Environmental Modeling Basic GIS Modeling Suitability Index Modeling.

Environmental Modeling Environmental Modeling

Basic GIS ModelingBasic GIS ModelingSuitability Index ModelingSuitability Index Modeling

GIS Modeling ApproachesGIS Modeling Approaches► GIS by itself GIS by itself

► GIS integrated with statisticsGIS integrated with statistics

► GIS integrated with process modelsGIS integrated with process models

1. The Delphi Approach1. The Delphi Approach      ► A procedure for obtaining and A procedure for obtaining and processing processing expert judgments to expert judgments to maximize the accuracy maximize the accuracy of the of the resulting estimates resulting estimates

► Main considerations   Main considerations      - Data, budget, and time can be    - Data, budget, and time can be constrained constrained for a scientific for a scientific evaluation evaluation    - Human mind is capable of making    - Human mind is capable of making quite quite accurate judgments accurate judgments

1. Delphi1. Delphi► Experts' role Experts' role

1. select appropriate variables 1. select appropriate variables

2. estimate magnitude of the ranking2. estimate magnitude of the ranking

3. assign the weights3. assign the weights

1. Delphi1. Delphi► The Delphi steps The Delphi steps    

1. ask each expert for an 1. ask each expert for an independent opinion on independent opinion on carefully carefully prepared questions prepared questions

2. calculate the median and range of 2. calculate the median and range of opinions opinions and feed these back and feed these back to the experts for to the experts for another another round of estimateround of estimate

3. repeat step 1 and 2 for a few 3. repeat step 1 and 2 for a few rounds rounds

4. use the median of the final round 4. use the median of the final round as the best as the best answer answer

* time and cost factors * time and cost factors

Simple ModelingSimple Modeling

Ranking and weighting

M Ruvane, UNC Chapel Hill

2. Land Suitability 2. Land Suitability AnalysisAnalysis

► Richmond Parkway, NY evaluation Richmond Parkway, NY evaluation

McHarg, I.L., 1969. Design with McHarg, I.L., 1969. Design with NatureNature

Korean War Veterans Parkway, in Staten Korean War Veterans Parkway, in Staten Island Island http://en.wikipedia.org/wiki/Richmond_Parkway_%28Staten_Island%29

2. Land Suitability 2. Land Suitability AnalysisAnalysis

► A total of 16 land variables A total of 16 land variables         e.g. slope, drainage, land values, e.g. slope, drainage, land values, etc.etc.     

► Each variable is ranked from 1 to 3 Each variable is ranked from 1 to 3

        e.g. slope<2.5%,3; 2.5%<slope<10%,2; e.g. slope<2.5%,3; 2.5%<slope<10%,2; slope>10%,1slope>10%,1

► The grand index The grand index

= summation of ranking * weighting = summation of ranking * weighting

Ian McHarg Richmond ParkwayIan McHarg Richmond Parkway

► SlopeSlopezone 1: slope > 10%zone 1: slope > 10%

zone 2: 2.5% < slope < 10% zone 2: 2.5% < slope < 10%

zone 3: slope < 2.5%zone 3: slope < 2.5%

► Surface drainageSurface drainagezone 1: streams , lakes, and pondszone 1: streams , lakes, and ponds

zone 2: natural drainage channels zone 2: natural drainage channels

zone 3: absence of surface waterzone 3: absence of surface water

Ian McHarg Richmond ParkwayIan McHarg Richmond Parkway

► Soil drainageSoil drainage► Bedrock foundationBedrock foundation► Soil foundationSoil foundation► Susceptibility to erosionSusceptibility to erosion► Land valuesLand values► Tidal inundationTidal inundation

Ian McHarg Richmond ParkwayIan McHarg Richmond Parkway

► Historic valuesHistoric values► Scenic valuesScenic values► Recreation valuesRecreation values► Water valuesWater values► Forest valuesForest values► Wildlife valuesWildlife values► Residential valuesResidential values► Institutional valuesInstitutional values

Ranking and WeightingRanking and Weighting1.0

0.8

0.6

0.4

0.2

1.0

0.8

0.6

0.4

0.2

20 40 60 80 100%

20 40 60 80 100%

20 40 60 80 100%

1.0

0.8

0.6

0.4

0.2

1.0

0.8

0.6

0.4

0.2

20 40 60 80 100%

Carrying capacity for grazers

Man-made water loss/total

Dissolved Oxygen Density of man-made structures

3. The DRASTIC Model3. The DRASTIC Model ► DevelopmentDevelopment

- By the National Water Well - By the National Water Well Association in 1987 for US EPA to Association in 1987 for US EPA to evaluate groundwater pollution evaluate groundwater pollution potential. potential.                  

