Identifying NHD Features

 

Introduction

 

The NHD Viewer serves as a gateway for downloading the National Hydrography Dataset (NHD) and other data themes from The National Map (TNM) and also allows for the exploration of NHD features. In this tutorial, you will learn how to identify various NHD features.

 

After completing this tutorial, you will be able to:

Identify a medium resolution NHD feature.

Identify a high resolution NHD feature.

Identify a watershed boundary.

 

  What is the difference between medium and high res NHD?

 

Identify a Medium Resolution NHD Waterbody

 

Goal: Identify a medium resolution feature and observe its attributes.

 

Step 1 Open the NHD Viewer

 

Go to the NHD Viewer.

 

Note that the viewer does not open to the full extent of the map but instead to a specific zoom level at a scale of 1:144,448. At this scale, medium resolution NHD is visible. You can tell this is medium resolution NHD by hovering your mouse over the medium resolution layer in the table of contents. A text bubble will come up telling you at which scales the layer become visible.

 

Saving a map using the NHD Viewer

 

Note that all layers in the Overlay panel are turned off.

 

What is a overlay?

 

This panel has three tabs, the Overlay tab, the Selection tab, and the Cart tab.

 

 

Hover your mouse over the Medium Resolution Layer. A text bubble will come up telling you at which scales

the layer becomes visible.  

 

Turn the Hydrography overlay on by clicking the box next to the layer.

 

 

Click on the Selection tab in the Viewer window pane on the left side of the screen.

 

 

Step 2 Set Identifiable Layers

 

Select "Identify Layers". The Viewer defaults to have all layers selectable. Notice that only hydrography layers are selectable. This is because the Hydrography overlay is turned on and no other themes are visible. If other overlays are turned on, they will also be selectable.

 

 

Click the option to Deselect All. If you perform an identify with all layers selected, multiple results will be returned.

 

 

 

Step 3 Identify a Medium Resolution NHDWaterbody Feature

 

Activate this feature class for identification by toggling the box next to it. This should be the only layer activated at this point.

 

Select the identify tool in the toolbox.

 

Click on the LakePond feature. With areal features, you can click anywhere within the boundaries of the feature. In the case of this LakePond, clicking on the blue polygon will result in a selection. When selecting a linear feature, it is easier to make your selection if you click and draw a box around a part of the flowline.

 


The feature will appear under the selection tab in the left window pane with a letter next to its name. The feature will be highlighted in green hatching.

 

 

Click on the feature's name (Null) on the left hand side of the Viewer and the feature's attributes will be displayed in a callout next to the feature in the map.

 

 

You may also download this feature, zoom to, or select more options to buffer or calculate the area of the feature.

 

When you download a selected feature you will get the hydrography for the current map extent.

 

Deselect the feature by using the "clear graphics" tool.  

 

Quiz

 

1. Why does this feature have a Null name and GNIS ID?

 

2.  The FCode for this feature is 39009. What does this mean?

 

3. The Reach Code of this feature is 10190003002230. In which Subbasin can this feature be found?

 

Answer Key

 

Identify a High Resolution NHD Flowline

 

Goal: Identify a high resolution feature and observe its attributes.

 

Step 1 Open the NHD Viewer

 

Go to the NHD Viewer.

 

Note that the viewer does not open to the full extent of the map but instead to a specific zoom level at a scale of 1:72,224. At this scale, high resolution NHD is visible. You can tell this is high resolution NHD by hovering your mouse over the high resolution layer in the table of contents. A text bubble will come up telling you at which scales the layer become visible.

 

Saving a map using the NHD Viewer

 

Note that all layers in the Overlay panel are turned off.

 

What is a overlay?

 

This panel has three tabs, the Overlay tab, the Selection tab, and the Cart tab.

 

Turn the Hydrography overlay on by clicking the box next to the layer.

 

 

Click on the Selection tab in the Viewer window pane on the left side of the screen.

 

 

Step 2 Set Identifiable Layers

 

Select "Identify Layers". The Viewer defaults to have all layers selectable. Notice that only hydrography layers are selectable. This is because the Hydrography overlay is turned on and no other themes are visible. If other overlays are turned on, they will also be selectable.

 

 

Click "Deselect All". If you performed an identify action with all the layers selected, multiple results would be returned.

 

 

Since we are viewing high resolution NHD at this scale, and we are going to identify a Flowline, turn on NHD Flowline - High by toggling the box next to it. This should be the only layer activated at this point.

 

 

Step 3 Identify a High Resolution NHDFlowline Feature

 

Select the identify tool in the toolbox.

 

Click on the Selection tab in the Viewer window pane on the left side of the screen. Then select "Identify Layers".

 

Click the option to Deselect All.

 

Select the flowline flowing out of Cherry Creek Dam by using the identify tool to draw a box around the Flowline.

 

 

The feature will appear under the selection tab in the left window pane with a letter next to its name. The

feature in the Viewer window will be highlighted in green.

 

 

Click on the feature's name and its attributes will be displayed in a callout next to the feature in the map.

 

 

 

You may also download this feature, zoom to, or select more options to buffer or calculate the distance, or length, of the feature.

 

When you download a selected feature you will get the hydrography for the current map extent.

 

Deselect the feature by using the "clear graphics" tool.  

 

Quiz

 

1. The Fcode of Cherry Creek is 46006. What does this mean?

 

2. The flow direction of Cherry Creek is attributed as "With Digitized". What does this mean?

 

Answer Key

 

Identify a Watershed Boundary

 

Goal: Identify the Subbasin that contains Denver.

 

Step 1 Open the NHD Viewer

 

Go to the NHD Viewer.

 

Note that the viewer does not open to the full extent of the map but instead to a specific zoom level at a scale of 1:1,155,581.

 

Saving a map using the NHD Viewer

 

Note that all layers in the Overlay panel are turned off.

 

What is a overlay?

 

This panel has three tabs, the Overlay tab, the Selection tab, and the Cart tab.

 

 

Turn the Hydrography overlay on by clicking the box next to the layer.

 

 

 

Click on the Selection tab in the Viewer window pane on the left side of the screen.

 

 

Step 2 Set Identifiable Layers

 

Select "Identify Layers". The Viewer defaults to have all layers selectable. Notice that only hydrography layers are selectable. This is because the Hydrography overlay is turned on and no other themes are visible. If other overlays are turned on, they will also be selectable.

 

 

Click on "Deselect All". If you performed an identify action with all the layers selected, multiple results would be returned.

 

 

Step 3 Select the Subbasin that Contains Denver

 

Since we are going to identify a Subbasin, activate the layer called Subbasins by clicking the box next to it. This should be the only layer activated at this point.

 

Use the identify tool  to click on or near the city of Denver to select the Subbasin. Subbasin 101900003 is now displayed under Results in the Selection Tab. The entire Subbasin is highlighted with green hatching in the map. 

 

 

In the selection tab, click on the Subbasin's name (10190003) and some information about the Subbasin will be displayed in a callout next to the feature in the map.

 

 

The callout also has options to Download the hydrography of the map extent, to zoom to the feature, and more options such as the option to use a buffer tool  or to calculate the area of the Subbasin.

 

Quiz

 

1. Which Hydrologic Region contains Denver?

 

2. What is a HUC?

 

Answer Key