Hydrologic and Erosion Responses of Burned Watersheds Active
The enhanced probability of catastrophic wildfires has increased our need to understand the risk of floods, erosion, and debris and contaminant transport in burned watersheds. This project investigates the relation between rainfall intensity and peak discharge; erosion and deposition processes; and water-quality impacts to minimize the loss of life and property resulting from post-wildfire floods.
SCIENTIFIC QUESTIONS
The enhanced probability of catastrophic wildfires in the western United States and elsewhere in the world has increased the need to understand the flooding risk and the erosion and depositional responses of burned watersheds. In addition, surface water flowing from burned areas may carry increased levels of sediment, organic debris, and chemicals that may contribute to significant degradation of municipal water supplies and aquatic habitats. Our project has three main thrusts: (1) we are investigating the relation between rainfall intensity and peak water discharge from burned watersheds, a relation that depends on the size of the rainstorm, the size of the burned area and burn severity, and the changes in infiltration capacity of the soil; (2) we are investigating the hillslope and channel erosion and deposition processes after wildfire with a focus on predicting these processes on a watershed or landscape scale rather than on a single hillslope plot or channel cross-section scale; and (3) we are examining the water quality impacts of wildfire and are synthesizing post-fire water-quality sampling protocols.
RESEARCH GOAL
An extensive body of literature exists on the effects of wildfire on watersheds. Wildfires have burned across the landscape of the western United States for centuries, but the magnitude of the geomorphic effect on the landscape is unknown. By understanding the magnitude of the runoff response and the erosion and deposition responses of recent wildfires, we can provide data for landscape evolution models in areas prone to wildfire. In addition, an understanding of the runoff response will contribute to better methods of predicting post-fire flooding to minimize the loss of life and property. Watershed-scale predictions of erosion and deposition from these natural disasters can be used by land managers to prioritize forest treatments based on erosion potential before and after wildfires. Moreover, we hope to contribute to an understanding of wildfire as an element of an ecosystem’s disturbance regime.
Selected USGS Publications
Linking hydraulic properties of fire-affected soils to infiltration and water repellency
Planning for an uncertain future - Monitoring, integration, and adaptation
Sample collection of ash and burned soils from the October 2007 southern California Wildfires
Synthesis of sediment yields after wildland fire in different rainfall regimes in the western United States
'Natural background' soil water repellency in conifer forests of the north-western USA: Its prediction and relationship to wildfire occurrence
Leachate Geochemical Results for Ash Samples from the June 2007 Angora Wildfire Near Lake Tahoe in Northern California
Infiltration and Runoff Measurements on Steep Burned Hillslopes Using a Rainfall Simulator with Variable Rain Intensities
Post-wildfire erosion response in two geologic terrains in the western USA
Linking runoff response to burn severity after a wildfire
Preliminary analytical results for ash and burned soils from the October 2007 southern California wildfires
Spatial structures of stream and hillslope drainage networks following gully erosion after wildfire
Critical shear stress for erosion of cohesive soils subjected to temperatures typical of wildfires
- Overview
The enhanced probability of catastrophic wildfires has increased our need to understand the risk of floods, erosion, and debris and contaminant transport in burned watersheds. This project investigates the relation between rainfall intensity and peak discharge; erosion and deposition processes; and water-quality impacts to minimize the loss of life and property resulting from post-wildfire floods.
SCIENTIFIC QUESTIONS
The enhanced probability of catastrophic wildfires in the western United States and elsewhere in the world has increased the need to understand the flooding risk and the erosion and depositional responses of burned watersheds. In addition, surface water flowing from burned areas may carry increased levels of sediment, organic debris, and chemicals that may contribute to significant degradation of municipal water supplies and aquatic habitats. Our project has three main thrusts: (1) we are investigating the relation between rainfall intensity and peak water discharge from burned watersheds, a relation that depends on the size of the rainstorm, the size of the burned area and burn severity, and the changes in infiltration capacity of the soil; (2) we are investigating the hillslope and channel erosion and deposition processes after wildfire with a focus on predicting these processes on a watershed or landscape scale rather than on a single hillslope plot or channel cross-section scale; and (3) we are examining the water quality impacts of wildfire and are synthesizing post-fire water-quality sampling protocols.
RESEARCH GOAL
An extensive body of literature exists on the effects of wildfire on watersheds. Wildfires have burned across the landscape of the western United States for centuries, but the magnitude of the geomorphic effect on the landscape is unknown. By understanding the magnitude of the runoff response and the erosion and deposition responses of recent wildfires, we can provide data for landscape evolution models in areas prone to wildfire. In addition, an understanding of the runoff response will contribute to better methods of predicting post-fire flooding to minimize the loss of life and property. Watershed-scale predictions of erosion and deposition from these natural disasters can be used by land managers to prioritize forest treatments based on erosion potential before and after wildfires. Moreover, we hope to contribute to an understanding of wildfire as an element of an ecosystem’s disturbance regime.
