Representation, Extraction, Attribution, and Delineation Rules

Elevation-Derived Hydrography Representation, Extraction, Attribution, and Delineation Rules

Chapter 12 of Section B, U.S. Geological Survey Standards, of Book 11, Collection and Delineation of Spatial Data

Techniques and Methods 11–B12

U.S. Department of the Interior U.S. Geological Survey

AAXXXX_fig 01 Cover. Examples of elevation-derived hydrography in different landscapes. From top to bottom, (1) a stream network running through mountains in Colorado; (2) stream channels flowing near farmland in Delaware; (3) canals and streams in an arid location in Colorado; and (4) waterways and other water features along the coast of Delaware. Elevation-Derived Hydrography— Representation, Extraction, Attribution, and Delineation Rules

By Christy-Ann M. Archuleta and Silvia Terziotti

Chapter 12 of Section B, U.S. Geological Survey Standards, of Book 11, Collection and Delineation of Spatial Data

Techniques and Methods 11–B12

U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior DAVID BERNHARDT, Secretary U.S. Geological Survey James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2020

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Suggested citation: Archuleta, C.M., and Terziotti, S., 2020, Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules: U.S. Geological Survey Techniques and Methods, book 11, chap. B12, 60 p., https://doi.org/ 10.3133/tm11B12 .

ISSN 2328-7055 (online) iii

Contents

Abstract ��1 Introduction ��1 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules Explanations ��1 Field Definitions and Domain Values for Attributes ��2 Requirement Terminology ��3 Area of Complex Channels ��4 Attribute/Attribute Value ��4 Delineation ��4 Representation Rules ��4 Data Extraction ��4 Capture Conditions ��4 Attribute Information ��6 Source Interpretation Guidelines ��6 Artificial Path ��7 Attribute/Attribute Value ��7 Delineation ��7 Representation Rules ��7 Data Extraction ��7 Capture Conditions ��7 Attribute Information ��9 Source Interpretation Guidelines ��9 Canal/Ditch ��10 Attribute/Attribute Value ��10 Delineation ��10 Representation Rules ��12 Data Extraction ��12 Capture Conditions ��13 Attribute Information ��13 Source Interpretation Guidelines ��13 Connector ��14 Attribute/Attribute Value ��14 Delineation ��14 Representation Rules ��14 Data Extraction ��14 Capture Conditions ��14 Attribute Information ��14 Source Interpretation Guidelines ��14 Culvert ��17 Attribute/Attribute Value ��17 Delineation ��17 Representation Rules ��17 Data Extraction ��17 Capture Conditions ��17 iv

Attribute Information ��17 Source Interpretation Guidelines ��19 Dam/Weir ��20 Attribute/Attribute Value ��20 Representation Rules ��20 Data Extraction ��20 Capture Conditions ��20 Attribute Information ��20 Source Interpretation Guidelines ��20 Drainageway ��23 Attribute/Attribute Value ��23 Delineation ��23 Representation Rules ��23 Data Extraction ��23 Capture Conditions ��23 Attribute Information ��23 Ice Mass ��25 Attribute/Attribute Value ��25 Delineation ��25 Representation Rules ��25 Data Extraction ��25 Capture Conditions ��25 Attribute Information ��25 Source Interpretation Guidelines ��25 Lake/Pond ��28 Attribute/Attribute Value ��28 Delineation ��28 Representation Rules ��28 Data Extraction ��28 Capture Conditions ��28 Attribute Information ��28 Source Interpretation Guidelines ��28 Pipeline ��32 Attribute/Attribute Value ��32 Delineation ��32 Representation Rules ��32 Data Extraction ��32 Capture Conditions ��32 Attribute Information ��32 Source Interpretation Guidelines ��34 Playa ��35 Attribute/Attribute Value ��35 Delineation ��35 Representation Rules ��35 Data Extraction ��35 v

Capture Conditions ��35 Attribute Information ��35 Source Interpretation Guidelines ��35 Reservoir ��37 Attribute/Attribute Value ��37 Delineation ��37 Representation Rules ��37 Data Extraction ��37 Capture Conditions ��37 Attribute Information ��37 Source Interpretation Guidelines ��37 Sea/Ocean ��40 Attribute/Attribute Value ��40 Delineation ��40 Representation Rules ��40 Data Extraction ��40 Capture Conditions ��40 Attribute Information ��40 Source Interpretation Guidelines ��40 Sink/Rise ��43 Attribute/Attribute Value ��43 Delineation ��43 Representation Rules ��43 Data Extraction ��43 Capture Conditions ��43 Attribute Information ��43 Source Interpretation Guidelines ��43 Stream/River ��46 Attribute/Attribute Value ��46 Delineation ��46 Representation Rules ��46 Data Extraction ��49 Capture Conditions ��49 Attribute Information ��49 Source Interpretation Guidelines ��49 Additional Elevation-Derived Hydrography Treatments and Elevation Specific Features ��50 Island ��50 Delineation ��50 Lake/Pond ��50 Sea/Ocean ��50 Stream/River ��50 Island/Sandbar ��52 Low-Confidence Area, Predetermined ��52 Attribute/Attribute Value ��52 Representation Rules ��52 vi

Data Extraction ��52 Capture Conditions ��52 Attribute Information ��52 Source Interpretation Guidelines ��52 Low-Confidence Area, Sparse Bare Earth ��56 Attribute/Attribute Value ��56 Representation Rules ��56 Data Extraction ��56 Capture Conditions ��56 Attribute Information ��56 Low-Confidence Area, Snow-Cover ��57 Attribute/Attribute Value ��57 Representation Rules ��57 Data Extraction ��57 Capture Conditions ��57 Attribute Information ��57 Source Interpretation Guidelines ��57 Acknowledgments ��60 References Cited ��60

Figures

1. Diagram showing shortest and longest axes of a lake/pond feature ��2 2. Photograph showing Toutle River, Washington, shown as an example of area of complex channels feature ��4 3. Map showing example of an area of complex channels along the Susitna River in Alaska ��5 4. Diagram showing inflow and outflow points of a lake/pond feature ��7 5. Map showing example of artificial path features in Lake Fannie in Minnesota ��8 6. Photograph showing Shadroe Canal Weir, Cape Coral, Florida, as an example of a canal ��10 7. Diagram showing shortest and longest axes of a canal/ditch feature ��10 8. Map showing Courtland and Superior Canals near the Nebraska-Kansas Stateline, as examples of canal/ditch features ��11 9. Image showing New Libby Dam, Kootenai River, Libby, Montana, as an example of where a connector could be used to connect the flow of the river from the bottom left side of the image to the lake on the top right side of the image ��14 10. Map showing Oroville Dam, California, to provide an example of a connector hydrographic feature ��15 11. Photograph showing example of a culvert on Town Creek, White County, Georgia ��17 12. Map showing Highway 211 in Virginia crossing unnamed streams as examples of a culvert hydrographic feature. ��18 13. Photograph showing Hoover Dam on Lake Mead, Arizona, as an example of a dam feature ��20 14. Map showing Hoover Dam on Lake Mead in Arizona, as an example of a dam/ weir feature ��21 vii

15. Photograph showing Mendenhall Glacier, Alaska, as an example of ice mass feature type ��25 16. Map showing Mendenhall Glacier in Alaska as an example of an ice mass feature ��26 17. Photograph showing Crater Lake, Oregon, as an example of a lake/pond feature ��28 18. Maps showing examples of natural lake/pond feature ��29 19. Photograph showing example of a pipeline feature ��32 20. Map showing the various pipelines that form the Governor Edmund G. Brown West Branch California Aqueduct as an example of pipeline features ��33 21. Photograph showing Clayton Valley Playa, Nevada, as an example of a playa feature ��35 22. Map showing Racetrack Playa in Death Valley, California, as an example of playa feature ��36 23. Photograph showing U.S. Department of Agriculture Harry K. Dupree Stuttgart National Aquaculture Research Center, Arkansas, as an example of a reservoir feature ��37 24. Map showing Unnamed reservoir in Florida, as an example of reservoir hydrographic feature ��38 25. Photograph of an ocean wave ��40 26. Map showing the Pacific Ocean near Yaquina Head, Newport, Oregon, as an example of a sea/ocean hydrographic feature ��41 27. Photograph showing ephemeral sinking stream in Winchester, Virginia ��43 28. Map showing sink and rise features on Santa Fe River, Florida, as examples of sink/rise hydrographic features ��44 29. Photograph showing Eagle Creek at Zionsville, Indiana, as an example of a river ��46 30. Diagram showing shortest and longest axes of a stream/river feature ��46 31. Map showing Nowitna River, Alaska, as an example of a stream/river hydrographic feature ��47 32. Image of Rikers Island, New York ��50 33. Map showing an island in the Saugatuck Reservoir in Connecticut as an example of treatment for lake/pond features ��51 34. Map showing “Sometimes Islands” in Lake Travis, Texas, as an example of an intermittent island/sandbar ��53 35. A great white heron standing atop mangrove roots, Boggy Key, a Florida Island ��54 36. Map showing a mangrove forest in western Florida as an example of a predetermined area of low confidence ��55 37. Photograph showing snow-cover in the Alaska Interior Mountain Range ��57 38. Map showing an area in the Alaska Range as an example of a low-confidence area, snow-cover ��58 viii

