Geographic Resources Analysis Support System (commonly termed GRASS GIS) is a geographic information system software suite used for geospatial data management and analysis, image processing, producing graphics and maps, spatial and temporal modeling, and visualizing.

Geographic information systems (GISs) have become a useful and important tool in the field of hydrology to study and manage Earth's water resources.

Distributed GIS refers to GI Systems that do not have all of the system components in the same physical location.