Hydrological Processes Journal Special Issue: Wildfire and Surficial Processes

Elsenbeer, H; Robichaud, P., issue editors. Hydrological Processes Journal 15(15): 30 October 2001.

Keywords: Hydrology, Wildfire, Surficial processes

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Abstract: Several severe wildfire seasons increased awareness of the role of fire in healthy ecosystems. Research has focused not only on fire, but also on its effect on ecosystem components and indicators, such as soils, water quality, and forest health. Precipitation events after wildfires may cause high sediment inputs to streams, destruction of aquatic habitat and downstream flooding, all of which may be part of the natural ecosystem response. If, however, fires are more severe due to past fire suppression and land management activities, then their impact may be greater than under natural conditions. Fire and erosion are both natural processes that have been impacted by land management activities such as fire suppression, logging, grazing, and road building during the last century. Regardless of past management activities, increases in runoff, erosion and sediment yields are of great concern, since they likely will have some downstream effect.
The ending of the 2000 fire season was a perfect backdrop for the 2000 American Geophysical Union fall meeting and special session Wildfire and Surficial Processes. Many researchers have started projects looking at the effects of fire from a hydrological and surficial perspective during the last 5 years. We wanted to capture and disseminate the new knowledge to aid in management decision-making and to suggest research directions for future fire events. This issue contains a selection of papers presented during the meeting.
The issue begins with articles addressing the fire-induced water repellency of soils in both laboratory and field studies. Letey reviews various methods to assess water-repellent soil conditions and discusses waterentry pressure as an alternative indicator of water-repellent soils. Huffman et al. compare two techniques to determine the degree of water repellency after prescribed fire and wildfires in the Colorado Front Range.
Several infiltration and runoff studies at the hillslope scale are presented. Martin and Moody show differences in infiltration rates from high burn severity areas to adjacent unburned areas in ponderosa pine forests. Pierson et al. indicate that range wildfires can reduce infiltration by 28% in the first year, but only on the areas under the burnt shrubs and not in the interspace areas. In a computer simulation exercise, Beeson et al. explore the spatial occurrence of overland flow after fire and map a landscape's vulnerability to post-fire effects. Benavides-Solorio and MacDonald do not detect differences in runoff between burned and unburned areas on the Colorado Front Range, but do detect an order-of-magnitude difference in sediment yields. Johansen et al. show that runoff doubled between burned and unburned plots and sediment yields were 20 times higher in a ponderosa pine forest near Los Alamos, New Mexico.
At the watershed scale, McLin et al. use the HEC model to predict fire-triggered changes in floodplain geometry. Moody and Martin use channel cross-sections to evaluate the depositional and erosive features after a wildfire. With the help of a GIS-based model, Wilson et al. predict an order-of-magnitude increase in erosion and sedimentation.
Cannon et al. examine immediate fire-related debris flows after the Los Alamos fires, which indicate threshold conditions for debris flow to occur, whereas Meyer et al. evaluate historic fire-related debris flows in the Idaho Batholith. Elliot and Parker use stratigraphic and geomorphic evidence in evaluating alluvial deposits. They use this information to develop recurrence probabilities for fire–flood sequences.

Moscow FSL publication no. 2001r