Tables

1A. Domain values for feature attributes ��3 1B. FCode domain values and descriptions ��3 2. Area of complex channels domain codes and attributes ��4 3. Area of complex channels representation rules ��4 4. Artificial path domain codes and attributes ��9 5. Artificial path representation rules ��9 6. Canal/ditch domain codes and attributes for non-National Hydrography Dataset features that are not used for elevation derivatives ��12 7. Canal/ditch domain codes and attributes for National Hydrography Dataset features that are used for purposes other than culverts or those used for hydroflattening ��12 8. Canal/ditch representation rules ��12 9. Connector domain codes and attributes ��16 10. Connector representation rules ��16 11. Culvert domain codes and attributes ��19 12. Culvert representation rules ��19 13. Dam/weir domain codes and attributes for non-National Hydrography dataset features ��22 14. Dam/weir domain codes and attributes for National Hydrography Dataset features ��22 15. Dam/weir representation rules ��22 16. Drainageway domain codes and attributes—feature is appropriate for use in hydroenforcement ��24 17. Drainageway domain codes and attributes—feature should not be used for hydroenforcement ��24 18. Drainageway representation rules ��24 19. Ice mass domain codes and attributes ��27 20. Ice mass representation rules ��27 21. Lake/pond domain codes and attributes ��31 22. Lake/pond representation rules ��31 23. Pipeline domain codes and attributes—feature should not be used for hydroenforcement ��34 24. Pipeline domain codes and attributes—feature is appropriate for use in hydroenforcement ��34 25. Pipeline representation rules ��34 26. Playa domain codes and attributes ��35 27. Playa representation rules ��35 28. Reservoir domain codes and attributes ��39 29. Reservoir representation rules ��39 30. Sea/ocean domain codes and attributes ��42 31. Sea/ocean representation rules ��42 32. Sink/rise domain codes and attributes ��45 33. Sink/rise representation rules ��45 ix

34. Stream/river domain codes and attributes—feature is appropriate for use in hydroenforcement ��48 35. Stream/river domain codes and attributes—feature is appropriate for use in hydroflattening ��48 36. Stream/river representation rules ��48 37. Low-confidence area, predetermined, domain codes and attributes ��54 38. Low-confidence area, predetermined, representation rules ��54 39. Low-confidence area, sparse bare earth, domain codes and attributes ��56 40. Low-confidence area, sparse bare earth, representation rules ��56 41. Low-confidence area, snow-cover, domain codes and attributes ��59 42. Low-confidence area, snow-cover, representation rules ��59

Conversion Factors

U.S. customary units to International System of Units

Multiply By To obtain Length foot (ft) 0.3048 meter (m) mile (mi) 1.609 kilometer (km) Area acre 0.4047 hectare (ha)

Abbreviations

3DEP 3D Elevation Program DEM digital elevation model EClass Elevation Class EDH elevation-derived hydrography FClass Feature Class FCode Feature Code lidar light detection and ranging NHD National Hydrography Dataset READ Representation, Extraction, Attribution, and Delineation

Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

By Christy-Ann M. Archuleta and Silvia Terziotti

the NHD; additionally, the READ Rules does not contain Abstract the full suite of features offered by the NHD. The features in this report were selected for acquisition because they can With the increasing availability of 3D Elevation Program be derived from elevation data, whereas some NHD features (3DEP) quality high resolution elevation data across the cannot be derived in this manner (for example, tunnels). United States and the pressing need for better integrated Additional steps must be taken to produce a dataset that may elevation and hydrography data, the U.S. Geological Survey be migrated into the full NHD feature set, including post- is developing guidance to improve the horizontal and vertical processing steps after data acquisition and quality assurance/ alignment of these datasets. The U.S. Geological Survey is quality control, and running NHD GeoConflation tools (see providing the Elevation-Derived Hydrography—Acquisition https://www.usgs.gov/core-science-systems/ ngp/national- Specifications for the acquisition of elevation-derived hydrog- hydrography/tools#GeoConflation). raphy for the United States, and the companion document The Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation (READ) Rules, which describes the parameters for the portrayal of hydrography features as Elevation-Derived Hydrography— derived from elevation data. The READ Rules provide a definition, example, attribute value list, delineation instruc- Representation, Extraction, Attribution, tions, representation rules, and data extraction rules for each and Delineation Rules Explanations hydrography feature required to meet the Elevation-Derived Hydrography—Acquisition Specifications. Feature definition—The official definition of the hydrographic feature. Attribute/attribute value list—Lists the specific codes Introduction that are required to populate the attribute table for each feature type. This report lists the representation, extraction, attribution, Delineation—Describes the limit or extent of a feature and delineation rules for elevation-derived hydrographic fea- that should be delineated. For instance, a lake/pond feature tures for the U.S. Geological Survey and is meant to be used should be delineated along its shoreline boundary, but the in conjunction with the Elevation-Derived Hydrography— shoreline could be defined in different ways for different situ- Acquisition Specifications Terziotti( and Archuleta, 2020). The ations, so the feature delineation rule narrows down what the intended purpose of the Elevation-Derived Hydrography— extent is in the context of the READ Rules. Representation, Extraction, Attribution, and Delineation Representation rules—Explains how to represent features (READ) Rules is to provide the requirements for collection depending on various factors. and representation of elevation-derived hydrography (EDH). Representation conditions—Explains when a feature The EDH features collected with the READ Rules will be should be delineated as a point, line, or polygon. suitable for use as breaklines to hydroflatten digital elevation Data extraction—Rules for when a feature should be models (DEMs); for processing for pre-conflation of features extracted, what attributes are applied, and how to understand to the National Hydrography Dataset (NHD); and for hydroen- different special-case scenarios based on the source and ancil- forcement of DEMs. lary datasets. The features collected with the READ Rules should Capture conditions—Defines the limits for the size of also follow the specifications outlined in the EDH— feature that should be captured or delineated for a specific Acquisition Specifications (Terziotti and Archuleta, 2020). It feature type. For instance, lake/pond features should only be should be noted that the READ Rules attribution parameters captured if they are 30 meters or greater along the shortest axis do not fulfill all the required attribution specifications for (see fig. 1 for explanation of shortest/longest axis). 2 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

1 would be a line feature that represents a stream/river and is suitable for conflation to NHD. An example of FClass equal to 2 would be a canal/ditch that adds too much complexity to the NHD but is collected to fulfill the needs of a funding partner. If a feature is not an NHD feature and is necessary for elevation processing, a 9 is used as the FClass. A polygon representing a low-confidence area is an example of a feature that Longest axis would not be used in the NHD but may be useful for elevation processing. Elevation Class (EClass)—A short integer one-digit code (table 1A) indicating whether a feature is used for elevation Shortest axis derivatives, hydroflattening, other non-specified elevation purposes, or an elevation dataset limitation feature. For instance, a low-confidence area is coded as a 9. A culvert is a special case of a feature with no associated NHD coding but is necessary for some elevation treatments. Culverts shall be coded as an EClass of 3. Figure 1. Diagram showing shortest and longest axes of a lake/ Feature Code (FCode)—A long integer field contain- pond feature. ing a coded value (table 1B). Most of the feature codes are equivalent to the NHD FCode value, which is a five-digit integer code representing various hydrologic feature types. For Attribute information—Definitions for the codes that instance, a lake/pond has FCode type 39000, and a Stream/ should be applied during data extraction. River has an FCode of 46000. The codes that do not have a Source interpretation guidelines—Explains different corresponding NHD code are included to differentiate features potential scenarios one may want to consider and how to deal that may be useful in describing limitations in the elevation with them when looking at complex situations in the source or dataset, potentially impacting hydrography and elevation ancillary datasets. For instance, if a lake/pond appears to be a derivatives. dry lake, it should be captured as a playa. Another example is Description—A 250-character free-text field with a text guidance as to the difference between lake/pond and reservoir description of FCode and EClass, or user-defined features not features, which can be confusing because there are many lake/ included in the domain list. pond features with “reservoir” in their name; however, they Source—A 128-character free-text field with a text should still be considered lake/pond features unless they have description of the elevation source data used for deriving the a geometric shape and are contained by a constructed basin. hydrography. Light detection and ranging (lidar) source data should include collection name, date, and quality level. Method—A 250-character free-text field with a text Field Definitions and Domain Values description of the method used for deriving the hydrography. For instance, software or models could be listed, or, if for Attributes applicable, digitizing techniques. In addition, this field allows recording of ancillary datasets. Feature Class (FClass)—A short integer one-digit code UserCode—A 25-character free-text field with a code (table 1A) defining whether a feature is intended for use as designated by the acquisition entity to identify features col- an NHD feature (1, will be used for conflation), a non-NHD lected by the data provider (User) outside the scope of features feature (2, outside of the collection criteria and not intended described in this specification document. This field is not to be used for conflation), or a non-hydrography feature (3, required. elevation dataset limitation). An example of FClass equal to Comments—A 250-digit long text field for data provider comments. Requirement Terminology 3

Table 1A. Domain values for feature attributes. Requirement Terminology [FClass, feature class; NHD, National Hydrography Dataset; EClass, feature class (elevation); 3D, three dimensional] Individual requirements that are defined in this report use “shall” or “will” statements, which have a specific meaning in Domain Feature the context of a specification requirement: value description • A “shall” statement means that the requirement FClass must be met. 1 NHD feature (will be used for conflation). • A “will” statement indicates that the requirement is 2 Non-NHD feature (outside of collection criteria). expected to be met wherever possible, but exceptions 9 Nonhydrography feature (elevation dataset to implementation may exist. limitation). EClass 0 Not used for elevation derivatives. 1 Used for hydroflattening (3D polygon). 2 Hydrographic feature used for elevation purposes, other than culverts or those used for hydroflattening. 3 Culvert—used for hydroenforcement. 9 Elevation dataset limitation.

Table 1B. FCode domain values and descriptions.

