Wildfire Induced Changes in Soil Properties.

A common occurrence resulting from wildfire is the development of a water repellant layer in the soil.  After fires, heavily burned areas are usually covered by a layer of ash and burnt soil.  The water repellant layer is typically found beneath the ash layer at or just below the soil surface and generally runs parallel to the mineral soil surface.   The fire induced Soil Water Repellency (SWR), can be highly variable in both time and space and difficult to quantify.  In post fire remediation efforts, SWR is often ignored simply because environmental managers are unsure how to properly assess the degree of hydrophobicity and associated consequences of the water repellency.   Following a September 2011 forest fire in Bastrop County, Texas twelve (4m x 4m) plots established in areas ranging from lightly burnt to heavily burnt.    Soil water repellency, unsaturated hydraulic conductivity, and soil water content have been measured periodically since the fire.  Initially, water repellency was strongly correlated with fire intensity.  One year after the fire, much of the soil remains hydrophobic.  The field data is coupled with a series of laboratory experiments in an effort to establish a quantitative relationship between fire severity and wildfire induced water repellency and its subsequent effects on hydraulic conductivity.