Planning for resilience to natural hazards

Vegetation Loss

Before the 2018 Camp Fire, the area was mostlt covered by green land such as Evergreen Forest, Deciduous Forest, and Mixed Forest. These forests dominated the landscape and were critical for maintaining the region’s ecological balance. The maps clearly show the extensive presence of these forest types prior to the wildfire.

Vegetation Loss

After the fire, these green areas were significantly reduced, replaced largely by Barren Land. The damage to forests has not only left vast areas barren but also disrupted the natural ecosystem and slowed vegetation recovery processes.

Urban Areas

Many urban areas that were once dense and vibrant have experienced changes, either being reduced in intensity or reclassified as Barren Land due to structural loss and damage during the wildfire.

Fuels, such as vegetation type and drought condition, play a primary role in fire propagation. For instance, dense forests or shrublands with dry vegetation due to prolonged drought provide abundant flammable material, accelerating fire spread.

Oxygen, influenced by wind patterns, sustains combustion and determines the fire's direction and speed. High winds can drive flames rapidly across landscapes, increasing the area burned.

Finally, the heat source, including environmental factors like heat waves or human activities, ignites and maintains the fire. Heat waves contribute to extreme dryness in vegetation, making it more susceptible to ignition.

(National Wildfire Coordinating Group, 2023) (Chuvieco et. al 2023)

The research by Fuentes-Ramirez et. al (2016) measures flammability metrics of various plant species, including invasive grasses and native shrubs, to understand their roles in fire dynamics. And it gives the flammable risks for different vegetation types.

A Drought is a deficiency of precipitation over an extended period of time resulting in a water shortage.

In the National Risk Index, a Drought Index score and rating represent a community's relative risk for Droughts when compared to the rest of the United States. The drought condition also contribute to both wildfire ignition, spread, and fuels accumulation that further increase the wildfire risk.

Heat Wave Condition

A Heat Wave is a period of abnormally and uncomfortably hot and unusually dry weather typically lasting two or more days with temperatures outside the historical averages for a given area. It dramatically increase the wildfire vulnearbility.

Strong Wind Index

Strong winds, exceeding 58 mph are highly damaging. They greatly increase wildfire risk by accelerating flame spread and carrying embers over long distances, igniting new fires and complicating containment efforts.

The Community Resilience Index (CRI) measures a community's ability to withstand, adapt to, and recover from disasters, integrating social, economic, infrastructural, and environmental factors. It identifies vulnerabilities and strengths, guiding disaster preparedness and resource allocation. Cutter et al. (2008)

Social vulnerability reflects a community's susceptibility to the adverse impacts of natural hazards, including disproportionate death, injury, and livelihood disruption.

Community Resilience reflects a community's ability to prepare for natural hazards, adapt to changes, and recover quickly from disruptions.

Wildfire Vulnearbility Equation

The Social Vulnerability Index (SVI) measures social and economic challenges that increase wildfire risk. The Community Resilience Index (CRI) shows a community's recovery ability and lowers risk when high. The Natural Vulnerability Index (NVI) includes environmental factors like flammable vegetation and drought that raise wildfire risk.

Wildfire Vulnearbility Equation

This formula provides a composite score, where higher values indicate greater wildfire vulnerability. Adjustments to the weights can be made based on regional studies or expert input to reflect California-specific conditions.

The regions with the highest wildfire vulnerability are concentrated in the Sierra Nevada foothills, the northern coastal mountains, and areas in southern California near urban-wildland interfaces. These areas likely combine high natural vulnerability (flammable vegetation and drought conditions) with social vulnerability (populations that may struggle to respond to wildfires).

Many highly vulnerable zones are located in the UWI, where human development meets wildland vegetation. These areas are prone to ignition sources and have dense populations.