Photogrammetry Based Analysis for the Risks Associated With Landfilling in Developing Countries: Case Study, Chunga Landfill, Lusaka, Zambia
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Solid waste is recognized globally as being a present and growing threat to a sustainable environment. Urban (and rural) growth correlates strongly with increasing waste production in all cities, presenting a particularly challenging problem to cities in Developing Counties that can often lack the resources and management strategies to effectively dispose of waste. The poor management of a landfill creates immediate environmental risks to the surrounding communities from disasters such as waste tip collapse, ground water pollution, and smoke plume production from landfill fires. Landfill topography can be assessed using Structure from Motion (SfM) photogrammetry. This research has used photogrammetry and geospatial analysis to map and assess risks posed by the only engineered Landfill (Chunga Landfill) in Lusaka, Zambia. Waste volume at the landfill was estimated at 761, 815 cubic metres, which accounts for 6.5 percent of the total landfill capacity. This is considerably a low waste volume, as the Lusaka population is currently estimated at 2,647,000, and some estimates suggest that the city creates around 1 million tonnes of waste annually. The low amount of waste at the landfill has been mainly attributed to low levels of city-wide municipal collection. Most waste is processed locally by individuals within the city and disposal of the total waste which is estimated at 40%. The geomorphology of Chunga landfill, based on my 3-D model derived from systematic UAV photogrammetric data shows a range of features including: a maximum waste tip height of 18. 85 m above ground; steep waste tip slopes of up to 53 degrees; a drainage system that is significantly uncontrolled and leaking pollutants into the wider environment; and abundant landfill fires with resulting pollutant plumes. The risk associated with these aspects includes: over-steepened and potentially unstable waste-tip slopes; respiratory and other human health impacts linked to fire-plumes and water pollution; risks to workers within the site near steep slopes and landfill fires. Landfill fires are first observed in 2013 and continue to burn until the present day, resulting in smoke plumes that blow west, south west and north west. There is significant exposure from these plumes to hundreds of thousands of residents who live within the plume trails, exposed to fine particulate matter and gases. The drainage system at Chunga landfill is observed to result in the pollution of Chunga river that flows from the north western region of the city to the south east. This situation occurs because Chunga landfill water and sludge streams do not all flow into the designated drainage pond, and thus impacts the surface and ground water quality, making it unfit for human consumption. The current drainage system threatens the stability of the waste heaps due to the presence of rivulets that cut away at the steep slopes of the waste heaps which may result in waste collapse. Recommendations for improving the environmental performance of the Chunga landfill facility include; waste slope maintenance by reducing steep slopes to at least 11 to 14 degrees, drainage maintenance by engineering drainage canals that drain in the designated drainage reservoir, extinguishing of landfill fires to reduce plume exposure and continued landfill monitoring by photogrammetry to track waste volume, height and waste tip slopes. The use of photogrammetry for landfill monitoring is a cost-effective method for analysing the change in geomorphology overtime and further research that has the potential to improve waste management practices in Lusaka and other developing cities. The use of drones in Lusaka is currently a growing field and faces challenges which stem from the access to Unmanned Aerial Vehicles (UAV’s) and the regulations allowing access to airspace.