Inverting Topography for Landscape Evolution Model Process Representation: 1. Conceptualization and Sensitivity Analysis
Inverting Topography for Landscape Evolution Model Process Representation: 1. Conceptualization and Sensitivity Analysis
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DOI：
10.1029/2018jf004961
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发表时间：
2018-12
期刊：
影响因子：
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通讯作者：
K. Barnhart;G. Tucker;Sandra G. Doty;C. Shobe;R. Glade;M. Rossi;M. Hill
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文献类型：
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作者：
K. Barnhart;G. Tucker;Sandra G. Doty;C. Shobe;R. Glade;M. Rossi;M. Hill
尽管社区做出了相当大的努力，但没有一套通用的方程来模拟长期的景观演变。为了确定一套合适的景观演变过程的法律，冰川后侵蚀切割山谷高达50米深的网站，我们产生了一组替代模型，并进行多模型分析。我们考虑的最基本模型包括水流动力通道切割、均匀岩性、线性扩散的山坡输运以及与流域面积成比例的地表水流量。我们系统地添加一个，两个或三个元素的复杂性，这个模型从四个类别之一：山坡过程，通道过程，地表水文，地质材料的表示。我们应用正式的模型分析方法的37个替代模型。全局莫里斯敏感性分析方法用于识别对模型输出影响最大和最小的模型输入参数。只有几个参数被确定为重要的，这一发现是一致的两个替代模型输出：一个基于收集的地形指标和一个使用的目标函数的基础上的地形差异。控制通道侵蚀的参数始终是重要的，而山坡扩散率是重要的，只有选择模型输出。初始和边界条件的不确定性与低灵敏度有关。敏感性分析提供了洞察模型动力学，是一个关键的步骤，在使用模型分析的机制假设检验景观演化理论。
Despite considerable community effort, there is no general set of equations to model long‐term landscape evolution. In order to determine a suitable set of landscape evolution process laws for a site where postglacial erosion has incised valleys up to 50 m deep, we generate a set of alternative models and perform a multimodel analysis. The most basic model we consider includes stream power channel incision, uniform lithology, hillslope transport by linear diffusion, and surface‐water discharge proportional to drainage area. We systematically add one, two, or three elements of complexity to this model from one of four categories: hillslope processes, channel processes, surface hydrology, and representation of geologic materials. We apply methods of formal model analysis to the 37 alternative models. The global Method of Morris sensitivity analysis method is used to identify model input parameters that most and least strongly influence model outputs. Only a few parameters are identified as important, and this finding is consistent across two alternative model outputs: one based on a collection of topographic metrics and one that uses an objective function based on a topographic difference. Parameters that control channel erosion are consistently important, while hillslope diffusivity is important for only select model outputs. Uncertainty in initial and boundary conditions is associated with low sensitivity. Sensitivity analysis provides insight to model dynamics and is a critical step in using model analysis for mechanistic hypothesis testing in landscape evolution theory.