PNW 581    Revised April 2020

Introduction

Surveys and maps are interrelated tools that help country managers understand property resource and make direction decisions. In this publication, we depict surveying with an accent on the Public Country Survey System, which serves as the basis for describing property boundaries in the Pacific Northwest. We also discuss the diverse types of maps used in woodland management and the technology used to collect and clarify geographic data.

Survey types and uses

State surveying is the process of gathering and analyzing information about the physical world. It'southward the science of determining relative positions of existing points on the world's surface or of establishing such points. People behave surveys when they desire to locate belongings boundaries, roads, structures, watercourses and other physical characteristics of the state. This piece of work is carried out by licensed surveyors using specialized equipment and techniques. Surveyors are most commonly employed by landowners to marking or remark property boundaries, easements and other legally deeded features. Surveyors tin also provide other services, such equally flood mapping and new road layout. When surveyors piece of work with property boundaries and other features described in your deed, they always work within the framework of the Public Land Survey System.

The Public Land Survey System

Most of the U.s.a. (outside the 13 original colonies, Kentucky, Tennessee and Texas) was surveyed using the Public Country Survey System. Survey work in the Pacific Northwest almost always references the PLSS, a rectangular survey system of public lands into townships of 36 square miles. The PLSS was first implemented in 1785 and became the standard for state patents and titles. It was implemented throughout the West equally public lands were transferred to individual buying. Today, the Bureau of Land Management maintains records of land condition, cadastral surveys (the process of creating, defining, marking and reestablishing the boundaries and subdivisions of public lands) and mining claims for Oregon, Washington and Idaho. When land leaves federal ownership, subsequent private championship transfers, rights and restrictions are recorded past the appropriate county assessor's function.

How the Public Country Survey System works

The PLSS uses a filigree of approximately one-mile-square sections (1 mile on a side). This rectangular survey arrangement was built on a serial of 37 points located throughout the The states. These points were precisely located through astronomical observations, and they never modify. These 37 points serve as reference points for surveys anywhere in the areas of the continental Usa covered by the PLSS (Figure 1). From each initial point, principal meridians run north and due south, and baselines run eastward and westward, creating the framework for the PLSS grid.

In Oregon and Washington, the rectangular survey system is referenced to the north-south Willamette Meridian and the east-westward Willamette Baseline. These two lines cross at an initial point called the Willamette Stone, located in the westward hills of Portland. In Idaho, the arrangement is referenced to the Boise Meridian and Baseline, the initial point of which is in Height, Idaho.

From each initial signal, a grid of townships is established north and south of the baseline and east and west of the principal meridian. Townships are approximately 6 miles on each side. They are numbered from the baseline, starting with Township 1 North (T1N) north to the Canadian border and Township one Southward (T1S) southward to the California and Nevada state lines.

The due east-west positions of a township are designated by its range. Ranges are numbered from the elevation west (for example, R1W) and e (for example, R1E). Thus, a township that is 2 grid locations s of the baseline and two filigree locations due east of the principal meridian would exist designated equally T2S, R2E (Figure 2).

Normal townships contain 36 sections. Each section is approximately 1-mile foursquare and contains 640 acres. All townships use the same organisation for numbering the sections inside them. Sections are numbered commencement with number 1 in the northeast corner, going west to number 6, then south to 7, east to 12, s to 13, and and so on (Effigy 2).

Every section has four quarter corners, which usually are the midpoint on each of the lines forming the boundaries of the section. Sections can be divided into quarters and halves by connecting these points. With a line fatigued north-southward or due east-west through the center of a section to connect 2 quarter corners, the section is divided into halves. Each half is identified by its location in the section (n half, s half, due east half or west half).

With lines drawn north-due south and due east-west through the center of a section to connect all four quarter corners, the section is divided into quarters (Figure ii). Again, each quarter is identified past its location in the department (northeast quarter, southeast quarter, northwest quarter or southwest quarter).

Halves and quarters tin can be subdivided further, ofttimes into quarter-quarter (sixteenth) sections. Thus, a twoscore-acre block might be identified equally the southwest quarter of the northwest quarter of Section 14, Township ii South, Range 3 West, Willamette Meridian. A legal description then follows in parentheses. The legal description for small ownerships often includes a packet identification number that may non match the quarters of a department. When these parcels deviate in shape from the usual subdivisions mentioned above, a licensed surveyor must necktie the property lines into previously established section corners or quarter-corners.

