River floodplains and reservoirs interact throughout a basin drainage network, defining a coupled human-water system with multiple feedbacks. Recent modeling developments have aimed to improve the representation of such processes at regional to continental scales. However, most large-scale hydrological models adopt simplified lumped reservoir schemes, where an offline routine is run with inflows estimated by the model, with limited consideration of the complementarity between floodplains and reservoirs on altering the hydrological regime at regional scale. This paper presents a novel approach that fully couples river-floodplain-reservoir hydrodynamic and hydrological models, significantly improving the representation of reservoir dynamics and operation in the river-floodplain-reservoir continuum at large scale and across multiple dam cascades. The model is applied to the Paraná River Basin with explicit simulation of 31 large dams and river hydraulic variables at basin scale. Three types of reservoir bathymetry representation are compared, from lumped to distributed methods, combined with three reservoir operation schemes and varying degrees of input data requirement within two parameterization scenarios (global and regional setups). The operation schemes were more relevant than the reservoir bathymetry representation to estimate downstream flows and water levels. While the data-driven operation scheme, based on linear regressions between observed water levels and dam outflows, provided the best estimates of both active storage and discharges, the more generic operation reasonably estimated discharges and peak attenuation, albeit not as accurately for active storage. The global parameterization of reservoir operation resulted in poorer performance compared to the regional-based one, but it satisfactorily modeled discharge and peak attenuation. Regarding the reservoir bathymetry representation, a basin scale comparison of the lumped and distributed schemes indicated the inability of the former to represent backwater effects. This was further corroborated by validating the longitudinal water level profile of Itaipu dam with ICESat satellite altimetry data. Finally, the model was used to show the complementarity between floodplains and reservoirs on attenuating floods at regional scale. Large scale models should move beyond offline coupling strategies, and include regional-based, data-driven reservoir operation schemes together with a distributed representation of reservoir bathymetry into river-floodplain hydraulic schemes. This will largely improve the estimation of river discharges, water levels and flood storage, and thus the model ability to represent the regional scale river-floodplain-reservoir continuum.

河流漫滩和水库在整个流域排水网络中相互作用，从而定义了具有多个反馈的人水耦合系统。最近的建模开发旨在改善这种过程在区域到大陆范围内的表示。但是，大多数大型水文模型采用简化的集总水库方案，其中运行离线程序，并根据模型估算的入水量，在区域规模上改变水文状况时，很少考虑洪泛区和水库之间的互补性。本文提出了一种新颖的方法，该方法将河漫滩-水库水动力模型和水文模型完全耦合在一起，显着改善了河漫滩-水库-水库连续体中大规模和跨多个大坝梯级的储层动力学和运行方式。该模型通过对31个大型水坝的显式模拟和流域规模的河流水力变量而应用于巴拉那河流域。从集总方法到分布式方法，比较了三种类型的储层测深表示形式，并结合了三种储层操作方案以及在两个参数化方案（全局和区域设置）内不同程度的输入数据需求。该操作方案比水库测深表示更重要，以估计下游流量和水位。虽然基于观测水位和大坝流出量之间的线性回归的数据驱动运行方案提供了对主动蓄水量和排放量的最佳估计，但更为通用的运行合理地估算了蓄水量和峰值衰减，尽管对于主动蓄水没有那么精确。与基于区域的储层调度相比，对储层调度的全局参数化导致性能较差，但可以令人满意地对流量和峰值衰减进行建模。关于水库测深表示，集总方案和分布方案的流域比例比较表明，前者无法表示回水效应。通过使用ICESat卫星测高数据验证Itaipu大坝的纵向水位剖面，进一步证实了这一点。最后，该模型用于显示区域尺度上的洪灾平原与水库之间的互补性。大型模型应超越离线耦合策略，并应包括基于区域的，数据驱动的水库调度方案以及水库测深的分布式表示形式到河漫滩水力方案中。这将大大改善对河流流量，水位和洪水蓄洪量的估计，从而提高代表区域规模的河流-洪泛平原-水库连续体的模型能力。