Agricultural Feasibility Analysis in China: A GIS-based Spatial Fuzzy Multi-Criteria Decision Making

Approach

Presenter: Fei CarnesDate: July 17, 2013

Email: fmeng@cga.harvard.edu

Glossary

1. RasterA raster consists of a matrix of cells (or pixels) organized into rows and columns (or a grid) where each cell contains a value representing information, such as temperature. Rasters are digital aerial photographs, imagery from satellites, digital pictures, or even scanned maps.

cell

• The entire area is divided into a uniform matrix of cells which are organized into a regular grid.

• All space is represented by cells, even where there is nothing of interest

• Rows and columns are used to designate their location.

• All cells must have a value. The number inside a cell represents some value for that cell location. The cell value may be an ID for a feature or it may be an attribute value.

• There is only one value for each cell.• Cells are independent data units. The

computer does not know if they are connected or not, but knows their relative position.

• Each cell has its size and area.

2. Raster vs. Vector

• Raster allows to illustrate gradual changes and variation in attributes from one place to another.

• Raster has a simple data structure—A matrix of cells with values representing a coordinate and sometimes linked to an attribute table.

• Raster allows to perform fast overlays with complex datasets

• Raster is better in advanced spatial and statistical analysis.

3. Spatial Modeling (Raster modeling)

• Suitablity Analysis

• Hydrologic Modeling

• Distance Modeling

... ...

3. Spatial Modeling• Suitablity Analysis ( feasiblity \ vulnerability \ sensitivity analysis)

• Hydrologic Modeling

• Distance Modeling

... ...

Where are the optimum locations for a new school, landfill?

Calculate optimal site locations by identifying possible influential factors. The optimal suitability map may provide new insight into the ideal areas where a new site should be located.

To solve ...

3. Spatial Modeling• Suitablity Analysis

• Hydrologic Modeling

• Distance Modeling

... ...

Provide methods for describing the hydrologic characteristics of a surface. Using an elevation raster data set as input, it is possible to model where water will flow, create watersheds and stream networks, and derive other hydrologic characteristics.

Where will the water flow to?To solve ...

3. Spatial Modeling• Suitablity Analysis

• Hydrologic Modeling

• Distance Modeling

... ...

Where will be the areas which has the nearest distance from a emergency helicopter?

To solve ...

Determine the least expensive method for a new road, flight pattern, shipping route, or any factor that is affected by time and cost.

4. Fuzzy

• Different approaches are used with continuous (quantitative) and categorical

(qualitative) data • Different functions available (linear, sigmoidal, J-shaped, user-defined)

How to standarize?

A method to standardized factors based on a series of specific mathematical functions. It reclassifies or transforms the input data to standardized scale ([0,1], [0,10] ,[0, 255], etc.).

5. Multi-Criteria Decision Making (MCDM)

• It considers multiple criteria in decision making environment.• It provides a framework to represent the decision groups into a single model.

GIS-based MCDM integrates the MCDM approach and GIS techniques to solve spatial issues. It has been received considerable attentions among planners since 1990s.

This method has been shown in studies related to site determination for a nuclear waste facility, forest conservation.

Objective

1. The main aim of this project is to solve data confidentiality issue.

3. Help people understand raster GIS analysis (spatial modeling).

2. Develop multi-criteria decision making technique using fuzzy approach for agricultural feasibility analysis.

Data & Software

Annual Precipitation

Accumulated Temperature >10 °C

Sunshine HoursWater

ResourcesElevatio

nSoil PHSoil

DepthSoil

Drainage

Source: Yu Deng, China Academy of Science

Source: CGA

Weather

Hydrology

Topography

Soil

Data ：

Software:

IDRISI is a GIS and image processing software, developed by Clark Labs, Clark University.

In 1993, IDRISI introduced the first instance of Multi-Criteria and Multi-Objective decision making tools in GIS.

Eighteen years later, IDRISI is still the industry leader, responsible for:• The first implementation of the Ordered-Weighted Average for multi-criteria evaluation that allows one to balance the relative amount of tradeoff between criteria with decision risk in balancing discordant information.• The first implementation of the MOLA heuristic for multi-objective land allocation.• The first GIS software implementation of Saatys Analytical Hierarchy Process (AHP).

ArcGIS is a platform for designing and managing solutions through the application of geographic knowledge.

Methodology

1. Data Determination and Processing2. Criteria Standardization (Fuzzy)3. Weight Determination4. Weighted Linear Combination (weighted overlay)

Methodology1. Data Processing

1) Denoise and reclassify imageries

3) Make sure all the data have the similar extents , and the same coordinate system. 2) Data transformation. e.g. river (shapefile) distance to river (raster); elevation slope(degree)

Annual Precipitati

on

Accumulated Temperature >10

°C

Elevation

Slope

Distance to River

Sunshine Hour

Soil Depth

Soil PH Soil Drainage

……

Methodology2. Fuzzy

Fuzzy evaluates the possibility that each pixel belongs to a fuzzy set by evaluating any of a series of fuzzy set membership functions. --- Idrisi Selva Help Document

Fuzzy membership

function

Annual Precipitation （ ml ） Fuzzy Annual Precipitation [0,1]

“0” is assigned to those locations that are definitely not a member of the specified set, “1” is assigned to those values that are definitely a member of the specified set. All the in-between values receive some membership values based on the function.

