Articles | Volume 20, issue 6
Research article
01 Jul 2016
Research article |  | 01 Jul 2016

Subgrid spatial variability of soil hydraulic functions for hydrological modelling

Phillip Kreye and Günter Meon

Abstract. State-of-the-art hydrological applications require a process-based, spatially distributed hydrological model. Runoff characteristics are demanded to be well reproduced by the model. Despite that, the model should be able to describe the processes at a subcatchment scale in a physically credible way. The objective of this study is to present a robust procedure to generate various sets of parameterisations of soil hydraulic functions for the description of soil heterogeneity on a subgrid scale. Relations between Rosetta-generated values of saturated hydraulic conductivity (Ks) and van Genuchten's parameters of soil hydraulic functions were statistically analysed. An universal function that is valid for the complete bandwidth of Ks values could not be found. After concentrating on natural texture classes, strong correlations were identified for all parameters. The obtained regression results were used to parameterise sets of hydraulic functions for each soil class. The methodology presented in this study is applicable on a wide range of spatial scales and does not need input data from field studies. The developments were implemented into a hydrological modelling system.

Short summary
The objective of this study is to improve the reliability of large-scale hydrological models. In environmental policies, many decisions are based on prognosis simulated by models. The parameterisation of these models is challenging due to the scarcity of available data. Particularly, parameters of soil properties are rare, but have a strong influence on model results. To account for the heterogeneity of soil properties, we developed a methodology that does not need additional field data.