[FCode, feature code; Desc, description]

FCode Desc 0 User-defined feature1 33400 Connector 33600 Canal/ditch 34300 Dam/weir 36100 Playa 37800 Ice mass 39000 Lake/pond 42800 Pipeline 43600 Reservoir 44500 Sea/ocean 45000 Sink/rise 46000 Stream/river 46800 Drainageway1 53700 Area of complex channels 55800 Artificial path Assigned based on Culvert1—adjacent feature description adjacent features2 991 Low-confidence area (predetermined) 992 Low-confidence area (sparse bare earth) 993 Low-confidence area (snow covered)

1New feature. 2FCodes include 33400, 42800, 33600, 46000, 46800, and 55800. See figure 11 and table 12 in Terziotti and Archuleta (2020). 4 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Area of Complex Channels a feature if acquired, and the source interpretation guidelines give additional information for special circumstances to help An area where a stream or river flows in an intricate determine whether a feature should be acquired or not. Not all network of interlacing channels with no permanent, primary features have source interpretation guidelines, and if this is the channel (figs. 2 and 3). Areas of complex channels are com- case, this will be indicated with “None.” monly found in Alaska, but may be found in other locations as well, and are often associated with glaciation and glacial till. Capture Conditions If area of complex channels contains at least five active Attribute/Attribute Value subchannels (connected to the main channel with water in them, not scarring because of river channel migration) and is Each feature requires domain codes and attributes to be greater than or equal to 320 feet (98 meters) along the shortest entered into the attribute table for the feature class (table 2). axis and greater than or equal to 984 feet (300 meters) along See “Field Definitions and Domain Values for Attributes” sec- the longest axis, then capture. tion for more information on EDH code definitions.

Delineation

The limit of area of complex channels is the outer banks of the outermost channels.

Representation Rules

When delineating a feature, it must be created with the appropriate geometry, either point, line, or polygon, which is determined by the size of the feature or the length along different axes of the feature (table 3). Special conditions: none.

Data Extraction

Table 2. Area of complex channels domain codes and attributes.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 53700 0 Area of complex channels Required Required --

Table 3. Area of complex channels representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) ------2-dimensional (polygon) greater than 0 -- -- Area of Complex Channels 5

EPLAATIO Area of complex channels Artificial path Stream/river or lake/pond Stream/river

0 1 2 MES

0 1 2 KMETERS

150°40'W 150°35'W 1030 102

61°30'N

6128

6126

612

6122

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 3. Example of an area of complex channels along the Susitna River in Alaska. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. 6 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Attribute Information FClass 1—NHD Feature (will be used for conflation). FCode 53700—Complex channel (area where a stream or river flows in an intricate network of interlacing channels). EClass 0—Not used for elevation derivatives.

Source Interpretation Guidelines If area of complex channels coincides with a 2-dimensional (polygon) stream/river, then capture both areas of complex channels and the other feature. For hydroflattening, permanent islands 1 acre (0.4 hectare) (approximately equal to a round island 236 feet [72 meters] in diameter) or larger shall be removed from all waterbody polygons. Artificial Path 7

Artificial Path

An abstraction to facilitate hydrologic modeling through open waterbodies (figs. 4 and 5). Data Extraction

Attribute/Attribute Value Data extraction rules fall into three categories: capture conditions, attribute information, and source interpretation Each feature requires domain codes to be entered into guidelines. The capture conditions explain the requirements the attribute table for the feature class (table 4). See “Field for a feature to be collected, and other pertinent informa- Definitions and Domain Values for Attributes” section for tion about acquisition. The attribute information explains the more information on EDH code definitions. definitions of the codes and attributes that must be applied to a feature if acquired, and the source interpretation guidelines give additional information for special circumstances to help Delineation determine whether a feature should be acquired or not. Not all features have source interpretation guidelines, and if this is the The limit of artificial path is the connection between case, this will be indicated with “None.” the inflow and outflow points of an in-line polygon, the line through a head or terminal open waterbody that connects to the inflow (for terminal), or the outflow point (for head) Capture Conditions (fig. 4). Artificial paths shall be placed in all polygons except isolated reservoirs, isolated lake/ponds, and isolated basins Representation Rules (reservoirs, lake/ponds, and basins not connected to the stream network). Artificial paths shall represent the shortest path When delineating a feature, it must be created with the from the inflow to the outflow without crossing through banks appropriate geometry, either point, line, or polygon, which is or islands. determined by the size of the feature or the length along different axes of the feature (table 5). Special conditions: none.

EPLAATIO

Inflow point Lake/pond

Artificial path

Stream/river

Connector

Outflow point

Figure 4. Diagram showing inflow and outflow points of a lake/pond feature. 8 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

EPLAATIO Stream/river or lake/pond Stream/river Artificial path Canal/ditch

0 1 2 MES

0 1 2 KMETERS

93°14'W 93°13'W 93°12'W 310 30 308

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 5. Example of artificial path features in Lake Fannie in Minnesota. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types but may not have the same density and other characteristics of elevation-derived hydrography. Artificial Path 9

Table 4. Artificial path domain codes and attributes.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 55800 2 Artificial path Required Required --

Table 5. Artificial path representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) -- greater than 0 -- 2-dimensional (polygon) ------

Attribute Information FClass 1—NHD Feature (will be used for conflation). FCode 55800—Artificial path (abstraction to facilitate hydrologic modeling through open waterbodies). EClass 2—Hydrographic feature used for elevation purposes, other than culverts or those used for hydroflattening.

Source Interpretation Guidelines None. 10 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Canal/Ditch

An artificial open waterway constructed to transport water, irrigate or drain land, connect two or more bodies of water, or serve as a waterway for watercraft (figs. 6, 7, and 8).

Attribute/Attribute Value

Each feature requires domain codes and attributes to be entered into the attribute table for the feature class (table 6). See “Field Definitions and Domain Values for Attributes” section for more information on EDH code definitions. For canal/ditch not conforming to representation conditions, or meeting the criteria of the exceptions noted in the capture conditions, refer to information in table 6. For canal/ditches not conforming to representation conditions, refer to information in table 7.

Delineation

The limit of canal/ditch is the top of the banks of the Figure 6. Shadroe Canal Weir, Cape Coral, Florida, as an artificial waterway. example of a canal. Photograph by Shane Prorok, U.S. Geological Survey.

EPLAATIO

Stream/river

Levee

Canal/ditch Artificial path

Stream/river

Canal/ditch Longest axis

Shortest axis

Figure 7. Diagram showing shortest and longest axes of a canal/ditch feature. Canal/Ditch 11

EPLAATIO Stream/river or lake/pond Canal/ditch Reservoir Connector Artificial path Pipeline Stream/river

0 1 2 MES

0 1 2 KMETERS

98°25'W 98°24'W 98°23'W 822 821 820

40°6'N

003

002

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 8. Courtland and Superior Canals near the Nebraska-Kansas Stateline, shown as examples of canal/ditch features. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. 12 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Table 6. Canal/ditch domain codes and attributesfor non-National Hydrography Dataset features (outside of collection criteria) that are not used for elevation derivatives.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class]

FClass FCode EClass Description Source Method UserCode 2 33600 0 Canal/ditch Required Required Required

Table 7. Canal/ditch domain codes and attributes for National Hydrography Dataset features (will be used for conflation) that are used for elevation purposes other than culverts or those used for hydroflattening.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 33600 2 Canal/ditch Required Required --

Representation Rules • greater than or equal to 50 feet (15 meters) but less than 80 feet (24 meters) for a distance less than 1 mile When delineating a feature, it must be created with the (1.6 kilometers), and is connected at both ends to a appropriate geometry, either point, line, or polygon, which is 1-dimensional (line) canal/ditch, determined by the size of the feature or the length along different axes of the feature (table 8). then canal/ditch is represented as a 1-dimensional (line) Special conditions: basic feature object. To accommodate variations in the shortest axis of • greater than or equal to 50 feet (15 meters) but less canal/ditch: than 80 feet (24 meters) for a distance greater than If the shortest axis (table 7) of canal/ditch is: or equal to 1 mile (1.6 kilometers), or greater than or • less than 50 feet (15 meters) but greater than or equal equal to 80 feet (24 meters) regardless of distance, to 20 feet (6 meters) for a distance less than 1 mile and is connected at both ends to a 1-dimensional (line) (1.6 kilometers), and is connected at both ends to a canal/ditch, 2-dimensionalcanal/ditch, then canal/ditch is represented as a 2-dimensional then canal/ditch is represented as a 2-dimensional basic (polygon) basic feature object. feature object. • greater than or equal to 50 feet (15 meters) but less Data Extraction than 20 feet (6 meters) for a distance less than 1 mile (1.6 kilometers), or less than 20 feet (6 meters) regard- Data extraction rules fall into three categories: capture less of distance, and is connected at both ends to a conditions, attribute information, and source interpretation 2-dimensional (polygon) canal/ditch, guidelines. The capture conditions explain the requirements for a feature to be collected, and other pertinent informa- then canal/ditch is represented as a 1-dimensional (line) tion about acquisition. The attribute information explains the basic feature object. definitions of the codes and attributes that must be applied to a feature if acquired, and the source interpretation guidelines

Table 8. Canal/ditch representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) -- less than 50 feet -- (15 meters) 2-dimensional (polygon) -- greater than 50 feet -- (15 meters) Canal/Ditch 13 give additional information for special circumstances to help If a canal or ditch passes through a siphon that meets determine whether a feature should be acquired or not. Not all capture conditions for pipeline, features have source interpretation guidelines, and if this is the then do not capture canal/ditch. See “Pipeline” section. case, this will be indicated with “None.” Do not capture canal/ditch associated with a cranberry bog or rice paddy. Capture Conditions If canal/ditch is named, or if canal/ditch is greater than or equal to 984 feet (300 meters) along the longest axis, then capture. If canal/ditch is needed to provide network connectivity, then capture. If canal/ditch is within agricultural fields and drains to another canal/ditch or other hydrologic feature, then do not capture (see following exception). The exception is if a project has a special need for canals and ditch features that are within agricultural fields and drain to another canal/ditch or other hydrologic feature, then these features should be coded with a separate Fcode (user defined) so that they can be excluded from the features to conflate to NHD. Note that a hydrologic network should not be broken if features are excluded.

