| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | November 8, 2013 |
| Latest Amendment Date: | November 8, 2013 |
| Award Number: | 1361454 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Thomas Torgersen
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | November 15, 2013 |
| End Date: | October 31, 2015 (Estimated) |
| Total Intended Award Amount: | $49,799.00 |
| Total Awarded Amount to Date: | $49,799.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
1500 ILLINOIS ST GOLDEN CO US 80401-1887 (303)273-3000 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
1500 Illinois Street Golden CO US 80401-1887 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Hydrologic Sciences |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Wildfires have a direct/immediate impact on physical and chemical processes in watersheds including acute loss of vegetation and soil organic matter, decreased soil cohesion, enhanced soil water repellency, ash layer deposition, decreased infiltration and increased runoff. These changes greatly impact the magnitude and timing of post-fire peak flows. Water quality is also impacted by fires often resulting in increases in nutrients and suspended sediment. The goal of this RAPID proposal is to collect immediate and essential field observations of hydro-geochemical behavior within pristine mountain reservoir systems following a catastrophic wildfire. The proposed work will address a significant gap in our knowledge of the coupling of hydrologic flux and water quality in sub-alpine, snow-dominated post-fire systems, especially with regards to trace metal behavior after a catastrophic wildfire.
The Rim Fire, which has burned 255,858 acres, is the third largest fire in California?s history and is one of the largest in the Sierra Nevada. Post-fire processes threaten water supplies to the city of San Francisco as well as 29 other wholesale buyers. Water supply from the Hetch Hetchy reservoir system (three lakes in total) is unfiltered and therefore especially vulnerable to increased turbidity and sediment loads as a consequence of the Rim Fire. Collected data will ultimately be used to develop models and predictive tools to quantify short and long-term impacts on water quantity, sediment flux and contaminant loads into Hetch Hetchy and other regional lakes which encompass a nearly singular input to the SF water supply system.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Wildfires have a direct/immediate impact on physical and chemical processes in watersheds including acute loss of vegetation and soil organic matter, decreased soil cohesion, enhanced soil water repellency, ash layer deposition, decreased infiltration and increased runoff. These changes greatly impact the magnitude and timing of post-fire peak flows. Water quality is also impacted by fires often resulting in increases in nutrients and suspended sediment. The goal of this project was to collect immediate field observations of hydro-geochemical behavior within a pristine mountain reservoir system following a catastrophic wildfire.
The Rim Fire, which burned 255,858 acres, was the third largest fire in California’s history at the time and was one of the largest in the Sierra Nevada. Post-fire processes threatened water supplies to the city of San Francisco as well as 29 other wholesale buyers. Water supply from the Hetch Hetchy reservoir system (three lakes in total) is unfiltered and therefore especially vulnerable to increased turbidity and sediment loads as a consequence of the Rim Fire. Primary work focused on the immediate field observations of hydro-geochemical behavior within the Hetch Hetchy reservoir system (which includes Cherry and Eleanor) following the Rim Fire of 2013. Mitigation costs for the fire were estimated at $127.35 million a and 200 structures were destroyed. Primary fuels for the fire included brush, oak, pine, and conifer over extremely steep terrain. Downstream values at risk included: O’Shaughnessy Dam and reservoir in the Hetch Hetchy Valley (water supply for the San Francisco Bay Area) and the Tuolumne River water system (supplies San Francisco and 29 other wholesale buyers in San Mateo, Santa Clara, and Alameda counties). Major impacted water bodies included: Tuolumne River, Eleanor Creek, Cheery Creek, Hetch Hetchy Reservoir, Lake Eleanor, and Cherry Lake.
Six study basins were utilized to evaluate water quality impacts within the Rim Fire area with burned land cover consisting of shrub/scrub and mixed forest. Field Sampling, soil analysis and water quality sampling was done. Soil analysis showed six regulated contaminants had concentrations that were consistently above detectable levels. Poly Aromatic Hydrocarbons (PAHs) concentrations in surface materials did increase with burn severity, but the increased level was still very low and no significant drinking water risk relative to PAH was discovered. Collected data is being utilized as part of a national post-fire water quality database and to develop predictive tools to quantify short and long-term impacts on water quantity, sediment flux and contaminant loads for burned watersheds in the western U.S.
Last Modified: 02/01/2016
Modified by: Terri S Hogue
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