StreamFlow

Running-StreamFlow

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Table of Content

This page explains how to run a StreamFlow simulation

Introduction

StreamFlow is an extension to the spatially-distributed snow model Alpine3D which allows the user to perform hydrological simulations. Both tools run independently, but Alpine3D needs to be configured in such a way that it outputs a set of files which are expected by StreamFlow as input data (see below). In case you do not know how to run an Alpine3D simulation, please have a look at the Alpine3D documentation.

Once the Alpine3D simulation is run, you can either copy the output data to a new folder or directly perform the StreamFlow simulation in the same folder as Alpine3D (StreamFlow was designed so that no conflict occurs). Similarly to the other tools of the Alpine3D suite, the behavior of StreamFlow is controlled by a configuration file. You can actually use the same one as for Alpine3D, simply adding the keys which are required by StreamFlow (see below).

Additionally to the output data generated by Alpine3D, StreamFlow requires specific files in order to run properly. The latter include the grid delineating the subwatersheds as well as two data files specifying the location and structure of the stream network. All these files can be generated by TauDEM, a tool that was designed to extract various hydrological variables from digital elevation models (see below).

Before being actually run, StreamFlow may need to be calibrated in case it is applied over a new catchment. As for any other hydrological model, this step may be quite computationally intensive since at least a thousand runs are typically required to obtain good parameter estimates. A few guidelines helping you efficiently calibrating the model can be found below.

Once calibrated, the model can eventually be run. The configuration file allows you to control many aspects of the simulation, such as the algorithm which is used to advect water along the stream network, whether stream temperature should be computed or not, or even the rate at which data should be written in the output files.

In summary, the usual procedure for running a StreamFlow simulation is the following:

  1. Configure and run Alpine3D so that it produces the data required by StreamFlow
  2. Create the simulation folder for the StreamFlow simulation, or simply re-use the Alpine3D one
  3. Create the configuration file for the StreamFlow simulation, or simply modify the Alpine3D one by adding the missing keys
  4. Use TauDEM to generate the additional files required by StreamFlow, and copy these files in the simulation folder of StreamFlow
  5. Calibrate StreamFlow
  6. Run the StreamFlow simulation by calling the executable on the command line with the proper options

Each one of these six steps is detailed in a dedicated section below.

Configuration of Alpine3D

At the very minimum, StreamFlow requires from Alpine3D the amount of water infiltrating into each subwatershed at every time step. Two possibilities are available for this:

  • In case you already have the grid delineating the subwatersheds (see section about TauDEM below), you can copy it in folder input\surface-grids of the Alpine3D simulation directory. Please make sure that this grid is in a format that is readable by Alpine3D (TauDEM generates a TIFF grid which needs to be converted; the list of Alpine3D compatible formats can be found in the MeteoIO documentation). You then need to add the following keys in section [INPUT] of the Alpine3D configuration file, with [format] to be replaced with the grid format (e.g. ARC), [folder] with the (absolute or relative) path to the folder in which the grid is located (e.g. ./input/surface-grids), and [file_name] with the grid name (without the path):

        GRID2D              = [format]
        GRID2DPATH          = [folder]
        CATCHMENT           = [file_name]
        CATCHMENT_NUMBERING = TAUDEM
        

    Additionally, the following line has to be added in section [OUTPUT] of the Alpine3D configuration file, where [folder] stands for the (absolute or relative) path to the folder in which the files containing the subwatershed infiltration rates will be generated by Alpine3D:

        CATCHMENTS_PATH = [folder]
        

Simulation folder

Although not strictly required, it is recommended that you create a new folder for each StreamFlow simulation with the same structure as recommended for Alpine3D. Alternatively, you can simply use the same folder as the one in which the Alpine3D simulation was run.

Configuration file

Generation of the stream network with TauDEM

Calibration

Calling the executable