Sometimes the filigree isn't perfect. For case, although every section is basically square and has four corners, these corners may not be shared with the bordering section. And although each department should be one square mile and there are 640 acres in a foursquare mile, not all sections have 640 acres. These discrepancies are a result of occasional measurement errors that were inevitable given the challenges of surveying vast areas. As well, because the Public Land Survey System uses plane surveying, which doesn't take into business relationship the curvature of the globe, surveyors would sometimes offset corners to avoid overlapping buying. The result is sections that don't have exactly 640 acres. Because of the procedure surveyors used to lay out townships initially, odd-shaped sections are generally along the western edges of townships.

Working with paper maps

Maps are used for many purposes and tin can exist created using different survey methods. This section describes some features common to all paper maps and also discusses the types of maps commonly used.

Features of a map

Map scales and distances

A scale is a relationship between the altitude on a map and the altitude on the basis. A scale tin can be found on paper maps, allowing you to accurately estimate ground distances from the map. Map scales are written either as a ratio (1:12,000) or a representation (1 inch = ane mile). In the first case, 1 inch on the map represents 12,000 inches (1,000 anxiety) on the footing. In the second case, 1 inch on the map represents 1 mile on the ground. In either case, you lot can discover the distance on the ground between ii points on the map by measuring with a ruler and multiplying past the map calibration.

To use the map scale to calculate altitude on the footing, select two points on a map. Measure the map distance using a ruler that shows inches and fractions of inches (virtually commonly twelfths or tenths of inches). Now multiply the measured distance by the map ratio. Catechumen inches to feet. You've calculated the horizontal ground distance between the two points! Notation that on steep basis, the horizontal distance calculated from a map will underestimate the gradient distance, which is the actual distance you lot would travel on the ground (see sidebar, ''Accounting for Slope").

Several websites allow users to impress maps to a specified scale (Table 1). Enlarging paper maps using a photocopier is another option, although distortion tin can be a problem. For example, a ane:24,000-calibration U.S. Geological Survey topographic (topo) map can exist enlarged 200% to a ane:12,000-scale topo map.

Direction

Maps are made with direction in mind, and the top of a map is usually oriented to truthful northward (run into "Magnetic Declination"). If you know how to read the direction between ii points on a map, then you can use a compass to find the aforementioned direction on the ground and move from point to point (Figure three).

Direction is expressed as an azimuth or begetting. Azimuth is based on the 360 degrees of a compass. Due-north is located at zilch or 360 degrees (they are 1 and the aforementioned). Azimuth is e'er read clockwise from n, so due-east is 90 degrees, due-south is 180 degrees, and due-west is 270 degrees. Bearings, yet, are based on 4 xc-degree quadrants. Beginning from a due north-south line, bearings are read from due north to either e or w or from south to either east or west. For example, a bearing of "N 45 degrees W" is the aforementioned as an azimuth of 315 degrees, and a bearing of "South xxx degrees East" is the same every bit an azimuth of 150 degrees (Figure 4). Bearings are no more than 90 degrees since each quadrant contains only 90 degrees.

Map work is nearly frequently done using azimuths rather than bearings considering azimuths are easier to read on a map when using a 360-caste protractor. Select two points on a map and describe a line running true north to south through one of the points and a line between the two points. Lay the protractor oriented n-s on the north-south line with the eye of the protractor on the point. Where the line crosses the edge of the protractor, read the truthful azimuth from indicate to point.

Commonly used maps and imagery

Many types of maps and imagery are available to us today. Some of those almost normally used past forestland owners include transportation, topographic, legal boundaries and aerial imagery. Historically printed on paper (and still bachelor as such), many of these resources are now available in digital formats (see "Working with Digital Maps"). Even if y'all rely on digital maps, it is wise to deport a backup paper map when traveling or navigating in unfamiliar terrain.