Attribute Information FClass 2—Non-NHD Feature (outside of collection criteria). FCode 33600—Canal/ditch (an artificial open waterway constructed to transport water, to irrigate or drain land, to connect two or more bodies of water, or to serve as a waterway for watercraft. May be a named feature). EClass 0—Not used for elevation derivatives. Another possibility is the following: FClass 1—NHD Feature (will be used for conflation). FCode 33600—Canal/ditch (an artificial open waterway constructed to transport water, to irrigate or drain land, to connect two or more bodies of water, or to serve as a waterway for watercraft. May be a named feature). EClass 2—Hydrographic feature used for elevation purposes, other than culverts or those used for hydroflattening.

Source Interpretation Guidelines Do not capture underground aqueducts as canal/ditch. See “Pipeline” section. Do not capture rivers that have been channelized to control flooding or erosion, or to maintain flow for navigation as canal/ditch. See “Stream/River” section (for example, Los Angeles River is a large channelized river, and coded as stream/river). Do capture as canal/ditch only those inland navigation waterways that are cut through land to bypass outcrops or rapids, or to connect two bodies of water. 14 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Connector Data Extraction

A known, but nonspecific, connection between two non- Data extraction rules fall into three categories: capture adjacent network segments. Connector feature types are used conditions, attribute information, and source interpretation when two constructed surface-water features appear to interact guidelines. The capture conditions explain the requirements but there is no discernable evidence of the interaction on the for a feature to be collected, and other pertinent informa- surface. A connector is used to show the connection between tion about acquisition. The attribute information explains the the lake/pond and the stream output through a dam (figs. 9 definitions of the codes and attributes that must be applied to and 10). a feature if acquired, and the source interpretation guidelines give additional information for special circumstances to help determine whether a feature should be acquired or not. Not all features have source interpretation guidelines, and if this is the case, this will be indicated with “None.”

Capture Conditions If connector is required to maintain connectivity between two network feature objects that represent area of complex channels, canal/ditch, lake/pond, reservoir, sea/ocean, or stream/river, then capture.

Attribute Information FClass 1—NHD Feature (will be used for conflation). Figure 9. New Libby Dam, Kootenai River, Libby, Montana, is FCode 34400—Connector (a known, but nonspecific, shown as an example of where a connector could be used to invisible connection between two nonadjacent network connect the flow of the river from the bottom left side of the image segments). to the lake on the top right side of the image. Photograph by U.S. EClass 2—Hydrographic feature used for elevation pur- Army Corps of Engineers. poses, other than culverts or those used for hydroflattening.

Attribute/Attribute Value Source Interpretation Guidelines

Each feature requires domain codes and attributes to be The following list of conditions indicates when and why entered into the attribute table for the feature class (table 9). the capture of connector is required: See “Field Definitions and Domain Values for Attributes” sec- 1. When connector is part of a network that is represented tion for more information on EDH code definitions. as being connected. 2. When there is a gap with no collected network feature Delineation object between pieces of the network; for example, at a 2-dimensional (polygon) dam/weir that causes a The limit of connector is the virtual line connecting two gap between an upstream lake/pond and a downstream nonadjacent network segments. stream/river.

Representation Rules

EPLAATIO Lake/pond Stream/river Dam/weir Canal/ditch Canal/ditch Connector Artificial path Pipeline

0 1 2 MES

0 1 2 KMETERS

121°32'W 121°31'W 1212 12128 1212 39°34'N

333

332

A 331

330

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203 Figure 10. Oroville Dam, California, is shown to provide an example of a connector hydrographic feature. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. 16 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Table 9. Connector domain codes and attributes.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 33400 2 Connector Required Required --

Table 10. Connector representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) -- greater than 0 -- but less than 50 feet (15 meters) 2-dimensional (polygon) -- greater than 50 feet -- (15 meters) Culvert 17

Culvert Data Extraction

Subsurface water conveyances under a transportation Data extraction rules fall into three categories: capture feature (figs. 11 and 12). conditions, attribute information, and source interpretation guidelines. The capture conditions explain the requirements for a feature to be collected, and other pertinent information about acquisition. The attribute information explains the definitions of the codes and attributes that must be applied to a feature if acquired, and the source interpretation guidelines give additional information for special circumstances to help determine whether a feature should be acquired or not. Not all features have source interpretation guidelines, and if this is the case, this will be indicated with “None.”

Capture Conditions If the culvert is greater than 5 feet (1.5 meters) along the longest axis, then capture.

Figure 11. Example of a culvert on Town Creek, White County, Georgia. Photograph by Alan Cressler, U.S. Geological Survey. Attribute Information FClass 1—NHD Feature (will be used for conflation). Attribute/Attribute Value EClass 3—Culvert—Used for hydroenforcement. FCode 0000—(See below). Each feature requires domain codes and attributes to be The rules for determining the correct FCode for a culvert entered into the attribute table for the feature class (table 11). are based on a priority ranking system. When a culvert sepa- See “Field Definitions and Domain Values for Attributes” sec- rates two or more features with different FCodes, the FCode tion for more information on EDH code definitions. of the culvert is selected based on the priority ranking of the features separated by the culvert (see Terziotti and Archuleta, Delineation 2020, for more information and examples). For single feature types entering and flowing out of The limit of the culvert is the edges of the water convey- a culvert: ance structure. If the culvert does not extend completely across 1. connector (FCode 33400), the higher elevation part of the DEM, hydroenforcement may fail at that location. 2. pipeline (FCode 42800), 3. canal/ditch (FCode 33600), Representation Rules 4. stream/river (FCode 46000), When delineating a feature, it must be created with the 5. drainageway (FCode 46800), and appropriate geometry, either point, line, or polygon, which is determined by the size of the feature or the length along differ- 6. artificial path (FCode 55800). ent axes of the feature (table 12). If more than two features flow into and out from a cul- Special conditions: vert, the prioritization of the FCodes is ranked to maintain the Culvert water conveyances may take many forms, such as connection of the primary features flowing through the culvert, a corrugated metal pipe running under a driveway, a massive as follows: concrete box under a superhighway, or a platform suspended over flowing water. The purpose of the culvert feature in the 1. stream/river (FCode 46000), stream network is to connect the water flowing across the con- 2. canal/ditch (FCode 33600), veyance to the flowing water without breaking the downstream flow in the network; therefore, culvert features will be delin- 3. pipeline (FCode 428000), and eated as simple lines connecting the upstream and downstream segments of single-line streams or as a segment of an artificial 4. connector (FCode 33400). path within 2-dimensional features. If no feature exists on both sides of the culvert, follow the priority ranking for two features separated by a culvert. 18 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

EPLAATIO Lake/pond Stream/river—Culvert Artificial path Connector Stream/river Dam/weir

0 0.2 0. ME

0 0.2 0. KMETER

802 80230 8021 80200 78°3'30"W 78°3'15"W 78°3'W

38300

382

38230

3821

38200

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 12. Highway 211 in Virginia crossing unnamed streams as examples of a culvert hydrographic feature. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types but may not have the same density and other characteristics of elevation-derived hydrography. Culvert 19

Source Interpretation Guidelines None.

Table 11. Culvert domain codes and attributes.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 Dependent on connecting features 3 Culvert - used for Required Required -- (see special conditions below). hydroenforcement

Table 12. Culvert representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) -- greater than 0 -- 2-dimensional (polygon) ------20 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Dam/Weir Data Extraction

A barrier constructed to control the flow or raise the level Data extraction rules fall into three categories: capture of water (figs. 13 and 14). conditions, attribute information, and source interpretation guidelines. The capture conditions explain the requirements for a feature to be collected, and other pertinent information about acquisition. The attribute information explains the definitions of the codes and attributes that must be applied to a feature if acquired, and the source interpretation guidelines give additional information for special circumstances to help determine whether a feature should be acquired or not. Not all features have source interpretation guidelines, and if this is the case, this will be indicated with “None.”

Capture Conditions If dam/weir is greater than or equal to 240 feet (73 meters) along the longest axis, then capture.

Attribute Information FClass 2—Non-NHD Feature (outside of collection criteria). FCode 34300—Dam/Weir (a barrier constructed to control the flow or raise the level of water. No information on the predominant construction material). EClass 0—Not used for elevation derivatives. Another possibility is the following: FClass 1—NHD Feature (will be used for conflation). Figure 13. Hoover Dam on Lake Mead, Arizona, as an example of FCode 34300—Dam/weir (a barrier constructed to con- a dam feature. Photograph by Michael R. Rosen, U.S. Geological trol the flow or raise the level of water. No information on the Survey. predominant construction material). EClass 0—Not used for elevation derivatives.

Attribute/Attribute Value Source Interpretation Guidelines Each feature requires domain codes and attributes to be None. entered into the attribute table for the feature class (table 13). See “Field Definitions and Domain Values for Attributes” section for more information on EDH code definitions. Another possible option is shown in table 14.

Representation Rules

EPLAATIO Stream/river or lake/pond Stream/river Dam/weir Connector Spillway Pipeline Artificial path

A 0 1 2 3 MES

0 1 2 3 KMETERS

114°50'W 11 110

36°10'N

360 A A

3600

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 14. Hoover Dam on Lake Mead in Arizona, shown as an example of a dam/weir feature. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. 22 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Table 13. Dam/weir domain codes and attributes for non-National Hydrography Dataset features (outside of collection criteria).

