Pub Date : 2021-06-05DOI: 10.1080/03736245.2021.1932564
M. Loubser
ABSTRACT Ultrasonic pulse velocity (UPV) measurement has previously been determined to be a good proxy for rock weathering intensity. As such, it has the potential to be useful for the establishment of relative weathering rates in culturally sensitive artefacts such as tombstones. This is the first study that makes use of an ultrasonic proxy in this manner to be carried out in South Africa, where many tombstones are constructed from locally produced gabbro stone. However, the delimitations of ultrasonic equipment have not been appropriately established for use on this particular lithology. This study investigates the relationship between UPV and the amount of time various tombstones have spent in situ at Cullinan Main Cemetery in South Africa, with the aim of determining if UPV can accurately be used to assess relative weathering rates for the tombstones there. Ultrasonic measurements were taken with two different transducer packages on 34 tombstones that had remained in the cemetery for between 15 and 100 years. The results show that there is a measurable, statistically significant positive relationship between inscription age and ultrasonic pulse velocity (UPV), supporting the hypothesis that UPV is a valid proxy for rock weathering with respect to South African gabbro tombstones.
{"title":"An assessment of ultrasonic pulse velocity measurement as a viable proxy for weathering in South African gabbro tombstones","authors":"M. Loubser","doi":"10.1080/03736245.2021.1932564","DOIUrl":"https://doi.org/10.1080/03736245.2021.1932564","url":null,"abstract":"ABSTRACT Ultrasonic pulse velocity (UPV) measurement has previously been determined to be a good proxy for rock weathering intensity. As such, it has the potential to be useful for the establishment of relative weathering rates in culturally sensitive artefacts such as tombstones. This is the first study that makes use of an ultrasonic proxy in this manner to be carried out in South Africa, where many tombstones are constructed from locally produced gabbro stone. However, the delimitations of ultrasonic equipment have not been appropriately established for use on this particular lithology. This study investigates the relationship between UPV and the amount of time various tombstones have spent in situ at Cullinan Main Cemetery in South Africa, with the aim of determining if UPV can accurately be used to assess relative weathering rates for the tombstones there. Ultrasonic measurements were taken with two different transducer packages on 34 tombstones that had remained in the cemetery for between 15 and 100 years. The results show that there is a measurable, statistically significant positive relationship between inscription age and ultrasonic pulse velocity (UPV), supporting the hypothesis that UPV is a valid proxy for rock weathering with respect to South African gabbro tombstones.","PeriodicalId":46279,"journal":{"name":"South African Geographical Journal","volume":"59 1","pages":"107 - 121"},"PeriodicalIF":1.4,"publicationDate":"2021-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80693843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-04DOI: 10.1080/03736245.2021.1934092
E. Mavhura, J. Mapuva
ABSTRACT Local authorities (LA) are vested with authority to preside over the affairs of local communities. This authority comes with responsibilities of reducing disaster risks and losses. Disaster risk reduction (DRR) has been a key goal of global frameworks for minimizing risk and losses from disasters. Despite global efforts to reduce disaster risk, research into what hinders LA in investing for DRR is limited. Using case study material from two rural councils in Zimbabwe, this study examined barriers that constrain LA in investing in DRR for resilience. The study used interviews that involved local authority and civil protection officials, the academia, policy makers and disaster practitioners. Results show that LA in Zimbabwe are constrained by inadequate legislative authority, unclear mandates for DRR and a lack of necessary resources. The study concludes that LA need strengthening through legislative reforms, devolution, and injection of financial and material resources to invest in DRR strategies.
