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

河流切割驱动了山坡地形，这种地形影响了土壤链条的化学性质。然而，这两个基本景观属性之间的联系，当它们随着底部河道切割而演变时，还没有得到定量的研究。该项目将基于泥沙收支的坡面地貌与土壤地球化学的空间变异结合在一起。使用建模、现场和实验室方法来检验两个关键假设。第一种假设认为，在给定的山坡位置，土壤化学风化的速度受到土壤运输和土壤生产中矿物质供应的速度的限制。第二种假设认为，土壤化学风化的速度由土壤中矿物的平均年龄和年龄分布决定。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和土壤生产率的地形序列测量以及机载激光条带测绘相结合。这项研究将在三个山坡上进行，在加利福尼亚州内华达山脉西部通往羽毛河的支流盆地内，底部航道的切削率不断增加。这项研究的结果将包括经历不同历史和基本沟道切削率的坡面土壤化学风化速率的时空动态。景观通常被描述为小溪和山坡的重复单元。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、维护合理的农业实践以及评估土壤和景观如何因各种自然和人为影响而变化有关。这些过程将在实地和实验室中进行研究，并通过开发复杂的数值模式进行研究。该项目将包括当地一所中学的科学教师，并将土壤-河流互动以及真实世界的科学研究带入这些课堂。

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.