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class]

FClass FCode EClass Description Source Method UserCode 2 34300 0 Dam/weir Required Required Required

Table 14. Dam/weir domain codes and attributes for National Hydrography Dataset features (will be used for conflation).

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 34300 0 Dam/weir Required Required --

Table 15. Dam/weir representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) -- less than 40 feet -- (for use on lines) 1-dimensional (line) -- less than 40 feet -- (for use on polygon waterbody features) 2-dimensional (polygon) -- greater than 40 feet -- (for use on polygon waterbody features) Drainageway 23

Drainageway If shortest axis of drainageway is greater than or equal to 50 feet (15 meters) and does not meet drainageway criteria, A watercourse that conveys or is likely to convey water collect as appropriate feature for capture conditions (stream/ but lacks a clearly defined channel or banks differentiating river, area of complex channels, playa, and others as needed). it from an ephemeral stream/river. Drainageways typically convey water for limited periods of time and do not carry Data Extraction perennial flow except when flow is the result of contributions from constructed subsurface or other human-induced drainage Data extraction rules fall into three categories: capture (for example, foundation drains or storm drains that intercept conditions, attribute information, and source interpretation groundwater). Drainageways may follow natural topographic guidelines. The capture conditions explain the requirements flow paths or be the results of human-made flow paths. for a feature to be collected, and other pertinent information about acquisition. The attribute information explains the Attribute/Attribute Value definitions of the codes and attributes that must be applied to a feature if acquired, and the source interpretation guidelines Each feature requires domain codes and attributes give additional information for special circumstances to help to be entered into the attribute table for the feature class determine whether a feature should be acquired or not. Not all (tables 16 and 17). See “Field Definitions and Domain Values features have source interpretation guidelines, and if this is the for Attributes” section for more information on EDH code case, this will be indicated with “None.” definitions. Another possible option is shown in table 17. Capture Conditions Drainageways have no clearly defined capture conditions. Delineation Modelling techniques (flow models, elevation surface models, logistic regression models, and so on) expose features and, The limit of a drainageway is the topographic flowpath or therefore, require further investigation to determine their status the approximate overland flow path between two disconnected and categorization as hydrographic features. drainage network features. May be determined by modelling techniques, but a clearly defined channel may not be easily recognized. Attribute Information FClass 1—NHD Feature (will be used for conflation). Representation Rules FCode 46800—Drainageway (a flowpath without a clearly defined channel). When delineating a feature, it must be created with the EClass 2—Hydrographic feature used for elevation pur- appropriate geometry, either point, line, or polygon, which is poses, other than culverts or those used for hydroflattening. determined by the size of the feature or the length along differ- Another possibility is the following: ent axes of the feature (table 18). FClass 1—NHD Feature (will be used for conflation). Special conditions: none. FCode 46800—Drainageway (a flowpath without a To accommodate variations in the shortest axis of clearly defined channel). drainageway: EClass 0—Not used for elevation derivatives. FOR EDH: If shortest axis of drainageway is less than 20 feet (6 meters) regardless of distance, and is connected at both ends to a 2-dimensional (polygon) stream/river, then drainageway is represented as a 1-dimensional (line) basic feature object. 24 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Table 16. Drainageway domain codes and attributes—feature is appropriate for use in hydroenforcement.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 46800 2 Drainageway Required Required --

Table 17. Drainageway domain codes and attributes—feature should not be used for hydroenforcement.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 46800 0 Drainageway Required Required --

Table 18. Drainageway representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) -- greater than 0 -- 2-dimensional (polygon) ------Ice Mass 25

Ice Mass Capture Conditions If ice mass is greater than or equal to 246 feet along the A field of ice formed in regions of perennial frost (figs. 15 shortest axis (or approximately 75 meters), then capture. and 16). Z-values (elevation values at a particular location) are measured at the boundary of the feature. Attribute/Attribute Value

Each feature requires domain codes to be entered into Attribute Information the attribute table for the feature class (table 19). See “Field FClass 1—NHD Feature (will be used for conflation). Definitions and Domain Values for Attributes” section for FCode 37800—Ice mass (a field of ice usually formed more information on EDH code definitions. in regions of perennial frost. Ice Mass primarily consists of glaciers). Delineation EClass 0—Not used for elevation derivatives.

The limit of ice mass is the extent of ice or snow. Source Interpretation Guidelines

Representation Rules None. If glaciers are contiguous, When delineating a feature, it must be created with the then the dividing line is the approximate line of diver- appropriate geometry, either point, line, or polygon, which is gence or confluence, as determined by the topography of the determined by the size of the feature or the length along differ- ice masses, or by the changes in color or texture, or both. ent axes of the feature (table 20). Special conditions: none.

Data Extraction

Figure 15. Mendenhall Glacier, Alaska, shown as an example of ice mass feature type. Photograph by Matt Artz, U.S. Geological Survey. 26 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

EPLAATIO Ice mass Artificial path Lake/pond Stream/river

0 1 2 MES

0 1 2 KMETERS

134°35'W 134°30'W 132

832

Mendenhall Glacier

830

828

826

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 16. Mendenhall Glacier in Alaska is shown as an example of an ice mass feature. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. Ice Mass 27

Table 19. Ice mass domain codes and attributes.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 37800 0 Ice mass Required Required --

Table 20. Ice mass representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) ------2-dimensional (polygon) greater than 0 -- -- 28 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Lake/Pond definitions of the codes and attributes that must be applied to a feature if acquired, and the source interpretation guidelines A standing body of water with a predominantly natural give additional information for special circumstances to help shoreline surrounded by land (figs. 17 and 18). determine whether a feature should be acquired or not. Not all features have source interpretation guidelines, and if this is the case, this will be indicated with “None.”

Capture Conditions For required lidar base specification breakline acquisition, waterbodies with a surface area of 2 acres (0.8 hectare) or greater (approximately equal to a round pond 328 feet [100 meters] in diameter) at the time of collection shall be flattened. For EDH feature collection, if lake/pond is greater than or equal to 100 feet (30 meters) along the shortest axis (or approximately 0.4 hectare), then capture (for required hydroflattening breaklines, not applicable).

Attribute Information

Figure 17. Crater Lake, Oregon, shown as an example of a lake/ FClass 1—NHD Feature (will be used for conflation). pond feature. Photograph by Willie Scott, U.S. Geological Survey. FCode 39000—Lake/pond (a standing body of water with a predominantly natural shoreline surrounded by land or a flooded river system where a dam has been built to with- Attribute/Attribute Value hold water). EClass 1—Use for hydroflattening (3-dimensional Each feature requires domain codes to be entered into polygon). the attribute table for the feature class (table 21). See “Field Definitions and Domain Values for Attributes” section for Source Interpretation Guidelines more information on EDH code definitions. Do not capture dry lakes as lake/pond. See Delineation “Playa” section. Refer to the feature definition to decide how to catego- The limit of lake/pond where stream/river enters or leaves rize a given feature instance. Do not use the proper name is determined by the conformation of the land. of the feature as a guide. Many features that are known The limit of lake/pond is the position of the visible edge as “Reservoirs” or labeled on the topographic map as of the waterbody (date of lidar collection). “Reservoirs” will be captured as lake/pond. “Stock Tanks” may be reservoir or lake/pond depending on their form. As a general rule, if a waterbody has a geometric shape or other Representation Rules information indicates it is contained by a constructed basin, capture it as reservoir. If it does not appear to be contained by When delineating a feature, it must be created with the a constructed basin, capture it as lake/pond. appropriate geometry, either point, line, or polygon, which is The minimum size for islands within lake/pond is 60 feet determined by the size of the feature or the length along differ- (18 meters) along the shortest axis. ent axes of the feature (table 22). For lidar base specification hydroflattening, perma- Special conditions: none. nent islands 1 acre (0.4 hectare) (approximately equal to a round island 236 feet [72 meters] in diameter) or larger Data Extraction shall be delineated within all waterbodies and excluded from hydroflattening. Data extraction rules fall into three categories: capture For examples of islands and intermittently submerged conditions, attribute information, and source interpretation islands that may be apparent on elevation surface, see guidelines. The capture conditions explain the requirements “Additional Elevation-Derived Hydrography Treatments and for a feature to be collected, and other pertinent informa- Elevation Specific Features” section. tion about acquisition. The attribute information explains the Lake/Pond 29

EPLAATIO Stream/river or lake/pond Stream/river Swamp/marsh Canal/ditch Artificial path

0 8 MES

0 8 KMETERS

122°20'W 122°15'W 12210 1220 12200

300

A A

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203 Figure 18. Examples of natural lake/pond feature. A, Crater Lake on Mount Mazama, Oregon, is shown as an example of natural lake/pond feature. B, North Fork Reservoir, North Carolina, is shown as an example of constructed lake/ pond feature. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. 30 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

EPLAATIO Lake/pond Stream/river Artificial path Connector

0 1 2 MES

0 1 2 KMETERS

82°22'W 82°21'W 821 8218 821

338 Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203 Figure 18. Examples of natural lake/pond feature. A, Crater Lake on Mount Mazama, Oregon, is shown as an example of natural lake/ pond feature. B, North Fork Reservoir, North Carolina, is shown as an example of constructed lake/pond feature. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography.—Continued Lake/Pond 31

Table 21. Lake/pond domain codes and attributes.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 39000 1 Lake/pond Required Required --

