.previous survey (1971) and then checking the results with those obtained previously: this eliminated 
the need for time consuming ground checking. 
Subsequently the 1977 aerial photographs were studied, and as a precaution, a ground survey check 
was made for a small sample. This was necessary because there were no "up to date" photographs for 
comparisons 
The ground check brought to light a number of differences. Namely, with a two year lapse in time 
since the photography was flown, some sites had extended; others had been reclaimed; whilst totally 
"new" derelict sites were also evident. 
The 1/10,000 maps used to record the data were very much out of date. The M5 motorway was not 
featured, the motorway Itself being a cause of some dereliction within the area. 
These problems were overcome by modifying the classification to allow these newly identified units 
to be Included, and by the Introduction of a reclamation category as fol lows: 
  
Category Abbreviation 
Residential RL 
Industrial | 
Commer cl al C 
Recreation RN 
Utility U 
More up to date maps at 1/2500 scale were aquired, and although because there were so many they were 
more cumbersome to use, they did feature the M5 motorway. 
Thus the survey was an air photo based study supplemented by ground survey checks. These were 
necessary to establish the changes, In terms of dereliction and reclamation, which have occurred 
between 1977 when the aerial photographs were flown, and 1979 when the fleld survey was carried out. 
THE SURVEY TECHNIQUE 
A mosaic was compiled using the aerial photographs, whilst the 1/2500 scale maps were at hand for 
reference purposes, co-ordinate values, and area measurement. 
The photographs were then stereoscopically examined, and all dereliction was plotted on acetate 
overlays placed on alternate photos within the flight strips. 
Scanning took place along the flight strips, adjacent strips being related by a 25$ lateral overlap. 
All sites identified regardless of area were transfered and recorded on the 1/2500 scale maps, and 
I+ was found benificial to record the complete Information on each site as it was identifed. This 
helped In reducing errors and In avoiding repetition. 
The alr photo scanning was then repeated, in order to check the accuracy of the interpretation. 
The next step was to check by field survey the air photo interpretation results. This would also 
reveal whether sites had been extended, or reclaimed. Some sites had undergone only partial 
reclamation. 
During the field survey evidence of "new" dereliction was sought, and it was appreciated that an air 
photo study using up to date photographs would have produced more accurate results. An exception to 
this was derelict buildings with roofs intact as these were unidentifiable from the air however 
recent the photography. 
A further check was carried out to ensure that none of the "new" dereliction discovered in the 
ground survey had been overlooked. 
This information was correlated on site schedules (see fig 2), and on the 1/2500 scale maps (see fig 
3). 
RESULTS 
The tabulated results (Tables 2 and 3) show within the sample area, the type and extent of 
dereliction, its distribution with respect to surrounding land use, and the net changes between 1977 
and 1979. 
All areas are recorded in hectares with the net changes shown as percentages of the 1977 figures. 
The table also provides the gross values of dereliction that occur in the sample area, for both 1977 
and 1979. 
It is clear from table 2 that neglected Waste Land (k) 89.41ha, and Demolished Sites (h) 335ha are 
the most prevalent types of degraded land within the sample area. Since they possess similar 
characteristics In terms of reclamation requirements, they have been combined (their totals and 
results are produced In table 3), and together account for 83.2% (123ha) of all dereliction within 
the sample area. This amount is In fact 7.7% of the gross sample area and is significant when 
compared with a total dereliction of 9.25% for the same sample area. 
Reclamation since 1977 within these two categories has reduced these figures to 60$ (89.1ha) of al! 
dereliction within the area le. 5.6% of the gross sample area, with total dereliction now only 7.2% 
(115ha) of the gross area (1500ha). 
  
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