# What is Process Model? Examples Include Environmental Models and Landslide Models (Especially for GATE-Geospatial 2022)

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A process model integrates existing knowledge about the environmental processes in the real world into a set of relationships and equations for quantifying the processes. Modules or sub-models are often needed to cover different components of a process model. Some of these modules may use mathematical equations derived from empirical data, while others may use equations derived from laws in physics.

Simple process may be prepared in GIS normally linked to other computer programs for complex & dynamic analysis.

## Common Process Models Using GIS

### Environmental Models

Environmental models are typically process models because they must deal with the interaction of many variables including physical variables such as climate, topography, vegetation, and soils as well as cultural variables such as land management.

### Landslide Models

A process model taken advantage of GIS. There are two types of landslide models:

• An example of a statistical model is a logistic regression model. Statistical model deals with probability of landslide based on slope characteristics.
• This section introduces the critical rainfall model as a physically based landslide model. The infinite slope model defines slope stability as the ratio of the available shear strength (stabilizing forces) , including soil and root cohesion, to the shear stress (destabilizing forces) . The critical rainfall model developed by Montgomery and Dietrich (1994) combines the infinite slope model with a steady-state hydrologic model to predict the critical rainfall that can cause landslide. can be computed by: where
• T is saturated soil transmissivity
• is local slope angle
• a is the upslope contributing drainage area
• b is the unit contour length
• is wet soil density
• is the internal friction angle of the soil
• is the density of water
• C is combined cohesion, which is calculated by: where,
• is root cohesion,
• is soil cohesion
• h is soil depth
• g is the gravitational acceleration constant.
• A DEM can be used to derive a, b, and in equation, whereas other parametres in equation and it must be gathered from existing data, field work, or literature survey. The critical rainfall model is regularly used for predicting shallow landslides triggered by rainfall events.

Developed by: