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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