A recently introduced multiscale model for representing the effects of small-scale hyporheic-zone biogeochemical processes is extended from the reach scale to river network scales. The model uses advection-dispersion-reaction equations for the channel network and one-dimensional advection-reaction subgrid models for the hyporheic zone. We summarize implementation in the integrated surface/subsurface hydrology modeling system Amanzi-ATS. The extension uses topologically defined meshes to represent stream/river networks and associates a hyporheic subgrid model with each channel grid cell. Biogeochemical reaction modeling capability residing in community software is accessed through an application programming interface. The implementation is verified against independent numerical solutions on a single reach. Mesh convergence studies show that commonly used semi-distributed representations can introduce significant spatial discretization error. Denitrification of farm runoff in a subbasin of the Portage River Basin in Ohio, USA is used to demonstrate the general-purpose reactive transport capability.

最近引入的用于表示小规模潜流带生物地球化学过程影响的多尺度模型从河段尺度扩展到河网尺度。该模型使用通道网络的平流-弥散-反应方程和低流带的一维平流-反应子网格模型。我们总结了集成地表/地下水文建模系统 Amanzi-ATS 中的实现。该扩展使用拓扑定义的网格来表示河流/河流网络，并将下流子网格模型与每个通道网格单元相关联。社区软件中的生物地球化学反应建模功能可通过应用程序编程接口访问。该实施针对单个范围内的独立数值解进行了验证。网格收敛研究表明，常用的半分布式表示会引入显着的空间离散化误差。美国俄亥俄州波蒂奇河流域的一个子流域农场径流的反硝化被用来展示通用的反应输运能力。