U.S. Department of the Interior U.S. Geological Survey Processing ArcHydro Datasets with NHDPlus Version 2, Emphasizing StreamStats Data Development Webinar Series Alan Rea and Pete Steeves ID and MA-RI Water Science Centers USGS

Webinar Series Overview May 9—Concepts and Preprocessing May 23—ArcHydro Data Development June 6—Basin Characteristics June 19—StreamStats-specific Datasets and Tools NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-2

Course Web Site DataPrepWorkshop/Workshop20 12/ NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-3

Today’s Agenda ArcHydro Concepts Using NHDPlus V2 for ArcHydro/StreamStats Tools for removing sinks Take-home assignment: Exercise 1 NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-4

ArcHydro Concepts “Global” directory structure Terrain Preprocessing Steps Data structures NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-5

NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-6

NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-7 Developing Datasets in Neighboring States Define your study area Study areas are 2 tiered –Tier 1 includes full or partial 8-digit Hydrologic Units (HUCs) where a complete set of ArcHydro datasets need to be produced –Tier 2 includes full HUCs upstream of your state and not overlapping your state

NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-8 Tier 1 Consideration for Massachusetts

NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-9 Tier 2 Consideration for Massachusetts

NHDPlusV2—StreamStats Webinars May-June, 2012Page 10 Global Data Sets All in Global.mdb geodatabase –hucpoly (tile boundaries) –streams (network to connect tiles) –huc_net_junctions (node points at ‘streams’ confluences and outlets for tile hucpolys) –huc_net (geometric network) –hucpoint (point locations at outlets) not used in StreamStats

NHDPlusV2—StreamStats Webinars May-June, 2012Page 11 Global Network

NHDPlusV2—StreamStats Webinars May-June, 2012Page 12 Directory Structure

ArcHydro Terrain Preprocessing Steps NHDPlusV2—StreamStats Webinars May-June, 2012Page 13

14 Flow Direction Grid (FDR) A 30 meter grid in national Albers projection Each cell points down hill to the neighboring cell with the lowest elevation Supports “rain drop” tools NHDPlusV2—StreamStats Webinars May-June, 2012

15 Flow Direction Grid NHDPlusV2—StreamStats Webinars May-June, 2012

16 Flow Accumulation Grid (FAC) A 30 meter grid in national Albers projection Each cell contains the number of grid cells that drain to that cell Used to generate an elevation-based “synthetic” stream network NHDPlus V2 improvement accumulation numbers only include cells within the RPU NHDPlusV2—StreamStats Webinars May-June, 2012

Page 17 Stream Definition

NHDPlusV2—StreamStats Webinars May-June, 2012StreamStats Data Prep Workshop August 5-7, 2008Page 18

NHDPlusV2—StreamStats Webinars May-June, 2012Page 19 Stream Segmentation

NHDPlusV2—StreamStats Webinars May-June, 2012StreamStats Data Prep Workshop August 5-7, 2008Page 20

NHDPlusV2—StreamStats Webinars May-June, 2012Page 21 Catchment Grid Delineation

NHDPlusV2—StreamStats Webinars May-June, 2012StreamStats Data Prep Workshop August 5-7, 2008Page 22

NHDPlusV2—StreamStats Webinars May-June, 2012Page 23 Catchment Polygon Processing

NHDPlusV2—StreamStats Webinars May-June, 2012Page 24 Drainage Line Processing

NHDPlusV2—StreamStats Webinars May-June, 2012Page 25 Adjoint Catchment Processing

NHDPlusV2—StreamStats Webinars May-June, 2012Page 26 Adjoint Catchment 151

NHDPlusV2—StreamStats Webinars May-June, 2012Page 27 Compact DataBase

NHDPlus Version 2 Concepts Overview of NHDPlus V2 Version 2 is new, not publicly released yet (soon, though) How NHDPlus V2 compares to typical StreamStats datasets NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-28

29 HydroDEM Process uses an AML called AGREE developed by University of Texas to “burn” NHD streams into the NED (NHDPlus V2 uses python and geoprocessing tools) Needed since NHD streams do not always match the NED flowpaths – “DEM Flowpath Displacement” NHDPlusV2—StreamStats Webinars May-June, 2012

