Helen Dyke, Trem Stamp, Hannah Chamberlain and Jackie Ullyett
The cynical attitude towards Geographical Information Systems (GIS) is that they are only good for producing pretty pictures. This paper refutes some of these arguments and shows, with examples from ongoing research, that they have much more to offer. Interrogation of data sets held within the GIS allows the communication of visual and quantitative information to organisations such as the Department of the Environment, the Agricultural Development Advisory Service, the Ministry of Agriculture Fisheries and Food, and the Environment Agency (EA). This output provides policy makers with the opportunity to evaluate alternatives in decisions affecting local, national and international issues such as habitat regeneration and pollutant abatement.
Use of GIS has been criticised by many non-specialists as only providing gratuitous or misguided embellishment of data sets or reports. While GIS cannot compensate for inadequacies in data sets it does provide a powerful tool for the spatial analysis and representation of data. Policy makers need to make decisions at a variety of scales from local to international. The examples contained within this paper will illustrate the use of GIS in transforming data to information valuable in the policy making process.
Functional techniques available to the GIS user range from simple spatial pattern identification to complex statistical analysis, but in all cases the results need to be communicated to others in a readily digestible form. One solution is to produce maps of the data which can effectively communicate large amounts of information which may otherwise be difficult to comprehend. In contrast, the use of, for example, a relational database, a statistics package or a spreadsheet for the manipulation and analysis of data may only provide the option of a tabular display of results.
Used judiciously, map presentation of results can highlight spatial patterns or trends and so provide an ideal basis for informed decisions on policy formulation or the direction for further analysis. However, the value of this exercise does depend on the design of the map which will greatly influence the effectiveness of communicating the spatial results. Maps, although generalising the underlying data to some extent, produce pictures which are easily understood by both scientists and policy makers. As Forrest and Pearson (1994) propose, 'there is no reason why something functional should not be aesthetically pleasing as well - the two should go hand in hand'.
Campbell and Masser (1992) suggest that GIS functionality will mainly be used to improve basic processing of information rather than enhance decision making. Current work at the ITE makes use of GIS to explore rapidly, different user-specified scenarios and present results in formats that allow policy makers to quickly identify different options for decision making. Graphical User Interfaces (GUIs) have been designed to provide a more user-friendly environment and to guide the novice through the data sets and analytical options available to them. The following examples show how GIS applications have been used at the ITE to assist in environmental policy making and management strategies at European, national, regional and local scales.
Until recently, legislation for the control of emission strategies at both the national and the international scale made little attempt to evaluate environmental benefits gained from the control measures imposed (CLAG, 1994). In response to increasing pressure to develop effects-based emission control policies the critical loads approach was formulated.
The original concept of critical loads, developed in the 1970s, has evolved into a valuable tool for addressing the problems of pollution control, gaining acceptance from both scientists and policy makers (Bull, 1995). This relatively simple concept has provided an effects-based approach to controlling emissions of acidifying pollutants and to considering the potential environmental benefits for a number of receptors, principally soil, freshwaters and vegetation (Hornung et al., 1995). The definition of a critical load adopted by the United Nations Economic Commission for Europe's (UNECE) Convention on Long Range Transboundary Air Pollution (LRTAP) is 'a quantitative estimate of exposure to one or more pollutants below which significant harmful effects on sensitive elements of the environment do not occur according to present knowledge', ie., if pollution loads are below the specified threshold then the receptor is considered protected.
In the United Kingdom the government included the development of the critical loads and levels approach in its pollution control policy as a means of aiming at environmental sustainability and protection (DOE, 1990). The Critical Loads Advisory Group (CLAG) was set up by the Department of the Environment (DOE) in 1991 to bring together experts on many key aspects of environmental sensitivity to acidifying pollutants and to review the impacts of these pollutants on receptors such as soils, freshwaters and vegetation. The mapping and data centre (MADC) was established at ITE Monks Wood to provide central database and GIS facilities for CLAG. The MADC also acts as the National Focal Centre for the UNECE Convention's Critical Loads Mapping Programme and provides national data for the production of European scale maps.