Table 22. Lake/pond representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) ------2-dimensional (polygon) greater than 0 -- -- 32 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Pipeline for a feature to be collected, and other pertinent information about acquisition. The attribute information explains the A surface or subsurface, closed or open, constructed con- definitions of the codes and attributes that must be applied to duit for conveying water (figs. 19 and 20). a feature if acquired, and the source interpretation guidelines give additional information for special circumstances to help determine whether a feature should be acquired or not. Not all Attribute/Attribute Value features have source interpretation guidelines, and if this is the case, this will be indicated with “None.” Each feature requires domain codes to be entered into the attribute table for the feature class (table 23). See “Field Definitions and Domain Values for Attributes” section for Capture Conditions more information on EDH code definitions. If pipeline conveys water between natural water fea- Another possible option is shown in table 24. tures such as stream/river or lake/pond features, is above ground, is not underwater, and is greater than or equal to 5 feet Delineation (1.5 meters) along the longest axis, then capture. The limit of an underground pipeline is the edge of the Note that the pipeline must connect to existing water ground scars or linear clearings, or other above ground arti- features or water conveyance on both ends. facts that can be detected from ancillary data or other methods. If pipeline conveys water underground, and the pipeline The limit of a near-ground or elevated pipeline is the is greater than 50 feet in length, then capture. extent of the structure. Note that the only required pipelines to capture are those that are above ground, but if an ancillary source is used, an underground pipeline can be added to connect above ground Representation Rules features. Source of the ancillary data must be cited. If pipeline conveys water under a road, and the road When delineating a feature, it must be created with the is less than 50 feet in width, then capture as a culvert (add appropriate geometry, either point, line, or polygon, which is EClass of 3) see culvert description for FCode, and not as determined by the size of the feature or the length along differ- pipeline. ent axes of the feature (table 25). Special conditions: none. Attribute Information Data Extraction FClass 1—NHD Feature (will be used for conflation). FCode 42800—Pipeline (a closed conduit, with pumps, Data extraction rules fall into three categories: capture valves and control devices, for conveying water). conditions, attribute information, and source interpretation EClass 0—Not used for elevation derivatives. guidelines. The capture conditions explain the requirements OR

Figure 19. Example of a pipeline feature. This example of a pipeline is an aqueduct pipeline feature in San Juaquin Valley, California. Photograph by U.S. Geological Survey. Pipeline 33

EPLAATIO

Lake/pond Canal/ditch Canal/ditch Connector Artificial path Pipeline Stream/river

0 2 MES

0 2 KMETERS

118°50'W 118

Governor Edmund G. Brown West Branch California Aqueduct

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 20. The various pipelines that form the Governor Edmund G. Brown West Branch California Aqueduct are shown as an example of pipeline features. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. 34 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

FClass 1—NHD Feature (will be used for conflation). FCode 42800—Pipeline (a closed conduit, with pumps, valves and control devices, for conveying water). EClass 2—Hydrographic feature used for elevation purposes, other than culverts or those used for hydroflattening.

Source Interpretation Guidelines None.

Table 23. Pipeline domain codes and attributes—feature should not be used for hydroenforcement.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 42800 0 Pipeline Required Required --

Table 24. Pipeline domain codes and attributes—feature is appropriate for use in hydroenforcement.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 42800 2 Pipeline Required Required --

Table 25. Pipeline representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) -- greater than 0 -- 2-dimensional (polygon) ------Playa 35

Playa Representation Rules

The flat area at the lowest part of an undrained desert When delineating a feature, it must be created with the basin, generally devoid of vegetation (figs. 21 and 22). appropriate geometry, either point, line, or polygon, which is determined by the size of the feature or the length along different axes of the feature (table 27). Special conditions: none.

Data Extraction

Data extraction rules fall into three categories: capture conditions, attribute information, and source interpretation guidelines. The capture conditions explain the requirements for a feature to be collected, and other pertinent information about acquisition. The attribute information explains the definitions of the codes and attributes that must be applied to a feature if acquired, and the source interpretation guidelines Figure 21. Clayton Valley Playa, Nevada, as an example of a give additional information for special circumstances to help playa feature. Photograph by Lisa Stillings, U.S. Geological Survey. determine whether a feature should be acquired or not. Not all features have source interpretation guidelines, and if this is the case, this will be indicated with “None.” Attribute/Attribute Value Capture Conditions Each feature requires domain codes to be entered into the attribute table for the feature class (table 26). See “Field If playa is greater than or equal to 200 feet (61 meters) Definitions and Domain Values for Attributes” section for along the shortest axis, then capture. more information on EDH code definitions. Attribute Information Delineation FClass 1—NHD Feature (will be used for conflation). FCode 36100—Playa (the flat area at the lowest part of The limit of playa is the extent of the lowest part of an undrained desert basin, generally devoid of vegetation. May the basin. be a named feature). EClass 0—Not used for elevation derivatives.

Source Interpretation Guidelines None.

Table 26. Playa domain codes and attributes.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 36100 0 Playa Required Required --

Table 27. Playa representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) ------2-dimensional (polygon) greater than 0 -- -- 36 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

EPLAATIO

Playa Artificial path Stream/river

0 1 2 MES

0 1 2 KMETERS

117°37'W 117°36'W 117°35'W 113 1133 1132

362

361

Racetrack Playa 360

363

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 22. Racetrack Playa in Death Valley, California, is shown as an example of playa feature. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. Reservoir 37

Reservoir a feature if acquired, and the source interpretation guidelines give additional information for special circumstances to help A constructed basin formed to contain water or other determine whether a feature should be acquired or not. Not all liquids (figs. 23 and 24). features have source interpretation guidelines, and if this is the case, this will be indicated with “None.”

Capture Conditions For required lidar base specification hydroflattening breakline acquisition, waterbodies with a surface area of 2 acres (0.8 hectare) or greater (approximately equal to a round pond 328 feet [100 meters] in diameter) at the time of collection shall be flattened. For EDH feature collection, if lake/pond is greater than or equal to 100 feet along the shortest axis (or approximately 0.4 hectare), then capture (for required hydroflattening breaklines, not applicable).

Attribute Information Figure 23. U.S. Department of Agriculture Harry K. Dupree Stuttgart National Aquaculture Research Center, Arkansas, shown FClass 1—NHD Feature (will be used for conflation). as an example of a reservoir feature. In the example, the reservoir FCode 43600—Reservoir (a constructed basin formed to is an aquaculture pond with a constructed shoreline. Photograph contain water or other liquids. Function or purpose of reservoir by U.S. Geological Survey. is unknown. Predominant construction material used to build the reservoir is unknown. The portion of the year the feature contains water is unknown). Attribute/Attribute Value EClass 1—Use for hydroflattening (3D polygon). Each feature requires domain codes to be entered into Source Interpretation Guidelines the attribute table for the feature class (table 28). See “Field Definitions and Domain Values for Attributes” section for Refer to the feature definition to decide how to catego- more information on EDH code definitions. rize a given feature instance. Do not use the proper name of the feature as a guide. Many features that are known as “Reservoirs” or labeled on the topographic map as Delineation “Reservoirs” will be captured as lake/ponds. “Stock Tanks” may be reservoir or lake/pond depending on their form. As The limit of reservoir is the rim of the constructed basin. a general rule, if a waterbody has a geometric shape or other information indicates it is contained by a constructed basin, Representation Rules capture it as reservoir. If it does not appear to be contained by a constructed basin, capture it as lake/pond. When delineating a feature, it must be created with the If reservoir is less than 100 feet along the shortest axis appropriate geometry, either point, line, or polygon, which is and is within 40 feet of another reservoir with the same attri- determined by the size of the feature or the length along differ- bute values, ent axes of the feature (table 29). then capture as one reservoir only if the combined areas Special conditions: none. are greater than or equal to 100 feet along the shortest axis. For lidar base specification hydroflattening, permanent islands 1 acre (0.4 hectare) (approximately equal to a round Data Extraction island 236 feet [72 meters] in diameter) or larger shall be delineated within all waterbodies. Data extraction rules fall into three categories: capture For examples of islands and intermittently submerged conditions, attribute information, and source interpretation islands that may be apparent on elevation surface, see guidelines. The capture conditions explain the requirements “Additional EDH Related Treatments and Elevation Specific for a feature to be collected, and other pertinent informa- Features” section. tion about acquisition. The attribute information explains the definitions of the codes and attributes that must be applied to 38 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

EPLAATIO Stream/river or lake/pond Artificial path Reservoir Stream/river Swamp/marsh Underground conduit

0 1 2 MES

0 1 2 KMETERS

82°35'W 82°34'W 82°33'W 8232 8231 8230

2 Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 24. Unnamed reservoir in Florida shown as an example of reservoir hydrographic feature. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. Reservoir 39

Table 28. Reservoir domain codes and attributes.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 43600 1 Reservoir Required Required --

Table 29. Reservoir representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) ------2-dimensional (polygon) greater than 0 -- -- 40 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Sea/Ocean Representation Rules

The great body of saltwater that covers much of the Earth When delineating a feature, it must be created with the (figs. 25 and 26). appropriate geometry, either point, line, or polygon, which is determined by the size of the feature or the length along different axes of the feature (table 31). Special conditions: none.

