I am very glad that our article Identifying relevant hydrological and catchment properties in active subspaces: An inference study of a lumped karst aquifer model was accepted for publication in Advances in Water Resources (Elsevier).
As before, this article comes out of a collaboration between the teams at TUM within the UNMIX project. Daniel Bittner and Gabriele Chiogna from the TUM Chair of Hydrology and River Basin Management and Steven Mattis, Barbara Wohlmuth, and I from the TUM Chair for Numerical Mathematics were interested in hydrological inferences that can be drawn out of looking at subspaces that are dominant for the behavior of karst systems. In particular, we studied a karst aquifer model that was applied to the Kerschbaum spring in Waidhofen a.d. Ybbs in Austria and used the active subspace method as a technique to study parameter sensitivities and correlations.
Congratulations to Daniel! I also want to thank everyone who contributed to this article and made this a valuable scientific contribution!
Journal link: doi:10.1016/j.advwatres.2019.103472
Abstract. The use of the active subspace method was recently proposed to reduce the dimension of complex hydrological models, perform sensitivity analysis of model parameters and quantify the uncertainty affecting model parameters. Although this inversion method is highly promising in terms of computational performance, a clear hydrological interpretation of the meaning of the active subspace that it identifies is missing. In this work, we infer how the active subspace changes in dimension and feature depending on geometrical and hydrological properties of the karst aquifer model LuKARS. We find that both the hydrotope area coverage and model parameters describing the catchment characteristics (here: water storage and discharge properties of the hydrotopes) have major impacts on the active subspace. Our results show that the active subspace method can be used to investigate the relation between the model structure, the area of a hydrotope and the simulated spring discharge.