Itzï is a dynamic, fully distributed hydrologic and hydraulic model that simulates 2D surface flows on a regular raster grid using simplified shallow water equations. It uses GRASS GIS as a back-end for reading entry data and writing results.

Itzï is released under the GPL v2+ license and free to use and distribute for any purpose.


Itzï allows to simulate surface flows from direct rainfall or user-given point inflows. It GIS integration simplifies the pre- and post-processing of data. Notably, to change the resolution or the extend of the computational domain, the user just need to change the GRASS computational region and the raster mask, if applicable. This means that map export or re-sampling is not needed.

Itzï uses raster time-series as entry data, allowing the uses of radar rainfall or varying friction coefficient.

In Itzï, the simulation duration could be represented in two ways. First, it could relative, i.e given as a number of hours, minutes and seconds, whatever the actual date is. Alternatively, the user can provide a start date and time, together with a duration or a end time. This second way is useful to simulate historical events with a known date, especially with input data with such time representation, for example rainfall.


Itzï is developed by Laurent Courty at the engineering institute of the National Autonomous University of Mexico.


The name Itzï comes from itsï, which means water in the Purépecha language, spoken mainly in the Mexican state of Michoacán.