Transportation maps

Although a transportation map (Figure 5) typically covers a large surface area, such as an entire state or canton, information technology can exist used to help describe the location of your property. Transportation maps vary in blueprint depending on who owns the state. Each government bureau usually uses a consequent design, simply in that location's little consistency among agencies and even less betwixt maps of private and public lands. Woods Service maps typically concentrate on roads on National Forest lands and might not show other connecting roads. BLM maps do the same for BLM lands. This inconsistency can be a problem if you're working in an surface area with checkerboard buying. Forest Service and BLM transportation maps are available at National Woods and BLM commune offices. State departments of transportation often produce maps at the state and canton levels.

Topographic maps

The U.S. Geological Survey produces topographic (topo) maps that show hydrology, vegetation, geologic features and human-made structures. Topo maps likewise incorporate contour lines that depict the lay of the country and tin be used to estimate an area'southward gradient (Effigy 6). Older USGS topo maps are available with a scale of 1:48,000 (ane inch on the map represents 48,000 inches or 4,000 feet on the ground), and newer seven.5-minute USGS topo maps are available with a scale of ane:24,000 (1 inch on the map represents 24,000 inches or two,000 feet on the footing). Historical and new USGS topo maps are available online (Tabular array 1).

Plat maps

Plat maps display the legal boundaries of one or more backdrop (Figure seven). These maps typically encompass a single section, although they may be larger or smaller depending on the number of subdivisions. Property lines are described by their length and direction and include some physical features and roads. A landowner skilled with a compass tin employ a plat to approximate belongings lines on the ground, just they should always utilize a surveyor to accurately locate holding boundaries. Plat maps are available in your county assessor'due south office. Many assessor's offices offer them online. Telephone apps brandish simplified versions showing property ownership.

Aeriform photographs

Aeriform photographs (Figure viii) are not maps but tin exist used for many of the same purposes. They are generally produced and printed at a one:12,000 calibration. Older aerial photos might be distorted, making azimuths and distances hard to measure. However, most all newer digital photos have been geometrically corrected (orthorectified) to account for distortions. Orthophotos can be used to calculate distances and azimuths.

Digital mapping engineering

Advances in digital mapping technology take increased the types of available map data and the mode users interact with maps. This department describes some common digital engineering used to collect information for mapping.

Remote sensing

Digital maps are commonly produced from remote sensing data. Remote sensing is the procedure of collecting data about the world using satellites, shipping and unmanned aerial vehicles. Aerial photographs are the most familiar product of remote sensing, simply images are besides collected past satellites orbiting globe. Additional remote sensing products include digital elevation models and LiDAR.

Digital height models

Digital elevation models employ surface data from remote sensing or topographic maps to produce terrain maps. These terrain maps are generally shaded to highlight topographic relief or represented as a 3D map. Some 3D map applications allow the user to view the landscape from different aspects (Figure 9). However, features in 3D visualizations tin appear exaggerated or overly steep and do non e'er accurately depict topographic features.

Calorie-free Detection and Ranging

Low-cal Detection and Ranging is a special form of remote sensing that uses lasers to detect distances. A LiDAR sensor flown over a forest tin can produce a digital top model and a detailed, 3-dimensional representation of vegetation. LiDAR terrain maps are detailed enough to reveal old stream channels, roadbeds and landslide sites. Since vegetation is also detected with LiDAR, the heights of trees can be used to delineate unlike stands in a forest (Figure 10). LiDAR imagery, when available, tin can be downloaded into a Geographic Information System or viewed online. The Oregon Department of Geology and Mineral Industries has gratis downloadable LiDAR for portions of the country as well equally a map viewer for viewing online (Tabular array one).

Global Positioning Arrangement

The Global Positioning System is a network of satellites orbiting earth, transmitting precise time and position data twenty-four hours and night. Satellite signals are broadcast to hand-held units on the ground. When the mitt-held device receives signals from three or more than satellites, it determines the user's position on earth. Manus-held units vary in cost from equally niggling as $100 for consumer-grade receivers up to tens of thousands of dollars for survey-course instruments. Many mobile devices such as smartphones and tablets have born GPS receivers that are accurate within 3–4 meters.

The accuracy of inexpensive GPS receivers and smartphones tin can be low, especially when copse or other obstacles don't allow a clear view of satellites. However, they can still exist useful for making rough estimations or for navigation in the field (Figure 11).

