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Hydrographic survey is exclusively focused on mapping the seabed for offshore oil exploration and drilling, with no relevance to navigation.
Answer: False
Explanation: Hydrographic survey encompasses a broad range of maritime activities, including navigation, marine construction, dredging, and offshore wind farm development, in addition to oil and gas exploration.
Offshore survey is a specialized branch of hydrographic survey that focuses on describing the condition of the seabed and subsea oilfield infrastructure.
Answer: True
Explanation: Offshore survey is indeed a specialized discipline within hydrography, concentrating on characterizing the seabed and assessing the state of subsea oilfield infrastructure, vital for the oil and gas industry.
The term 'hydrography' is often used synonymously with 'maritime cartography' because survey data is transformed into nautical charts.
Answer: True
Explanation: The close relationship between hydrography and maritime cartography stems from the fact that raw hydrographic survey data is ultimately processed and presented as nautical charts for end-users.
What constitutes the fundamental definition of hydrographic survey?
Answer: The scientific process of measuring and describing features relevant to various maritime activities.
Explanation: Hydrographic survey is defined as the scientific process of measuring and describing features pertinent to various maritime activities, including navigation, marine construction, and offshore development.
Which of the following is NOT a specific application supported by hydrographic surveys, in addition to maritime navigation and construction?
Answer: Identifying suitable locations for terrestrial wind farms.
Explanation: Hydrographic surveys support maritime applications such as subsea cable routing and offshore wind farm development, but not terrestrial wind farm siting.
What key feature is NOT primarily emphasized during a hydrographic survey?
Answer: Atmospheric pressure
Explanation: Hydrographic surveys emphasize features like water depths, shorelines, and submerged obstructions, but not atmospheric pressure, which is a meteorological parameter.
How does the term 'hydrography' relate to 'maritime cartography'?
Answer: They are often used synonymously because survey data is transformed into nautical charts.
Explanation: The terms are frequently used interchangeably because the data collected through hydrographic surveys is ultimately processed and presented as nautical charts, which fall under maritime cartography.
What is the primary focus of 'offshore survey'?
Answer: Describing the condition of the seabed and subsea oilfield infrastructure.
Explanation: Offshore survey is a specialized branch of hydrography dedicated to characterizing the seabed and assessing subsea oilfield infrastructure, crucial for the oil and gas industry.
The International Hydrographic Organization (IHO) plays a crucial role in standardizing hydrographic products to enhance hydrography and ensure safe navigation.
Answer: True
Explanation: The IHO actively coordinates national hydrographic offices and publishes standards and specifications to improve hydrographic practices and guarantee safe navigation globally.
Nautical charts are solely required by national regulations and are not mandated by international bodies for vessel safety.
Answer: False
Explanation: Nautical charts are mandated for vessel safety by international bodies such as the International Maritime Organization (IMO) and the Safety of Life at Sea (SOLAS) convention, in addition to national regulations.
Private organizations primarily conduct hydrographic surveys for governmental clients, rarely engaging with commercial industries.
Answer: False
Explanation: Private organizations conduct large-scale hydrographic and geophysical surveying for both commercial industries, such as dredging and oil exploration, and governmental clients.
National hydrographic offices typically have a commercial heritage and are integrated within private surveying companies.
Answer: False
Explanation: National hydrographic offices historically evolved from a naval heritage and are commonly integrated within national naval structures, rather than having a commercial heritage or being part of private companies.
Governmental entities at sub-national levels are prohibited from conducting hydrographic surveys within their jurisdictions.
Answer: False
Explanation: Governmental entities at sub-national levels are authorized to conduct or contract for hydrographic surveys within their jurisdictions, often adhering to national standards.
Industries installing submarine cables require only general surveys, not detailed ones, before installation.
Answer: False
Explanation: Industries involved in installing submarine cables or power cables require detailed surveys of proposed cable routes prior to installation, often utilizing advanced acoustic imagery equipment.
Which organization coordinates national hydrographic offices and promotes product standardization?
Answer: The International Hydrographic Organization (IHO)
Explanation: The IHO is the international body responsible for coordinating national hydrographic offices and promoting standardization to enhance hydrography and ensure safe navigation.
What is a key reason nautical charts are required on vessels?
Answer: For safety purposes, mandated by IMO, SOLAS, and national regulations.
Explanation: Nautical charts are internationally and nationally mandated for vessel safety, providing critical information for navigation and hazard avoidance.
