Methods for Evaluating Arbitrary Hydrologic Models and Process Modules in the Next Generation Water Resources Modeling Framework

The model agnostic Next Generation National Water Model (Nextgen NWM) design considers application of a variety of hydrological models and process modules to forecast streamflow across the United States and U.S. territories. While this framework allows scientific evaluation of the performance of different model formulations and process modules, execution requires development of the evaluation workflow. We developed a methodology to evaluate outputs from a mosaic of dissimilar model formulations. We applied two models in the study catchments using the framework, namely the conceptual functional equivalent (CFE) of the National Water Model and conceptual TOPMODEL, which uses high-resolution DEM inputs to estimate the distribution of topographic wetness index. The study domain included 31 catchments covering approximately 180 km2 in the headwaters of Sugar Creek Basin in North Carolina. We focused simulations on three extreme rainfall events in December 2015, July/August 2011, and August 2008. This example use of the framework generated a variety of continuous and event-based evaluation metrics used to grade different model formulations for inclusion in the framework mosaic of models.