GIS: Geographical Information Systems
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A GIS is a Geographical Information System - and it may come as a surprise that Geographical Information Systems have a role in garden management! The three words in the title signify the characteristics of a GIS:
- ‘Geographical’ reminds us that it deals with geographical, or spatial, data.
- ‘Information’ reminds us that a GIS is a way of handling data – it is a spatial database.
- ‘System’ reminds us that it dates from the 1970s, when everything to do with computers was described as a ‘system’.
GIS do not fall into the category of design software but most of the world’s mapping agencies are now using GIS to produce their maps, even if they are then sold on paper. There is a discussion of the role of GIS in landscape and planning in Turner, T. City as landscape (1996). The uses of GIS in garden management include:
- map data, on which to base a garden design, is now available in digital form and can be related to other types of data (soils, landcover, geology etc) in a GIS. At present this is practical only for large projects.
- the creation of a spatial database in which to record details of all the plant material in a garden: species, planting date, management operations etc. This data can be analysed in the GIS
- a GIS is of great assistance in managing a historic garden: (1) the GIS can store a set of historical plans and bring to a common scale for comparative purposes - this is done by rubber sheeting (2) the GIS can produce new maps to show the garden at different points in history (3) the GIS can be used, as on an archaeological project, to store full details of the hard and soft materials found on the historic garden site.
GIS also has a major role in landscape architecture and city planning. If you take a city plan and draw over it with a green marker pen, you can design an ‘open space system’ with parks and parkways. This is what Patrick Abercrombie did for London in 1943. It is still the foundation of open space planning for London. But what does the green ink actually mean:
- a network of parkland owned and managed by a local authority?
- a network of land with public access?
- a network of land which has not been built upon (including paved areas? Including roads?)
- a network of vegetated space (including private gardens and nature reserves?)
- The ‘parkways’ on the original Abercrombie plan are a case in point. Although they were used to interconnect parks, they were actually a special category of road with wide vegetated margins.
These considerations force us to the conclusion that simply classifying land as ‘greenspace’ is inadequate. We need to:
- define areas of land (eg as ‘greenspace’)
- specify which policies apply to different parts of the greenspace (eg ‘accessible’, ‘vegetated’, ‘managed as parkland’, ‘managed as nature reserve’, ‘solid’, ‘void’)
- With paper plans, this is not an easy task. With a GIS, it is simple. The two most characteristic features of a GIS are:
- database tables, from which the maps are generated
The database can hold much of the data which landscape architects use: soils, geology, water, user preferences, contours etc etc. You can either purchase the data or you can put it in yourself. It can generate 3-D models and generate aerial photographs over them, with geographic precision. But this is difficult.
Environmental Systems Research Institute (ESRI) is a GIS supplier. The organisation was started by a landscape architect and it is now the world’s largest GIS company. ESRI make several products:
- ArcView: a comparatively easy-to-use programme
- ArcInfo: a very sophisticated programme
- ArcGIS: a scalable product, allowing the aquisition of additional modules to increase the functionality