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Precise Leveling and the Effect of Gravity

Course developer

Prior knowledge

BūvZ6045, Geodetic Support System I

Replaced course

BūvZ5057 [GBUV5057] Precise Leveling and the Effect of Gravity

Course abstract

The aim of the study course is to introduce students to the rationale, development and preconditions for the creation of precise leveling networks. Geodetic signs, their types, installation. Gravity potential, normal gravity and its vertical gradient, as well as gravity potential anomalies. Students learn precision leveling instruments, testing and adjusting geodetic instruments. Units of gravity and methods of measurement. Acquaintance with pendulum tools for relative gravity determination, gravimeters and gravimetric measurement methodology. Knowledge about the sources of leveling errors, their elimination. Class I and II leveling methodology. Leveling over water barriers. Correction of measured elevations for the length of the leveling rod scale and the transition to the normal height system. Leveling grid alignment, point height calculation, accuracy estimation and use of gravimetric measurements to determine the geoid model.

Learning outcomes and their assessment

Knows the structure of the national precision leveling network, leveling tools and accessories, Class I and II leveling methodology, possible sources of error, processing of measurement results and assessment of accuracy. Instruments and accessories used in gravimetry, force field and potential, force of gravity and its measurement methodology, possible sources of measurement errors, processing of measurement results and evaluation of accuracy - exam
Is able to apply knowledge of inspection and adjustment of geodetic instruments, installation of geodetic marks, leveling and organization of gravity force measurements. – practical works
Able to apply the acquired knowledge to organize accurate measurements of leveling and gravity forces in accordance with the requirements, to choose a suitable walking location and appropriate auxiliary devices, depending on the terrain conditions, to be able to detect and eliminate possible measurement errors. To process and evaluate the obtained results, to be able to detect and eliminate possible measurement errors, to analyze and evaluate the relationship of measurement results in determining and refining the geoid model – practical works

Course Content(Calendar)

1. Introduction to the essence of the synergy of precise leveling and gravity forces. Geodetic reference systems, its tasks, historical context and significance in the national economy. Interdisciplinary context in the development of geodetic reporting systems. (2h)
2. History of development, development and justification of maintenance of precision leveling networks. (2h)
3. Development of precision leveling in Latvia (2h)
4. The need to establish a national class I leveling network (core network). Constructive principle of network scheme. (2h)
5. Linking the sea level to the altitude system. Linking Baltic Sea observation posts to the leveling network. (2h)
6. Field of force. Potential. Level surfaces. (2h)
7. The main tasks of potential theory. The force of gravity and its potential. Normal gravity. Gravity force anomalies. (2h)
8. Earth's perturbed potential, determination. (3h)
9. Precision leveling tools and leveling methodology (2h)
10. Sources of precision leveling errors (3h)
11. Geodetic signs, their types and sustainability of application in the development of the geodetic network. (2h)
12. Pendulum devices for determining the relative force of gravity. (3h)
13. Gravimetric study of the earth. (2h)
14. Development and application of geoid models. (3h)
15. Territorial spatial models, level visions, their visualization. (2h)
16. Integrated geodetic networks, the role of geodetic networks in the maintenance of the State Spatial Reference System. (2h)

Practical works (24h)
1. Survey of a given area and assessment of the geodetic support situation (6h)
2. Development of an integrated geodetic network project for a given territory. (12h)
3. Visualization of dynamic parameters of level surfaces of a given territory (6h)

Requirements for awarding credit points

The exam consists of:
• oral exam on the theoretical part;
• practical work is included;
• independent works have been developed.

Description of the organization and tasks of students’ independent work

Students must select Literature and regulations and prepare for practical work.
Preparation of descriptions of practical works after the development of their practical part.
Preparing for the oral exam.

Criteria for Evaluating Learning Outcomes

The assessment of the exam depends on the cumulative assessment of the semester, the percentage distribution of which is as follows:
• oral exam - 40%
• Practical work - 40%
• Independent work - 20%.

Compulsory reading

1. Bikše J. Augstākā ģeodēzija. Mācību līdzeklis., Rīga:, RTU, 2007. Pieejams: https://dom.lndb.lv/data/obj/69010.html
2. 2. Žagars J., Zvirgzds J., Kaminskis J. Globālās navigācijas satelītu sistēmas (GNSS). Ventspils: Ventspils Augstskola, 2014:, 231 lpp.
3. I, II un III klases nivelēšanas instrukcija VZD 2001.
4. "Mikro-g LaCoste absolūtie gravimetri" http://microglacoste.com/absolutemeters.php).
Micro-g LaCoste, Inc. 2022. gads Skatīts 31.01.2022

Further reading

LR un EU normatīvie regulējumi saistībā par ģeodēzisko sistēmu uzturēšanu un kalibrāciju.

Periodicals and other sources

www.mernieks.lv; www.lgia.gov.lv; www.gim-internationa.com; www.iugg.com

Notes

Academic master's study program "Environmental, Water and Earth Engineering" full- time studies