Optimal vertical datum for Tanzania

  • Prosper E. Ulotu Ardhi University

Abstract

Review of the advantages and disadvantages of the current Tanzania Tide Gauge (TG) vertical Datum (VD) has revealed that some of the problems cannot be solved to conform to the Satellite geodesy era timely and cost effectively. The current VD is costly and uneconomic. By changing to a Global Navigation Satellite Systems (GNSS) compatible VD, most of the problems of the current Tide Gauge-Vertical Datum (TG-VD will disappear and thus boost greatly economic and social prosperity.

One of the current objectives of the International Association of Geodesy (IAG) is to establish a global homogeneous gravity potential vertical datum, a task assigned to the Global Geodetic Observing System (GGOS). From GGOS, realization of the IAG objective is very much dependent on the unification of compatible local and regional VDs. Hitherto, New Zealand realized a new VD based on a geoid model in 2009, and Canada in 2013. The goal of the USA government is to change from TG-VD to geoid model VD by 2022, similarly a lot more countries and regions are striving for the same, and so should Tanzania.

The data for a reliable gravimetric geoid model for Tanzania is ready. A few but not serious and solvable problems are envisaged if a GNSS compatible geoid model based VD replaces the current TG-VD. The advantages of Tanzania changing from the Tide Gauge VD to geoid model VD in this era of GNSS and other satellite technologies are enormous with long term solutions and surpass the expected problems by far. In addition to meeting the IAG/GGOS objective, it will enable the SPILL project to complete the NSRS which is partly ready with the horizontal component only, i.e. TAREF11.

 

Keywords: vertical datum. tide gauge. geoid model. GNSS-position. orthometric height

References

Amos, M 2010, ‘New Zealand VD 2009’. New Zealand Surveyor, no. 300, 2010.

Amos, MJ & Featherstone, WE 2009, ‘Unification of New Zealand’s local VDs: iterative gravimetric quasi-geoid computations’, J Geod, vol. 83, no. 1, pp. 57-68.

Dickson, WL 1965, ‘Primary Levelling Heights of Benchmark’, Technical report to the Ministry of Lands, Settlements and Water Supply, Survey and Mapping Division, Dar es Salaam.

Filmer, MS & Featherstone, WE 2012, ‘Three viable options for a new Australian vertical datum’, J Spatial Sci, vol. 57, no. 1, pp. 19-36, DOI: 10.1080/14498596.2012.679248.

Forsberg, R 2003, An overview manual for the GRAVSOFT Geodetic Gravity Field Modelling Programs, KMS - National Survey and Cadastre of Denmark including comments to programs by Tscherning CC (Univ. CPH) and Knudsen P (KMS).

Forsberg, R, Olesen, AV, Mtamakaya, J, Tarimo, C & Ulotu, PE 2013, Preliminary geoid model for Tanzania from airborne and surface gravity, Scientific research report submitted to the Surveys and Mapping Division of the Ministry of Lands, Housing and Human Settlements Development, Dar Es Salaam, Tanzania.

Heiskanen, WA & Moritz, H 1967, Physical geodesy. WH. Freeman and Company, San Francisco, USA.

Hofmann-Wellenhof, B & Moritz, H 2005, Physical geodesy. Springer Wien New York.

Huang, J, Véronneau, M, Henton, J & Héroux, P 2011, ‘A Prototype of a Geoid-Based Height System in Canada’, XXV IUGG General Assembly, Earth on the Edge: Science for Sustainable Planet, Melbourne, Australia, IAG G06: Towards a unified World Height System, 28 June-7 July.

John, S & Deus, D 2009, ‘Transformation of the Tanzania national levelling datum to the geoid’, Geophysical Research Abstracts, vol. 11, EGU2009-11339, EGU General Assembly, 19-24 April, 2009,Vienna, Austria. http://meetings.copernicus.org/egu2009

John, S, Laswai, ZJM, Richard, BK, Stephen, DM & Msemo HO 1991, ‘Proposal for rigorous systems of heights for East Africa’, Technical report Department of Land Surveying Ardhi Institute Dar Es Salaam Tanzania, no. 90-1,

Kotsakis, C, Fotopoulos, G & Sideris, MG 2001, ‘Optimal fitting of gravimetric geoid model undulations to GPS/levelling data using an extended similarity transformation model’, Proceedings of the annual scientific meeting of the Canadian Geophysical Union of Ottawa, Canada, May 14-17.

