The development of TOPKAPI (until April 2011)
The physically based rainfall-runoff model Topographic Kinematic Approximation and Integration model (TOPKAPI) uses the kinematic wave approach to simulate subsurface flow, overland flow due to saturation excess and channel flow [Todini and Ciarapica, 2001]. Its original formulation has been developed by the Group of Todini (University of Bologna / ProGeA) from the conceptual ARNO model [Todini, 1996]. The original version has been applied to various case studies in Italy [Ciarapica and Todini, 2002], Switzerland [Foglia et al., 2009], China [Liu et al., 2005], and South Africa [Sinclair and Pegram, 2010], encompassing a variety of catchments scales from 0.56 km2 to more than 10,000 km2.
The Chair of Hydrology and Water Resources Management (HWRM) at ETH Zurich has modified the original TOPKAPI model in the framework of the European FP7 Project “ACQWA”, as described in Finger at al. , in order to make the model suitable for glacierized mountain areas. In particular, the code was adapted to allow coupling and calibration with satellite snow cover images. Auxiliary material is provided by Finger et al.  with a detailed description of all changes to the original TOPKAPI coding.
In order to investigate climate change effects on hydropower production Finger et al.  applied the reservoir module of the original TOPKAPI version [Todini and Mazzetti, 2008], and furthermore implemented water abstraction, diversion of natural mountain streams and routing of pressurized water to turbines and coupling of the model to results from a dynamic glacier retreat model. All changes made by Finger are described in the above mentioned study.
The modified TOPKAPI versions described in Finger et al [2011 and 2012] has recently also been applied by Pellicciotti et al. [2012 ] and Regetli and Pellicciotti  to case studies in South America and Himalaya. HWRM at ETH Zurich is currently working on a newer version of TOPKAPI.
Feel free to contact me if you have any questions concerning the TOPKAPI-Version used by Finger et al. Please contact HWRM at ETH or Prof Todini for other Versions of TOPKAPI.
All mentioned references are listed below (please contact me in case you want a copy of a particular reference):
Finger, D., F. Pellicciotti, M. Konz, S. Rimkus, and P. Burlando (2011), The value of glacier mass balance, satellite snow cover images, and hourly discharge for improving the performance of a physically based distributed hydrological model, Water Resour. Res., 47, W07519, doi:, 10.1029/2010wr009824.
Finger, D., G. Heinrich, A. Gobiet, and A. Bauder (2012), Projections of future water resources and their uncertainty in a glacierized catchment in the Swiss Alps and the subsequent effects on hydropower production during the 21st century, Water Resour. Res., 48, W02521, doi: 10.1029/2011wr010733.
Ragettli, S., and F. Pellicciotti (2012), Calibration of a physically based, spatially distributed hydrological model in a glacierized basin: On the use of knowledge from glaciometeorological processes to constrain model parameters, Water Resour. Res., 48, W03509, doi: 10.1029/2011wr010559.
Pellicciotti, F., C. Buergi, W. W. Immerzeel, M. Konz, and A. B. Shrestha (2012), Challenges and Uncertainties in Hydrological Modeling of Remote Hindu Kush-Karakoram-Himalayan (HKH) Basins: Suggestions for Calibration Strategies, Mt. Res. Dev., 32(1), 39-50, doi: 10.1659/mrd-journal-d-11-00092.1.
Todini, E., and L. Ciarapica (2001), The TOPKAPI model, in Mathematical models of large watershed hydrology, edited by V. P. Singh, Water Resources Publications, Littleton, Colorado, USA.
Todini, E. (1996), The ARNO rainfall-runoff model, J. Hydrol., 175(1-4), 339-382.
Todini, E., and C. Mazzetti (2008), TOPKAPI - TOPographic Kinematic AProximation and Integration - user manual and refrences, 137 pp, Protezione e Gestione Ambientale, Bologna.