Field Studies and Electronic Surveys Notes

Field Studies and Electronic Surveys

Today's Schedule

  • Location Importance: Emphasizing the significance of location in field studies.
  • Electronic Survey Methods: Discussing the use of technology in conducting surveys.
  • Phone Surveys: Utilizing smartphones for data collection.
  • Final Project: Detailing the mock grant proposal assignment.

Understanding Location

Relative Location
  • Describing a location in relation to other landmarks or regions. Example: Huntsville, TX, is located in the West Gulf Coastal Plain along US Interstate 45, approximately 70 miles north of downtown Houston.
Absolute Location
  • Defining a location using precise coordinates. Example: 30.7235° N, 95.5508° W

Location, Location, Location!

  • Tools like GARMIN and Trimble are used for determining location.
Latitude (Y-coordinate)
  • Measures the north-south position of a point on Earth.
  • Ranges from 0° at the equator to 90° at the North and South poles.
  • Lines of latitude run parallel to the equator and are called parallels.
Longitude (X-coordinate)

  • Measures the east-west position of a point on Earth.

  • Ranges from 0° at the prime meridian to 180°.

  • Lines of longitude run perpendicular to the equator and are called meridians.

  • Diagram showing Equator, latitude (North (+), South (-)), longitude (West (-), East (+)), Prime Meridian and their degree ranges.

Measurement Units

Benefits of Quantification
  • Provides precise descriptions and allows for replicable analysis.
Linear Units
  • Traditional: feet, varas, etc.
  • Systematic: meters, etc. (SI System).
Angular Units
  • Circle, degrees (360°), minutes, seconds.
  • Radians (2∏2\prod /circle).
Problem of False Precision
  • Understanding the limitations of precision in measurements.
  • Questioning the real meaning of values like “4.342431 ft.”
Significant Figures
  • Principles for use in scientific research.

Location Systems: Point Locations

Cartesian/Planar (Flat) Coordinates
  • Represented as x, y, z (elevation).
Universal Transverse Mercator (UTM)
State Plane Coordinate System (SPCS)
Spherical/Geographic Coordinates
  • Latitude and Longitude.
  • Illustration of UTM point system with zones.

Survey: The Science of Determining Relative Positions

  • Definition: Determining the relative positions of points on the Earth’s surface.
Geodetic Survey
  • Covers distances large enough that the curvature of Earth is significant.
  • Establishes a network of precisely located control points.
  • Takes into account the true size, shape, and gravity fields of the Earth.
    • The geoid is the surface of the Earth’s gravity field which best fits global mean sea level
  • Provides significant precision.
  • Establishes highly accurate control networks
Plane Survey
  • Assumes the Earth’s surface to be a plane (flat).
  • Straight lines & angles are sufficient.
  • More common than geodetic surveys.
  • Precise enough for small-scale surveys in a limited area, such as a construction site.
  • Used to determine legal boundaries, construction surveys, and small-area topographic or control surveys.

Many Names for Plane Surveys…

  • Topographic Survey.
  • Property Survey.
  • Site Survey.
  • Construction Survey.
Topographic Survey
  • Gathers data on the location of natural and human-made features, contours, and ground elevation to create a topographic map.
Property Survey (or Boundary Survey)
  • Establishes property lines for a lot.
  • Used to create a plat.
  • Plat: An officially drawn map of a land area that defines the boundaries between different parcels of property to scale.
Site Survey (Plot Survey or Lot Survey)
  • Combination of a property survey and topographic survey.
  • May be required to receive a construction permit.
Construction Survey
  • Locates points and elevations that can be used to establish correct locations and elevations for engineering and architectural projects.

National Geodetic Survey

Functions:
  • Defines & manages the National Spatial Reference System.
  • Sets standards for geodetic surveys.
  • Maintains a database of U. S. geodetic markers.
National Spatial Reference System (NSRS)
  • Common set of reference points for all surveys.
    • Horizontal Datum = Collection of points of known latitude and longitude.
    • Vertical Datum = Collection of points of known elevation.
    • Benchmark (BM) = Permanent mark that establishes a point of known elevation.

Benchmarks

  • A location whose exact elevation is known and is noted on a brass or aluminum plate.
  • Bench marks are shown on maps by an X with the letters BM written next to them.
  • There are approximately 240,000 stations gathered over the last two centuries in the United States. This data is made available through the National Geodetic Survey Data Explorer.
  • Tidal bench marks are stable objects containing a marked point of known elevation with respect to a datum, and they are used to monitor the stability of a nearby water level station.