Devices equipped with GPS can be used to estimate areas, distances and elevations, and they can also exist used to collect data for Geographic Information Systems. Alternatively, features from a map or GIS (such equally property lines or points of interest) can exist uploaded to a mobile device. This allows for like shooting fish in a barrel navigation to those features on the footing.

Unmanned aerial vehicles

Unmanned aerial vehicles

Unmanned aerial vehicles, too called drones, can take aerial photographs over minor properties. This allows for relatively inexpensive remote sensing. Drones produce high-resolution aeriform photographs, LiDAR and thermal sensing data that are immediately bachelor for employ and analysis. Landowners and foresters use them for insect or disease surveys, forest inventory, map harvest units, wild animals monitoring and fire detection (Figures 12 and 13). Many professional person consultants employ aerial mapping drone engineering science. Inquire to run into examples of the types of products they tin can produce to see if they will fit your needs. If y'all purchase your ain drone for aerial photographs, follow all local and Federal Aviation Assistants regulations and licensing requirements.

Working with digital maps

Digital maps have a tremendous range in capabilities including:

  • Static maps you can view, print or download.
  • Searchable maps with data.
  • Map interfaces with digital drawing or measuring tools.

This section includes types of features that can be found on digital maps and websites.

Digital map features

Web-based resources offer free, easy access to high-quality aerial photographs and geographic data. The functions and capabilities of digital maps vary by site. Some sites have tools for mapping and simple geographic measurements and analyses. Other sites are repositories or libraries for digital maps and information. It is a good practice to take a await at the source of the information, the date it was created and the general accuracy or precision of the data.

Map resolution

The resolution of a digital aerial photo depends on the camera used. An aerial digital image is fabricated upwards of pixels. The pixel size in a digital aerial photo represents a distance on the ground. For case a photo taken at a one-meter resolution has pixels that stand for a 1-meter distance on the footing. This allows you to differentiate objects in the prototype that are one meter or larger. The higher the resolution, the more detailed the imagery. Depression-resolution imagery can seem grainy or blurry when zooming into the photo. Zooming in on a loftier-resolution aerial photo provides detailed views of features on the ground.

Calibration

Some digital map interfaces show a calibration that adjusts equally you zoom in and out of the map. The Web Soil Survey allows you to calibrate the map calibration to your computer's screen resolution, allowing yous to select and employ a specific map scale. When printing out a digital map, measure the scale bar with a ruler to ensure the paradigm is printed to the right scale.

Georeferenced maps and photos

Georeferenced digital maps have features that are associated with a geographic coordinate organization. This allows you to view the ground coordinates of map features and to use the map in digital mobile applications (apps) and GIS. Georeferenced topo maps tin be downloaded from the USGS TopoView site (Tabular array 1) or other providers.

Photos taken with a smartphone or a digital photographic camera are too typically georeferenced (also referred to as geotagging) to the ground coordinates where the photograph is taken. Georeferenced photos can be linked to digital maps using a variety of software and programs, including Google Earth and Avenza Maps (Tabular array one). Linking georeferenced photos to a digital map can be a useful way to proceed track of management activities on your property.

Map layers, data and tools

Investigate the functions offered by the different digital map websites. Some websites have map viewer applications that allow the user to select map data layers to overlay on a base of operations map or view tables of associated data. Other possible functions include tools to measure altitude, calculate area or describe shapes. These tools are typically accessed with a menu bar and often accept a assistance directory where you tin can learn more about the capabilities of the application.

Normally used digital maps and websites

Digital map resource include aerial imagery, tax lots, roads, boundaries of counties and government state ownerships, topographic maps, LiDAR, soils and vegetation cover. Historical maps are a keen resources to find onetime place names, locations of homesteads and other historical features. In addition to USGS map sources, scanned historical maps are frequently available in academy digital archives.

Google Earth

Google Earth is a web-based geographic browser that accesses satellite and aeriform imagery to produce a 3D interactive world. Information technology is bachelor for gratuitous for both bones and advanced versions. Google Earth allows the user to search for specific addresses or coordinates and see points of involvement from diverse angles. The program has many functions that allow the user to acquire virtually specific places of interest. These "layers" tin can include photo and video, assuasive the user to interact with various recorded locations.

