WatershedGIS Emma Gildesgame Katie Lebling and Ian Mc

Watershed/GIS Emma Gildesgame, Katie Lebling and Ian Mc. Cullough

What is GIS? • Geographic Information System • Arc. GIS 9. 3. 1 – Arc. Map – Arc. Catalog • Manny Gimond Master of GIS

What does GIS do? • Map generation • Spatial analysis • Data storage and organization • Modeling

GIS maps consist of multiple layers

Types of Datasets • Vector (feature) Point Polyline Polygon

Attribute Tables Layers have attributes, which are basically data attached to each layer Each polygon can have several fields (columns)

Types of Datasets • Raster – Made of pixels – Each pixel has a numerical value – Cell size (resolution) can be adjusted

Types of Datasets Image files Scanned Oakland tax map (jpg) Digital orthophotoquad (for land use digitizing)

GIS in BI 493 • Present data in a way that can be understood by a wide range of audiences – Numerical data – Spatial information

Models to be Generated • • • Erosion potential Erosion impact Septic suitability Development impact Phosphorus loading

Erosion Potential • Why: Erosion prevention • Data: Soil type, slope, land use • From: ME GIS, NAIP, NRCS

Erosion Impact • Why: future development, incl. lots away from shoreline • Data: Erosion potential evaluated as a function of distance from lake

Septic Suitability • Why: quality of existing septic systems, planning for future construction • Data: Slope, K-factor • From: ME GIS, NRCS

Development Impact • Why: determine effects of future development on the lake • Data: Assessment cards, soil, slope, land use, water proximity • From: Towns of Belgrade and Oakland, ME Office of GIS, NRCS

Phosphorus Loading • Why: Lake health indicator, erosion indicator • Data: land use, [phosphorus] field data • From: Water samples and Land Use/GIS group

Other Maps Ü Depth (ft) • • • Soil types Permeability K-Factor Buffer Quality Water Quality Sampling Sites • Roads • Bathymetry* 21. 4 - 30 30. 1 - 38. 1 38. 2 - 46. 6 46. 7 - 55. 2 55. 3 - 64. 3 64. 4 - 73. 4 73. 5 - 81. 9 82 - 89. 5 89. 6 - 96. 6 96. 7 - 104. 1 104. 2 - 111. 2 111. 3 - 118. 3 118. 4 - 126. 3 126. 4 - 136. 4 136. 5 - 150 0 0. 125 0. 5 Miles Bathymetry of Pleasant Pond, ME

How to build a model Modeling erosion potential in the Belgrade Lakes region Input variables Soil Slope Land use

How to build a model Convert vector land use data to raster Vector Raster Each land use type has an erosion potential rating of 0 -9

How to build a model Convert vector soil data to raster Vector Reclassified K-factor = 11. 6 Kf +1 Raster Reclassified K-factors on scale of 1 -7

How to build a model Slope data already is a raster! Slope raster Convert to percentages • But it still needs to be reclassified Reclassified on scale of 1 -9

How to build a model Multiply raster values by variable weight • Soil K-factor: 40% • Slope: 30% • Land use: 30% Soil Slope Land use For example, the soil raster values were all multiplied by 0. 4, to reflect the 40% weighting in the model

How to build a model Add up the weighted variables with the Raster Calculator in Spatial Analyst

Voíla! Higher cell values indicate higher erosion potential

Questions?