EstSim prototype simulator
Summary of key issues:
|Description||The purpose of developing the Prototype Simulator was to take a systems-based description of the geomorphological elements present within an estuary, and through a mathematical formalisation of the influences between the morphological and process components, investigate its response to natural and anthropogenic changesThe Prototype Simulator is based on a Boolean network approach and is able to describe an evolutionary trajectory for a specified estuary given the present rule-base and associated function library.|
|Temporal applicability||Medium to long term (Decades to centuries).|
|Spatial applicability||Estuary wide.|
|Links with other tools||The Simulator may be useful for evaluating quantitative models by providing information on the direction of change.The Simulator could provide benefits as both an educational tool and as a geomorphological resource to guide the conceptual development of modelling studies.|
|Data sources||- Understanding of past functioning of estuary
- Morphological components of an estuary
- Gross geomorphological properties of estuary
|Necessary software tools / skills||- Geomorphological expertise
- Access to / experience of MATLAB Code
|Typical analyses||Assessment of evolutionary trajectory of estuary following specified intervention.|
|Limitations||The Simulator in its present form is not a suitable tool for evaluating estuary management options. This is because of the inability of the Simulator to distinguish between large and minor effects; a result of the Boolean architecture (i.e. due to its “all or nothing” binary approach). This makes it inappropriate for use as the only source of information with which to inform decisions regarding regulation and development.
Formulation of mathematical functions to characterise the known geomorphological behaviour and linkages within a system involves a high degree of ‘operator variance’. As a result, much of the geomorphological knowledge formalised within the Simulator is subjective.
The Prototype Simulator requires some knowledge of estuary morphology, both to set up for specific estuaries and to interpret the results. This limits the range of users that can apply it in estuary studies. As with the output of any modelling exercise it is necessary to verify the output state in context and against observations or objective judgments.
The Prototype Simulator in its current state is a research tool and as such a number of the logical relationships within the Prototype Simulator, as it currently stands, require further validation. These issues are not a criticism of the method but an acknowledgement that the development of this type of model is an ongoing process.
Within the Boolean network approach, estuary evolution is modelled as a se ries of steps but these are not linked to any real time scales. The timescale of a given behavioural response to a specified action can therefore not be determined.
The Simulator provides a reasonable guide to the direction of change of the estuary system following a change in forcing, but it does not capture the complexities of real estuary systems. In fact a major strength of the Simulator is its simplicity but this means that it cannot determine whether the associated change resulting from intervention is negligible or considerable.
|Example applications||Research was completed within FD2117 to identify an up to date and relevant list of management questions applicable to UK estuaries, mapped against relevant legislation. These questions were used to derive a series of scenarios for undertaken a targeted pilot testing exercise. Pilot testing was undertaken on the Teign and Thames estuaries.|
Background: R&D Project FD2117
The Prototype Simulator was developed within R&D project FD2117, Development and Demonstration of Systems Based Estuary Simulators (EstSim) (EstSim Consortium, 2007). The project has investigated an alternative, yet complimentary, approach to help understand morphological behaviour in estuaries. This involves the application of a systems-based approach to estuary environments. One of the key aims of the approach developed is to provide a qualitative framework to understand and explain the behaviour of geomorphological features within estuaries, the linkages that exist between them and hence their response to change.
A system-based approach involves defining the individual components that make up a given environment and characterising how these components interact in order to understand the system organisation and define its behaviour, see Coast & estuary behaviour systems - PDF 265KB (ABPmer, 2007). Systems-based thinking is a well-established conceptual framework in geomorphology, but methodologies for converting system diagrams into practical simulation tools have not previously been investigated.
EstSim has applied these systems-based concepts to estuaries to define and subsequently formalise the understanding of the system in a way that allows the qualitative prediction of long-term estuary morphological evolution and responses to environmental change (e.g. sea-level rise or sediment supply changes) or interventions (e.g. dredging or coastal protection). This research has been used to demonstrate the potential of such a systems-based approach.
Further details of the research undertaken within FD2117 can be found at the web based interface developed for the project: http://www.discoverysoftware.co.uk/estsim/EstSim.html