Data Extraction

Attribute/Attribute Value Capture Conditions Capture all. Each feature requires domain codes to be entered into the attribute table for the feature class (table 30). See “Field Definitions and Domain Values for Attributes” section for Attribute Information more information on EDH code definitions. FClass 1—NHD Feature (will be used for conflation). FCode 44500—Sea/ocean (the great body of saltwater Delineation that covers much of the Earth. May be a named feature). EClass 1—Use for hydroflattening (3D polygon). The limit of sea/ocean is the approximate line of mean high water. In areas where rivers enter sea/ocean, the limit is where Source Interpretation Guidelines the conformation of the land and water makes the division obvious, or, if the land and water do not suggest an obvious The minimum size for islands within sea/ocean is 1 acre limit, the limit is where the river reaches a width of 1 nauti- (0.4 hectare) along the shortest axis. cal mile (6,076.1 feet or 1.15 statute miles) with no further For lidar base specification hydroflattening, permanent constrictions. islands 1 acre (0.4 hectare) (approximately equal to a round A boundary waterbody is any waterbody that contains the island 236 feet [72 meters] in diameter) or larger shall be boundary of the collection (that is, the actual opposite bank delineated within all waterbodies. or shore is not being mapped). Boundary waterbodies may be For examples of islands and intermittently submerged a single water surface elevation (for example, lake) or gradi- islands, which may be apparent on elevation surface, see ent (for example, river). Boundary waterbodies will contain “Additional Elevation-Derived Hydrography Treatments and either a centerline or an Elevation Terminus line, depending on Elevation Specific Features” section. circumstances. Sea/Ocean 41

EPLAATIO Sea/ocean Stream/river Stream/river or lake/pond Pipeline Artificial path

0 2 MES

0 2 KMETERS

124°10'W 120

Yaquina Head, Newport, Oregon

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 26. The Pacific Ocean near Yaquina Head, Newport, Oregon, is shown as an example of a sea/ocean hydrographic feature. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. 42 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Table 30. Sea/ocean domain codes and attributes.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 44500 1 Sea/ocean Required Required --

Table 31. Sea/ocean representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) ------2-dimensional (polygon) greater than 0 -- -- Sink/Rise 43

Sink/Rise Data Extraction

The place at which a stream disappears into an under- Data extraction rules fall into three categories: capture ground conduit or reappears at the surface from an under- conditions, attribute information, and source interpretation ground conduit, or an isolated depression where the network guidelines. The capture conditions explain the requirements ends (figs. 27 and 28). for a feature to be collected, and other pertinent information about acquisition. The attribute information explains the definitions of the codes and attributes that must be applied to a feature if acquired, and the source interpretation guidelines give additional information for special circumstances to help determine whether a feature should be acquired or not. Not all features have source interpretation guidelines, and if this is the case, this will be indicated with “None.”

Capture Conditions If stream disappears and reappears downstream on stream/river, then capture at the point of disappearance and reappearance.

Figure 27. Ephemeral sinking stream in Winchester, Virginia. Attribute Information Photograph by Benjamin V. Miller, U.S. Geological Survey. FClass 1—NHD Feature (will be used for conflation). FCode 45000—Sink/rise (the place at which a stream Attribute/Attribute Value disappears underground or reappears at the surface in a karst area. SinkRise also exists as an NHDPoint. May be a named Each feature requires domain codes to be entered into feature). the attribute table for the feature class (table 32). See “Field EClass 0—Not used for elevation derivatives. Definitions and Domain Values for Attributes” section for more information on EDH code definitions. Source Interpretation Guidelines Delineation None.

The limit of sink/rise is the place at which a stream disappears underground or reappears at the surface.

Representation Rules

EPLAATIO Stream/river or lake/pond Underground conduit—Not mapped from light detection and ranging, Reservoir shown for explanatory purposes (! only Swamp/marsh Connector

Artificial path (! Sink/rise

Stream/river

82°38'W 82°37'W 82°36'W 823 823 8233

(! 29°56'N (! (!

29°55'N

23 (!

Base from U.S. Geological Survey digital data, various scales, various dates 0 1 2 MES Albers Equal-Area Conic proection ell-known identifier: 10203 0 1 2 KMETERS

Figure 28. Sink and rise features on Santa Fe River, Florida, shown as examples of sink/rise hydrographic features. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. Sink/Rise 45

Table 32. Sink/rise domain codes and attributes.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 45000 0 Sink/rise Required Required --

Table 33. Sink/rise representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) greater than 0 -- -- 1-dimensional (line) ------2-dimensional (polygon) ------46 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Stream/River Delineation

A body of flowing water figs.( 29, 30, and 31). The delineation of stream/river features should adhere to the following rules, describing the boundary limits of the feature, and other delineation rules: • The boundary limit of stream/river: o is determined by the position of the visible edge of the banks as depicted on the digital elevation model (as of date of lidar collection). o where it enters or leaves lake/pond ▪ is determined by the conformation of the land. o where it enters sea/ocean ▪ is determined by the location where the conformation of the land and water makes the division obvious, or, if the land and water do not suggest an obvious limit, the limit is where the stream reaches a width of 1 nautical mile (6,076.1 feet or Figure 29. Eagle Creek at Zionsville, Indiana, shown as an 1.15 statute miles) with no further constrictions. example of a river. Photograph by U.S. Geological Survey. o Where flattening is required, ▪ flattened streams and rivers shall present a flat and level water surface bank-to-bank (perpendicular to the apparent flow centerline). ▪ flattened streams and rivers shall present a gradi- Shortest axis Longest axis ent downhill water surface, following the immediately surrounding terrain. • Other delineation rules o The upper limit of stream/river is where the feature first becomes evident as a channel. o In cases of sharp turns of rapidly moving water, where the natural water surface is notably not level bank-to-bank, the water surface will be represented as it exists while maintaining an aesthetic carto- graphic appearance. Figure 30. Diagram showing shortest and longest axes of a stream/river feature. o The entire water surface edge shall be at or below the immediately surrounding terrain. Attribute/Attribute Value o Stream channels shall break at culvert locations leav- ing the roadway over the culvert intact. Each feature requires domain codes to be entered into the attribute table for the feature class (table 34). See “Field o Streams shall be continuous at bridge locations. Definitions and Domain Values for Attributes” section for more information on EDH code definitions. Another possibility is shown in table 35. Representation Rules

EPLAATIO Stream/river or lake/pond Artificial path Stream/river

0 1 2 MES

0 1 2 KMETERS

154°25'W 154°20'W 11 110 10

630

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 31. Nowitna River, Alaska, shown as an example of a stream/river hydrographic feature. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. 48 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Table 34. Stream/river domain codes and attributes—feature is appropriate for use in hydroenforcement.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 46000 2 Stream/river Required Required --

Table 35. Stream/river domain codes and attributes—feature is appropriate for use in hydroflattening (three-dimensional polygon)

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 1 46000 1 Stream/river Required Required --

Table 36. Stream/river representation rules.

[--, no data; NHD, National Hydrography Dataset]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) -- less than 50 feet -- (15 meters) NHD less than 98 feet (30 meters) hydroflattening breakline 2-dimensional (polygon) -- greater than 50 feet -- (15 meters) NHD greater than 98 feet (30 meters) hydroflattening breakline

Special conditions: then stream/river is represented as a 1-dimensional To accommodate variations in the shortest axis of stream/river: (line) basic feature object. • For lidar base specification collection (not collecting • greater than or equal to 50 feet (15 meters) but less optional features), streams and rivers of approximately than 80 feet (24 meters) for a distance less than 100 feet (30 meters) or greater nominal width shall be 0.6 mile (1 kilometer), and is connected at both ends to flattened (captured as a polygon). a 1-dimensional (line) stream/river, • For EDH feature collection, if shortest axis of then stream/river is represented as a 1-dimensional stream/river is (line) basic feature object. less than 50 feet (15 meters) but greater than or equal • greater than or equal to 50 feet (15 meters) but less to 20 feet (6 meters) for a distance less than 0.6 mile than 80 feet (24 meters) for a distance greater than (1 kilometer), and is connected at both ends to a or equal to 0.6 mile (1 kilometer), or greater than or 2-dimensional (polygon) stream/river, equal to 80 feet (24 meters) regardless of distance, then stream/river is represented as a 2-dimensional and is connected at both ends to a 1-dimensional (line) (polygon) basic feature object. stream/river, • less than 50 feet (15 meters) but greater than or equal then stream/river is represented as a 2-dimensional to 20 feet (6 meters) for a distance greater than or (polygon) basic feature object. equal to 0.6 mile (1 kilometer), or less than 20 feet (6 meters) regardless of distance, and is connected at both ends to a 2-dimensional (polygon) stream/river, Stream/River 49

Data Extraction

Capture Conditions If stream/river flows from lake/pond or spring/seep, or if stream/river is greater than or equal to 984 feet (300 meters) along the longest axis, then capture.

Attribute Information FClass 1—NHD Feature (will be used for conflation). FCode 46000—Stream/river (a body of flowing water. Portion of the year the feature contains water unknown). EClass 2—Hydrographic feature used for elevation purposes, other than culverts or those used for hydroflattening. Another possible option is the following: FClass 1—NHD Feature (will be used for conflation). FCode 46000—Stream/river (a body of flowing water. Portion of the year the feature contains water unknown). EClass 1—Used for hydroflattening (3D polygon).

Source Interpretation Guidelines The minimum size for islands within stream/river is 60 feet (18 meters) along the shortest axis. If a stream flows in a braided pattern, then see “Area of Complex Channels” section. For lidar base specification hydrographic breakline, permanent islands 1 acre (0.4 hectare) (approximately equal to a round island 236 feet [72 meters] in diameter) or larger shall be delineated within all waterbodies. 50 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Additional Elevation-Derived Sea/Ocean Hydrography Treatments and Elevation The minimum size for islands within sea/ocean is 1 acre (0.4 hectare) along the shortest axis. Specific Features For lidar base specification hydroflattening, permanent islands 1 acre (0.4 hectare) (approximately equal to a round The following describes treatments and additional fea- island 236 feet [72 meters] in diameter) or larger shall be tures that should be applied during the acquisition of reser- delineated within all waterbodies. voirs, sea/ocean, and other waterbody features and should be taken into consideration as treatments for the depiction of waterbodies. The treatments and additional features can also Stream/River be used to convey additional information about the level of confidence for elevation data in certain acquisition areas. The minimum size for islands within stream/river is 60 feet (18 meters) along the shortest axis. If a stream flows in a braided pattern, then see “Area of Complex Channels” section. Island For lidar base specification hydrographic breakline, permanent islands 1 acre (0.4 hectare) (approximately equal to A permanent island is an area of exposed land, sur- a round island 236 feet [72 meters] in diameter) or larger shall rounded by water (figs. 32 and 33). These are features to be be delineated within all waterbodies. collected in and of themselves but also are a treatment. Islands need to be erased from lake/pond features.

