GRP/TGR

Objectives and general principles

GRP is a software designed to provide real-time flood forecasts over gauged catchments, with lead times of up to 120 h (or 5 days for a daily time-step functioning).
It is based on hydrological modeling representing the transformation of rainfall into streamflow at the catchment scale (GRP hydrological model).
It can be run at the sub-hourly to daily time steps and can thus be applied on catchments representing a wide range of response times. It can adapt to various hydroclimatic conditions thanks to the calibration of its parameters and the use of additional modules (e.g. the Cemaneige module for snow conditions). It has a module for estimating uncertainties associated with forecasts (based on the principles of the OTAMIN tool).

Detailed functioning of the software

Software structure
The GRP software is split in two modules:

• A calibration modules: it can be used for basic data analysis and proposes different calibration options to find the most optimal set of model parameters. Graphical results are displayed to guide the user in his/her choice. Once the optimal configuration has been selected, the module builds a real-time database that will feed the real-time module.
• A real-time module: using the parameters obtained with the calibration module, provides real-time flow forecasts. This module must be continuously fed with the latest observed flow and precipitation data and future precipitation scenarios. It also allows hindcast of past events to evaluate the behavior of the model and to practice in crisis situations. Graphical outputs are also provided by this utility.

Time-step

The software can run at different time steps from sub-hourly to daily. The accepted time steps are 5 min, 6 min, 15 min, 30 min, 1 h, 3 h, 6 h, 12 h and 1 day.

Data needed

The software must be fed with precipitation data, potential evapotranspiration data (PE) and observed streamflow data (and temperatures if the user wishes to use the CemaNeige snow module). Continuous time series at least 2-year long are needed for a proper functioning of the tool.
Flow and temperature data must be instantaneous. They are then automatically converted on average values to the desired time step.
The precipitation data must be cumulated values over time steps equal to or less than the chosen time step.
PE data are cumulated data on the chosen time step or the daily time step. In the second case, they are automatically disaggregated by the software at the required time.

Software environment needed

R software (version >= 3.2.1) is required to use the GRP software. It is freely available.
The GRP software runs in Windows or Linux environment.

Users

The GRP software is used by the Vigicrues network, an information service on the flood risk for the main rivers in France (with the use of the national hydrometric network, and observation and forecast data produced by Météo-France). It is also used by various water managers and in the field of research and teaching.

How to access the software?

The GRP software was developed mainly through a collaboration with the Central Hydrometeorological and Flood Forecasting Service (SCHAPI) of the Ministry in charge of the environment.
It is provided with a license agreement, free of charge for State services and teaching and research applications, paying otherwise (license fee: 500 €).
Contact @ INRAE François Tilmant