End Evictions Campaign


MAPPING INFORMALITY IN KHAYELITSHA



Khayelitsha is a peri-urban township situated on the outskirts of Cape Town. The most recent census was carried out in 2011 which reported a total number of 64,761‬ informal structures in areas designated orange in the above map. The outdated data does not illustrate the current situation in Khayelitsha. This mapping project aims to add on the scant of spatial analysis data by tracking the hot spots of informal structures and providing percentages of formal/informal building footprints. Maps and numbers generated from the process will be used to identify the trend of change in informal structures. With this knowledge acquired through spatial analysis, people would be able to further dig into the driving force of the increase of informal building footprint makeup.



KEY FINDINGS



Informal Dwellings in 2011



A heat map based on the aerial image of 2011 (census year) was created. The locations of high-density informal structure areas shown in the heat map are consistent with the locations of informal settlements according to the census map. The largest informal settlement ("shack not in backyard") was situated in Khayelitsha T3-V2. Other large informal settlements are found in Khayelitsha T2-V2b and Monwabisi. The northwest corner of the area designated as Khayelitsha has the highest density of informal structures and the highest count of "shack in backyard" units identified.



The Boundary Change of Informal Settlements Between 2015, 2018, and 2019



The map below shows the boundaries of informal settlements which were manually digitized according to the aerial image of 2015 and 2019. The most prominent boundary expansion of informal settlements was observed in Khayelitsha T2-V2B. Other informal settlement expansions occurred in Bongani TR Section, Silver Town, Solomon Mahlangu, Khayelitsha T3-V5, and Khayelitsha T3-V2. From February 2018 to February 2019, there was a rapid growth of informal settlements with a rate of 45.6%. From 2015 to 2019, the area of informal settlements increased by 60.85%, increasing to 8.18 square kilometers which overrode the area covered by formal developments.



Growth in Land Covered by Formal Developments Between 2011 to 2019



Between February 2011 and February 2019, there was barely any increase in the area of formal developments. The increasing rate of the area of informal settlements was 25.5 times faster than that of the area of formal developments.



Ratios of Formal to Informal Building Footprints of 2011, 2015 to 2019



Aerial images in January/February of years 2011, 2015 to 2019 was classified by ERDAS IMAGINE supervised classification tool. Since the supervised classification was conducted based on the maximum likelihood of each pixel to the classification criteria derived from machine learning of training sites manually assigned, there are unavoidable nuances between the classification results of each year. Therefore, calculating ratios of formal to informal building footprints of each year will generate more accurate data than the direct calculation of area or percentage of each category. Based on the refined classified raster of Khayelitsha, the ratios were calculated and showed in the table below.



Estimate the Number of Informal Dwellings and Population in Khayelitsha



The 2011 census of Khayelitsha was set as a benchmark to estimate the number of informal dwellings and the total population of Khayelitsha. Because the area covered by formal developments did not increase significantly, we assumed that the number of formal dwellings remained constant from 2011 to 2019 and then estimate the number of informal dwellings based on the ratios of formal/informal building footprints. The estimations are as follows:



We should note that the estimations are based on the assumption that the number of formal dwellings was constant regardless of the actual growth which might take place through redevelopment. Thus, the actual numbers of dwellings and population are greater than the estimations.



Tracking the Hotspots of Informal Settlements



The maps below illustrate the hot spots and density variations of informal structures in Khayelitsha for each year from 2015 to 2019. The density scales were assessed based on the distribution of informal building footprints in each year. Therefore, the maps provide a visual representation of the density of a given area compared to the rest of the map for a single given year and do not provides cross-density comparisons across different years.


In general, while the hot spots of informal settlements increased significantly between 2011 and 2015, there was no notable change across 2015 to 2017. Ostensible expansions of informality happened in the periods of 2017-18 and 2018-19.



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Amazing image description



Aerial image source: USGS and LANDSAT 8 Mission
Area Calculations were based on WGS 1984 World Mercator projectionAnalysis was achieved through ERDAS IMAGINE and ArcGIS


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Mapping Process

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