SplashTool 4.0 is now available for download — the most powerful SplashTool release to date.
Below is a complete overview of the changes.
Faster computational core
By optimizing the GPU-based computational core, iteration performance has been significantly increased. Depending on catchment structure and individual hardware configuration, speed improvements of 2× to 3× can be expected.
Due to GPU-internal operations, results may differ slightly from SplashTool 3.2 at a few locations by a very small margin. The results of SplashTool 4.0 are neither more nor less correct than those of SplashTool 3.2. The underlying algorithm remains unchanged.
SplashTool 3.2 and SplashTool 4.0 work with Nvidia GPUs up to Ada generation (e.g. Nvidia RTX 40XX). Blackwell GPUs (e.g. Nvidia RTX 50XX) will be supported in a future release.
Automatic computation mode selection
At startup, SplashTool checks whether GPU-based computation can be initialized using a compatible NVIDIA graphics card.
- If available, GPU mode is enabled automatically.
- Otherwise, CPU mode is selected.
CPU mode can be forced manually via the advanced settings.
The current state of an ongoing iteration can be exported to the results directory at any time via a dedicated button.
Updated license verification
The license verification mechanism has been redesigned for improved robustness. Replacing minor hardware components, such as a network card, no longer requires generating a new license request for the same machine.
As a result of this change, existing single-user license holders must request a new license file after installing SplashTool 4.0. Affected customers will receive detailed instructions automatically via email.
Removal of the legacy flow accumulation method
Up to SplashTool version 2, flow accumulation was calculated as an absolute value without directional balancing. As a result, flow directions could not be derived from these outputs.
The newer differentiated method is clearly preferred by users. To keep the codebase lean and avoid unnecessary configuration complexity, the legacy flow accumulation method has been removed in version 4.0.
User interface enhancements
- Optional Light Mode and new Dark Mode
- Automatic theme selection based on system settings
- Language and appearance can now be configured directly in the graphical user interface (no more manual editing of configuration files required)
In addition, numerous smaller UI refinements improve overall usability.
Persistent settings
Configuration options such as input and output paths remain stored when SplashTool is closed and are restored on the next launch.
Progress indicator
A progress bar is displayed during iteration. The progress value represents an approximate estimate.
Startup bug fix
SplashTool can now be launched from any working directory. This simplifies integration with other software and command-line execution.
This release represents the most extensive set of changes since the introduction of the graphical user interface in 2021. With these improvements, SplashTool is significantly more user-friendly and behaves as expected from modern engineering software.