GIS models can use specific procedures to generate useful information from existing basic spatial data. An example of this kind of modeling is this runoff generation for an area used to generate some discharge hydrographs which can later be used in flood evaluations.
In this example, the case of a runoff hydrograph generation in a mountainous area, the main datasets used are landuse, urban areas with buildings, altitude data and streams identified from satellite images.
Using formulas specific to hydrologic modeling a layer of estimated runoff depths for a basin in a mountainous area.
By concentrating the runoff using a flow speed estimation, different discharge hydrographs could be calculated at certain points in the mountainous basin.
Hydrographs from different parts of the basin or for different rainfall events(storms) can be compared to assess the damage and impact.
Using such a model can prevent disasters caused by flash floods that are frequent in mountainous areas. One example can be seen in the next picture.
These models are not limited to floods, this is just an example. Lots of natural phenomena like landslides, avalanches or urban development can be modeled in order to create an appropriate infrastructure or take prevention measures. GIS modeling can also be used in business placement, tourism or any other areas involving spatial data.