Empirical and Theoretical Integration of Geochemical and Morphologic Evolution of Soil-Covered Hillslopes: Responses to Channel Incision

河流切口驱动坡面地形，坡面地形影响土壤链的化学性质。然而，这两种基本景观特性之间的联系，随着它们对基底通道切割的响应而演变，尚未得到定量研究。该项目将基于泥沙收支的斜坡地貌学与土壤地球化学的空间变化相结合。模型、现场和实验室方法被用来检验两个关键假设。第一个假设认为，在给定的山坡位置，土壤化学风化的速率受到通过土壤运输和土壤生产的矿物供应速率的限制。第二个假设认为，土壤化学风化的速率是由土壤中矿物质的平均年龄和年龄分布决定的。将开发两个独立的山坡土壤质量平衡和矿物颗粒跟踪模型，并将其与土壤和基岩元素化学的地形序列测量和土壤生产速率以及机载激光测绘相结合。该研究将在加利福尼亚内华达山脉西部羽毛河支流盆地内的三个山坡上进行，这些斜坡的基底通道切割率正在增加。本研究的结果将包括经历不同历史和基底通道切割速率的山坡土壤化学风化速率的时空动态。景观通常以河道和山坡的重复单元为特征。本研究将探讨河道形成与土壤之间的复杂耦合关系。这两个过程都与有效管理土地利用、保持良好的农业做法以及评价土壤和景观如何响应各种自然和人为影响有关。这些过程将在实地以及在实验室和通过发展一个复杂的数值模型进行调查。该项目将包括当地一所中学的科学教师，并将土壤流互动和现实世界的科学研究带入这些教室。

River incision drives hillslope topography and this topography affects the chemical properties of the soil catena. However, the linkages between these two fundamental landscape properties as they evolve in response to basal channel incision, have not yet been quantitatively studied. This project integrates hillslope geomorphology based onsediment budgets with the spatial varioation in the geochemistry of soil. Modeling, field, and laboratory approaches are used to examine two key hypotheses. The first hypothesis states that at a given hillslope position, the rate of soil chemical weathering is limited by the rates of mineral supplies via soil transport and soil production. The second hypothesis states that the rate of soil chemical weathering is determined by the mean age and age distribution of minerals in the soil. Two independent models of hillslope soil mass balance and mineral grain tracking will be developed and combined with toposequence measurements of soil and bedrock elemental chemistry and soil production rates and Airborne Laser Swath Mapping. The study will be conducted at three hillslopes with increasing rates of basal channel incision within a tributary basin to the Feather River in the western Sierra Nevada, California. The outcomes from this study will include the temporal and spatial dynamics of soil chemical weathering rates within hillslopes experiencing different history and rates of basal channel incision rates. Landscapes are often characterized as repeating units of stream channels and hillslopes. This study will investigate the complex coupling between the formation of stream channels and soils. Both of these processes are relevant to managing land use effectively, maintianing sound agricultural practices, and evaluating how soils and landscapes change in response to a variety of natural and human-induced influences. The processes will be investigated in the field as well as in the laboratory and through the development of a sophisticated numerical model. The project will include science teachers in a local middle school and bring soil-stream interactions plus real-world scientific research into these classrooms.