Survey/Data Collection with GPS

  • Navigation
  • Best for collecting points
  • Can track lines but not super accurate
  • Most handhelds have 3 m accuracy – know the error
  • When setting up GPS, check CS, accuracy, measurement units
  • Take good notes to accompany GPS
  • Label all points and ensure notes correspond.
  • Include photos as necessary.

Survey/Data Collection with Phone

  • Not very accurate but suitable for some situations.
  • Offline functionality is often important.
  • Can easily add pictures and notes to points.
  • Applications: ESRI Field Maps, Qfield, MerginMaps, Avenza Maps.

Measuring a Direction/Angle

Horizontal Angles
  • Brunton pocket transit
  • Theodolite
  • Autolevel
Vertical Angle
  • Brunton pocket transit
  • Abney level
  • Theodolite
  • Laser rangefinder

More Measurements

  • Requires a visual line-of-sight.
  • A theodolite is an optical surveying instrument; measures vertical and horizontal angles.
  • A total station is an electronic/optical surveying instrument; combines a theodolite and an electronic distance meter (EDM) to measure distances.
  • An automatic level is an optical instrument used to establish or verify points in the same horizontal plane.

Other Related Equipment

  • Tripod
  • Leveling Rod
  • Professional Tape Measure
  • Field Book

Locating a Point

Another Location
  • Intersection: Finding a new location by intersecting lines from two known landmarks on the ground.
  • Direction (Azimuth) and Distance from known point/s.
Your Location
  • GPS
  • Resection: A method of finding one's own location on a map by sighting two known landmarks.

Measuring Distance

  • The purpose of mapping will determine the necessary precision.
Common Techniques:
  • Least Precise: pacing—useful to calculate scale of mapped area.
  • Measuring Tape or Taping.
  • Stadia markings.
  • Laser Range Finders.
  • Electronic distance measurements (EDM).
  • Total Station (the most accurate).

Advanced Land Survey Techniques

Instruments

  • Nikon
  • Auto Level
  • Total Station
  • Transit

Autolevels

  • A dumpy level, builder’s auto level, leveling instrument, or automatic level is an optical instrument used to establish or verify points in the same horizontal plane. It is used in surveying and building with a vertical staff to measure height differences and to transfer, measure and set heights.
  • The instrument and staff are used to gather and/or transfer elevations (levels) during site surveys or building construction. Measurement generally starts from a benchmark with known height determined by a previous survey, or an arbitrary point with an assumed height.
  • Need to determine our starting elevation!

Auto Level (AKA dumpy)

  • Commonly used on building sites.
  • Internal compensator can automatically level the instrument.
  • Measures the difference in elevation between the line of sight and a point.
  • Bulls Eye Level, Telescope, Leveling Screws, Horizontal Angle Rotation Ring, Eyepiece, Horizontal Tangent Knob, Sight Diopter Adjustment Ring, Mirror. Diagram provided.

Reading the Rod

  • Vertical crosshair
  • Stadia hairs
  • Beveled hatch marks
  • Horizontal crosshair
  • View through the telescope of rod. Example provided.

Stadia Readings

  • Example :
    • Upper Stadia Reading = 5.30 ft
    • Rod Reading = 5.25 ft
    • Lower Stadia Reading = 5.20 ft

Stadia Readings

  • Estimate distance between rod and instrument.
  • Rod intercept is the difference between stadia readings.
  • Estimated distance:
    • Stadia multiplier typically = 100 – Indicated on inside of instrument case or in Instructional Manual.

Stadia Readings

  • Upper Stadia Reading = 5.30 ft
  • Lower Stadia Reading = 5.20 ft
  • Rod Intercept = 0.10 ft
  • Using the stadia readings, you can estimate the distance between the instrument and the rod. First find the rod intercept by subtracting the lower stadia reading from the upper stadia reading. Then multiply the rod intercept by the stadia multiplier (usually 100).

Stadia Reading

  • Example:
    • Rod Reading = 5.06 ft
    • Lower Stadia = 4.99 ft
    • Upper Stadia = 5.13 ft

Putting it All Together

Two Ways of Mapping a Region:
  • Traversing – used to locate specific features.
    • Framework consists of connected lines with known length and angles.
    • Suitable for survey of long, narrow strip (road, canal, etc.).
  • Triangulation – used to establish a control network over a region.