Which of the following entities often funds hydrographic surveys of public waterways when developing adjacent areas?
Answer: Companies, universities, and investment groups.
Explanation: Companies, universities, and investment groups frequently fund hydrographic surveys of public waterways, especially when developing adjacent areas or supporting large public projects.
How have national hydrographic offices typically been structured historically?
Answer: Integrated within national naval structures, evolving from a naval heritage.
Explanation: National hydrographic offices have a strong historical connection to naval operations and are frequently integrated within national naval frameworks.
What type of equipment do industries installing submarine cables increasingly use for detailed surveys?
Answer: Advanced acoustic imagery equipment, previously found primarily in military applications.
Explanation: For detailed route surveys, industries installing submarine cables are increasingly adopting sophisticated acoustic imagery equipment, which was once exclusive to military applications.
Modern hydrographic surveys primarily rely on traditional methods like lead lines and sounding poles due to their proven accuracy.
Answer: False
Explanation: Modern hydrographic surveys predominantly utilize advanced electronic sensor systems and aircraft for increased efficiency and comprehensive data collection, moving beyond the labor-intensive and limited coverage of traditional methods.
Wire-drag surveying was introduced into hydrography in 1904, with Nicholas H. Heck being instrumental in its development.
Answer: True
Explanation: Nicholas H. Heck of the United States Coast and Geodetic Survey was indeed a key figure in developing and perfecting wire-drag surveying, which was introduced in 1904.
The wire-drag method was less efficient and more laborious than lead lines and sounding poles for comprehensive area surveys.
Answer: False
Explanation: Wire-drag surveying was a significant advancement, offering a quicker, less laborious, and more complete survey of an area compared to the earlier methods of lead lines and sounding poles.
Sidescan sonar and multibeam swath systems were developed in the 1980s, rendering the wire-drag system obsolete.
Answer: False
Explanation: Sidescan sonar and multibeam swath systems emerged in the 1950s, 1960s, and 1970s, not specifically the 1980s, and their superior capabilities did indeed lead to the obsolescence of the wire-drag system.
What were the primary limitations of the earliest hydrographic surveying methods like lead lines and sounding poles?
Answer: They were labor-intensive, time-consuming, and prone to leaving gaps in coverage.
Explanation: Lead lines and sounding poles were manual, slow, and provided only discrete measurements, leading to incomplete seabed coverage.
Who played a significant role in developing and perfecting wire-drag surveying between 1906 and 1916?
Answer: Nicholas H. Heck
Explanation: Nicholas H. Heck of the United States Coast and Geodetic Survey was instrumental in the development and refinement of wire-drag surveying during this period.
How did the wire-drag method function to detect underwater obstructions?
Answer: By using a wire stretched between two ships that would become taut and form a 'V' shape upon encountering an obstruction.
Explanation: The wire-drag method involved towing a submerged wire between two vessels; an obstruction would cause the wire to tighten and form a 'V', indicating its presence and depth.
What technological advancements ultimately rendered the wire-drag system obsolete?
Answer: The emergence of sidescan sonar and multibeam swath systems.
Explanation: The superior capabilities of sidescan sonar and multibeam swath systems for underwater imaging and comprehensive depth data collection led to the obsolescence of the wire-drag system.
Single-beam echosounders, introduced in the 1930s, provided comprehensive depth data for the entire seabed, eliminating gaps in coverage.
Answer: False
Explanation: Single-beam echosounders, while faster than previous methods, only provided depth information directly beneath the vessel, leaving significant gaps in coverage between survey lines.
A multibeam echosounder (MBES) utilizes beamforming technology to produce a wide swath of depth soundings from a single acoustic pulse.
Answer: True
Explanation: MBES systems are distinguished by their use of beamforming technology, which allows them to extract directional information from returning sound waves and generate a wide swath of depth soundings from each acoustic pulse.
The value of acoustic backscatter data from MBES technology is not explicitly recognized as a survey deliverable in the hydrographic community.
Answer: False
Explanation: The hydrographic community explicitly recognizes the value of acoustic backscatter data from MBES technology, requiring its logging and rendering as a high-resolution, geo-referenced survey deliverable.
Multispectral multibeam echosounders represent a new innovation, providing 'multiple look' depth measurements and spatially and temporally coincident multispectral backscatter data.
Answer: True
Explanation: Multispectral multibeam echosounders are indeed an advanced innovation, offering enhanced capabilities for acquiring richer data through 'multiple look' depth measurements and coincident multispectral backscatter data.
