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Alternate Development Scenarios & Impacts: Sample Property Analysis

Explore the impacts of alternate development scenarios on land use, impervious surfaces, natural resources, and more. Analysis presented at Rockingham Planning Commission Meeting on April 12, 2006.

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Alternate Development Scenarios & Impacts: Sample Property Analysis

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  1. Testing Out SCENARIO360 C. David Wickliffe GIS Specialist Rockingham Planning Commission Commission Meeting April 12, 2006

  2. Alternate Development Scenarios & impacts Sample Property Analysis

  3. Alternate Development Scenarios & Impacts Current Status & Up to 3 alternates Impacts

  4. indicators charts Alternate Development Scenarios • Land Use • Impervious Surfaces • Natural Resources • Unfragmented Lands • Open Space arrangement of the development • Water Use • Municipal Services Costs

  5. Greenland Circuit Rider = David West Existing major development proposal with alternate scenarios CAD files of scenarios available Selection of the Sample Community

  6. Sample Development Area • Approx 130 Total acres • 18 acres in Greenland • 110 acres in Rye For our Evaluation Purposes – just treat entire development as completely within Greenland

  7. commercial and residential development – 13 single family homes 128 acres of forest Existing Conditions ‘As of Right’ – zoning compliant Dev 1 –(alternate 1 = ‘Senior Village’) Dev 2 (alternate 2 = ‘Larger Senior Village’) commercial and a major senior housing facility and townhouse buildings – 300 housing units commercial and a senior housing facility with apartment buildings – 200 housing units Alternate Development Scenarios

  8. Process to GIS Layers Got CAD files from Developer Data Development • Impervious surfaces • Buildings • Roads • Parking lots • Land Use • Commercial • Residential • Forest • Recreational • Fragmented Land • Loss to Unfragmented Blocks • Road Centerlines • To compute road length

  9. 4 scenarios • Run simultaneously • Each has own data view • All map layers are linked so on/off status is same • All indicators, assumptions, charts exist for each scenario • But only need to make each one once –they’re automatically replicated for all scenarios • Just need to put in Differing GIS Layers (Land Use, Impervious Surfaces and Roads AND change the assumptions per scenario

  10. Assumptions- set up • Our categories: General, Land Use, Natres, ImpSurf, Open Space, Water Use, Budget, Set Up

  11. Writing Formulas FORMULA EDITOR • similar to MS-Excel functions • But with spatial functions, too! FORMULA WIZARD No problem for easy formulas through the Wizard – can be a steep learning curve for more difficult formulas

  12. Charts for Indicators • Easy to set up • Not very customizable though some options Set Up/Edit

  13. Saved Views • Arrange Similar Charts • + their indicators/assumptions CREATED SEVERAL SAVED VIEWS OF RELATED CHARTS

  14. Look at Charts In analysis

  15. Unfragmented Land and Open Space Indicators

  16. Unfragmented land outline Our Saved Views: Unfrag OS (Unfragmented Lands & Open Space) Side by side comparison

  17. Unfrag OS (Unfragmented Lands & Open Space)

  18. subject_fragland Unfragmentedlands UnfragCov Unfrag OS (Unfragmented Lands & Open Space)

  19. Unfrag OS (Unfragmented Lands & Open Space)

  20. MaxUnFragPotNew MaxUnFragBloc MaxFragBloc

  21. UnfragmentedLands Dynamic attribute : FragCov Indicator : MaxFragBloc Indicator : MaxUnFragBloc Acreage of Overlap with subject Fragland , 1 value for each unfragmented polygon Maximum value of FragCov Acreage of Unfragmented Lands polygon corresponding to MaxFragBloc (acreage of polygon with the largest overlap with subject fragmented lands) Acreage of Largest affected block MINUS the overlap from the Subject Fragland the ‘New’ acreage of the largest affected block with development

  22. Our Saved Views: Unfrag OS (Unfragmented Lands & Open Space)

  23. Subject LandUse Dynamic attribute : A2Pratio Indicator : maxOSLandu Unfrag OS (Unfragmented Lands & Open Space) Compactness Ratio , 4pA/p2, 1 value for each LU polygon (better than simple area/perimeter ratio) Area of of largest non-developed LU polygon, reselected by Land Use code Gets the Compactness Ratio for the polygon of the largest non-developed poly

  24. Our Saved Views: Unfrag OS (Unfragmented Lands & Open Space)

  25. Gets the Area for the polygon of the largest non-developed (Open Space) poly

  26. Back to Community Viz Following are slides of each chart

  27. Where’d we get sample assumptions? • Town Reports • EPA water use estimate • Just guessed – until better values are avaliable

  28. Assumptions Figured from Town Reports Police Fire Roads Refuse

  29. Report Generator Does 2 scenarios at a time Used for Planning Board Handouts

  30. Errors

  31. Possibilities To improve the Analysis Town/Watershed-wide Cumulative Indicators • The acreage and percentage coverage by impervious surfaces could be given for the subject development as well as the whole watershed. Therefore, the town could monitor the cumulative effect of each development within the watershed. More Indicators for Town Departments/Services • Get all departments that are affected by any change in population and/or development to supply any assumptions and indicators that they use – or may wish to use, to submit them to the planning board for inclusion in Scenario 360. • Planning Board is in the vanguard of the community’s control over development and growth • Could consider the many issues a development may have on • the community, • watershed • region. Require Submission of Digital Plans

  32. Possibilities To improve the Analysis

  33. Conclusions • Software has steep learning curve (this project took approx 200 hrs! • Although there were some diversions • We spent time discovering what could be done and how to do it, and included some dead ends with lost effort (but that’s why we did this evaluation) • Error messages and sometimes bombing out of program for unknown reasons • Had to remake project 3 times over, in the beginning • output is only as good as the input (as well as the process logic). • Indicator Accuracy depends on the accuracy of the input GIS layers • How legitimate are the assumptions • How well are the indicator formulas are composed. • Whether you must devise your own indicators or adopt preexisting ones can make a big difference. • Requires ArcGIS ArcView to run = $1500 software • Helps people visualize and organize development considerations and impacts • Great potential! – just needs lots of set-up time. • Once a community Analysis is ‘set-up’ - new development proposals could be fairly minor work to implement • Costs under $200 now! - perhaps best value ArcGIS extension there is

  34. end

  35. List of Charts With descriptions

  36. Our Saved Views: general

  37. Our Saved Views: Land Use

  38. Our Saved Views: Land Use

  39. Our Saved Views: Impervious

  40. Our Saved Views: Impervious

  41. Our Saved Views: Natural Resources Helpful just to visualize natural resources In relation to development Side by side comparison- map layout

  42. Our Saved Views: Natural Resources

  43. Our Saved Views: Natural Resources

  44. Our Saved Views: Natural Resources

  45. Our Saved Views: Natural Resources

  46. Our Saved Views: Natural Resources

  47. Our Saved Views: Natural Resources

  48. Our Saved Views: Water Use

  49. Our Saved Views: Budget

  50. Our Saved Views: Budget

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