{"title":"Barriers for local authorities to invest in disaster risk reduction: evidence from Zimbabwe","authors":"E. Mavhura, J. Mapuva","doi":"10.1080/03736245.2021.1934092","DOIUrl":"https://doi.org/10.1080/03736245.2021.1934092","url":null,"abstract":"ABSTRACT Local authorities (LA) are vested with authority to preside over the affairs of local communities. This authority comes with responsibilities of reducing disaster risks and losses. Disaster risk reduction (DRR) has been a key goal of global frameworks for minimizing risk and losses from disasters. Despite global efforts to reduce disaster risk, research into what hinders LA in investing for DRR is limited. Using case study material from two rural councils in Zimbabwe, this study examined barriers that constrain LA in investing in DRR for resilience. The study used interviews that involved local authority and civil protection officials, the academia, policy makers and disaster practitioners. Results show that LA in Zimbabwe are constrained by inadequate legislative authority, unclear mandates for DRR and a lack of necessary resources. The study concludes that LA need strengthening through legislative reforms, devolution, and injection of financial and material resources to invest in DRR strategies.","PeriodicalId":46279,"journal":{"name":"South African Geographical Journal","volume":"1 1","pages":"122 - 136"},"PeriodicalIF":1.4,"publicationDate":"2021-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83269829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-26DOI: 10.1080/03736245.2021.1917447
S. Dlamini, E. Block, I. Rampedi
ABSTRACT The purpose of this study was to explore students’ environmental perceptions and some of the determinants of these perceptions at the University of Johannesburg in the Gauteng province, South Africa. Students were asked if they perceive a positive future for the environment in Gauteng. Study results revealed that a large majority of students were neutral on whether they perceived a positive future for the environment in Gauteng, which may indicate their indifference or ambivalence to environmental issues in the province. The findings also alluded to the significance of gender (females), hometown origin (urban), and age as determinants of students’ perceptions of the environment. Variables like faculty and campus were not strong determinants of students’ perceptions of the environment. These results may be considered in the design of environmental policies and education meant to improve environmental behaviour in the province.
{"title":"Understanding students’ environmental perceptions and some of their determinants in Gauteng province: a case study at the University of Johannesburg, South Africa","authors":"S. Dlamini, E. Block, I. Rampedi","doi":"10.1080/03736245.2021.1917447","DOIUrl":"https://doi.org/10.1080/03736245.2021.1917447","url":null,"abstract":"ABSTRACT The purpose of this study was to explore students’ environmental perceptions and some of the determinants of these perceptions at the University of Johannesburg in the Gauteng province, South Africa. Students were asked if they perceive a positive future for the environment in Gauteng. Study results revealed that a large majority of students were neutral on whether they perceived a positive future for the environment in Gauteng, which may indicate their indifference or ambivalence to environmental issues in the province. The findings also alluded to the significance of gender (females), hometown origin (urban), and age as determinants of students’ perceptions of the environment. Variables like faculty and campus were not strong determinants of students’ perceptions of the environment. These results may be considered in the design of environmental policies and education meant to improve environmental behaviour in the province.","PeriodicalId":46279,"journal":{"name":"South African Geographical Journal","volume":"63 1","pages":"89 - 106"},"PeriodicalIF":1.4,"publicationDate":"2021-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78885804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-05DOI: 10.1080/03736245.2021.1907219
A. J. van der Walt, J. Fitchett
ABSTRACT Extreme Temperature Events (ETEs), including heatwaves, warm spells, cold waves and cold spells, have disastrous impacts on human health and ecosystems. The frequency, intensity, and duration of ETEs is projected to increase due to climate change. However, very little research has been done on ETEs in South Africa, and only a few attempts have been made to identify and examine trends. Currently, ten known publications have examined ETEs across South Africa, the majority of which use the South African Weather Service (SAWS) climate database as the primary source. The general findings indicate that the incidence and duration of extreme warm temperatures are increasing, while cold extremes are decreasing. However, inconstancies exist in the indices used to identify ETEs, selection of meteorological stations, study period, and statistical methods used to examine trends. We review the methodological approaches to define ETEs, the extreme temperature indices adopted, the selection of meteorological stations, study periods, data quality and homogeneity, statistical trend analysis, and results. From these, we propose an approximate number of stations to adequately portray temperature variability on a national and regional level. Finally, we reflect on projections of ETEs under current climate change conditions, and the implications of cold and warm ETEs in a South African context.
{"title":"Extreme Temperature Events (ETEs) in South Africa: a review","authors":"A. J. van der Walt, J. Fitchett","doi":"10.1080/03736245.2021.1907219","DOIUrl":"https://doi.org/10.1080/03736245.2021.1907219","url":null,"abstract":"ABSTRACT Extreme Temperature Events (ETEs), including heatwaves, warm spells, cold waves and cold spells, have disastrous impacts on human health and ecosystems. The frequency, intensity, and duration of ETEs is projected to increase due to climate change. However, very little research has been done on ETEs in South Africa, and only a few attempts have been made to identify and examine trends. Currently, ten known publications have examined ETEs across South Africa, the majority of which use the South African Weather Service (SAWS) climate database as the primary source. The general findings indicate that the incidence and duration of extreme warm temperatures are increasing, while cold extremes are decreasing. However, inconstancies exist in the indices used to identify ETEs, selection of meteorological stations, study period, and statistical methods used to examine trends. We review the methodological approaches to define ETEs, the extreme temperature indices adopted, the selection of meteorological stations, study periods, data quality and homogeneity, statistical trend analysis, and results. From these, we propose an approximate number of stations to adequately portray temperature variability on a national and regional level. Finally, we reflect on projections of ETEs under current climate change conditions, and the implications of cold and warm ETEs in a South African context.","PeriodicalId":46279,"journal":{"name":"South African Geographical Journal","volume":"25 1","pages":"70 - 88"},"PeriodicalIF":1.4,"publicationDate":"2021-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85294453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-03-24DOI: 10.1080/03736245.2021.1901239
A. Pretorius, E. Kruger, S. Bezuidenhout
ABSTRACT South Africa has periods of drought, which lead to water restrictions. Enhanced public awareness and understanding of water scarcity and drought might contribute to the sensible use of water resources. In this article the level and nature of public awareness towards water scarcity and drought in South Africa were determined using Google Trends over a period of 10 consecutive years from 1 January 2009–1 January 2019. Google Trends has real-time datasets, which examines search terms on Google and offers insight into current interests. The data were used to establish the level of public awareness regarding water scarcity and drought. Pre-drought searches were compared to searches done during drought conditions and the correspondence between Google Trend searches and media headlines were identified. People’s searches reflected that they were more environmentally aware during media reported environmental crises.
