The effect of Land Use Cover Change model resolution on scale of aggregation AAG Meeting _ March 2006 Amélie Davis & Dr. Bryan Pijanowski

The effect of Land Use Cover The effect of Land Use Cover Change model resolution on scale of Change model resolution on scale of

aggregationaggregation

AAG Meeting _ March 2006Amélie Davis & Dr. Bryan Pijanowski

March 8, 2006AAG MEETINGChicago, Illinois

OutlineOutline

► Agricultural expansion scenarios for East African countries based on Land Transformation Model (LTM) results and UN Population estimates

► Urbanization scenarios based on Multi- Criteria Evaluation (MCE) and UN Population estimates

► Scaling issues and aggregation errors


LTM for Agricultural ExpansionLTM for Agricultural Expansion

• Land use change forecast model using neural networks

• Forecast Agricultural expansion based on future UN population estimates

• Drivers:

_ _

_ _

_ _


Diagram of StepsDiagram of Steps

Figure out which drivers to include

Figure out the number or urban cells per country

Calculate ratio people per Ag Cells in

landscape

Use ratio to extrapolate pop urban to 2050 by 5

year increments

Run LTM on East Africa to forecast agricultural expansion pick best

PCM

Project Agricultural use using LTM neural

network outputs

Mask out water bodies, parks and agriculture

Include Urban expansion (use different

method)


Agriculture Forecast: Agriculture Forecast: 2005 (left) 2030 (right)2005 (left) 2030 (right)


Results for East AfricaResults for East Africa

• 2005 to 2030 in 5year increments

• Notice that Uganda “runs out” of agricultural space by 2020


Urbanization SimulationUrbanization Simulation

Use Multi-Criterion Evaluation• Based on 1983 book by Voogd & 1991 paper by Carver et al. • Also part of IDRISI software• Similar to LTM in the use of drivers• Uses expert judgment to weigh input

drivers• Simple implementation in GIS


6 drivers for Urbanization6 drivers for Urbanization Distance to urban Focal sum of urban close Focal sum of urban

far

Distance to roads a roads b roads c


• Standardization of drivers from zero to one with larger number being more likely to urbanize.

Ex: dist to road: max - # / min-max• Pair wise comparison of each driver to establish

their weights.

Ex: distance to urban is extremely more important when compared to distance to roads

Based on ‘expert’ judgment

Steps for MCESteps for MCE


• Approximate weight calculation• Implement them in raster calculatorEx: multiply your drivers by their weights. Make sure

you exclude the cells which cannot urbanize (already urban, parks, lakes, ocean)

Problem city boundaries are too smooth.

Resemble edges of focal sum drivers Multiply those 2 drivers by a

random map

Weighing of Drivers Weighing of Drivers


2001

2001

2050

2005

2030


East Africa Urbanization East Africa Urbanization

• MCE map • Red/orange =

greatest likelihood of urbanization

• Problems with Ethiopia and Mozambique

not enough information in drivers


Urban in 2000Urban in 2000


Urban Forecast for 2005Urban Forecast for 2005




















Same MCE but for Nairobi at 1km Same MCE but for Nairobi at 1km spatial resolutionspatial resolution


1km MCE Results1km MCE Results

• Original urban in red• Urbanization in green

2005

2050

2025


Modeling ImplicationsModeling Implications

• Visually maximum ‘smooth’ transitioning of urbanization at 1km seems to be 5 years

• Patterns of urbanization with same method but different spatial resolution are different

Which model do you use?

Should weights be reevaluated for different spatial resolutions?

1km resolution 90m resolution resampled at 1km


Scaling IssuesScaling Issues

• Different

Patterns

• Different information passed on to climate model


Conclusions and Next StepsConclusions and Next Steps

• Merge Urbanization with Agricultural expansion maps

• Study the interaction of different fractional covers of urban at varying spatial resolutions of the LULCC change map with disparate spatial resolution climate grid which scale will be best suited to couple both models?

• How will shape and patterns within the landscape influence this coupling?



Documents

The effect of Land Use Cover Change model resolution on scale of aggregation AAG Meeting _ March 2006 Amélie Davis & Dr. Bryan Pijanowski