Combined use of point rain gauges, radar, microwave link and level measurements in urban hydrological modelling Morten Grum a, T , Stefan Kraemer b , Hans-Reinhard Verworn b , Axel Redder c a PH-Consult, Ordruphøjvej 4, DK 2920 Charlottenlund, Denmark b Institut fu ¨r Wasserwirtschaft, Universita ¨t Hannover, Appelstr. 9a, 30167 Hannover, Germany c Emschergenossenschaft/Lippeverband, Kronprinzenstr. 24, 45128 Essen, Germany Received 18 May 2004; received in revised form 4 October 2004; accepted 15 October 2004 Abstract A methodology has been developed for the combined exploitation of the information content in several different types of rainfall and hydrological measurements. The methodology is based on simple rain plane and runoff models that are incorporated into a stochastic state–space model approach. State estimation is done using the extended Kalman filter in combination with a maximum likelihood estimation criterion and an off-line optimisation routine. This paper presents the preliminary results of the application of the methodology for the combined use of multiple rainfall and runoff data on a 4800 ha urban catchment within the Emscher river basin in Germany. The time series used come from 12 rain gauges, a C-band and an X-band radar covering the same area and a microwave link. The preliminary results support the methodology’s potential as a technique for the combined use of different types of rainfall and runoff data. The results are discussed in terms of applicability, the methodology’s limitations and future improvements. D 2005 Elsevier B.V. All rights reserved. Keywords: Rainfall; Distributed rainfall; Rainfall measurement; Microwave link; Radar; Stochastic state–space modelling 0169-8095/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.atmosres.2004.10.013 T Corresponding author. E-mail address: mg@phc.dk (M. Grum). Atmospheric Research 77 (2005) 313 – 321 www.elsevier.com/locate/atmos