{"title":"Google trends and water conservation awareness: the internet’s contribution in South Africa","authors":"A. Pretorius, E. Kruger, S. Bezuidenhout","doi":"10.1080/03736245.2021.1901239","DOIUrl":"https://doi.org/10.1080/03736245.2021.1901239","url":null,"abstract":"ABSTRACT South Africa has periods of drought, which lead to water restrictions. Enhanced public awareness and understanding of water scarcity and drought might contribute to the sensible use of water resources. In this article the level and nature of public awareness towards water scarcity and drought in South Africa were determined using Google Trends over a period of 10 consecutive years from 1 January 2009–1 January 2019. Google Trends has real-time datasets, which examines search terms on Google and offers insight into current interests. The data were used to establish the level of public awareness regarding water scarcity and drought. Pre-drought searches were compared to searches done during drought conditions and the correspondence between Google Trend searches and media headlines were identified. People’s searches reflected that they were more environmentally aware during media reported environmental crises.","PeriodicalId":46279,"journal":{"name":"South African Geographical Journal","volume":"8 1","pages":"53 - 69"},"PeriodicalIF":1.4,"publicationDate":"2021-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79542485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-28DOI: 10.1080/03736245.2021.1894597
Rivash Pahlad, Ş. Procheş
ABSTRACT Although amateur birding makes important contributions towards conservation and the tourism industry, the precise motivations driving birders have not been extensively investigated. The aims of this study were to analyse birders’ highlights for birding trips within southern Africa and to establish whether local and foreign birders preferred to see rare or morphologically unusual birds, as opposed to common or morphologically indistinct birds. Morphological traits included: average body size, colour and unusual features; rarity-related traits included: maximum abundance, and range. A total of 673 terrestrial birds were included, and morphological and rarity-related traits were recorded for each species. Birding trip reports for long (two to four weeks) trips across southern Africa that included full sightings lists and highlights were used to indicate which species qualified as highlights (morphologically unusual, rare or both). Both among local and foreign birders, large-bodied birds were the main highlights, with the other characteristics not retrieved as significant. This contradicts the expectation that local birders would be more interested in rarity; however, this result could be explained by the fact that only long birding trips were considered, whereas rarity may more often be sought by specialized local birders on shorter, targeted trips.