Early acoustic sounder operating frequencies showed no noticeable dependency on seabed type for measured depths.
Answer: False
Explanation: While early acoustic sounder frequencies had little bearing on depths over hard bottoms, a noticeable frequency dependency was observed when surveying soft bottoms, with higher frequencies proving more effective.
The National Ocean Survey (NOS) established a study team in 1979 to develop a new deep-water depth sounder.
Answer: False
Explanation: The NOS study team established in 1979 was tasked with developing functional specifications for a replacement shallow water depth sounder, not a deep-water one, specifically to address challenges in 'floating mud' environments.
The first generation of multibeam echosounders was primarily designed for mapping the seafloor in deep water.
Answer: True
Explanation: The initial objective of multibeam echosounders was to accurately map bathymetry in deep-water environments, capturing both peaks and depressions of the seafloor.
Marty Klein's introduction of dual-frequency side scan sonar demonstrated that different acoustic frequencies could produce distinct images of the seabed.
Answer: True
Explanation: Marty Klein's dual-frequency side scan sonar indeed showed that spatially and temporally coincident backscatter at widely separated acoustic frequencies could generate two distinct and unique images of the seascape.
The grounding of the Queen Elizabeth 2 in 1992 led to a decreased emphasis on full bottom coverage surveys in shallow water.
Answer: False
Explanation: The grounding of the Queen Elizabeth 2 in 1992 actually prompted an *increased* emphasis on achieving full bottom coverage in shallow water surveys, leading to greater use of high-frequency MBES.
The 'snippet' modification to multibeam echosounder imagery improved quality by reducing the number of echo amplitude measurements.
Answer: False
Explanation: The 'snippet' modification enhanced multibeam echosounder imagery by *increasing* the number of echo amplitude measurements and achieving a more uniform spatial distribution of pixels, not by reducing them.
When did single-beam echosounders begin to be widely utilized in hydrographic surveying?
Answer: In the 1930s.
Explanation: Single-beam echosounders and fathometers were introduced and began to be used in the 1930s, significantly increasing the speed of sounding data acquisition.
What was a key limitation of single-beam echosounders, despite their increased speed of data acquisition?
Answer: They only provided depth information directly beneath the vessel, leaving gaps in coverage.
Explanation: A significant drawback of single-beam echosounders was their inability to provide comprehensive seabed coverage, as they only measured depth directly below the vessel, resulting in unsounded areas.
How does a multibeam echosounder (MBES) determine water depth?
Answer: Based on the time it takes for acoustic waves to reflect off the seabed and return to the receiver.
Explanation: MBES calculates water depth by precisely measuring the two-way travel time of acoustic waves from the transceiver to the seabed and back.
What additional information does logging high-resolution, geo-referenced backscatter intensity from MBES technology provide beyond just depth?
Answer: Information about the seabed's characteristics beyond just depth.
Explanation: High-resolution backscatter intensity data from MBES offers valuable insights into the physical properties and characteristics of the seabed, complementing bathymetric data.
What was observed about higher frequency single vertical beam echosounders in relation to soft sediments?
Answer: They provided detectable echo amplitudes from high porosity sediments.
Explanation: Higher frequency single vertical beam echosounders were found to be effective in detecting echoes from high porosity soft sediments, even when lower frequencies failed to penetrate.
What was the primary objective of the first generation of multibeam echosounders?
Answer: To map the seafloor in deep water and obtain accurate bathymetry.
Explanation: The initial design and deployment of multibeam echosounders were focused on acquiring accurate bathymetric data for deep-water seafloor mapping.
What event prompted a significant shift in emphasis towards full bottom coverage surveys in shallow water using MBES?
Answer: The grounding of the Queen Elizabeth 2 off Cape Cod, Massachusetts, in 1992.
Explanation: The grounding incident highlighted the critical need for comprehensive seabed mapping in shallow waters, leading to increased adoption of MBES for full bottom coverage.
How did the 'snippet' modification enhance multibeam echosounder imagery?
Answer: By increasing the number of echo amplitude measurements and achieving a more uniform spatial distribution of pixels.
Explanation: The 'snippet' modification improved imagery quality by providing more numerous and uniformly distributed echo amplitude measurements, enhancing the detail and accuracy of the rendered pixels.
What was the outcome of the National Ocean Survey (NOS) study regarding shallow water depth sounders initiated in 1979?
