Map-Making with the NHD Bill Wheaton Research Triangle Institute (919)

Mapmaking with the NHD Topics Topics  Map Design and Layout  Using NHD Content in Maps  Displaying Other Data with NHD

Map Design and Layout Modern Tools Don’t Alleviate the Need for Proper Map Design and Layout Modern Tools Don’t Alleviate the Need for Proper Map Design and Layout  Who is the audience?  What is the map communicating?  What are the uses for the map?  Colors, projections, use of white space, etc.

Feature Issues What are the NHD Feature Classes? What are the NHD Feature Classes?  Region.wb : Waterbodies  Region.rch : Waterbody Reaches  Region.lm : Area Landmarks  Route.drain : Network Features  Route.rch : Linear Reaches  Route.lm : Linear Landmarks  nhdpt.pat : Point features  nhdduu.patdom : Digital Update Units (quad/cu bdy)

Feature Issues Unusual Features Unusual Features

Feature Issues Overlapping Features Overlapping Features  Most common between lake/ponds and 2-D reaches  Other Cases:  2-D: swamp/marsh and lake/pond;swamp/marsh and lake/pond; foreshore and sea/ocean;foreshore and sea/ocean; rapids and 2-d stream/riverrapids and 2-d stream/river  1-D: Bridge, Overpass, CanalBridge, Overpass, Canal  Issue: within same feature class (drawing order issue) or different feature class (no drawing order issue)

Feature Issues Overlapping Features (continued) Overlapping Features (continued)  How to know:  Examine the NHD.RXP file  Where poly# is duplicated, you have overlapping features  Select out RCH features, then perform a frequency…Those records with count gt 1 are overlapping.  DEMONSTRATION….

Finding Overlapping 2-D Features NHD.RXP File Select All but RCH Summarize by Poly# Count gt 1 are Overlaps

Feature Issues Overlapping Features (continued) Overlapping Features (continued)  How to symbolize:  Choose ‘see through’ symbols  OR– choose which feature you care about more  Demo...

2-D Overlaps... Sea/Ocean Foreshore Lake/Pond Submerged Stream/River

Feature Issues Artificial Paths on Coastlines… Artificial Paths on Coastlines…  Problems:  Around Some Islands, Not Around Others  May Not Want to See Them Anyway  How to ‘Hide’ them  Reselect Reaches Having ‘Non-Flowing’ Connections  Do Left/Right Analysis to Find APs that Have Land on One Side AP on Coast

Using NHD Attributes NHD.FCODE NHD.FCODE  Contains Every Unique Combination of Feature and Attributes  Used for Distinguishing Between Perennial and Intermittent (e.g.)  Relate by FCODE, 5-digit code present in feature tables

Feature Types vs. Attributes

Using the NHDDUU Coverage Contains the “Digital Update Units” Contains the “Digital Update Units”  Currently the 1:100K Quads and CU that Make Up the Dataset  NHDDUU.PATDOM : Region Feature Class Containing Those Boundaries  With Future Updates, Could be Any Geographic Area

FOD-ifacts 2-D Features that Touch CU Boundary are Not Split… 2-D Features that Touch CU Boundary are Not Split… Clever Use of DUU Can Hide Them… Clever Use of DUU Can Hide Them… Mask Areas by Selecting DUU Polys Mask Areas by Selecting DUU Polys Symbolize with Background Color (white) Symbolize with Background Color (white) Draw Those Polys on Top of 2-D Features Draw Those Polys on Top of 2-D Features

Labeling NHD Features Names are on: Names are on:  Route.RCH: streams/rivers  Region.RCH: lake/pond  Region.WB: Other 2-D waterbodies  Region.LM: Big Dams, etc.  Route.LM: Small Dams, etc.  NHDPT: Springs, Seeps, Waterfalls, etc.

Handling Multiple CUs “One at a Time” is Tedious for Large Areas “One at a Time” is Tedious for Large Areas Use append_NHD (available on NHD Web Site) Use append_NHD (available on NHD Web Site)  AML  Initial Release or Flow Validated Inputs, but Not a Mixture  Handles Overlaps/Duplicate Features, and Other Nastiness

Displaying Reaches What’s the Point Unless You Have Additional Information Related to Them? What’s the Point Unless You Have Additional Information Related to Them? Displaying Events Displaying Events Displaying Flow, Displaying Stream Order, etc. Displaying Flow, Displaying Stream Order, etc.

Projections NHD Delivered in “non-projected”, Decimal-Degree Coordinates NHD Delivered in “non-projected”, Decimal-Degree Coordinates Project On-the-fly or Permanently for Proper Maps Project On-the-fly or Permanently for Proper Maps

Scale Issues At Small Scales, May not Want to Show 2- D Stream/Rivers, Use Drains Only, Symbolize APs Like Stream/Rivers At Small Scales, May not Want to Show 2- D Stream/Rivers, Use Drains Only, Symbolize APs Like Stream/Rivers Make 2-D Feature Outlines Invisible Make 2-D Feature Outlines Invisible At Very Large Scales, May See APs Outside their 2-D Features At Very Large Scales, May See APs Outside their 2-D Features Quad Edge Problems More Apparent at Large Scales... Quad Edge Problems More Apparent at Large Scales...

Using NHD with Other Sources The Usual Issues: The Usual Issues:  Registration  Scale  Source DRGs DRGs DOQQs DOQQs DEM/NED DEM/NED

Happy Mapping!