Laboratory Experiments to Understand Post-Wildfire Processes on Soil Sealing for Hydrologic Fluxes in Complex Terrain

众所周知，野火引发的洪水和侵蚀可能会给当地社区带来高昂的代价。然而，改变土壤特性以增加洪水和侵蚀的具体过程还没有被很好地了解。土壤封闭是野火后研究较少的过程之一，因为土壤封闭的最大影响发生在野火发生后不久，此时进行实地观察可能是困难和危险的。然而，野火后的这段时间也是由于缺乏植被而导致高破坏性洪水的最高风险。为了研究野火发生后立即发生的土壤封闭过程，该项目的调查人员将进行实验室实验，模拟土壤和灰烬材料上的降雨。研究结果将提供有关野火后土壤封存过程的新信息，并对森林管理和减灾产生影响。此外，该项目将支持四名大学生的技能发展，以及开发一门关于土壤侵蚀的四年级和五年级的科学课程。该项目的主要研究问题是：在野火发生后，陆地表面的坡度如何影响土壤封堵过程，以及这如何影响后续降雨事件的入渗？随着坡度的增大，地表灰分侵蚀率增加。因此，据推测，经历了更多灰分储存的土壤表面将促进土壤封闭过程，从而在以后的降雨事件中减少入渗，从而增加径流。为了验证这一假设，实验室规模的降雨模拟将在模拟的烧毁土壤条件下在一定的坡度范围内进行。研究人员将通过(1)通过降雨试验量化坡角对地表灰尘侵蚀和地表储存的影响，以及(2)在降雨试验后确定灰分滞留(如果有的话)对土壤性质的影响，以观察坡角的影响。该项目由水文科学和既定的激励竞争研究计划(EPSCoR)共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

It is well understood that floods and erosion following a wildfire can be costly to local communities. However, the specific processes that alter soil characteristics to increase flooding and erosion are not well understood. Soil sealing is one of the less studied post-wildfire processes because the peak impact of soil sealing occurs immediately after a wildfire when it can be difficult and dangerous to make field observations. However, this time period immediately after a wildfire also holds the highest risk for high damage flooding due to the lack of vegetation. To investigate the soil sealing processes that occur immediately after a wildfire, the investigators in this project will conduct laboratory experiments to simulate rainfall on burned soils and ash materials. The outcomes will provide new information about post-wildfire soil sealing processes with implications for forest management and disaster mitigation. Additionally, this project will support the development of technical skills for four college students and the development of a 4th and 5th grade science lesson on soil erosion.The overarching research question of this project is: how does the slope angle of a land surface affect soil sealing processes immediately after a wildfire, and how does this impact infiltration for consequent rain events? As slope angle increases, surface ash erosion rates will increase. As a result, it is hypothesized that soil surfaces that experience increased storage of ash will promote soil sealing processes that decrease infiltration during later rain events, thereby increasing runoff. To test this hypothesis, laboratory scale rainfall simulations will be conducted at a range of slope angles on simulated burned soil conditions. Investigators will observe the effect of slope angle by (1) quantifying the effect of slope angle on surface ash erosion and surface storage through rainfall experiments, and (2) determining the effect of ash retention, if any, on soil properties after rainfall experiments. This project is jointly funded by Hydrologic Sciences and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.