- Publications
Selected USGS Publications
Filter Total Items: 30Linking hydraulic properties of fire-affected soils to infiltration and water repellency
Heat from wildfires can produce a two-layer system composed of extremely dry soil covered by a layer of ash, which when subjected to rainfall, may produce extreme floods. To understand the soil physics controlling runoff for these initial conditions, we used a small, portable disk infiltrometer to measure two hydraulic properties: (1) near-saturated hydraulic conductivity, Kf and (2) sorptivity, SAuthorsJohn A. Moody, David Kinner, Xavier ÚbedaPlanning for an uncertain future - Monitoring, integration, and adaptation
The 6.7 billion human inhabitants of the earth have the ability to drastically alter ecosystems and the populations of species that have taken eons to evolve. By better understanding how our actions affect the environment, we stand a better chance of designing successful strategies to manage ecosystems sustainably. Toward this end, the Third Interagency Conference on Research in the Watersheds (ICSample collection of ash and burned soils from the October 2007 southern California Wildfires
Between November 2 through 9, 2007 scientists from the U.S. Geological Survey (USGS) collected samples of ash and burned soils from 28 sites in six areas burned as a result of the Southern California wildfires of October 2007, including the Harris, Witch, Santiago, Ammo, Canyon, and Grass Valley Fires. The primary goal of this sampling and analysis effort was to understand how differences in ash aAuthorsTodd M. Hoefen, Raymond F. Kokaly, Deborah A. Martin, Carlton J. Rochester, Geoffrey S. Plumlee, Greg Mendez, Eric G. Reichard, Robert N. FisherSynthesis of sediment yields after wildland fire in different rainfall regimes in the western United States
Measurements of post-fire sediment erosion, transport, and deposition collected within 2 years of a wildfire were compiled from the published literature (19272007) for sites across the western United States. Annual post-fire sediment yields were computed and grouped into four measurement methods (hillslope point and plot measurements, channel measurements of suspended-sediment and sediment erosionAuthorsJ. A. Moody, D.A. Martin'Natural background' soil water repellency in conifer forests of the north-western USA: Its prediction and relationship to wildfire occurrence
Soils under a wide range of vegetation types exhibit water repellency following the passage of a fire. This is viewed by many as one of the main causes for accelerated post-fire runoff and soil erosion and it has often been assumed that strong soil water repellency present after wildfire is fire-induced. However, high levels of repellency have also been reported under vegetation types not affectedAuthorsS.H. Doerr, S.W. Woods, D.A. Martin, M. CasimiroLeachate Geochemical Results for Ash Samples from the June 2007 Angora Wildfire Near Lake Tahoe in Northern California
This report releases leachate geochemical data for ash samples produced by the Angora wildfire that burned from June 24 to July 2, 2007, near Lake Tahoe in northern California. The leaching studies are part of a larger interdisciplinary study whose goal is to identify geochemical characteristics and properties of the ash that may adversely affect human health, water quality, air quality, animal haAuthorsPhilip L. Hageman, Geoffrey S. Plumlee, Deborah A. Martin, Todd M. Hoefen, Monique Adams, Paul J. Lamothe, Todor I. Todorov, Michael W. AnthonyInfiltration and Runoff Measurements on Steep Burned Hillslopes Using a Rainfall Simulator with Variable Rain Intensities
Multiple rainfall intensities were used in rainfall-simulation experiments designed to investigate the infiltration and runoff from 1-square-meter plots on burned hillslopes covered by an ash layer of varying thickness. The 1-square-meter plots were on north- and south-facing hillslopes in an area burned by the Overland fire northwest of Boulder near Jamestown on the Front Range of Colorado. A sinAuthorsDavid A. Kinner, John A. MoodyPost-wildfire erosion response in two geologic terrains in the western USA
Volumes of eroded sediment after wildfires vary substantially throughout different geologic terrains across the western United States. These volumes are difficult to compare because they represent the response to rainstorms and runoff with different characteristics. However, by measuring the erosion response as the erodibility efficiency of water to detach and transport sediment on hillslopes andAuthorsJ. A. Moody, D.A. Martin, S.H. CannonLinking runoff response to burn severity after a wildfire
Extreme floods often follow wildfire in mountainous watersheds. However, a quantitative relation between the runoff response and burn severity at the watershed scale has not been established. Runoff response was measured as the runoff coefficient C, which is equal to the peak discharge per unit drainage area divided by the average maximum 30 min rainfall intensity during each rain storm. The magniAuthorsJ. A. Moody, D.A. Martin, S.L. Haire, D.A. KinnerPreliminary analytical results for ash and burned soils from the October 2007 southern California wildfires
The U.S. Geological Survey (USGS) collected ash and burned soils from about 28 sites in southern California wildfire areas (Harris, Witch, Ammo, Santiago, Canyon and Grass Valley) from Nov. 2 through 9, 2007 (table 1). USGS researchers are applying a wide variety of analytical methods to these samples, with the goal of helping identify characteristics of the ash and soils from wildland and suburbaAuthorsGeoffrey S. Plumlee, Deborah A. Martin, Todd Hoefen, Raymond F. Kokaly, Philip Hageman, Alison Eckberg, Gregory P. Meeker, Monique Adams, Michael Anthony, Paul J. LamotheSpatial structures of stream and hillslope drainage networks following gully erosion after wildfire
The drainage networks of catchment areas burned by wildfire were analysed at several scales. The smallest scale (1-1000 m2) representative of hillslopes, and the small scale (1000 m2 to 1 km2), representative of small catchments, were characterized by the analysis of field measurements. The large scale (1-1000 km2), representative of perennial stream networks, was derived from a 30-m digital elevaAuthorsJ. A. Moody, D.A. KinnerCritical shear stress for erosion of cohesive soils subjected to temperatures typical of wildfires
[1] Increased erosion is a well-known response after wildfire. To predict and to model erosion on a landscape scale requires knowledge of the critical shear stress for the initiation of motion of soil particles. As this soil property is temperature-dependent, a quantitative relation between critical shear stress and the temperatures to which the soils have been subjected during a wildfire is requiAuthorsJ. A. Moody, Smith J. Dungan, B.W. Ragan