TY - JOUR

T1 - A one-step similarity approach for the regionalization of hydrological model parameters based on self-organizing maps

AU - Wallner, Markus

AU - Haberlandt, Uwe

AU - Dietrich, Jörg

N1 - Funding Information: The authors thank their colleagues and student assistants for useful comments and support. Special thanks go to Graham Cuff, Maria Mercedes Buzzella, Sven van der Heijden and Diego A. Rivera. The study was integrated in a joint research project about climate change impact in Lower Saxony (KLIFF). We acknowledge funding by the Ministry of Science and Culture, Lower Saxony. We are also thankful for the right to use data from the German National Weather Service (Deutscher Wetterdienst DWD), Meteomedia AG, NLWKN Niedersachsen, Landesamt für Geoinformation und Landentwicklung Niedersachsen, Landesamt für Bergbau, Energie und Geologie and the German Federal Institute for Geosciences and Natural Resources. Furthermore we would like to thank the two anonymous reviewers and the editor for their contributions to improve this publication.

PY - 2013/6/8

Y1 - 2013/6/8

N2 - A novel one-step similarity approach for the regionalization of hydrological parameters has been developed. The method automatically associates model parameters (MP) with catchment descriptors (CD), using techniques based on Self-Organizing Maps (SOM-B). The combination of the one-step approach with the automatic association reduces the problem of equifinality and avoids subjective predefinition of relationships between CDs and MPs. Further positive properties of the SOM-B are the feasibility to use discrete variables as CDs and the ability to capture interdependencies between MPs. The SOM-B was validated against a known one-step regionalization method which is based on linear transfer functions (LT-B). Furthermore the influence of different factors like combination CDs, or size of the SOM, on the regionalization performance of the SOM-B was analyzed. The hydrological model used for the evaluations was a modified version of the HBV-IWS, which simulates continuous hourly discharge series. The investigations were carried out in 41 catchments of the Aller-Leine river basin in Northern Germany. For the validation a spatial split-sampling in 12 donor and 29 validation catchments, as well as a temporal split-sampling were applied. The results showed that: (I) MPs regionalized with the SOM-B approach led to similar or slightly better model performance than with the LT-B method, (II) some hydrologically plausible relationships between MPs and CDs were adjusted automatically without any predefinition by the SOM-B, (III) the relationships between CDs and MPs were more transparent using the SOM-B approach, (IV) the sensitivity of different factors of the SOM-B on the performance was smaller than expected.

AB - A novel one-step similarity approach for the regionalization of hydrological parameters has been developed. The method automatically associates model parameters (MP) with catchment descriptors (CD), using techniques based on Self-Organizing Maps (SOM-B). The combination of the one-step approach with the automatic association reduces the problem of equifinality and avoids subjective predefinition of relationships between CDs and MPs. Further positive properties of the SOM-B are the feasibility to use discrete variables as CDs and the ability to capture interdependencies between MPs. The SOM-B was validated against a known one-step regionalization method which is based on linear transfer functions (LT-B). Furthermore the influence of different factors like combination CDs, or size of the SOM, on the regionalization performance of the SOM-B was analyzed. The hydrological model used for the evaluations was a modified version of the HBV-IWS, which simulates continuous hourly discharge series. The investigations were carried out in 41 catchments of the Aller-Leine river basin in Northern Germany. For the validation a spatial split-sampling in 12 donor and 29 validation catchments, as well as a temporal split-sampling were applied. The results showed that: (I) MPs regionalized with the SOM-B approach led to similar or slightly better model performance than with the LT-B method, (II) some hydrologically plausible relationships between MPs and CDs were adjusted automatically without any predefinition by the SOM-B, (III) the relationships between CDs and MPs were more transparent using the SOM-B approach, (IV) the sensitivity of different factors of the SOM-B on the performance was smaller than expected.

KW - Catchment similarity

KW - Hydrological modeling

KW - Regionalization

KW - Self-Organizing Maps

KW - Ungauged catchments

UR - http://www.scopus.com/inward/record.url?scp=84878436288&partnerID=8YFLogxK

U2 - 10.1016/j.jhydrol.2013.04.022

DO - 10.1016/j.jhydrol.2013.04.022

M3 - Article

AN - SCOPUS:84878436288

VL - 494

SP - 59

EP - 71

JO - Journal of hydrology

JF - Journal of hydrology

SN - 0022-1694

ER -