Hydrologic process synthesis across diverse landscapes: Providing theoretical support for spatially varying model formulations in future instantiations of the National Water Model

A premise for the Next Generation Water Resources Modeling Framework (NextGen) is that a single model will not work equally well everywhere. Under this premise, the NextGen framework offers the flexibility for users to configure models as a heterogeneous mosaic of alternative algorithmic formulations that faithfully represent the dominant hydrologic processes across different parts of the modeling domain. For example, a different set of algorithms may be used to simulate hydrological processes in the glacier-fed basins in Alaska, the pothole landscapes in North Dakota, the tile-drained Midwest, and the karst landscape in Kentucky, to name a few. However, a key research gap is that there is currently limited understanding on the spatial variability of dominant hydrologic processes across large domains. Filling this gap is necessary to provide theoretical support for the NextGen paradigm of heterogeneous algorithmic formulations and hence to improve the scientific basis of future operational versions of the National Water Model (NWM). To address this research gap, we propose to conduct a synthesis of dominant hydrologic processes under different combinations of climate-terrain-human forcings, engaging the broader community of catchment and Critical Zone scientists. The product from this research will be a continental “Hydrologic Mosaic”, with each landscape in the mosaic described by a set of perceptual and conceptual models.