International Commission for the Conservation of Atlantic Tunas (ICCAT), Fisheries

Dr Peter Baker, Centre for Agriculture and Bioscience International (CABI), Commodities

Professor John Mumford, Centre for Environmental Policy, Imperial College London, Policy and Risk in the Environment

Dr Polina Levontin, Centre for Environmental Policy, Imperial College London, Fisheries

Professor Doktor Hermann Waibel, Hannover University, Agricultural economics

Dr Jonathan Knight, Centre for Environmental Policy, Imperial College London, Environmental Policy and Decision Making

Dr Walter Enkerlin, North American Plan Protection Organization (NAPPO), Sterile Insect Technique

Dr Ana Larcher Carvalho, Centro de Estudo Africanos, Lisbon, Aid policy

Dr Johnson Holt, Centre for Environmental Policy, Imperial College London, Modelling and Decision Making in the Environment

Ms Megan Quinlan, Centre for Environmental Policy, Imperial College London, Policy evaluation and design

Mr Wim Mullié, Consultant, Ecotoxicology