UK data sets for this work are usually raster grids at 1km, 10km or 20km resolution. They include the 1km empirical critical loads of acidity for soils, 10km freshwater acidity critical loads and 20km interpolated and modelled acid deposition. Critical load, deposition and exceedance maps (which show where the critical load is exceeded by deposition) 'although of secondary importance to the data, can be easily understood by both scientists and politicians' (Hall, 1994). Within a GIS, critical loads can be calculated and mapped using different statistics and different resolutions. Using a map rather than a table illustrates the effects of such calculations much more effectively. For example, changes in the pattern of modal critical loads of acidity for soils when mapped at the 1km, 10km, 20km and 150km resolutions are easily observable (Figure 1). As the spatial resolution decreases, the same general picture is conveyed although, inevitably, some detail is lost. ARC GRID is used to calculate areas where the pollutant load exceeds the threshold values (critical load) for soils, vegetation or freshwaters. "Stock at risk" in these areas can be identified from the ITE Land Cover Map (derived from satellite imagery) (Fuller et al., 1994) and digital boundaries of Sites of Special Scientific Interest (SSSIs). This provides policy makers with maps showing the geographical and numerical extent of damage or protection.
In Europe, the critical loads approach has played a major role in the UNECE LRTAP Convention discussions. The Helsinki Protocol of 1985, calling for a flat rate emission reduction of sulphur dioxide by 30% (the "30% Club"), was replaced by the Second Sulphur Protocol signed in 1994. This is an effects-based protocol using the results of integrated assessment models, which incorporate geographical distribution of critical loads, pollutant emissions and abatement costs, to develop optimised emission reduction strategies. European scale maps of critical loads, modelled deposition and exceedances were used during these negotiations. For the UK, the Protocol identifies 80% reductions of sulphur emissions from 1980 levels by the year 2010.
Critical loads are still playing a part in LRTAP Convention protocol negotiations with the focus on a new protocol covering nitrogen oxides and ammonia. At the European scale, integrated assessment models are again being used to develop cost-effective targets for nitrogen emission reductions. Nitrogen (oxidised and reduced) is a more complex pollutant than sulphur in that it can have both acidifying and nutrient effects on the environment. To address these problems, GIS is being used to calculate a "Critical Loads Function" to allow the effects of sulphur and nitrogen deposition to be considered simultaneously (Bull et al., 1995). This method provides national policy makers with a series of maps indicating the deposition reductions required to achieve protection and the benefits of different reduction options.
To date, national and European critical loads maps have proved valuable in policy formulation and protocol negotiations for abatement of sulphur and nitrogen emissions. The critical loads approach may, in future, be used in the development of other protocols, for example, the control of heavy metal emissions.
Since 1994, when the Second Sulphur Protocol was signed, there has been a requirement for the UK to significantly reduce sulphur emissions. An estimated 70% of all UK sulphur dioxide emissions are from coal and oil fired power stations (RGAR, 1990). The Environment Agency (EA) is the statutory authority in England and Wales with the responsibility for regulation of emissions from prescribed processes under Integrated Pollution Control (IPC) (DOE, 1990).
Processes regulated under IPC regularly submit estimates of future operating loads to the EA. The national, regional and local implications of emissions (based on these future scenarios) need to be assessed by the EA in terms of peak demand, total energy output and the effects of sulphur emissions on the environment. The critical loads approach, outlined earlier, can be employed in this context to assess the impact of different sulphur emissions on the environment. Human health impacts can be assessed by making use of European Union guidelines (EC directives 80/779/EEC and 85/203/EEC) on acceptable long and short term exposure to sulphur dioxide.
To facilitate the setting of effects-based authorisations, a GIS-based Spatial Decision Support System (SDSS) has been developed at ITE for use by the EA in their evaluation of the impacts of alternative emission reduction scenarios (Wadsworth and Brown, 1995). The system runs in the GRID module of ArcInfo, using maps and C programs to analyse user-specified scenarios. While not designed to provide a definitive answer, the system may assist in the decision making process. The SDSS is easy to use, flexible and capable of displaying information in a clear and easily interpretable manner. The graphical user interface (GUI) provides easy and quick generation of results without the user having to master the intricacies of a GIS. Maps and statistics are generated by the SDSS to provide policy makers with a useful means of assessing the national or regional impacts of different user-defined scenarios.
