Surveying Techniques & Data Documentation Flashcards

What is the primary purpose of surveying in floodplain studies?

Answer: To obtain precise elevation and location data for floodplain mapping

Surveying is fundamental in floodplain studies because it provides the precise elevation and location data necessary for accurate floodplain mapping. This data is used to delineate flood hazard zones, determine Base Flood Elevations (BFEs), and create detailed terrain models that are essential inputs for hydraulic modeling. Accurate surveys ensure reliable flood risk assessments and effective mitigation planning.

Which instrument is commonly used for measuring vertical and horizontal angles in surveying?

Answer: Theodolite

A theodolite is a precision optical instrument commonly used in surveying to measure both horizontal and vertical angles with high accuracy. These angular measurements are crucial for establishing precise bearings, elevations, and positions of points on the Earth's surface. In floodplain surveying, theodolites are vital for accurately mapping terrain, structures, and flood boundaries.

What is a benchmark in surveying?

Answer: A permanent reference point with known elevation

A benchmark in surveying is a permanent, precisely located reference point with a known elevation above a specific vertical datum, such as mean sea level. Surveyors use benchmarks as control points to establish consistent and accurate elevations for all other points in a survey. This ensures the reliability of elevation data used for floodplain mapping and construction projects.

Why is data documentation important in floodplain surveying?

Answer: It provides a record to verify and support survey results

Thorough data documentation in floodplain surveying is crucial because it creates a comprehensive and verifiable record of all measurements, observations, and calculations. This record allows for verification of survey results, helps resolve any discrepancies, and provides essential legal support for floodplain determinations and compliance. Without proper documentation, the integrity and defensibility of survey data can be compromised.

Which document certifies the elevation of a building or land parcel?

Answer: Elevation certificate

An Elevation Certificate is an official FEMA form that certifies the elevation of a building's lowest floor and other relevant features in relation to the Base Flood Elevation (BFE). This document is critical for determining flood insurance rates and demonstrating that a building complies with NFIP floodplain management regulations. It provides essential data for flood risk assessment and mitigation.

What is the purpose of field notes in surveying?

Answer: To document survey data accurately

Field notes are essential in surveying as they provide a primary, accurate, and contemporaneous record of all observations, measurements, and conditions encountered during a survey. These detailed notes are crucial for processing survey data, ensuring the integrity and quality of the survey, and serving as a reliable reference for future verification or analysis. They capture critical information that might not be recorded by instruments alone.

Which GPS technology is used for high accuracy in surveying?

Answer: Differential GPS (DGPS)

Differential GPS (DGPS) is a technology that significantly enhances the accuracy of standard GPS by using a network of fixed ground-based reference stations. These stations broadcast correction signals that account for errors in satellite signals, allowing DGPS to achieve much higher precision, often down to sub-meter or centimeter levels. This high accuracy is critical for detailed surveying tasks, including floodplain mapping and elevation determination.

How is survey data typically stored and managed?

Answer: Using specialized software and databases

Survey data is complex and requires robust systems for effective management. Specialized software (like CAD or GIS) and databases are essential for accurately storing, organizing, analyzing, and retrieving this detailed spatial information. This approach ensures data integrity, facilitates collaboration, and supports long-term accessibility for various projects and legal requirements.

What is the function of a plumb bob in surveying?

Answer: To ensure vertical alignment

A plumb bob is a fundamental surveying tool used to establish a true vertical line. It consists of a weight suspended by a string, and when held steady, gravity pulls it directly downwards. This vertical reference is crucial for accurately centering surveying instruments over a ground point, transferring points vertically, and ensuring that construction elements are perfectly plumb.