| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | August 26, 2013 |
| Latest Amendment Date: | July 23, 2015 |
| Award Number: | 1324894 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Justin Lawrence
jlawrenc@nsf.gov (703)292-2425 EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | January 1, 2014 |
| End Date: | December 31, 2017 (Estimated) |
| Total Intended Award Amount: | $226,147.00 |
| Total Awarded Amount to Date: | $226,147.00 |
| Funds Obligated to Date: |
FY 2015 = $79,905.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
2215 RAGGIO PKWY RENO NV US 89512-1095 (775)673-7300 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
755 E. Flamingo Rd. Las Vegas NV US 89119-7363 |
| 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, Geomorphology & Land-use Dynam |
| Primary Program Source: |
01001516DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): | |
| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
The majority of fire research to date has focused on the negative impacts of large, medium-to-high intensity burns, which typically cause massive combustion of litter and organic matter in the topsoil followed by increases in soil erosion, runoff, and loss of nutrients. The positive role of fires in vegetation succession and nutrient cycling also is well recognized. In contrast, low-intensity burns (with soil temp. of <220 degrees C) are presumed to cause minimal soil degradation and landscape/ecosystem alteration. As a result, there has been only limited research investigating potential negative consequences of such burns, although they account for almost half of total burned areas in the United States. Furthermore, climate change is expected to increase the frequency and area of land exposed to such low-intensity burns. Recent long-term studies on the effect of low-intensity fires on soil structure, however, are revealing that substantial loss of soil aggregate stability and porosity occurs several months to a few years after the burn has occurred. These degradations in soil structure often are followed by reduced infiltrability and increased soil erosion. The overarching goal of this proposed research is to investigate the impacts of low-intensity fires on soil structure and the implication for soil hydrology, erosion, and nutrient dynamics. Specifically, this project is designed to test three hypotheses: a) soil structure deterioration is caused by micro-scale stresses created within aggregates due to rapid vaporization or thermal expansion of soil particles as well as preferential volatilization of mostly hydrophilic simple organic molecules; b) disaggregation and subsequent surface sealing result in reduced infiltration and increased erosion; and c) preferential mobility of nutrient-rich dislodged fine aggregates and particles results in accelerated loss of nutrients and carbon via lateral and vertical transport. The proposed research will be conducted using soil samples collected from arid and semi-arid ecosystems in eastern Nevada and will mimic characteristics of past low-intensity burns of the region.
Improved understanding of how low-intensity fires can lead to land/ecosystem degradation will benefit society by enabling more effective design of controlled burns as well as post-burn land management practices. This knowledge also can play an important role in planning for mitigation of the effects of low-intensity fires in sensitive ecosystems and landscapes of arid/semi-arid regions that are expected to experience more fires as a result of climate change. This research will expand on-going collaboration with the Bureau of Land Management, thereby facilitating adoption of new advances to support science-based resource management. In addition, this project will provide educational and advanced research training to one Ph.D.-level student and one postdoctoral researcher. ?Science boxes? will be employed to engage K-12 students in results of the proposed project.
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.
In this project, we studied how water repellency affects water infiltration into soil. This is important because fire can turn soil water repellent. From water repellent soil, rainwater runs off rather than infiltrates into the soil, which leads to flooding and debris flow. We were able to show how infiltration an water repellency are related through capillarity, the force that helps soil to take up water spontaneously. We developed an infiltration model that relates infiltration with water repellency in a physically meaningful way and were able to validate the model with laboratory experiments. We currently work on incorporating our infiltration model into existing hydrology models to better predict the effect of fire on stream and debris flow. This study also provides an answer to the long-standing question: "What does water drop penetration time really tell us about infiltration after a fire?"
The model developed in this project opens up a new, more fundamental way to simulate water infiltration into fire-affected soil. It also shows how to account for water repellency in process-based hydrology models. This is a critical step towards improved post-fire flood and debris flow modeling, which will help to further develop flood protection and mitigation strategies, the design of flood control infrastructure and, eventually, reduce the risk for life and property due to post-fire flooding and debris flow.
Last Modified: 03/31/2018
Modified by: Markus Berli
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