Quantifying the effect of surface sealing on post-fire runoff and erosion in the western U.S.

野火可以暂时增加径流和侵蚀率在森林流域的几个数量级，这些加速径流和侵蚀率具有相当大的地貌，生态和社会意义。表面密封-形成一层薄薄的、水力传导率极低的表层-可能通过雨溅引起的压实和分解、火山灰堵塞土壤孔隙或形成低传导率的火山灰壳，造成火灾后径流和侵蚀的增加。然而，有很少的工作在何种程度上表面密封有助于增加火灾后的径流和侵蚀，所涉及的密封机制，或因素，有助于增加密封的潜力，和表面密封的影响还没有被纳入预测模型的火灾后径流和侵蚀。该项目将进行一项密集的、基于实地和实验室的研究，以（1）确定美国西部野火后地表封闭对径流和侵蚀增加的贡献程度; (2)确定表面密封的各种机制和导致密封形成的可能性增加的因素;以及（3）根据被烧毁地区的土壤和灰烬特性，开发火灾后表面密封可能性的预测模型。 该研究将基于六个现场和实验室实验。 这项工作将导致定量的，基于过程的理解火灾后的表面密封和野火相关的径流和侵蚀过程的新的理解。

Wildfires can temporarily increase runoff and erosion rates in forested watersheds by several orders of magnitude, and these accelerated runoff and erosion rates have considerable geomorphic, ecological and societal significance. Surface sealing -- the formation of a thin surface layer with a very low hydraulic conductivity -- may contribute to increases in runoff and erosion after fire either through rainsplash induced compaction and disaggregation, the clogging of soil pores by ash, or the formation of low conductivity ash crusts. However, there has been very little work on the extent to which surface sealing contributes to increased runoff and erosion after fire, the sealing mechanisms involved, or the factors that contribute to an increased potential for sealing, and surface sealing effects have not been incorporated into predictive models of post fire runoff and erosion. This project will conduct an intensive, field and lab based research study to (1) determine the extent to which surface sealing contributes to increased runoff and erosion after wildfires in the western U.S.; (2) determine the various mechanisms of surface sealing and the factors that lead to an increased probability of seal formation; and, (3) develop a predictive model of the probability of surface sealing after fires, based upon the soil and ash properties in burned areas. The research will be based on six field and lab experiments. The work will result in quantitative, process-based understanding of post-fire surface sealing and new understanding of wildfire related runoff and erosion processes.