A State-of-the-Art probabilistic inflow forecasting tool

At Stucky and Gruner we can now propose the Tethys operational hydrological forecasting system.

Tethys is a state-of-the-art probabilistic forecasting system. It relies on the Global Forecasting System by the National Oceanic and Atmospheric Administration (NOAA), near real-time satellite observations, and ground measurements to perform inflow forecasts for the chosen Reservoir. Data is processed using the Generalized Pareto Uncertainty algorithm and the RS Minerve hydrological modeling software.

What is an inflow forecasting tool?

Water is one of our most precious resources and indeed a scarce resource in some parts of the world, so basic needs can be better met if better flow forecasting techniques are used. It can and should be used continuously to achieve potential profits in energy generation, for example. Beyond that, it is most useful in the presence of extreme events, which are, by definition, rare, and should provide sound information to be acted upon, both in the case of floods and droughts. The value of inflow forecasting systems is thus often considered too late, after the event has passed and damages are done. The time to the next extreme event (normally, but not always, long) allows the occasion to be forgotten.

What is different about the Tethys forecasting system?

Using a data-driven approach and machine learning models, the system is capable of producing reliable probabilistic forecasts. The use of the term “probabilistic” implies that the forecasts attempt to characterize not only future discharges or accumulated flows, but also the uncertainty that is associated with the predictions.  

The image illustrates the improvement  of going from deterministic to probabilistic predictions. Shaded gray bands’ values correspond to the probability of observations being found within them.

Why choose Tethys over traditional methods?

Typical forecasting methodologies are expensive to setup, complex to prepare and maintain, or simply not reliable. Tethys is a powerful and practical method of producing reliable hydrological forecasts efficiently and effectively. Tethys is non-parametric, which means that it can be used to predict not only inflows but many other variables.

It is currently being developed for the Enguri Dam and under use at Rogun Dam and the Cahora Bassa Dam, have a look at the website here.

Tethys - inflow forecasting tool - Rogun

More information

The Tethys Forecasting System was initially developed by Doctor José Pedro Matos for his doctoral thesis at the École Polytechnique Fédérale de Lausanne (EPFL, https://www.epfl.ch/labs/lch/), in Switzerland, as part of the ADAPT (African Dams) research project. The initial development was financed by the Swiss Competence Centre Environment and Sustainability (CCES) and EPFL. The current version of the forecasting system has been further developed at Stucky Ltd with the main aim of producing operational inflow forecasts.

For more information, please read an application of Tethys to the prediction of suspended sediment concentrations in the Yangtze River or Dr Matos’ Doctoral Thesis here:



and his other publications here :


The above article has been written based on and directly citing from Dr Matos’s work.

Tethys - inflow forecasting tool - Southern Africa

Your contact person

Marcelo Leite Ribeiro
Head of Department, HYD Hydroelectric plant
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