1. Piloting High-Resolution NHDPlus for Minnesota Susanne Maeder Minnesota Geospatial Information Office American Water Resources Association GIS Specialty Conference New Orleans, LA March 27, 2012

2. Project Goals EPA NHDPlus v2 Design Document (EPA, USGS): –Quick to run – can refresh Med-Res frequently –Ability to distribute functions so that other users can create data –Ability to build from scratch with higher-res source data Minnesota’s Project Goals: –Test Build of High-Res NHDPlus v. 2 Data for Minnesota –Understanding Data Inputs –Understanding NHDPlus Build/Refresh v. 2 Tool –Evaluating Results

3. Area of Interest All drainage upstream of Lake Pepin, beginning with 070101

4. Input Data Sets Core Inputs: NHD, WBD, NED High-Res NHD – rigorous editing required WBD – 8/25/2011 version based on MN DNR ‘catchments’ layer NED – USGS statewide 10-m DEM Ancillary Data: Stream gages, diversions, additions, removals Stream Gages (flow benchmarks) –USGS NHDPointEvents/NWIS data; DNR-PCA HYDSTRA Large-Scale Diversions Additions/removals (DNR Water Appropriation Permits); consumptive use

5. NHDPlus v. 2 Creation Steps Source: Horizon Systems

6. High-Res NHD Data Preparation High-Res NHD Data Preparation NHDGeoEdit QA/QC Process NHDPlus Build/Refresh QA/QC Process NHDUpdate/NHD GeoEditor Version 4.0 - Released March 13, 2012 - Full NHDPlus Build/Refresh QA/QC Tools? - Only runs on NHD Model 2.1(ComID issue)

7. NHD Data Preparation Issues NHDPlus Build/Refresh QA/QC –Need to be able to unequivocally identify the main flow path and construct a traversable flow network –GNIS names are very important –Ensure calculation of VAA values –Potential severe errors: Flow table entry never navigated; improper network end; invalid or duplicate flow table entry; potential loop; incomplete divergence –Warnings/ informational errors: Isolated network; circular named path, possible inflowing connection

10. NHD Data Preparation – Selecting Main Path PlusFlowlineVAA DivFracMP

11. NHD Data Preparation – Selecting Main Path

16. Questions? Lake Itasca State Park – Headwaters of the Mississippi Photo Source: Minnesota Department of Natural Resources