Figure 32. Image of Rikers Island, New York. The National Map Viewer, U.S. Geological Survey.

Delineation Lake/Pond The minimum size for islands within lake/pond is 60 feet (18 meters) along the shortest axis. For lidar base specification hydroflattening, permanent islands 1 acre (0.4 hectare) (approximately equal to a round island 236 feet [72 meters] in diameter) or larger shall be delineated within all waterbodies and excluded from hydroflattening. Island 51

EPLAATIO Stream/river or lake/pond Stream/river Swamp/marsh Connector Artificial path

0 1 2 MES

0 1 2 KMETERS

73°24'W 73°23'W 73°22'W 321 320 31

118

116

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 33. An island in the Saugatuck Reservoir in Connecticut shown as an example of treatment for lake/pond features. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. 52 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Island/Sandbar Capture Conditions Established prior to the collection and agreed upon by the Intermittently/partially submerged islands or parts of data producer and the customer. islands are submerged at the time of collection (fig. 34). These Topology rules for adjacent features do not apply to low- are most often found in coastal areas because of tidal varia- confidence areas. For instance, they do not need to be snapped tions during the collection, or in rivers collected while at a to adjacent features. high flow. If island/sandbar is disconnected from the shore or is visible at the time of collection, then treat as an island (remove from lake/pond or sea/ocean feature). Otherwise, treat Attribute Information as shoreline. FClass 9—Non-Hydrography Feature (elevation dataset limitation). FCode 991—Low-confidence area (pre-determined). Low-Confidence Area, Predetermined EClass 9—Elevation dataset limitation.

A reference polygon used by the 3D Elevation Program (3DEP) to define an area where lidar penetration to the bare- Source Interpretation Guidelines earth surface is expected to be difficult to determine. These None. areas would be established prior to the collection and agreed upon by the data producer and the customer. Examples might include known areas of mangroves or triple-canopy tropical rainforest (figs. 35 and 36). Low-confidence areas may overlap other hydrographic features.

Attribute/Attribute Value

Each feature requires domain codes to be entered into the attribute table for the feature class (table 37). See “Field Definitions and Domain Values for Attributes” section for more information on EDH code definitions.

Representation Rules

Data Extraction

EPLAATIO Lake/pond Artificial path Dam/weir Stream/river Island sandbar Connector

Sometimes Islands 0 2 MES

0 2 KMETERS

98°2'W 98°W 97°58'W 6 2

30°28'N

Sometimes Islands

30°26'N

302

3022

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 34. “Sometimes Islands” in Lake Travis, Texas, shown as an example of an intermittent island/sandbar. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. 54 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Figure 35. A great white heron standing atop mangrove roots, Boggy Key, a Florida Island. Photograph by Heather Henkel, U.S. Geological Survey.

Table 37. Low-confidence area, predetermined, domain codes and attributes.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 9 991 9 Low-confidence area, Required Required -- predetermined

Table 38. Low-confidence area, predetermined, representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) ------2-dimensional (polygon) greater than 0 -- -- Low-Confidence Area, Predetermined 55

EPLAATIO Sea/ocean Artificial path Stream/river or lake/pond Stream/river Reservoir Connector Canal/ditch Canal/ditch Low confidence area—Predetermined

0 1 2 MES

0 1 2 KMETERS

81°50'W 818

2620

Note: Swamps in this area are Florida magroves, which are typically predetermined low confidence areas.

2618

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203 Figure 36. A mangrove forest in western Florida shown as an example of a predetermined area of low confidence. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. 56 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Low-Confidence Area, Sparse Bare Data Extraction Earth Data extraction rules fall into three categories: capture conditions, attribute information, and source interpretation At this time (2020), the 3DEP does not have a criterion guidelines. The capture conditions explain the requirements for defining areas of low confidence based on the point cloud for a feature to be collected, and other pertinent informa- ground surface or derived DEM rasters. Any criteria for “low tion about acquisition. The attribute information explains the confidence,” including how these areas shall be delineated, definitions of the codes and attributes that must be applied to shall be established prior to the collection and agreed upon a feature if acquired, and the source interpretation guidelines by the data producer, the customer, and the U.S. Geological give additional information for special circumstances to help Survey National Geospatial Program. Low-confidence areas determine whether a feature should be acquired or not. Not all may overlap other hydrographic features features have source interpretation guidelines, and if this is the case, this will be indicated with “None.” Attribute/Attribute Value Capture Conditions Each feature requires domain codes to be entered into the attribute table for the feature class (table 39). See “Field Topology rules for adjacent features do not apply to low- Definitions and Domain Values for Attributes” section for confidence areas. For instance, they do not need to be snapped more information on EDH code definitions. to adjacent features.

Representation Rules Attribute Information

When delineating a feature, it must be created with the FClass 9—Non-Hydrography Feature (elevation dataset appropriate geometry, either point, line, or polygon, which is limitation). determined by the size of the feature or the length along differ- FCode 992—Low-confidence area, sparse bare earth. ent axes of the feature (table 40). EClass 9—Elevation dataset limitation. Special conditions: none.

Table 39. Low-confidence area, sparse bare earth, domain codes and attributes.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 9 992 9 Low-confidence area - sparse Required Required -- bare earth

Table 40. Low-confidence area, sparse bare earth, representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) ------2-dimensional (polygon) greater than 0 -- -- Low-Confidence Area, Snow-Cover 57

Low-Confidence Area, Snow-Cover give additional information for special circumstances to help determine whether a feature should be acquired or not. Not all A reference polygon used by the 3DEP to define where features have source interpretation guidelines, and if this is the it can be determined that there was snow on the ground at the case, this will be indicated with “None.” time of collection. Light dusting of snow that does not alter the ground elevation more than about 0.8 inch (2 centimeters) is Capture Conditions inconsequential and should not be delineated. Low-confidence areas may overlap other hydrographic features (figs. 37 If snow is greater than approximately 2 centimeters deep, and 38). then capture. Topology rules for adjacent features do not apply to low- confidence areas. For instance, they do not need to be snapped Attribute/Attribute Value to adjacent features. Each feature requires domain codes to be entered into the attribute table for the feature class (table 41). See “Field Attribute Information Definitions and Domain Values for Attributes” section for more information on EDH code definitions. FClass 9—Non-Hydrography Feature (elevation dataset limitation). FCode 993—Low-confidence area, snow-cover. Representation Rules EClass 9—Elevation dataset limitation.

When delineating a feature, it must be created with the appropriate geometry, either point, line, or polygon, which is Source Interpretation Guidelines determined by the size of the feature or the length along different axes of the feature (table 42). None. Special conditions: none.

Data Extraction

Figure 37. Snow cover in the Alaska Interior Mountain Range. Photograph by Shawn Carter, U.S. Geological Survey. 58 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

EPLAATIO

Ice mass Artificial path Stream/river

0 1 2 MES

0 1 2 KMETERS

151°5'W 10

628

626

622

Base from U.S. Geological Survey digital data, various scales, various dates Albers Equal-Area Conic proection ell-known identifier: 10203

Figure 38. An area in the Alaska Range (150.8094829°W 62.9773695°N ) shown as an example of a low-confidence area, snow-cover. Source data are from the National Hydrography Dataset (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types, but may not have the same density and other characteristics of elevation-derived hydrography. Low-Confidence Area, Snow-Cover 59

Table 41. Low-confidence area, snow-cover, domain codes and attributes.

[FClass, Feature Class; FCode, Feature Code; EClass, Elevation Class; --, no data]

FClass FCode EClass Description Source Method UserCode 9 993 9 Low-confidence area - snow Required Required -- cover

Table 42. Low-confidence area, snow-cover, representation rules.

[--, no data]

Kind of feature object Area Shortest axis Longest axis 0-dimensional (point) ------1-dimensional (line) ------2-dimensional (polygon) greater than 0 -- -- 60 Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules

Acknowledgments References Cited

The authors would like to acknowledge the exper- Terziotti, S., and Archuleta, C.M., 2020, Elevation-Derived tise and research contributions of Hans Karl Heidemann, Hydrography Acquisition Specifications: U.S. Kristina Yamamoto, Karen Adkins, Stephen Aichele, Robert Geological Survey Techniques and Methods, book 11, Wheelwright, David Anderson, Lori Phillips, and Al Rea. chap. B11, 74 p., https://doi.org/10.3133/ tm11B11.

U.S. Geological Survey, 2020, USGS TNM Hydrography (NHD): accessed February 28, 2020, at https://hydro.nationalmap.gov/arcgis/ rest/services/nhd/ MapServer. For more information about this publication, contact: Director, USGS National Geospatial Technical Operations Center 1400 Independence Road Rolla, MO 65401 573–308–3500

For additional information, visit: https://www.usgs.gov/core-science-systems/ngp/ngtoc

Publishing support provided by the Rolla Publishing Service Center Archuleta and Terziotti—Elevation-Derived Hydrography—Representation, Extraction, Attribution, and Delineation Rules—Techniques and Methods 11–B12 ISSN 2328-7055 (online) https://doi.org/10.3133/tm11B12