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Statistical Bulletin ENV/2002/1: Scottish Vacant and Derelict Land Survey 2001

Annex: Considerations when interpreting the data

Removal and Addition of Sites. The means by which new sites are detected are largely centred on the expert knowledge of local authority planning officers. It is very important to note that Table 16, which shows new sites added since the previous survey, show only entirely new sites. Sites which have increased in size since the previous survey are not shown. Similarly, when part of a site is brought back into use, that part is detailed in the 'B' data set, and the part not brought back into use remains in the survey 'A' data set ( link).

Changes in Site Details. Changes in site details can also cause other difficulties in interpreting the data. The most notable are when two separate sites become joined by the inclusion of a further piece of vacant or derelict land, and alternatively when a single site has a central area brought back into use, such that the remaining disused area does not form a single contiguous site. The first of these scenarios is the most awkward from a statistical viewpoint, as data regarding previous use etc. for both sites are unlikely to be compatible. Where this happens, details from the largest contributing site are used to describe the new, compound site.

Definition of Contamination. The SVDLS bulletin reports on sites which are available for re-use, and as such contamination is defined in terms of its potential impact on development, either as a direct result of the contamination itself or through the costs of remediation prior to re-development. This differs considerably from the definition of contamination set out in Part IIA (Contaminated Land) of the Environmental Protection Act 1990, which refers to land causing a threat to human health or the wider environment. It seems likely that all derelict sites which are contaminated under the Part IIA definition should also be regarded as contaminated under the SVDLS definition, but not necessarily vice versa. Another issue lies in the measurement of contaminated land, in that it can only be confirmed to be contaminated after it has been tested. Although this is obvious, it implies that the amount of recorded contaminated land bears a direct relationship with the amount tested for contamination, and as such the availability of resources for testing might have a strong influence on the data presented.

Ownership. Details of ownership are not always readily available to local authorities, and this is reflected by the large amount of land of 'Unknown' ownership shown in Table 5. Annex Chart A illustrates the relationship between unknown ownership and the length of time sites have lain vacant or derelict. Each column represents the percentage of all sites in that category for which ownership is unknown. Using the percentage values gives a clearer picture of the extent of the problem by standardising the 'number' of sites in each age category. Ownership was unknown for 26 per cent of the sites that had lain vacant or derelict since 2001, representing 18 hectares of land.

Annex Chart A: Percentage of sites where principal owner is unknown by period since which they have lain vacant or derelict, 2001

Previous Use and Length of Time Vacant or Derelict. Knowledge of the use to which a site was formerly put is important in assessing it for potential contamination. The triple of previous, intended and actual usages of reclaimed derelict land and vacant land brought back into use is also important in determining the success of local plans. In order to carry this assessment through, it is necessary to have information about the previous use of sites. However, there appears to be a relationship between the length of time a site has been vacant or derelict and the information available about its previous use, as shown in Annex Chart B. For each time period, the percentage of sites for which there is no available information about previous use is given. The longer a site has been disused, the less likely is the possession of information about its previous use. The exception to this is in the very oldest class of sites, which is also the single largest class, containing 1,091 sites out of a total of 4,670.

Annex Chart B: Percentage of sites where previous use is unknown by period since which they have lain vacant or derelict, 2001

Land area eligible in the survey. Although all derelict land should be included in the survey, the recording of vacant land is restricted to urban areas where the resident population exceeds 2,000 people, and the 1km region which surrounds them. As a consequence, the actual land area surveyed for vacant land is often considerably smaller than the total land area of each local authority, especially in the case of the more rural areas. The figures contained in this bulletin should thus be interpreted as showing derelict land throughout Scotland, but only urban vacant land. Figures for the urban and rural land areas of each local authority are shown in Annex Table A.

Annex Table A: Derelict land as a percentage of total area by local authority area, 2001 ^1,2

1 Figures may not sum due to rounding
2 Total urban and rural areas for local authorities are estimates. Urban areas are defined as those settlements with populations greater than 1,000 during the census in 1991.
3 1993 data have been used for this authority (Highland)
4 2000 data have been used for this authority (Moray)

Definitions/Interpretations. The SVDLS guidelines clearly state the definitions for the recording of vacant and derelict land. Where difficulties are encountered, the guidelines have been modified to assist in the provision of uniform returns, but ultimately the survey relies on the consistent application of definitions between local authorities and through subsequent years. Some of the changes reported in Annex Table B (sites removed for 'definitional' reasons) come about following a reappraisal of the survey guidelines by local authority planning officers. Since the last survey, 355 hectares of land were removed from the survey for definitional reasons, of which 241 hectares were located in West Lothian (West Lothian did not complete the survey in 2000).

Annex Table B: Sites removed for definitional reasons, by local authority area, 2001 ¹

1 Figures may not sum due to rounding
2 The figures for West Lothian are sites removed for definitional reasons, compared with sites recorded in 1999, as they did not participate in the 2000 survey.

Annex Table C shows sites that have been removed from the survey due to naturalisation, which appear to have blended back into the surrounding landscape.

Annex Table C: Sites removed due to naturalisation, by local authority area, 2001 ¹

1 Figures may not sum due to rounding

Local authority participation

Participation of Local Authorities. It is important to remember throughout the interpretation of the figures reported in this bulletin that not all local authorities participated in the survey in every year. There are two main impacts arising from this:

• Comparisons between years must be made with extreme care, and only for individual local authorities where suitable data exist.

• Where a local authority has not provided data every year, the recorded change will be since the last survey, and will thus reflect several years' worth of change.

The majority of local authorities have provided data for the years 1990 and 1993 - 2001 for the Scottish Vacant and Derelict Land Survey. Non-participating councils are identified for each year in Annex Table D. All councils participated in the 1990 and 1993 surveys.

Annex Table D: Local authorities NOT participating in the survey, 1994 - 2001

1 Only Banff and Buchan District did not respond
2 Only the SVDLS-A data file was provided

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