Methodology

2.1 Fuzzy (for continues\ quantitative data)In Idrisi: “ FUZZY” module provides 4 fuzzy membership function types

* Sigmoidal (“ S-Shape”)

* J-Shaped * Linear * User-defined

a = membership rises above 0; b = membership becomes 1; c = membership falls below 1; d = membership becomes 0

Monotonically increasing

Monotonically decreasing

Symmetric

Control Points:

. Control points

Methodology2.1 Fuzzy (continues data)

Annual Precipitati

on

Accumulated Temperature>10

°CElevation

Slope

Distance to River Sunshine

Hour

Sigmoidal increasing

0 1500ml

-117

48003200 9600

Sigmoidal Symmetric

0 2700 m

Linear

0 7

Sigmoidal decreasing

0 max

Linear

0 max

Linear

FuzzyPrecipitati

on

FuzzyTemperature

FuzzyElevation

FuzzySlope

FuzzyDistance to

River

FuzzySunshine hour

Methodology

2.2 Fuzzy (for categorical \ qualitiative data)Reclassify and assign new values to each

category.

For example, land use types.

0

1Deciduous forest

Coniferous forest

Cropland

0.8

0.6

0.2

Methodology2. 2 Fuzzy (categorical data)

Soil PH Soil Depth

Soil Drainage

FuzzySoil PH

FuzzySoil Depth

FuzzySoil

Drainage

<4.5 or >8.5

Other

[4.5, 5.5) or [7.2,8.5)

0.2

0.6

0

[5.5, 5.8) or [6.9,7.2)

0.8

[5.8, 6.9) 1

Old Values

New Values

Shallow (10-50cm)Very shallow (<10cm)

Moderately deep (50-100cm)

0.4

0.6

0.1

Deep (100-150cm)

0.8

Very deep (150-300cm)

1

Old Values

New Values

Well

Low

0.6

0.8

0

0.9

1

Old Values

New Values

…

…

Methodology2. Fuzzy

FuzzySoil PH

FuzzySoil Depth

FuzzySoil

Drainage

FuzzyPrecipitati

on

FuzzyTemperature

FuzzyElevation

FuzzySlope

FuzzyDistance to

River

FuzzySunshine hour

Feasibility Map

Methodology3. Weight Determine

Determine the weight intuitively BUT it requires looking at all criteria together, this will not allow for negotiation or compromise looking at criteria two at a time.

--- How important is each factor?--- We can give different weights to different factors, and all the weights must add up to 1

• It lets you compare criteria two at a time. • The user specifies the relative importance of one criteria compared to another and does this for all possible combinations of criteria.

• The procedure will then tell you how consistent are all of your comparisons and it will develop weights for you for each criteria.

Analytic Hierarchy Process (AHP)

Methodology3. Weight Determine

Analytic Hierarchy Process (AHP)

Intensity of Importanc

eDefinition Explanation

1 Equal importance Two activities contribute equally to the objective

3 Moderate importance Experience and judgments slightly favor one activity over another

5 Strong importance Experience and judgment strongly favor one activity over another

7 Very strong or demonstrated importanceAn activity is favored very strongly over another and dominance is

demonstrated in practice

9 Extreme importanceThe evidence favoring one activity over another is of the highest

possible order of affirmation2， 4， 6，

8 Intermediate value between the two adjacent judgments When compromise is needed

Steps: 1. Estimate the pertinent data 2. Create pairwise comparison decision matrix 3. Calculate the weights and check consistency （ CR<0.1)

Table1. The fundamental scale

Methodology3. Weight Determine

* Klaus D. Goepel, Singapore http://bpmsg.com/

* Idrisi --- “Weight” module

* ……

* By hand

Methodology3. Weight Determine

  Ratio Ratio Rank

1 Weather

0.46

1.1 accumulated temperature 0.56

1  1.2 sunshine 0.09  1.3 annual precipitation 0.35

2 Hydrology0.07

2.1 distance to river 14

     

3 Topography0.32

3.1 elevation 0.252

  3.2 slope 0.75

4 Soil

0.15

Texture  

3  4. 1 PH 0.12  4.2 Depth 0.23  4.3 Drainage 0.65

* Klaus D. Goepel, Singapore http://bpmsg.com/

4. Weighted Overlay

Methodology

∑0

𝑛

𝑎𝑖∗𝑏𝑖 ai: pixcel value of factor i ； bi: weight of pixel i ； n: numbers of factors

S =

apply weights to several inputs and combine them into a single output.

2.2

2.2

3.3

2.2

1.1

1.1

1.1

2.2

2.2

3 3 2

1 3 1

2 1 1

=2.4

2.4

3.0

1.9

1.6

1.1

1.3

2.4

1.9

Factor 1 Factor 2( Weight = 0.75) ( Weight = 0.25)

Output

Output (top left cell = 2.4) = 2.2*0.75 + 3* 0.25

4. Weighted Overlay

Methodology

*0.46

*0.07

*Wn

……

feasibility map

Weather Hydrology

Overview

*W1 *W2 *Wn

……Suitability ratings from different hierarchy

……

……

*W’1

Criteria layer

Standardize criteria

Final feasibility map

*W’n

Result

Summary

• There are a variety of possible answers to one suitability problem.

• Different answers for the same problem result from: – Considering criteria to be a factor or constraint – How the factor is standardized (what function, what thresholds) – How each factor is weighted

Limitation

1. Different fuzzy functions apply to different crop production areas.2. Not considering seasonal influence.

3. Lack of data, such as soil texture.

Thank You !

Questions and Comments?