Browsing by Subject "Geography and Environmental Studies"

Now showing 1 - 4 of 4
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    Aerial photography and environmental impact analysis : the potential contribution of comparative interpretation of multi-temporal aerial photographs to Environmental Impact Analysis
    (1984) Bayne, Sandra Maureen; Fuggle, Richard Francis; Stauth, Roy Bryan
    The hypothesis was advanced that comparative interpretation of multi-temporal aerial photographs can be used as a tool in Environmental Impact Analysis (EIA). To test this hypothesis a site, Silwerstroomstrand, approximately 40 kilometres north of Cape Town on the West coast was chosen. An analysis of the site was carried out using aerial photographs taken in 1938, 1960, 1968, 1971, 1977, 1981 and 1983 at scales ranging from 1:7 000 to 1:50 000. Development of the site for recreation began in 1972 and in 1976 for water extraction. Pre-development photographs, 1938, 1960, 1968 and 1971, were stereoscopically compared and the observations were interpreted using a systems approach. From the analysis of the photographs and information on past landuse, the dynamics of the site were described with particular attention to the response of that environment to perturbations such as fire and removal of vegetation. Development actions were analysed to establish any similarity to past perturbations and on the basis of similarities, predictions of probable future responses of the site (and hence impacts) were made. The predicted impacts were compared with: 1. the interpretation of post-development photographs. 2. Impacts identified by a multi-disciplinary panel after a visit to the site. It was found that the major limitation of multi-temporal aerial photographs was the spatial resolution of the early (pre 1970) photographs. However, the capabilities of the tool for quantitative and semi-quantitative data gathering; promoting an understanding of spatial and temporal relationships; monitoring change; communicating information and the fact that it is economical means that it has a positive contribution to make to Environmental Impact Analysis is suggested that the optimal use of the tool of comparative interpretation of multi-temporal aerial photography is to combine it with other tools such as site visits and multi-disciplinary panels.
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    Open Access
    A climatology of the coastal low in the SW Cape
    (1987) Heydenrych, Clive Malcolm; Keen, Cecil
    The Coastal Low is a shallow cyclonic mesoscale weather 'disturbance' which migrates around the southern African subcontinent on a fairly regular basis. It is generated and maintained by the synoptic scale circulations. The movement and surface characteristics have been well documented by a number of authors but few detailed studies have been undertaken on its vertical structure in southern Africa. In addition to this, most of the previous work has been of a meteorological nature. This study has concentrated on a more climatic approach in its investigation of the vertical and· surface features of the Coastal Low as it migrates through the South Western (SW) Cape. The SW Cape is a 'transition region' for the migration of the Coastal Low; situated between the west and south coasts with a distinct local climate due to the complex topography of the region. This fact tends to alter the characteristic features of the Coastal Low system but appears not to prevent the Coastal Low from migrating through the region. The Coastal Low is regarded as being an internal trapped Kelvin wave and corrected surface pressure values best indicate its migration characteristics. However upper air analysis indicates that temperature values (between 950- 900mb) at the level of the inversion, produce one of the best signatures of the Coastal Low's passage. This is related to the strong subsidence from above the 850mb level in the pre-Low period. This strong divergence dynamically compresses the lower layers into low level wind speed maxima on either side of the centre of the system. The Coastal Low appears to have a very complex structure, and two results from this study in the. SW Cape bear particular mention. Firstly the offshore flow at the escarpment level is weakly defined. Secondly also, the longshore spatial extent of the Coastal Low system has been estimated to have an 'inner' diameter of 150-200km and an 'outer' diameter of approximately 1000km.
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    NM2002 impact assessment : impact assessment report
    (1992) Lochner, Paul
    The purpose of this report is to: * assess the biophysical and socio-economic impacts of closure of De Beers Namaqualand Mines (DBNM) * provide preliminary suggestions for mitigation measures. DBNM anticipate that they will close in approximately 10 years' time. By the year 2002, all diamond deposits which are currently economically viable to mine on a large-scale would have been exploited. Closure is anticipated to have a significant impact on DBNM employees, their households, and towns where the households of employees live. Furthermore, closure is anticipated to have a significant impact on the Namaqualand economy. Therefore, DBNM commissioned the EEU to undertake an assessment of the impacts resulting from mine closure, to ascertain the effects on their employers and their affected households and communities. Through discussions with DBNM the scope for this assessment was established: * Briefly to describe the current biophysical, social and economic environments in Namaqualand and identify different trends in the region. * To assess in detail the socio-economic impacts resulting from the closure of DBNM. In addition, this report considers the impacts on the biophysical environment resulting from the closure of DBNM, because the socio-economic well-being of employees from rural areas of Namaqualand and Transkei is intrinsically linked to changes in the biophysical environment. Lastly, this report also contains preliminary suggestions for mitigating the impacts of closure.
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    The use of jacaranda leaves to determine the distribution of trace elements in Pretoria
    (1986) Walker, Nigel Peter; Fuggle, Richard Francis
    The spatial distribution of trace elements in Pretoria is investigated by reference to the concentrations of lead, iron, manganese, zinc and copper in Jacaranda leaf samples. Different methods of sample preparation and analysis are examined. The variation in the trace element concentrations on a leaf and within a tree; temporal variations (daily and monthly); spatial variations (along a road, in different land-use zones); and the effect of meteorological variables (rain and wind) are investigated. Differences between the results from two annual surveys, the distributions and anomalies for each of the examined elements are discussed. The relationship between results from leaf and adjacent air-filter and/or deposit gauges is examined. The linear regression equations for lead, iron, manganese and zinc are used to simulate the atmospheric concentrations of these elements. The application of leaf sampling to augment and clarify the results from the existing Pretoria atmospheric monitoring network is discussed. It is concluded that the technique can be successfully applied to determine the distributions of trace elements in Pretoria. There is little variation in the concentrations of zinc and copper. The high leaf lead concentrations are found in the City centre and at points of traffic convergence. Anomalies of manganese occur in the southern suburbs, probably derived from the soil, and for iron to the west of the City centre, the possible source of which is industrial activity. The influence of Iscor, the iron and steel works, to the west of Pretoria is clearly shown by the distribution of iron in Pretoria. The comparison with the results from the deposit gauges is poor. The correlation between the air-filter and leaf results is particularly good for lead and iron. The simulated distributions of lead and zinc are very similar, suggesting that traffic is the source of both. Of the existing atmospheric monitoring stations in Pretoria the site at Munitoria is located in a position well within the overall central area exhibiting the highest lead, iron and zinc concentrations. It is concluded that additional atmospheric monitoring sites are required to determine the sources of the anomalies for iron and manganese, the existence of which were unknown prior to this study.