This Week's Instrument

  • Nikon Auto Level

Tripod

Auto Level

Select Study Area, Determine Elevation

  • Need to determine this ahead of time to get our starting elevation.
  • Tuesday!
  • Accurate digital elevation model
  • Google Earth (less accurate)
  • Benchmark

Set up and Stabilize Tripod

Attach Instrument to Tripod

Sighting the Instrument

Stadia and Crosshairs

  • Diagram provided with Top Stadia, Bottom Stadia and Crosshairs illustrated.

Surveyor's Field Notes

  • Example of surveyor's field notes provided and explained including:

*PT Name of the Location
*BM Bench Mark = Known Elevation
*BS - Backsight
*HI - Height of Instrument
*FS - Foresight
*ELEV. - Calculation of PT Height
*Stadia Reading of Top Stadia and Bottom Stadia
*Dist.' (Top Stadia - Bottom Stadia) x 100
*HI = BM + BS

Taking Readings

  • Have Assistant hold the rod vertically
  • Focus the Eyepiece
  • Stadia over the Rod Markings
  • Take readings at the Top and the Bottom Stadias and the Crosshair.
  • Record data in Surveyor’s Field Book

Data Recording

  • Field notes example shown of:
    *PT
    *BS
    *HI
    *FS
    *ELEV.
    *STADIA (Top/Bottom)
    *DIST.

Horizontal Distance Using Stadia

  • ONLY AN APPROXIMATION!
  • Horizontal distance = (Top Stadia - Bottom Stadia) x Stadia Ratio
  • AUTO LEVEL AT-G6 example provided with values:
    • Magnification 24X
    • Telescope Aperture 30mm(1-1/6in.)
    • Field of view 1° 30°
    • Minimum focus 0.5m(1.6ft.)
    • Compensator Range ±15'
    • Circle Diameter 117mm(4-5/8in.)
    • Circular level sensitivity 8'/2mm
    • Stadia Ratio 100
    • Constant 0

Horizontal Distance Using Stadia

  • Distance from POR to TP = (8.50-7.92) x 100 = 58 ft
  • Distance from TP to TP1 = (10.77-10.13)x100 = 64 ft

Terms 1

  • Benchmark (BM): a permanent, marked point of known elevation
  • Temporary Benchmark (TBM): a semi-permanent point of established elevation used on the specific job
  • Point of Reference (POR): Either the benchmark or the Temporary Benchmark chosen for this job

Terms 2

  • Turning Point (TP): A point temporarily used to transfer an elevation
  • Backsight (BS): A rod reading taken on a point of elevation (POR) in order to establish the height of the instrument
  • Height of Instrument (HI): The elevation of the line of sight through the level

Terms 3

  • Foresight (FS): A rod reading taken from a turning point, or a point of reference to an identified point to establish elevation

Proposal Details

  • Draft (outline format) due 7 March, final due 1 May
  • Construct a grant proposal in the spirit of the NSF GRFP – National Science Foundation Graduate Research Fellowship.
  • Research proposal should reflect research interests and contain some sort of field work aspect.
  • GRFP applicants are required to provide two statements:
    • Personal, Relevant Background and Future Goals Statement (3 pages max).
    • Graduate Research Plan Statement (2 pages max).
    • References, footnotes, citations, images, etc. can occur on additional pages.
  • Refer to the info/templates here: https://nsfgrfp.org/applicants/statements/

Proposal Details

  • Research Plan Statement should reflect your own research interests and contain some sort of field work aspect.
  • Example ideas:
    • Environmental impact on forestry resources of election of different political parties
    • Impacts of earthquake hazards on cultures and societies
    • Measuring the deformation of fossils to understand post depositional processes
    • Erosion and agriculture in a climate sensitive location
    • Flood hazards and fluvial geomorphology of the Mississippi river
    • The effect of climate change and sea level rise on vulnerable population

Components of Research Plan

  • This Research Plan Statement should be a clear and well-organized proposal.
  • Typical proposal outline (may have additional subsections):
    • Introduction
    • Objective
    • Methodology
    • Anticipated Results and Products
    • Intellectual Merit
    • Broader Impacts
    • References

Mock NSF-GRFP Details

Important Questions to Ask:
  • What issues in the scientific community are you most passionate about?
  • Do you possess the technical knowledge and skills necessary for conducting this work, or will you have sufficient mentoring and training to complete the study?
  • Is this plan feasible for the allotted time and institutional resources?
  • How will your research contribute to the "big picture" outside the academic context?
  • How can you draft a plan using the guidelines presented in the essay instructions?
  • How does your proposed research address the Intellectual Merit and Broader Impacts criteria?

GroupMe

  • For use during Tues. labs (and ONLY during labs).
  • Students can create their group or class group.