30 How the Agree AML works “ stream burning ” NHDPlusV2—StreamStats Webinars May-June, 2012

31 NED versus HydroDEM NHDPlusV2—StreamStats Webinars May-June, 2012

32 Hydrologically Conditioned DEM WBD NHD NHD Reach Catchments

33 Only Certified WBD used in “ walling ” process NHDPlus V1 – NHDPlus – V2 Now available for entire US! NHDPlusV2—StreamStats Webinars May-June, 2012

34 NHDPlus Refinements Further modified the DEM surface within waterbodies to create a “Bathymetric Gradient” Catchments were generated for the NHD coastal reaches and sinks NHDPlusV2—StreamStats Webinars May-June, 2012

35 Bathymetric Gradient in Waterbodies (also dropped in NHDPlus V2) Wall Waterbodies lowered NHDPlusV2—StreamStats Webinars May-June, 2012

36 Standard DEM Flow lines NHDPlusV2—StreamStats Webinars May-June, 2012

37 Flow lines with Bathymetric Gradient NHDPlusV2—StreamStats Webinars May-June, 2012

Key NHDPlus V2 Terms Vector Processing Unit (VPU) –Generally hydrologic regions –A few exceptions Raster Processing Unit (RPU) –Smaller units for raster processing NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-38

NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-39

NHDPlus V2 Structure \NHDPlusPN (Drainage Area) \NHDPlus17 (Vector Processing Unit - VPU) \NHDSnapshot \NEDSnapshot \WBDSnapshot \NHDPlusAttributes \NHDPlusCatchment \NHDPlusBurnComponents \NHDPlusfdrfac17a, b, c, d \NHDPlusHydrodem17a, b, c, d … plus a whole lot more… We will use these 40

NHDPlus V2 Structure \NHDPlusBurnComponents BurnlineEvent.shp BurnAddLine.shp BurnWaterbody.shp BurnAddWaterbody.shp Wall.shp Sink.shp LandSea.shp NHDPlusV2—StreamStats Webinars May-June,

NHD Snapshot NHD Data Improvements for NHDPlus V2 – More names, correct placement – More lakes – Lakes split by quad lines merged – Isolated networks connected – Real sinks (non-contributing areas) identified – Duplicate geometry removed – Microgaps closed – Great Lakes drainage connected NHDPlusV2—StreamStats Webinars May-June,

ArcHydro Catchments vs. NHDPlus Catchments Both define catchments, but differently NHDPlus catchments are generated for each MedRes NHD flowline ArcHydro catchments are generated from a fac threshold, and are much BIGGER StreamStats uses ArcHydro catchments NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-43

Comparisons NHDPlus DEM resolution: 30-m NHD scale: 1:100K WBD scale: 1:24K Tiles: RPUs Typical StreamStats Implementation DEM resolution: 10-m NHD scale: 1:24K WBD scale: 1:24K Tiles: 8-digit HUCs NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-44

Sinks in NHDPlus V2 A sink causes the raster representaion of flow to stop Actually created by inserting a NODATA cell in the HydroDEM grid There are many more sinks in NHDPlus V2 than there were in V1 Sinks inserted wherever streams stop NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-45

Sink Examples NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-46

Reasons to remove sinks Map errors or omissions Seasonal flow differences “Swiss cheese” watersheds Mapping sink watersheds (non- contributing areas) Differing interpretations, e.g. peak flows vs. low flows NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-47

Tools for removing sinks NHDPlus User Tools Only for ArcHydro, does not do a full update of NHDPlus NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-48

Sink Removal Process 1.Identify which sinks to remove, store in a separate shapefile 2.Run Remove NHDPlus sinks tool (spits out “overlapping” sinks) 3.Check results, make sure no problems 4.Run Update fdr tool 5.Repeat #2 - 4 for overlapping sinks, iterate until no more overlaps 6.When all done, update fac NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-49

Take-home Exercise First do Exercise 0—Installing the Tools Exercise 1—Removing Sinks from NHDPlus V2 –First look at NHDPlus V2 data structures –Remove a sink using the tools –Update fdr and fac NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-50

Exercise 1 NHDPlusV2—StreamStats Webinars May-June, 2012Page 1-51