Lemoine, FG, Kenyon, SC, Factor, JK, Trimmer, RG, Pavlis, NK, Chinn, DS, Cox, CM, Klosko, SM, Luthcke, SB, Torrence, MH, Wang, YM, Williamson, RG, Pavlis, EC, Rapp, RH & Olsen, TR 1998, ‘The development of the joint NASA GSFC and NIMA geopotential model EGM96’, NASA Technical Publication.

Maduka, PR 2013, ‘Digital mapping of the lateral density variation of the upper crust in Tanzania’, B.Sc. Dissertation, Department of Geomatics, School of Geospatial Sciences and Technology, Ardhi University

Merry, CL 2007, ‘AGP07 an updated geoid model for Africa’, Presented, Symposium G2, XXIV General Assembly of the IUGG, Perugia, Italy, July 2007.

Molodensky, MS, Eremeev, VF & Yurkina, MI 1962, ‘Methods for study of the external gravity field and figure of the Earth’, Translation from Russian (1960), Israel program for scientific translation, Jerusalem.

NRCan 2011, Height Reference System Modernization, Geodetic Survey Division, Earth Sciences Sector, Natural Resources Canada, viewed March 2014, http://www.geod.nrcan.gc.ca/hm/index_e.php.

Ntambila, D 2012, Validation of the recent geoid models for Tanzania, M.Sc. dissertation of the SGST, Ardhi University (ARU) Tanzania.

Olliver, JG 2007, ‘The gravimetric geoid model of Tanzania’, Survey review, vol. 39, no. 305, pp. 212-225

Pavlis, NK, Holmes, SA, Kenyon, SC & Factor, JK 2008, ‘An Earth Gravitational Model to degree 2160: EGM2008’, presented at the 2008 general assembly of the European Geosciences Union, Vienna, Austria, April 13-18, 2008.

Roman, D & Weston, N 2012, ‘Beyond GEOID12-Implementing a New Vertical Datum for North America’, FIG Working Week 2012, TS04B - Heights, Geoid and Gravity, 5691. Rome, Italy, 6-10 May 2012.

Sánchez, L 2013, ‘Towards a vertical datum standardisation under the umbrella of Global Geodetic Observing System’, JGS, vol. 2, no. 4, pp. 325–342. DOI: 10.2478/v10156-012-0002-x.

Sjöberg, LE 2003a, ‘A general model for modifying Stokes’ formula and its least-squares solution’, J Geod vol. 77, pp. 459-464.

Sjöberg, LE 2003b, ‘A Computational scheme to model the geoid model by the modified Stokes’ formula without gravity reductions’, J Geod, vol. 77, pp. 423-432.

Sjöberg, LE 2010, ‘A strict formula for geoid-to-quasigeoid separation’, J Geod, vol. 84, pp. 699-702.

Sjöberg, LE. 2012, ‘The geoid-to-quasigeoid difference using an arbitrary gravity reduction model’, Stud Geophys Geod, vol. 56, pp. 929-933.

Sjöberg, LE 2013, ‘The geoid or quasigeoid- which reference surface should be referred for a national height system?’, JGS, vol. 3, pp. 103-109.

Ulotu, PE 2009, ‘Geoid Model of Tanzania from Sparse and Varying Gravity Data Density by the KTH Method’, PhD Thesis, the Royal Institute of Technology (KTH), Stockholm, Sweden.

Ulotu, PE 2013, ‘Validation of Gravimetric Geoid Model TZG08 Using GPS Levelling Method in Mainland Tanzania’, Journal of Building & Land Development, Vol. 21, no. 1.

Willison, DK 2013, ‘Geoid model validation using geoid slopes, study cases: AGP07, TZG07, TZG08 and EGM08 on 28 TPLN Benchmarks’, BSc. Dissertation, Department of Geomatics, SGST, Ardhi University, Tanzania, 2012/13.

Wonnacott, R & Merry, C 2012, ‘A New Vertical Datum for South Africa?’, Scientific report of the Department of Rural Development and Land Reform, Cape Town, South Africa.
Published
2016-05-26
How to Cite
ULOTU, Prosper E.. Optimal vertical datum for Tanzania. Journal of Land Administration in Eastern Africa, [S.l.], v. 3, n. 2, p. 367-376, may 2016. ISSN 2453-5869. Available at: <http://journals.aru.ac.tz/index.php/JLAEA/article/view/49>. Date accessed: 19 sep. 2017.
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