Remote sensing detection of fires in informal settlements – IRIS-Fire (Improving the Resilience of Informal Settlements against Fire) – Dr David Rush and Dr Lesley Gibson
Remote sensing applications are continually broadening – primarily through improvement of spatial and temporal resolution of satellite data. IRIS-Fire is an interdisciplinary research project, for which remote sensing techniques are pivotal. The project aims to improve the resilience of informal settlements to fire, carried out by an international team based at The University of Edinburgh and Stellenbosch University, South Africa. Dr David Rush, a project engineer and Dr Lesley Gibson, a remote sensing expert delivered an insight into the research the IRIS-Fire project is undertaking.
Informal settlements are growing around the world with the trend of urbanisation. These settlements are densely packed and haphazardly constructed – with narrow pathways between buildings, chaotic electric cables and highly flammable construction materials. These factors make informal settlements extremely vulnerable to fire. IRIS-Fire is currently focused in the City of Cape Town, where 18-33% of the population resides in informal households. The city experiences at least 1 informal settlement fire per day. The Imizamo Yethu fire in 2017 is an extreme example, where the dwellings of 10,000 people were destroyed.
To improve the resilience of informal settlements to fires, the project is attempting to understand the conditions under which fires occur. Dr Lesley Gibson introduced us to the integral use of remote sensing in the identification of fire events in informal settlements. IRIS-Fire aims to produce a monitoring and analysis framework using satellite data. The purpose of this is to detect fire events, subsequently higher resolution imagery can be used to observe the settlement structure before the fire occurred. A Google Earth time series detects the burnt regions by identifying the change in the optical reflectance signal from the ground surface. Optical sensors are currently the focus of the IRIS-Fire project, particularly SPOT and Sentinel-2 blue band, which have a 10m resolution. Synthetic Aperture Radar methods are also being taken into consideration.
In Cape Town, IRIS-fire has found limited detectable spectral change associated with the burning itself. The rebuilding process, however, has a distinct optical spectral character, as a result of the emergency rebuild kits (the metal roofs of these rebuild kits are extremely shiny) provided by the city of Cape Town to households affected by a fire. This increase in reflectance of the shiny roofs is detectable by satellite. Dr Lesley Gibson informed us of the success in detecting regions exposed to fires by this change in optical spectral reflectance. Research is still underway to reduce the influence of noise and false positives, exploring options such as ratio approaches and spatial autocorrelation.
Dr David Rush introduced us to the research taking place to improve understanding of the computational fluid dynamics of fire, both inside individual buildings and across settlements structures. This includes collecting samples from dwellings to understand their flammability and fuel load and surveys on fire history. Experiments are taking place, in which model settlements are being set alight to consider how settlement structures, such as Euclidian distances influence fire risk and the impact of fuel load, size and ventilation. The experiments are being carried out to develop a mapping algorithm to identify critical at-risk areas within informal settlements.
This seminar was a great insight into this innovative interdisciplinary project. Coalescing the knowledge of engineers, social scientists, fire safety scientists and remote sensing specialists, to improve the resilience of informal settlements against fires. The remote sensing portion provides a method for identifying settlements impacted by the fire, allowing for a time series to assess the structure pre-fire. The modelling of fire dynamics by the project engineers is attempting to produce a mitigation/prevention strategy to improve the resilience of the settlements to fire. While still in the research phases, IRIS-Fire is progressing towards producing a generic risk-mapping framework and best practice resilience-based technical guidelines to improve the fire resilience informal settlements. This will be initially applied to the Western Cape with potential to be extrapolated to wider regions with informal settlements.
Sarah Cheesbrough, MSc Earth Observation and Geoinformation Management