GIS Analysis in Land Management Presented by: Jimmy West, The Schneider Corporation

Presentation Overview: Creating Computer Generated Watersheds Use of Drainage Calculation Software to Assess Drainage with Parcels, Watersheds & Soils Layers

Accuracy… Fancy software does not equal accurate data Additional data layers will only be as accurate as basemap Parcels must be maintained and up to date through a known date – almost all GIS layers will refer back to ownership information

Watersheds of the Past?

Software Used to Create Computer Generated Watersheds ESRI – ArcInfo ESRI – Spatial Analyst Tools What is needed?

Data Layer Sources Needed for Computer Generated Watersheds 2’ contours – seamless Linear stream features – seamless and topologically correct 2’ contours – seamless Linear stream features – seamless and topologically correct

Computer Generated Watershed Raster Processes Elevation Raster Flow Direction Raster Flow Accumulation Raster Raster Streams Layer Make grid 2x bigger

Assumptions and Obstacles: …and 3 things to know about drainage Water runs downhill Water drains into streams Obstacles “Sinks” and “Peaks” Culverts

“Fill” Process for Sinks and Peaks

Streams at Culverts

Zoomed Stream Elevation Raster

“Burning” in the Streams

Creation of Computer Generated Watersheds Hydrology Modeling extension is used to “burn in streams” and build watersheds using raster images created from contour data Computer generated watersheds are merged/attributed to match County’s existing tiered administrative watershed system

Computer Generated Watersheds Threshold = 500 Watersheds

Tiered Watershed Layer

Drain Calc Overview Preparing Data For Use in Drain Calc Multiple assessment methodologies One rate per acre assessments Proportional assessments

Tiered Watershed Layer

Watershed/Parcel Overlay

Watershed/Parcel Intersect - Lower

Watershed/Parcel Intersect - Upper

Watershed/Parcel/Soil Intersect

Range of Watershed Assessment Options Flat rate per benefited acre Setting minimum assessment amount(s) Additional assessment options Soils Parcel class/landuse Distance from hydrological features other

Individual Watershed Projects

Defined Watershed Project

Apply Assessment Rule Selections

Soil Type Rule Example

Import Parcel Data

Define Hearing/Notice Report Info

Generate Reports/Notices

Print Assessment Schedule