The SDSS uses the critical loads approach as a method of evaluating reduction scenarios or optimisation. The 1km empirical critical loads of acidity for soils, provided by CLAG, are used by the SDSS for assessing the impacts of different sulphur deposition scenarios. Wherever sulphur deposition exceeds the specified critical load it is assumed there is a risk of damage to the environment. For each point source, 20km resolution sulphur deposition fields (footprints) are modelled using the Hull Acid Rain Model (HARM). HARM is a receptor orientated Langrangian statistical model which describes the behaviour of air parcels which arrive at locations across the UK (Metcalfe et al., 1995). The disaggregation of emissions within the model allows the contribution from individual sources to be determined by simply 'switching off' emissions from all other sources. Deposition fields can be generated by scaling individual point source footprints, assuming a linear response exists between source (point source) and receptor (soils, freshwaters etc). Summing estimates of all major sources produces alternative national sulphur deposition maps based on the contribution of point source emissions under different operating scenarios.
The SDSS runs an interactive optimisation model, written in C, to provide the user with alternative sulphur emission scenarios based on one or more constraints. Examples of user specified constraints could be the limiting of total sulphur emissions to less than a specified number of tonnes per year or the absence of exceedance of critical loads across the country. In addition, restrictions on the capacity of the electricity distribution network act as a constraint on optimisation in some regions since power generation needs to be balanced geographically. Optimisation routines are available in two basic forms:
minimisation of environmental damage subject to economic constraints
maximisation of energy production subject to environmental constraints.
The results of an optimisation routine are considered in terms of their effects on exceedance of critical loads.
The system can be used in both the reactive and the proactive mode. In the reactive mode, rapid analysis in response to specific proposals put forward by power generators or the EA can be carried out. In proactive mode, optimisation in terms of power generation or environmental damage can be explored. Alternatively, the effect of different generating patterns on exceedance of critical loads can be examined.
The SDSS is continually being developed and expanded at the ITE in response to the EA's ongoing need to assess the environmental impacts of possible emission reduction scenarios. An increased choice of optimisation routines will strengthen and facilitate efficient decision making for power production management and atmospheric pollution abatement strategies.
In 1993 the Ministry of Agriculture, Food and Fisheries (MAFF) commissioned the ITE, the Agricultural Development Advisory Service (ADAS) and Silsoe College to develop a Wetlands GIS. Its primary aim was to enable informed decision making by MAFF's ESA project officers through the application of management prescriptions to improve Environmentally Sensitive Areas (ESAs).
Over the past 40 years, there has been a sharp decline of lowland wet grassland habitats due to the intensification and drainage of land for farming practices. Since the introduction of ESAs in 1987 by MAFF, a variety of different management schemes have been adopted. The management strategy depends on the nature of the land and its current agricultural use, and aims to preserve and enhance the ecological diversity of the current habitat. Limited funding for ESAs, means it is important for the conservationist to quickly target ecologically valuable habitats that may require management prescriptions. For the landowner, it is important that the management scheme selected integrates conservation with current farming practices. Where hydrological management is a feature of an ESA prescription to reintroduce wetland environments, an understanding of the implications that effective management strategies have upon the local ecology, agriculture and hydrology is of the utmost importance.
The Wetlands GIS was created foremost as a research tool, although it demonstrates the potential for evaluating alternative management options for the restoration of lowland wet grassland habitats. It provides a method of integrating extensive and diverse data sets considered important in the development of these habitats, and the spatial context to view and evaluate management options.
Data have been collected from four study sites. These include the River Ray (Upper Thames Tributary ESA), Southlake Moor and West Sedgemoor (Somerset Levels and Moors ESA) and Halvergate (the Broads ESA). The environmental data types used within the Wetlands study include: flora, fauna, hydrology, soil, land use and agriculture. The data were collected over a three year period using each field as a key "map object" so giving the attributes a spatial link. "Information buttons" have been incorporated to present metadata which specify the provenance and age of data to aid in the decision making.
