MAgPIE - An Open Source land-use modeling framework

4.3.5

created with goxygen 1.3.0

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 | B: landmatrix_dec18)
  Description Unit A B
vm_landdiff_forestry Aggregated difference in forestry land compared to previous timestep \(10^6 ha\) x x
vm_landdiff_natveg Aggregated difference in natveg land compared to previous timestep \(10^6 ha\) x x

Output

module outputs
  Description Unit
fm_luh2_side_layers
(j, luh2_side_layers10)
luh2 side layers \(grid cell share\)
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_cost_land_transition
(j)
Costs for lu transitions \(10^6 USD_{05MER}/yr\)
vm_croplandexpansion
(j, land)
Sources of cropland expansion \(10^6 ha\)
vm_croplandreduction
(j, land)
Targets of cropland reduction \(10^6 ha\)
vm_land
(j, land)
Land area of the different land types \(10^6 ha\)
vm_landdiff Aggregated difference in land between current and previous time step \(10^6 ha\)
vm_landexpansion
(j, land)
Land expansion \(10^6 ha\)

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 This realization does not track sources and targets of land transitions. Interface variables like vm_croplandexpansion and vm_croplandreduction are therefore not meaningful.

(B) landmatrix_dec18

The landmatrix_dec18 realization tracks land use transitions by directly counting sources and targets of conversions.

The following three equations describe the general structure of the land transition matrix. The first equation defines the total amount of land to be constant over time.

\[\begin{multline*} \sum_{land\_from10,land\_to10} v10\_lu\_transitions(j2,land\_from10,land\_to10) = \sum_{land} pcm\_land(j2,land) \end{multline*}\]

\[\begin{multline*} \sum_{land\_from10} v10\_lu\_transitions(j2,land\_from10,land\_to10) = vm\_land(j2,land\_to10) \end{multline*}\]

\[\begin{multline*} \sum_{land\_to10} v10\_lu\_transitions(j2,land\_from10,land\_to10) = pcm\_land(j2,land\_from10) \end{multline*}\]

The following two equations calculate land expansion and land contraction based on the above land transition matrix.

\[\begin{multline*} vm\_landexpansion(j2,land\_to10) = \sum_{land\_from10\$\left(not sameas(land\_from10,land\_to10)\right)}\left( v10\_lu\_transitions(j2,land\_from10,land\_to10)\right) \end{multline*}\]

\[\begin{multline*} v10\_landreduction(j2,land\_from10) = \sum_{land\_to10\$\left(not sameas(land\_from10,land\_to10)\right)}\left( v10\_lu\_transitions(j2,land\_from10,land\_to10)\right) \end{multline*}\]

Additionally the following two equations calculate the sources and targets of all cropland related conversions.

\[\begin{multline*} vm\_croplandreduction(j2,land\_to10) = v10\_lu\_transitions(j2,"crop",land\_to10) \end{multline*}\]

\[\begin{multline*} vm\_croplandexpansion(j2,land\_from10) = v10\_lu\_transitions(j2,land\_from10,"crop") \end{multline*}\]

Small costs of 1 $ per ha on gross land-use change avoid unrealistic patterns in the land transition matrix

\[\begin{multline*} vm\_cost\_land\_transition(j2) = \sum_{land}\left( vm\_landexpansion(j2,land) + v10\_landreduction(j2,land)\right) \cdot 1 \end{multline*}\]

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:

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

Some of the land use transitions are restricted: No planted forest on natveg areas

v10_lu_transitions.fx(j,"primforest","forestry") = 0;

Conversions within natveg are not allowed

v10_lu_transitions.fx(j,"primforest","other") = 0;
v10_lu_transitions.fx(j,"secdforest","other") = 0;

Forestry can only increase Primforest can only decrease

v10_lu_transitions.fx(j,land_from10,"primforest") = 0;
v10_lu_transitions.up(j,"primforest","primforest") = Inf;

Secdforest can only decrease (during optimization) Urban land is fixed

v10_lu_transitions.fx(j,land_from10,"urban") = 0;
v10_lu_transitions.fx(j,"urban",land_to10) = 0;
v10_lu_transitions.fx(j,"urban","urban") = pcm_land(j,"urban");

Limitations There are currently no known limitations of this realization.

Definitions

Objects

module-internal objects (A: feb15 | B: landmatrix_dec18)
  Description Unit A B
f10_land
(t_ini10, j, land)
Different land type areas \(10^6 ha\) x x
q10_cost
(j)
Costs for lu transitions \(10^6 USD_{05MER}/yr\) x
q10_croplandexpansion
(j, land_from10)
Cropland expansion constraint \(10^6 ha\) x
q10_croplandreduction
(j, land_to10)
Cropland reduction constraint \(10^6 ha\) x
q10_land
(j)
Land conversion constraint \(10^6 ha\) x
q10_landdiff Land difference constraint \(10^6 ha\) x x
q10_landexpansion
(j, land)
Land expansion constraint \(10^6 ha\) x x
q10_landreduction
(j, land)
Land reduction constraint \(10^6 ha\) x x
q10_transition_from
(j, land_from10)
Land transition constraint from \(10^6 ha\) x
q10_transition_matrix
(j)
Land transition constraint cell area \(10^6 ha\) x
q10_transition_to
(j, land_to10)
Land transition constraint to \(10^6 ha\) x
v10_landreduction
(j, land)
Land reduction \(10^6 ha\) x x
v10_lu_transitions
(j, land_from10, land_to10)
Land transitions between time steps \(10^6 ha\) x

Sets

sets in use
  description
cell(i, j) number of LPJ cells per region i
clcl climate classification types
clcl58 simple climate classes
ef58(man58) Peatland emissions factors
emis58 Wetland emission types
i all economic regions
j number of LPJ cells
j2(j) Spatial Clusters (dynamic set)
land Land pools
land_from10(land) Land pools
land_to10(land) Land pools
land58(land) Managed land types
luh2_side_layers10 side layers from LUH2
man58 State of managed peatland
potnatveg(luh2_side_layers10) potentially forested biomes
stat58 Peatland status
t_all(t_ext) 5-year time periods
t_ini10 Time periods with land initialization data
t(t_all) Simulated time periods
type GAMS variable attribute used for the output

Authors

Jan Philipp Dietrich, Florian Humpenoeder, Kristine Karstens

See Also

11_costs, 13_tc, 14_yields, 30_crop, 31_past, 32_forestry, 34_urban, 35_natveg, 39_landconversion, 50_nr_soil_budget, 52_carbon, 58_peatland, 59_som, 71_disagg_lvst, 80_optimization

References