Answer: The development of a class of vertical-beam depth sounders that ping at two acoustic frequencies simultaneously.
Explanation: The NOS study led to the development of dual-frequency vertical-beam depth sounders, designed to address the specific challenges of shallow water surveying, particularly in 'floating mud'.
Crowdsourcing in hydrographic surveying, through projects like OpenSeaMap, involves volunteer vessels recording position, depth, and time data.
Answer: True
Explanation: Projects such as OpenSeaMap and TeamSurv exemplify crowdsourcing in hydrography, where volunteer vessels contribute position, depth, and time data using their standard navigation instruments.
Crowdsourced hydrographic surveys consistently match the accuracy standards of rigorous systematic surveys.
Answer: False
Explanation: While beneficial for continuous coverage and cost savings, crowdsourced hydrographic surveys rarely achieve the same rigorous accuracy standards as traditional systematic surveys, though high data density and algorithms can yield sufficient accuracy for many purposes.
The General Bathymetric Chart of the Oceans (GEBCO) project provides a global series of maps depicting the general shape of the world's ocean floors.
Answer: True
Explanation: GEBCO is a publicly available bathymetric chart project that offers a global series of maps illustrating the general morphology of the world's ocean floors, serving as a key reference.
Lidar technology is unsuitable for hydrographic surveying in shallow-water environments.
Answer: False
Explanation: Lidar (light detection and ranging) technology is, in fact, an effective and efficient method for hydrographic surveying in appropriate shallow-water environments.
Modern hydrographic surveying data is increasingly collected under a single standard and then extracted for specific uses, unlike historical practices.
Answer: True
Explanation: With advancements in collection and processing, modern hydrographic data is often acquired under a unified standard, allowing for subsequent extraction and customization for diverse applications, a departure from historical practices.
The post-processing stage in hydrographic surveying primarily involves collecting more data to fill gaps, rather than correcting existing data.
Answer: False
Explanation: Post-processing in hydrographic surveying involves thinning collected data, correcting for errors, and applying environmental effects, rather than collecting new data to fill gaps.
Corrections for factors like tides, heave, salinity, and thermoclines are applied during post-processing because the velocity of sound varies with temperature and salinity.
Answer: True
Explanation: These corrections are crucial during post-processing because the velocity of sound, which is fundamental for accurate depth measurements, is directly influenced by variations in water temperature and salinity.
What is a primary benefit of utilizing crowdsourcing for hydrographic surveys?
Answer: Cost savings and potential for continuous survey coverage.
Explanation: Crowdsourcing offers significant advantages in terms of reduced costs and the ability to achieve ongoing, widespread survey coverage, though accuracy may vary.
What is the General Bathymetric Chart of the Oceans (GEBCO) project?
Answer: A global series of maps depicting the general shape of the world's ocean floors.
Explanation: GEBCO is a collaborative international project that produces a comprehensive series of maps illustrating the general bathymetry of the world's oceans.
Which advanced technology can be effectively employed for hydrographic surveying in suitable shallow-water areas?
Answer: Lidar (light detection and ranging).
Explanation: Lidar technology is a highly effective and efficient method for acquiring hydrographic data in appropriate shallow-water environments.
What types of platforms are NOT mentioned as being used for modern integrated hydrographic surveying equipment?
Answer: Fixed-wing commercial airliners.
Explanation: Modern hydrographic surveying equipment is deployed on various marine and underwater platforms, but fixed-wing commercial airliners are not typically used for this purpose.
Why are corrections for factors like tides, heave, salinity, and thermoclines applied during post-processing of hydrographic survey data?
Answer: Because the velocity of sound, used for depth measurement, varies with temperature and salinity.
Explanation: These environmental corrections are essential because the speed of sound in water, which is critical for accurate depth determination, is significantly affected by variations in temperature and salinity.
What is the typical accuracy of crowd-sourced hydrographic surveys, when algorithms and high data density are applied?
Answer: Plus or minus 0.1 to 0.2 meters.
Explanation: With the application of advanced algorithms and sufficient data density, crowd-sourced surveys can achieve an accuracy of approximately 0.1 to 0.2 meters, which is adequate for many requirements.
What is the primary purpose of the post-processing stage in hydrographic surveying?
Answer: To thin out collected data, correct for errors, and apply environmental effects.
Explanation: Post-processing is a critical phase where raw data is refined, errors are corrected, and environmental influences are accounted for, preparing the data for its intended final use.