Value-Added Attributes for High- Resolution NHD NHD Stewardship Conference March 30, 2012 New Orleans, Louisiana Josh Lear Nebraska Department of Natural Resources

Goals: Understand how Value-Added Attributes translate to high resolution NHD Understand Value added attributes – How they are derived – How to use them Find a simple solution to navigating divergences

Agenda Context for discussion Preparation and evaluation Observations Conclusions

Subregion Niobrara

THE NAVIGATION ISSUE Divergence Stream Gage Point of Diversion GNIS_ID FCode ReachCode

Value Added Attributes FromNode/ToNode StartFlag/TerminalFlag VPUin/VPUout StreamLevel StreamLevel Divergence Divergence DnDrainCount DnDrainCount Hydrosequence DnLevel UpHydroSeq/DnHydroSeq/DnMinorHydroSeq StreamOrder/StreamCalc LevelPathID TerminalPathID UplevelPathID/DnLevelPathID PathLength ArbolateSum RtnDIV

Navigation Determinants DNR GNIS_ID Fcodes ReachCodes Value-Added Attributes GNIS_ID Ftype LengthKM + boundary information DNR relationships are local VAA relationships are system-wide

Evaluation Prepared 1015 using NHDPlus QAQC Tools 4 Variations based on FlowDirection: – All features “WithDigitized” – Braids “Uninitialized” – Canals “Uninitialized” – Canals and braids “Uninitialized” VAAs calculated All Divergences evaluated for downstream navigation

Preliminary Results – (AllFlow) 457 Divergences 108 failed using the DNR approach (24%) – Not enough information VAAs always navigated the divergence – Divergent flag – 82 Divergent flags assigned incorrectly

Observations: Errors still existed in the Flowline Braids, Field drains Removing braids improved VAAs Canals - flow the wrong direction – Canals w/no returns – disconnected drains – Canal w/returns distort the VAAs significantly Removing canals improved VAAs

Canal – StreamLevel Error

Observations: Substantial agreement between methods GNIS_ID FCodes played a minor role ReachCode

ReachCode Miss

Preliminary Conclusions: VAAs are a superior solution Information is the key – On the flowline – In the VAA program

To Do: Recalculate and Re-evaluate VAAs for 1015 – Configuration: Braids, Field Drains, Canals off Calculate VAAs Canals on Look at the other attributes Catch my flight home

Thanks: Jeff Simley and USGS Cindy McKay and Horizon Systems Inc. NHD Community

What I would like to see: Move forward with VAAs Add additional information to flowlines – Feature codes, names, ??? – ReachCodes Use all available information to assign VAAs at high-res “Strategically” assign VAA’s

Medium Resolution NHD High Resolution NHD Information available changes Names, Fcodes - dilution ReachCodes - increases

Medium VS. High Attributes are the same Reaches are reaches Accuracy is better Many more features Increase in features is small unnamed features GNIS_Names – MR is proportionally more thoroughly named ReachCodes – MR features to reaches ≈ 1:1 – HR features to reaches ≈ 2:1

Management Considerations: More rigorous editing More complicated workflow More management considerations at the state level Facilitate the addition of new information through new and/or better attributes – FCodes canals, artificial paths – Names –(GNIS and ancillary?) – ReachCodes – Flow State? – Classes? Software evolution

Four ReachCodes?