Web Soil Survey

The online Web Soil Survey, produced by the National Cooperative Soil Survey and operated by the USDA Natural Resource Conservation Service, allows you to view soil data and associated information (Tabular array 1). Soil surveys provide users with data on soil blazon, properties, qualities and limitations for use (Figure 14). Users tin can use downloaded soil reports as references for state management activities.

County revenue enhancement lots

County tax lot maps are useful for mapping, property analysis and planning purposes. Some counties have map viewer applications for viewing tax lot information, plats and additional canton planning information. Investigate your county tax assessor site (Tabular array i) to run across what digital map resource your county provides. For specific information regarding individual tax lots, contact your canton assessor.

Digital libraries and data sets

Digital libraries and data sets are compilations of digital map data for a specific region or theme. These sites often provide a variety of additional features, including map viewer applications that allow you to take simple measurements and view multiple layers and linked resource data. Examples include Oregon Explorer, Atlas of the Pacific Northwest, Inside Idaho, Washington Geospatial Open up Data, USGS National Map Viewer, USGS TopoView and CalTopo. The National Geographic Trail Maps website has downloadable USGS 7.five-minute topo maps that can be printed out to scale on four letter-size (8.5-by-eleven-inch) sheets of paper (Table 1). The CalTopo website allows you to select mapping layers and download the file equally a georeferenced PDF that can and then be uploaded to mapping apps for use offline in the field (Table 1).

Ecotrust Forest Planner

Ecotrust Forest Planner is a spider web-based tool used for forest management and scenario planning for landowners in Oregon and Washington. This tool provides a variety of resource layers and tools to help landowners explore forest management alternatives (Table 1).

Geographic Information System

A Geographic Data Organisation links information nerveless near the earth'southward features and resources to a digital base map. Information on each type of resource is stored as a mapping layer, like layers of acetate laid over one another (Figure xv). Resource layers commonly include the Public Land Survey System, topography, transportation, water, vegetation, geology and land ownership. Digital aeriform photographs are as well commonly used in a GIS. The layering of different features allows for complex analyses and modeling as well as detailed, efficient mapmaking.

GIS is more often than not used by owners of large backdrop, but some modest woodland owners observe it useful. However, commercially available programs with a licensing fee might exist out of accomplish for modest woodland owners. Yous might consider a variety of complimentary applications now available.

Apps

Several apps are bachelor for users to download onto mobile devices, such as smartphones and tablets. A user will interact with these apps to accomplish a task in the field, such as mapping a property purlieus, inventorying a stand of copse, inputting data, referencing data or georeferencing photos. Non all apps are complimentary. Prices vary, and so be sure to read the fine impress regarding subscription services or whatever actress costs for downloading maps or information.

All smartphones and tablets take a bones map app preloaded onto the device. Most of these bones map apps, such as Google Maps, perform basic functions such as navigation and saving points of involvement. For a more than detailed map experience, an app such as Avenza Maps (Table 1) tin be downloaded. This app allows the user to download maps for offline employ (no cell service required), apply the device'due south built-in GPS to track your location on any map, plot locations and photos, measure distance and surface area, and more than.

To perform a forest inventory, an app such as Plot Hound can exist useful. This app allows the user to download cruises and plots to their device, navigate to each plot with their phone's built-in GPS and compass, and enter information collected in the field.

For soils data, an app such every bit SoilWeb can be a bang-up tool (Table 1). This app is based on the USDA'southward National Cooperative Soil Survey and provides GPS-based soil information for your electric current location. This app can be used in the field where cell coverage is bachelor to amend sympathise the soil types and how to optimally use the soil.

For more data

Textbooks
  • Paine, D.P. and J.D. Kiser. 2012. Aeriform Photography and Image Interpretation. New York. John Wiley Inc.
  • Kiser, J.D. 2010. Surveying for Forestry and the Natural Resources. Corvallis, OR: John Bell and Assoc.
Publications
  • Unmanned Aerial Vehicles (Drones): How they operate and their potential for improving your forest and rangeland management (EM9190).

