# Model Documentation

### | Version 4.0

created with goxygen 0.21.1

# 10_land

# Land (10_land)

## Description

The land module coordinates and analyzes all land related activities by summing up all land types and calculating the gross changes in land use between two time steps of optimization given the recursive dynamic structure of MAgPIE model.

## Interfaces

Interfaces to other modules

### Input

module inputs (A: feb15)
| Description | Unit | A
--- | --- | --- | ---
vm_landdiff_forestry | Aggregated difference in forestry land compared to previous timestep | \(10^6 ha\) | x
vm_landdiff_natveg | Aggregated difference in natveg land compared to previous timestep | \(10^6 ha\) | x

### Output

module outputs
| Description | Unit
--- | --- | ---
pcm_land (j, land) | Land area in previous time step | \(10^6 ha\)
pm_land_start (j, land) | Land initialization area | \(10^6 ha\)
vm_landdiff | Aggregated difference in land between current and previous time step | \(10^6 ha\)
vm_landexpansion (j, land) | Land expansion | \(10^6 ha\)
vm_land (j, land) | Land area of the different land types | \(10^6 ha\)

## Realizations

### (A) feb15

This realization defines the total amount of land to be constant over time.

\[\begin{multline*} \sum_{land} vm\_land(j2,land) = \sum_{land} pm\_land\_start(j2,land) \end{multline*}\]

The following two equations calculate the land expansion and land contraction.

\[\begin{multline*} vm\_landexpansion(j2,land) \geq vm\_land(j2,land)-pcm\_land(j2,land) \end{multline*}\] \[\begin{multline*} v10\_landreduction(j2,land) \geq pcm\_land(j2,land)-vm\_land(j2,land) \end{multline*}\]

The gross changes in land are calculated based on land expansion, land contraction and land changes from within the modules 35_natveg and 32_forestry:

\[\begin{multline*} vm\_landdiff = \sum_{j2,land}\left( vm\_landexpansion(j2,land) + v10\_landreduction(j2,land)\right) + vm\_landdiff\_natveg + vm\_landdiff\_forestry \end{multline*}\]

> Limitations There are currently no known limitations of this realization.

## Definitions

### Objects

module-internal objects (A: feb15)
| Description | Unit | A
--- | --- | --- | ---
f10_land (t_ini10, j, land) | Different land type areas | \(10^6 ha\) | x
q10_landdiff | Land difference constraint | \(10^6 ha\) | x
q10_landexpansion (j, land) | Land expansion constraint | \(10^6 ha\) | x
q10_land (j) | Land conversion constraint | \(10^6 ha\) | x
q10_landreduction (j, land) | Land reduction constraint | \(10^6 ha\) | x
v10_landreduction (j, land) | Land reduction | \(10^6 ha\) | x

### Sets

sets in use
| description
--- | ---
land | Land pools
t_ini10 | Time periods with land initialization data

## Authors

Jan Philipp Dietrich

## See Also

13_tc, 14_yields, 30_crop, 31_past, 32_forestry, 34_urban, 35_natveg, 39_landconversion, 50_nr_soil_budget, 52_carbon, 59_som, 71_disagg_lvst, 80_optimization

## References