One of the main advantages of the Wetlands GIS is that it has the potential to integrate modelled hydrological data into any GIS queries. Models to predict the water regimes across the lowland catchments were run by ADAS using hydrological and soil data from various sample points (Miles et al.,1995). Environmental field data were examined with the water management scenario output from the ADAS model.
The policy maker needs to recognise the optimal hydrological conditions required for:
Re-introduction of wetland conditions.
The consequences of different water management strategies on neighbouring field habitats and agriculture (Treweek et al.,1995).
Studying spatial patterns displayed by the GIS, for example in the relationship between species groupings and hydrological regimes, it is possible to develop habitat restoration hypotheses such as:
Why particular patterns occur
Whether similar patterns occur under the same conditions at different sites.
Further detailed exploration of the data may then be undertaken using statistical analysis to determine whether or not a pattern is spurious.
The Wetlands GIS is designed specifically for non-GIS users. A large number of queries may be made using the GIS functionality hidden behind a menu-driven Graphical User Interface (GUI). As the user steps through the menu-system queries can be iteratively developed. The menu-system includes spatial display for query outputs.
An example of using the Wetlands GIS as an environmental planning tool is seen in the identification of arable fields at the River Ray sites which have the potential for reversion to lowland wet grassland communities.
The process of analysis would be as follows:
Identify fields which currently sustain the rare lowland wet grassland communities that are to be re-established (source fields).
Identify and rank the location of suitable arable fields in relation to source fields using buffer zones of varying distances.
Whilst distance is likely to influence the potential of seed dispersal from source fields, other factors, such as field site wetness, will also influence the restoration of target wetland plant communities. The decision maker may therefore decide to select arable fields which have a similar hydrology to a 'source' field by:
Statistical analysis of the modelled hydrological data for the 'source' field, estimating average values for the different hydrological variables.
Identification of all fields in the catchment which share the hydrological regime of the 'source' field.
Examination for the selected fields of the ranked values derived previously so that only those fields which share the hydrological regime of the source fields and fall within a suitable zone of proximity are identified as a possible target for reversion from arable to wet grassland communities (Figure 2).
Selection criteria can be altered in this type of query to allow for wider hydrological tolerance regimes or different seasons and the types of agricultural practices in neighbouring fields. A variety of other environmental queries and examples of hypothesis development can be made within the Wetlands GIS (Treweek et al., 1996).
At the field scale, the Wetlands GIS has been found to be a useful tool in exploring management options for the reconstruction of particular lowland wetland habitats. It not only directs attention to potential target sites but also enables the planners to take into account other factors such as the farm economics of the site.
This paper has identified a number of examples which highlight the importance of mapping and GIS in decision making processes and the value of user-specific and spatial decision support systems as management tools. The examples demonstrate that GIS provides the functionality to manipulate spatial data at scales ranging from local and regional to national and European. Information generated from these data can easily be understood and interpreted by both policy makers and scientists. Decision makers (including politicians, civil servants, landowners and managers) all need, appreciate and benefit from the clear, concise and efficient presentation of information through GIS.
As an integral part of ongoing research at ITE, environmental information is regularly being supplied to policy makers. GIS continues to play an important role in the manipulation of the best available data, and in the production of maps for use by policy makers in decisions at all scales.
We gratefully acknowledge the support of the United Kingdom Department of the Environment, the Environment Agency, the Ministry of Agriculture, Fisheries and Food, ADAS, the Royal Society for the Protection of Birds, Silsoe College and the Universities of Edinburgh and Hull. The authors would also like to thank Jane Hall, Ruth Swetnam, Mike Brown and Keith Bull of ITE for their useful comments and suggestions on the production of this manuscript.
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Helen Dyke, Trem Stamp, Hannah Chamberlain and Jackie Ullyett
Scientific Officers Environmental Information Centre Institute
of Terrestrial Ecology
Monks Wood
Abbots Ripton
Huntingdon
Cambridgeshire
PE17 2LS
Telephone: 01487 773381
Fax: 01487 773467
Email: H.Dyke@ite.ac.uk