{"title":"Birdwatching in a southern African context: explaining highlights on bird lists","authors":"Rivash Pahlad, Ş. Procheş","doi":"10.1080/03736245.2021.1894597","DOIUrl":"https://doi.org/10.1080/03736245.2021.1894597","url":null,"abstract":"ABSTRACT Although amateur birding makes important contributions towards conservation and the tourism industry, the precise motivations driving birders have not been extensively investigated. The aims of this study were to analyse birders’ highlights for birding trips within southern Africa and to establish whether local and foreign birders preferred to see rare or morphologically unusual birds, as opposed to common or morphologically indistinct birds. Morphological traits included: average body size, colour and unusual features; rarity-related traits included: maximum abundance, and range. A total of 673 terrestrial birds were included, and morphological and rarity-related traits were recorded for each species. Birding trip reports for long (two to four weeks) trips across southern Africa that included full sightings lists and highlights were used to indicate which species qualified as highlights (morphologically unusual, rare or both). Both among local and foreign birders, large-bodied birds were the main highlights, with the other characteristics not retrieved as significant. This contradicts the expectation that local birders would be more interested in rarity; however, this result could be explained by the fact that only long birding trips were considered, whereas rarity may more often be sought by specialized local birders on shorter, targeted trips.","PeriodicalId":46279,"journal":{"name":"South African Geographical Journal","volume":"26 1","pages":"411 - 419"},"PeriodicalIF":1.4,"publicationDate":"2021-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78348967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-02-09DOI: 10.1080/03736245.2021.1883471
J. Knight, J. Fitchett
ABSTRACT This study highlights a significant methodological and practical issue involving the use of a magnetic compass in aeolian studies in the field. Geomagnetic declination can significantly affect field measurements of wind direction from anemometers as well as measurement of the orientation of geomorphic features such as sand dunes, depending on geographic location. It is therefore surprising how often methodological descriptions of published aeolian studies, including those in southern Africa, neglect to describe any declination corrections applied to field measurements or instrumental records. This results in uncertainty in the validity of data reported in such studies, particularly where actual wind directions may be very different (>20° in some cases) from measured values. Drawing from examples in the literature from southern Africa and other key locations globally, this study discusses the need for greater clarity in the declination corrections applied when wind direction is being measured and reported, especially where wind datasets from different sources are being used or integrated, or when published studies are being compared.
{"title":"Issues of measuring and interpreting wind direction","authors":"J. Knight, J. Fitchett","doi":"10.1080/03736245.2021.1883471","DOIUrl":"https://doi.org/10.1080/03736245.2021.1883471","url":null,"abstract":"ABSTRACT This study highlights a significant methodological and practical issue involving the use of a magnetic compass in aeolian studies in the field. Geomagnetic declination can significantly affect field measurements of wind direction from anemometers as well as measurement of the orientation of geomorphic features such as sand dunes, depending on geographic location. It is therefore surprising how often methodological descriptions of published aeolian studies, including those in southern Africa, neglect to describe any declination corrections applied to field measurements or instrumental records. This results in uncertainty in the validity of data reported in such studies, particularly where actual wind directions may be very different (>20° in some cases) from measured values. Drawing from examples in the literature from southern Africa and other key locations globally, this study discusses the need for greater clarity in the declination corrections applied when wind direction is being measured and reported, especially where wind datasets from different sources are being used or integrated, or when published studies are being compared.","PeriodicalId":46279,"journal":{"name":"South African Geographical Journal","volume":"11 1","pages":"35 - 52"},"PeriodicalIF":1.4,"publicationDate":"2021-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91318971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-14DOI: 10.1080/03736245.2021.1872413
David García-Álvarez, María Teresa Camacho Olmedo
ABSTRACT Input data is one of the main sources of uncertainty in Land Use Cover Change (LUCC) modelling. Research has focussed on the sensitivity of LUCC models to the spatial resolution of Land Use Cover (LUC) maps. However, little attention has been paid to the way that spatial resolution is changed. Both the spatial resolution and the resampling method change the modelled landscape composition and configuration. This may affect the way Cellular Automata LUCC models behave and, accordingly, the landscapes they simulate. This paper analyses the sensitivity of a standard LUCC model (Metronamica) to changes in the spatial resolution and resampling method of input LUC maps. Results prove how the model is more sensitive to changes in the spatial resolution than to variations of the resampling method. This last component has not much influence in the simulated landscape, although it alters the landscape composition.
{"title":"Sensitivity of a standard Land Use Cover change cellular automata model to resample input Land Use Cover maps","authors":"David García-Álvarez, María Teresa Camacho Olmedo","doi":"10.1080/03736245.2021.1872413","DOIUrl":"https://doi.org/10.1080/03736245.2021.1872413","url":null,"abstract":"ABSTRACT Input data is one of the main sources of uncertainty in Land Use Cover Change (LUCC) modelling. Research has focussed on the sensitivity of LUCC models to the spatial resolution of Land Use Cover (LUC) maps. However, little attention has been paid to the way that spatial resolution is changed. Both the spatial resolution and the resampling method change the modelled landscape composition and configuration. This may affect the way Cellular Automata LUCC models behave and, accordingly, the landscapes they simulate. This paper analyses the sensitivity of a standard LUCC model (Metronamica) to changes in the spatial resolution and resampling method of input LUC maps. Results prove how the model is more sensitive to changes in the spatial resolution than to variations of the resampling method. This last component has not much influence in the simulated landscape, although it alters the landscape composition.","PeriodicalId":46279,"journal":{"name":"South African Geographical Journal","volume":"29 1","pages":"540 - 560"},"PeriodicalIF":1.4,"publicationDate":"2021-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78221384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-05DOI: 10.1080/03736245.2021.1876753
B. J. van der Merwe
ABSTRACT Landform allometry has been a topic of inquiry since at least the 1970s. In this study, the presence of allometry is investigated for a barchan dunefield in northern Namibia. Using a combination of traditional morphometric parameters and techniques borrowed from geometric morphometrics it is shown that barchan allometry is present. This allometry is a combination of positive and negative allometry. Barchans show a definite change in mean shape as the size of the dune increases becoming more asymmetric. Differences in horn length, along with dune width, show positive allometry indicating that it changes faster than the shape changes. Barchan bilateral asymmetry and stoss length show negative allometry indicating that changes in these variables lag behind changes in size. Together, these results hint at the possible presence of threshold size differences beyond which distinct shape changes can be observed.
