Award details

Novel approaches to environmental modelling and risk assessment using concepts derived from statistics, entropy, chaos and complexity theory

Reference	BBS/E/C/00031566
Principal Investigator / Supervisor	Professor Tom Addiscott
Co-Investigators / Co-Supervisors
Institution	Rothamsted Research
Department	Rothamsted Research Department
Funding type	Research
Value (£)	61,660
Status	Completed
Type	Institute Project
Start date	01/04/1997
End date	31/03/1999
Duration	24 months

Abstract

This is a project that seeks to build on concepts, some old, some very recent, that have not yet been fully explored in the context of environmental modelling. Statistics is an important element in modelling soil processes because of the spatial variation in the soil properties used as parameters, and it is a key component in the validation procedures for all models. It also strongly relevant to decision-support systems, which often need to provide guidance in the face of uncertainty; this necessitates the provision of information in probabilistic terms. A possible development in this field is the use of statistical procedures developed for evaluating investment options under uncertainty. Farming and other forms of environmental management all operate with options. The use of entropy concepts is based on the understanding that soil- plant systems are open systems, because they exchange both energy and matter with their surroundings. They should therefore tend towards a steady state characterised by minimum entropy production. The non-equilibrium thermodynamic theory surrounding the principle of minimum entropy production provides a good analogue of the behaviour of natural and agricultural ecosystems subjected to perturbations. Entropy production is therefore a useful measure of sustainability in these systems and probably in many others too. Some useful generalisations can be made from the principle. It implies, for example, that the most sustainable systems are likely to be those in which there is least perturbation, suggesting that continuous arable production may be one of the more sustainable options. The principle also provides certain caveats, notably that the capacity for self-organisation must be retained in the system; in practice this means that the biological potential of the system must be maintained. Measuring entropy is not always simple in laboratory chemical systems and it cannot be fully quantified in a natural or agricultural ecosystem. One approach to this problem is an `audit of small molecules'. This is based on the concept that entropy-increasing processes are those which degrade complex ordered structures of large molecular weight into small ions and molecules such as carbon dioxide, ammonia and nitrate, while processes such as photosynthesis lessen entropy by building small molecules into larger and more organised units. Chaos theory and complexity theory are also included in this RO, because many of the processes that we model could show the kinds of behaviour described by these theories, and because non-linearity in processes and models, an existing interest, is one root of chaotic behaviour. We have identified a possible link between chaos and modelling, but we do not wish to put it in an information system at this stage. Two main objectives can be identified. One is the completion of a concept note on the entropy topic for BBSRC that was severely delayed by OASIS. The other is the further exploration of the ideas discussed above with Dr Jim Harris, University of East London and other interested parties. The outline of a paper has been laid down. Work during the past year suggests four objectives for the coming year: 1) Writing a paper expounding the role in the soil of each of the three levels of thermodynamics identified by Prigogine and Stengers (Classical thermodynamics, better described as thermostatics, linear thermodynamics and non-linear thermodynamics). 2) Writing a paper on chaos in soils. A request has been received from an editor. 3) (With N.A. Mirza) Examining models for transport processes in the soil for evidence of chaotic behaviour. 4. (With T.W. Willison) Investigating denitrification for evidence of chaotic behaviour by applying theory developed for insect populations to measurements of denitrification.

Summary

unavailable

Committee	Closed Committee - Engineering & Biological Systems (EBS)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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