Spatial analysis to understand how does land management practices are associated with house loss in wildfires

Peri-urban communities in fire-prone region around the world are at increasing risk from wildfires due to increase in population growth and climate change. In this article, the authors study that what land management practices are more effective to reduce the house loss during the wildfires. There is no evidence yet the effectiveness of fuel reduction treatments. Houses are a critical asset to protect during wildfires and are easily destroyed when exposed to flame. To protect houses commonly used fuel reduction practices are grazing, clearing, prescribed burning and mechanical removal of biomass from area near to these houses.

In this article, authors carry out the empirical (observation) research using GIS within the boundaries of three wildfires that ignited in the state of Victoria, in south-eastern Australia. Figure 1.

To collect data they sample they allocated 499 points randomly to the study area in GIS and number of sample allocated were proportional to the area of each of three strata. Then the house is selected nearest to each point using fine-scale high aerial imagery (35 cm to 50 cm pixel resolution). If two houses were in same sample area they did only select one house to study, with 40 m area around it to measure several variables. 24 potentially variable were recorded at each home reflecting three main driver; weather condition which was measured as Forest Fire Danger Index (FFDI) it incorporate all weather component; humidity, temperature, drought factor and wind speed; terrain was measured as slop, tropical position, and aspect; fuel was measured (a) as within 40 m of centroid of house which is maximum distance wooden structure will catch fire (b) percentage of landscape in upwind direction from each house to nearest wildfire boundary (c) distance from house to fuel variable in upwind direction. They also measure another variable such as cover of trees and shrubs within 40 m, number of building or structure in upwind direction from the house, upwind distance from houses to public forest land.

The result shows that greater proportion of houses were lost where there was higher % cover of trees and shrubs within 40 m; where the vegetation was dominated by remnant instead of plants; there was more building within 40 m; group of trees and shrubs were closer in the upwind direction as shown in above figure. It is predicted that all fuel reduction treatments will work more effectively if these treatments carried out closer to the house rather than at distant from house.