{"title":"The relationship between barchan size and barchan morphology: a case study from Northern Namibia","authors":"B. J. van der Merwe","doi":"10.1080/03736245.2021.1876753","DOIUrl":"https://doi.org/10.1080/03736245.2021.1876753","url":null,"abstract":"ABSTRACT Landform allometry has been a topic of inquiry since at least the 1970s. In this study, the presence of allometry is investigated for a barchan dunefield in northern Namibia. Using a combination of traditional morphometric parameters and techniques borrowed from geometric morphometrics it is shown that barchan allometry is present. This allometry is a combination of positive and negative allometry. Barchans show a definite change in mean shape as the size of the dune increases becoming more asymmetric. Differences in horn length, along with dune width, show positive allometry indicating that it changes faster than the shape changes. Barchan bilateral asymmetry and stoss length show negative allometry indicating that changes in these variables lag behind changes in size. Together, these results hint at the possible presence of threshold size differences beyond which distinct shape changes can be observed.","PeriodicalId":46279,"journal":{"name":"South African Geographical Journal","volume":"115 1","pages":"119 - 138"},"PeriodicalIF":1.4,"publicationDate":"2021-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77540771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-29DOI: 10.1080/03736245.2020.1863253
Moreblessings Shoko, J. Smit
ABSTRACT Shack extraction is a growing application area for solving contemporary geographical complexities in developing countries. Traditional ground-based surveys that provided shack counts are being overtaken by the opportunities around rapid advances in spatial data collection. The ability to automate and report high accuracies against ground truth remains key to the complex nature of the digital shack extraction matrix. This study uses 8 cm aerial footage and laser scanning data to map informal settlement areas within built environments. The research design includes a set of experiments in defining the footprint of shacks obtained through profiling sampled shack/non-shack areas. Average shack heights, behaviour of unclassified points, number of non-ground points, scan texture and intensity variations were investigated. A five-parameter signature was applied to a pit-free normalized digital surface model (NDSM) and as expected on both test and validation, proved suitable for distinct shacks identification. This approach reported a 95% large settlement detection within a 1-metre-wide boundary position tolerance, coupled with a few false positives in isolated cases of multi-storey, sheds and also complex shacks. The results are proposed for inclusion in city-wide urban planning frameworks that can also be tweaked to include social and environmental parameters.
{"title":"LiDAR derived shack footprint for the City of Cape Town, South Africa","authors":"Moreblessings Shoko, J. Smit","doi":"10.1080/03736245.2020.1863253","DOIUrl":"https://doi.org/10.1080/03736245.2020.1863253","url":null,"abstract":"ABSTRACT Shack extraction is a growing application area for solving contemporary geographical complexities in developing countries. Traditional ground-based surveys that provided shack counts are being overtaken by the opportunities around rapid advances in spatial data collection. The ability to automate and report high accuracies against ground truth remains key to the complex nature of the digital shack extraction matrix. This study uses 8 cm aerial footage and laser scanning data to map informal settlement areas within built environments. The research design includes a set of experiments in defining the footprint of shacks obtained through profiling sampled shack/non-shack areas. Average shack heights, behaviour of unclassified points, number of non-ground points, scan texture and intensity variations were investigated. A five-parameter signature was applied to a pit-free normalized digital surface model (NDSM) and as expected on both test and validation, proved suitable for distinct shacks identification. This approach reported a 95% large settlement detection within a 1-metre-wide boundary position tolerance, coupled with a few false positives in isolated cases of multi-storey, sheds and also complex shacks. The results are proposed for inclusion in city-wide urban planning frameworks that can also be tweaked to include social and environmental parameters.","PeriodicalId":46279,"journal":{"name":"South African Geographical Journal","volume":"31 1","pages":"1 - 15"},"PeriodicalIF":1.4,"publicationDate":"2020-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86020651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"社会学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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