Abstract. Peat growth is a frequent phenomenon in European river valleys. The presence of peat in the floodplain stratigraphy makes them hotspots of carbon storage. The long-term dynamics of alluvial peatlands are complex due to interactions between the peat and the local river network, and as a result, alluvial peatland development in relation to both regional and local conditions is not well understood. In this study, a new modelling framework is presented to simulate long-term peatland development in river floodplains by coupling a river basin hydrology model (STREAM) with a local peat growth model (modified version of Digibog). The model is applied to two lowland rivers in northern Belgium, located in the European loess (Dijle river) and sand (Grote Nete river) belts. Parameter sensitivity analysis and scenario analysis are used to study the relative importance of internal processes and environmental conditions on peatland development. The simulation results demonstrate that the peat thickness is largely determined by the spacing and mobility of the local river channel(s) rather than by channel characteristics or peat properties. In contrast, changes in regional conditions such as climate and land cover across the upstream river basin showed to influence the river hydrograph, but have a limited effect on peat growth. These results demonstrate that alluvial peatland development is strongly determined by the geomorphic boundary conditions set by the river network and as such models must account for river channel dynamics to adequately simulate peatland development trajectories in valley environments.

中文翻译：

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模拟温带河流泛滥平原的长期冲积泥炭地动态

摘要。泥炭生长是欧洲河谷常见的现象。漫滩地层中泥炭的存在使它们成为碳储存的热点。由于泥炭与当地河流网络之间的相互作用，冲积泥炭地的长期动态是复杂的，因此，与区域和当地条件相关的冲积泥炭地发展尚不清楚。在本研究中，提出了一种新的建模框架，通过将流域水文模型 (STREAM) 与当地泥炭生长模型（Digibog 的修改版）耦合来模拟河流泛滥平原的长期泥炭地开发。该模型应用于比利时北部的两条低地河流，位于欧洲黄土（Dijle 河）和沙地（Grote Nete 河）带。参数敏感性分析和情景分析用于研究内部过程和环境条件对泥炭地发展的相对重要性。模拟结果表明，泥炭厚度主要由当地河道的间距和流动性决定，而不是由河道特征或泥炭特性决定。相比之下，上游流域气候和土地覆盖等区域条件的变化显示出影响河流水位线，但对泥炭生长的影响有限。这些结果表明冲积泥炭地的发展很大程度上取决于河网设置的地貌边界条件，因此模型必须考虑河道动力学，以充分模拟山谷环境中的泥炭地发展轨迹。