Sidebars

PLSS Survey monuments and begetting trees

The positions of section corners and subdivisions are typically marked with mail service and cap survey monuments. The legal description is stamped into the cap, ending with the engagement of the survey. A sixteenth corner at the far northwest of Section fourteen would be labeled NW 1/16 S 36. Begetting copse are often marked near corners to help subsequent surveyors or landowners locate the survey monuments. Bearing tree tags depict the direction in bearings and distance to the corner monument.

Accounting for gradient

When yous use a map's scale to measure the altitude between points, you mensurate the horizontal (or map) distance. This is the "as-the-crow-flies" distance and doesn't accept topography into account. When traveling on the basis, you travel the slope altitude, which volition be longer (unless the basis is perfectly flat).

Magnetic declination

World'due south magnetic field doesn't align perfectly with the Northward and South poles. Because of this offset, there is a true north (the direction to the Northward Pole) and magnetic north (the way a magnetic compass will point). Maps are usually oriented with true northward direct up, so to navigate using a magnetic compass y'all need to account for the offset between true northward and magnetic north. This compass adjustment is called magnetic declination. Magnetic declination shifts over time and will vary depending on your physical location on the earth. In the Pacific Northwest, declination ranges from 12 degrees eastward in eastern Idaho to 17 degrees e in northwest Washington. You can find the precise declination for your area past visiting the National Oceanic and Atmospheric Administration's National Centre for Environmental Information.

Table i: Online resources

Digital information with special features and links

Google Earth

Satellite and aerial imagery; 3D images; searchable, historic photos;, measure out distances and area; drawing tools.

Web soil survey

Soil data and associated information. Download soils reports, set and print maps to calibration. Aerial photo base of operations map imagery.

(see App version below):

County tax Lots

Tax lot package and planning data. Search for tax lots using street address or latitude and longitude coordinates. Some counties provide a mapping interface with a diversity of planning data layers. Availability of features varies by county.

Oregon tax lots

  • ormap.net
  • oregon.gov/DOR/programs/property/Pages/county-contact.aspx

Washington tax lots

  • dor.wa.gov/find-taxes-rates/property-tax/canton-assessor-and-treasurer-websites

Idaho tax lots

  • https://idahoparcels.united states of america/spider web/
  • maps.idaho.gov/parcels.html
Digital libraries and data sets

The following sites provide a multifariousness of aerial imagery, topographic maps and additional information and features.

Oregon Explorer

Aerial imagery, geographic data, map viewer.

Oregon Geospatial Enterprise Office

Links to free spatial data.

University of Oregon map collection

Oregon Department of Geology and Mineral Industries

LiDAR coverage where available.

Atlas of the Pacific Northwest

Geographic data and historical maps for Oregon, Washington and Idaho.

Inside Idaho

Aeriform imagery, geographic data and topographic maps.

Idaho Geospatial part

Links to complimentary spatial data.

Academy of Idaho map collection

Washington Geospatial Open Data

Aerial imagery, geographic data and topographic maps.

Academy of Washington map drove

The USGS National Map Viewer

Aerial imagery, geographic data and topographic maps. Map viewer allows users to draw and measure out distance and area, and obtain topographic contour data.

The USGS TopoView

Topographic map database with several file formats including a GeoTIFF format that is georeferenced for use with GIS and true calibration for printing.

National Geographic Trail Maps

Downloadable USGS 7.five-minute quad maps. Print out a map to scale on four letter of the alphabet-sized sheets of newspaper.

CalTopo

Downloadable topographic terrain and imagery, among other mapping layers. Download georeferenced PDF format for use in mapping apps such every bit Avenza Maps.

Ecotrust Forest Planner

Provides a range of imagery, topographic and data resource layers on a map viewer that allows the user to draw and save stands and explore wood management alternatives. Requires users to create an account.

Applications (apps) for smartphones and tablets

This is a brusque list of ordinarily used apps for mapping. We recommend that users upload maps from a trusted app store or website.

Google Maps

Bachelor equally a default on many smartphones.

Avenza Maps

Download maps, aerial photos and link georeferenced photos.

Plot Hound

Design and download prowl, navigate to plots, enter data.

SoilWeb

GPS-based soil information for the location of the user created by the USDA's Natural Resource Conservation Service and the University of California, Davis Soil Resource Laboratory.