-- It used the Delphi method to It used the Delphi method to design parameters by compiling design parameters by compiling responses from more than 40 of the responses from more than 40 of the nation's leading groundwater nation's leading groundwater scientists.scientists.

3. DRASTIC3. DRASTIC► The modelThe model         D - Depth to water table         D - Depth to water table         R - Recharge         R - Recharge         A - Aquifer media             A - Aquifer media             S - Soil media          S - Soil media          T - Topography         T - Topography         I  - Impact of vadoes zone         I  - Impact of vadoes zone         C - Conductivity of the          C - Conductivity of the aquifer aquifer

Range Rating0-5 105-15 915-30 730-50 550-75 375-100 2100+ 1

Ranges and Ratings for Depth to Water

Depth to Water (Feet)

Ranges and Ratingsfor Net Recharge

Net Recharge (inches)Range Rating0-2 12-4 34-7 67-10 810+ 9

Ranges and Ratings for Aquifer Media

Aquifer MediaRanges RatingMassive Shale 2Metamorphic/Igneous 3Weathered Metamorphic/Igneous 4Glacial Till 5Bedded Sandstone, LimestoneAnd Shale Sequences 6Massive Sandstone 6Massive Limestone 6Sand and Gravel 8Basalt 9Karst Limestone 10

Ranges and Ratings for Soil Media

Soil MediaRanges RatingThin or Absent 10Gravel 10Sand 9Peat 8Shrinking and/or Aggregated Clay 7Sandy Loam 6Loam 5Silty Loam 4Clay Loam 3Muck 2Nonshrinking andNonaggregated Clay 1

Ranges and Ratings for Topography

Topography (Percent Slope)Range Rating0-2 102-6 96-12 512-18 318+ 1

Ranges and Ratings for Impact of the Vadose Zone Impact of the Vadose Zone Media

Range RatingConfining Layer 1Silt/Clay 3Shale 3Limestone 6Sandstone 6Bedded Limestone,Sandstone, Shale 6Sand and Gravel withsignificant Silt and Clay 6Metamorphic/Igneous 4Sand and Gravel 8Basalt 9Karst Limestone 10

Ranges and Ratings for Hydraulic Conductivity

Hydraulic Conductivity (GPD/FT2)

Range Rating1-100 1100-300 2300-700 4700-1000 61000-2000 82000+ 10

4. The Judgment Impact 4. The Judgment Impact MatrixMatrix

► It suits for evaluation of complex It suits for evaluation of complex systems systems

► Estimation structure Estimation structure         components -> environmental         components -> environmental elements -> elements -> societal elements -> societal elements -> grand indexgrand index

► The matrix The matrix         components x link (0,1) x         components x link (0,1) x element set1 x element set1 x element set2 x element set2 x weights (for element 2) weights (for element 2)

► The links, environmental, societal The links, environmental, societal and weights and weights can be determined by can be determined by the Delphi method  the Delphi method 

4. JIM4. JIM

Element i

Element 2

Element 1

Element m

Policy

Element i

Element 2

Element 1

Element m

Component 1

Component 2

Component i

Component m

5. A Mock Project5. A Mock Project ► What is the problem What is the problem Where to spray to control mosquito Where to spray to control mosquito pop pop

► Factors that affect sprayFactors that affect spray

1: areas of high human pop 1: areas of high human pop density density 2: adjacent to water bodies2: adjacent to water bodies

3: low elevation3: low elevation

► Find data for each factorFind data for each factor

► Apply functions to the dataApply functions to the data

Find DataFind Data► Factor 1: Factor 1: areas of high areas of high population population densitydensity

R Brancoto, SUNY BuffaloR Brancoto, SUNY Buffalo

Find DataFind Data► Factor 2:Factor 2: adjacent to adjacent to waterwater

► Function:Function: bufferbuffer

T Tatignani, SUNY BUffalo

FunctionFunction

Function: Buffer width Function: Buffer width

==

PointsPoints Lines Lines Polygons Polygons

M Ruvane, UNC Chapel Hill

Find DataFind Data► Factor 3:Factor 3: low elevationlow elevation

NIMA & NASA

Ranking and WeightingRanking and Weighting

Suitability = Layer1*1 + Layer2*3 + Suitability = Layer1*1 + Layer2*3 + layer3*3layer3*3

M Ruvane, UNC Chapel Hill

Slope

Aspect

Distance to roads

Distance to trails

From Richard Aspinall

Suitability Index ModelingSuitability Index Modeling

Owen Earley, GIS/EM4 2000Owen Earley, GIS/EM4 2000