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

河流的下切作用决定了坡面地形，而坡面地形又影响着土壤链的化学性质。然而，这两个基本的景观属性之间的联系，因为它们在响应基底通道切割的演变，尚未进行定量研究。该项目将基于沉积物收支的山坡地貌学与土壤地球化学的空间变异相结合。建模，现场和实验室的方法来检查两个关键的假设。第一种假说认为，在一个给定的山坡位置，土壤化学风化的速度是有限的，通过土壤运输和土壤生产的矿物质供应的速度。 第二种假说认为土壤化学风化的速率取决于土壤中矿物的平均年龄和年龄分布。 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和机载激光条带测绘相结合。本研究将在加州西塞拉内华达州的Feather河支流流域内的三个山坡上进行，这些山坡的基底河道切割率不断增加。本研究的结果将包括土壤化学风化率在山坡经历不同的历史和基沟切割率的时间和空间动态。景观的特点往往是重复单位的溪流渠道和山坡。本研究将探讨河道形成与土壤之间的复杂耦合。这两个过程都与有效地管理土地使用、维持健全的农业做法以及评估土壤和景观如何因各种自然和人为影响而发生变化有关。这些过程将在现场和实验室中进行研究，并通过开发一个复杂的数值模型。该项目将包括当地一所中学的科学教师，并将土流相互作用加上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.