The integrated hydrologic model intercomparison project, IH‐MIP2: A second set of benchmark results to diagnose integrated hydrology and feedbacks

Abstract

Emphasizing the physical intricacies of integrated hydrology and feedbacks in simulating connected, variably saturated groundwater‐surface water systems, the Integrated Hydrologic Model Intercomparison Project initiated a second phase (IH‐MIP2), increasing the complexity of the benchmarks of the first phase. The models that took part in the intercomparison were ATS, Cast3M, CATHY, GEOtop, HydroGeoSphere, MIKE‐SHE, and ParFlow. IH‐MIP2 benchmarks included a tilted v‐catchment with 3‐D subsurface; a superslab case expanding the slab case of the first phase with an additional horizontal subsurface heterogeneity; and the Borden field rainfall‐runoff experiment. The analyses encompassed time series of saturated, unsaturated, and ponded storages, as well as discharge. Vertical cross sections and profiles were also inspected in the superslab and Borden benchmarks. An analysis of agreement was performed including systematic and unsystematic deviations between the different models. Results show generally good agreement between the different models, which lends confidence in the fundamental physical and numerical implementation of the governing equations in the different models. Differences can be attributed to the varying level of detail in the mathematical and numerical representation or in the parameterization of physical processes, in particular with regard to ponded storage and friction slope in the calculation of overland flow. These differences may become important for specific applications such as detailed inundation modeling or when strong inhomogeneities are present in the simulation domain.

A Subgrid Approach for Modeling Microtopography Effects on Overland Flow

“…Like the more typical diffusion wave equation (e.g., Gottardi & Venutelli, ), this approximation is valid for zero bed slope but is much less nonlinear than the typical approximation and is therefore easier to solve. This approximation has been shown sufficiently accurate on a variety of benchmark problems (Kollet et al, ).…”

Numerical Solution of Richards' Equation: A Review of Advances and Challenges

“…The need for more rigorous computational science with standards like reproducibility and repeatability of numerical experiments has been recognized across a number of fields (Collberg and Proebsting, 2016). It can be seen, for example, in efforts to develop clear understanding of benchmarking, verification, and validation for computational codes in fields like nuclear engineering and aerospace engineering (Babuska and Oden, 2004;Oberkampf and Trucano, 2007 (Maxwell et al, 2014;Kollet et al, 2017) and the International Soil Modeling Consortium (http:// soil-modeling.org; verified 10 Feb. 2017) represent welcome steps in this direction. This is also an area where government agencies (e.g., NOAA, the US National Weather Service, Office of Water Prediction) could make a major contribution.…”

Physically based modeling in catchment hydrology at 50: Survey and outlook

“…Benchmarking is essential for establishing a standard set of test cases and for bringing together the modeling community to directly and openly assess competing formulations, parameterizations, and algorithms [ Smith et al ., ; Sebben et al ., ]. An early example of a benchmark problem in subsurface hydrology is the Borden sand aquifer in southern Ontario [ Sykes et al ., ; Mackay et al ., ], which has been used extensively in solute transport investigations and is one of the test cases selected for the Phase 2 ISSHM intercomparison study [ Kollet et al ., ]. This intercomparison effort for physically based, integrated, catchment‐scale hydrological models follows similar initiatives in subsurface reactive transport, radionuclide migration, carbon sequestration, land data assimilation, and land surface modeling [ Larsson , ; Henderson‐Sellers et al ., ; Boone et al ., ; Pruess et al ., ; Xia et al ., ; Steefel et al ., ].…”