Articles | Volume 9, issue 12
https://doi.org/10.5194/gmd-9-4491-2016
https://doi.org/10.5194/gmd-9-4491-2016
Model description paper
 | 
21 Dec 2016
Model description paper |  | 21 Dec 2016

StreamFlow 1.0: an extension to the spatially distributed snow model Alpine3D for hydrological modelling and deterministic stream temperature prediction

Aurélien Gallice, Mathias Bavay, Tristan Brauchli, Francesco Comola, Michael Lehning, and Hendrik Huwald

Abstract. Climate change is expected to strongly impact the hydrological and thermal regimes of Alpine rivers within the coming decades. In this context, the development of hydrological models accounting for the specific dynamics of Alpine catchments appears as one of the promising approaches to reduce our uncertainty of future mountain hydrology. This paper describes the improvements brought to StreamFlow, an existing model for hydrological and stream temperature prediction built as an external extension to the physically based snow model Alpine3D. StreamFlow's source code has been entirely written anew, taking advantage of object-oriented programming to significantly improve its structure and ease the implementation of future developments. The source code is now publicly available online, along with a complete documentation. A special emphasis has been put on modularity during the re-implementation of StreamFlow, so that many model aspects can be represented using different alternatives. For example, several options are now available to model the advection of water within the stream. This allows for an easy and fast comparison between different approaches and helps in defining more reliable uncertainty estimates of the model forecasts. In particular, a case study in a Swiss Alpine catchment reveals that the stream temperature predictions are particularly sensitive to the approach used to model the temperature of subsurface flow, a fact which has been poorly reported in the literature to date. Based on the case study, StreamFlow is shown to reproduce hourly mean discharge with a Nash–Sutcliffe efficiency (NSE) of 0.82 and hourly mean temperature with a NSE of 0.78.

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Short summary
This paper presents the improvements brought to an existing model for discharge and temperature prediction in Alpine streams. Compared to the original model version, it is now possible to choose between various alternatives to simulate certain parts of the water cycle, such as the technique used to transfer water along the stream network. The paper includes an example of application of the model over an Alpine catchment in Switzerland.