Numerical modeling of the effects of water flow, sediment transport and vegetation growth on the spatiotemporal patterning of the ridge and slough landscape of the Everglades wetland
Numerical modeling of the effects of water flow, sediment transport and vegetation growth on the spatiotemporal patterning of the ridge and slough landscape of the Everglades wetland
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DOI：
10.1016/j.advwatres.2010.07.009
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发表时间：
2010-10
影响因子：
4.7
通讯作者：
M. Lago;F. Miralles-Wilhelm;M. Mahmoudi;V. Engel
中科院分区：
文献类型：
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作者：
M. Lago;F. Miralles-Wilhelm;M. Mahmoudi;V. Engel
已经开发了一个数值模型来模拟湿地中山脊和泥沼景观的时空格局，其特征是平行于水流方向拉长的波峰（山脊）和山谷（泥沼）。该模型公式由综合地表水和地下水流、沉积物输送、土壤增生以及植被生长引起的枯枝落叶产生的控制方程组成。模型模拟显示了空间格局如何随着时间的推移而自组织，通过水流场驱动的沉积物沉积和侵蚀而产生山脊和泥沼。水深、流速和泥沙输送过程的时空分布是由植被和地形异质性引起的差异流引起的。该模型采用代表美国佛罗里达半岛南部大沼泽地湿地的值进行参数化。模型模拟的敏感性在数值网格大小、横向植被生长和凋落物产生率方面进行了测试。使用该模型模拟的沿着和垂直于流动方向的图案的特征波长随着时间的推移发展成类似于现场观察的山脊和泥沼形状。此外，模拟的山脊和泥沼之间的高程差异与现场常见的高程差异相同。研究发现，山脊和泥沼的宽度是由植被生长简化公式中的横向植被生长距离参数控制的，这补充了早期的建模结果，其中单独的差异泥炭增生机制并不能重现对山脊和泥沼横向波长的观察。这项工作的结果表明，山脊和泥沼模式的发生是植被横向生长能力的结果，增强了山脊区域的沉积物沉积，通过泥沼区域增加的沉积物侵蚀来平衡以满足水流的连续性。沉积物输送、水流、植被和土壤动态过程之间的相互作用需要通过详细的现场实验进一步探索，并使用本工作中开发的模型公式来指导数据收集和解释。这应该是未来研究山脊和泥沼地区模式形成和稳定性的重点领域之一。
A numerical model has been developed to simulate the spatiotemporal patterning of the ridge and slough landscape in wetlands, characterized by crests (ridges) and valleys (sloughs) that are elongated parallel to the direction of water flow. The model formulation consists of governing equations for integrated surface water and groundwater flow, sediment transport, and soil accretion, as well as litter production by vegetation growth. The model simulations show how the spatial pattern self-organizes over time with the generation of ridges and sloughs through sediment deposition and erosion driven by the water flow field. The spatial and temporal distributions of the water depth, flow rates and sediment transport processes are caused by differential flow due to vegetation and topography heterogeneities. The model was parameterized with values that are representative of the Everglades wetland in the southern portion of the Florida peninsula in the USA. Model simulation sensitivity was tested with respect to numerical grid size, lateral vegetation growth and the rate of litter production. The characteristic wavelengths of the pattern in the directions along and perpendicular to flow that are simulated with this model develop over time into ridge and slough shapes that resemble field observations. Also, the simulated elevation differences between the ridges and sloughs are of the same order of those typically found in the field. The width of ridges and sloughs was found to be controlled by a lateral vegetation growth distance parameter in a simplified formulation of vegetation growth, which complements earlier modeling results in which a differential peat accretion mechanism alone did not reproduce observations of ridge and slough lateral wavelengths. The results of this work suggest that ridge and slough patterning occurs as a result of vegetation's ability to grow laterally, enhancing sediment deposition in ridge areas, balanced by increased sediment erosion in slough areas to satisfy flow continuity. The interplay between sediment transport, water flow and vegetation and soil dynamic processes needs to be explored further through detailed field experiments, using a model formulation such as the one developed in this work to guide data collection and interpretation. This should be one of the focus areas of future investigations of pattern formation and stability in ridge and slough areas.