Hydrological impacts of wildfires at a global scale

Wildfires can affect the hydrological regime of a watershed until vegetation is reestablished and the hydrological cycle returns to its previous state. Wildfire induced changes can lead to increased high flows due to vegetation destruction that affects rainfall interception, evapotranspiration, but also fire induced soil imperviousness. Floods or water cycle changes after wildfire events have been extensively studied at a fire event and basin level, or at regional scale, yet changes at a global scale have not been studied systematically. Based on a wide discharge observation inventory from 651 basins globally and MODIS burned area data between 2001 and 2018, we show that the average annual discharge tends to increase in the first two years after the wildfire event, but gradually tends to return to its previous state. Furthermore, it is also found that high flow events tend to increase with wildfire size. This work focuses to a better understanding of the hydrological impacts of wildfires, and hence contribute to the improved modeling representation of fire – hydrology processes.