Journal of Geosciences and Geomatics

This study was an attempt to examine the changes of the YAKHAR Glacier of Damavand Using remote sensing and GIS Technologies. The remote sensing is the best equipment that helps us to find and estimate the area of YAKHAR glacier in the impassable mountainous regions. Moreover, GIS technologies help to design and prepare a map from the region. This study amid to prove this glacier is active and has changed during the recent years. This study was a quantitative survey and the quantitative data was collected with digital topographic map at the scale 1:50000 and 1:25000, Satellite images Landsat TM&ETM+ and IRS P5 (panchromatic). In order to correct those satellite images, the researchers applied geometrical correction and radiometric correction. The quantitative data was analyzed with calculating algorithm changes and plus subtracting from corresponding bands on the satellite images in order to measure Principal Components Analysis (PCA). Moreover, the researchers used Inter band ETM, IRS, and GIS software to indicate the severe chances of glacier via fuzzy logic model. The findings of this study reveal that the area of the YAKHAR glacier is decreasing and its current size is 1/8km. The crucial reasons of the decreasing are the lack of glacier recharge and the heat of smoke emerging from Damavand volcano. Furthermore, the global warning has impact on rising temperatures and melting YAKHAR glacier in this region and also abrupt slope prevents to form the YAKHAR glaciers.

Journal of Geosciences and Geomatics. 2016, 4(1), 15-20. DOI: 10.12691/jgg-4-1-3
Pub. Date: March 03, 2016

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Empirical Modelling of Refraction Error in Trigonometric Heighting Using Meteorological Parameters

by D. Gaifillia, V. Pagounis, M. Tsakiri and V. Zacharis

Original Research

Refraction is a complex problem in terrestrial optical measurement and can be regarded as a major source of systematic error in the precise determination of height differences using trigonometric heighting. This paper deals with the development of an empirical model to estimate vertical refraction corrections from meteorological measurements gathered by freely available meteorological sensors. The proposed methodology can produce more realistic local estimates for the refraction coefficient than the typically used single generic value. Along with presentation of the proposed method, this study also presents experimental data to illustrate that the produced results are comparable to those obtained by surveying observations.

Journal of Geosciences and Geomatics. 2016, 4(1), 8-14. DOI: 10.12691/jgg-4-1-2
Pub. Date: January 24, 2016

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Accuracy Assessment of Cartesian (X, Y, Z) to Geodetic Coordinates (φ, λ, h) Transformation Procedures in Precise 3D Coordinate Transformation – A Case Study of Ghana Geodetic Reference Network

by Bernard Kumi-Boateng and Yao Yevenyo Ziggah

Original Research

Ghana a developing country still adopt the non-geocentric ellipsoid known as the War Office 1926 as its horizontal datum for all surveying and mapping activities. Currently, the Survey and Mapping Division of Lands Commission in Ghana has adopted the satellite positioning technology such as Global Positioning System based on a geocentric ellipsoid (World Geodetic System 1984 (WGS84)) for its geodetic surveys. It is therefore necessary to establish a functional relationship between these two different reference frames. To accomplish this task, the Bursa-Wolf transformation model was applied in this study to obtain seven transformation parameters namely; three translations, three rotations and a scale factor. These parameters were then used to transform the WGS84 data into the War office system. However, Ghana’s national coordinate system is a projected grid coordinate and thus the new War Office coordinates (X, Y, Z) obtained are not applicable. There is therefore the need to project these coordinates onto the transverse Mercator of Ghana. To do this, the new war office data (X, Y, Z) attained must first be transformed into geodetic coordinates. The reverse conversion from cartesian (X, Y, Z) to its corresponding geodetic coordinate (φ, λ, h) is computation intensive with respect to the estimation of geodetic latitude and height. This study aimed at evaluating the performance of seven methods in transforming from cartesian coordinates to geodetic coordinates within the Ghana Geodetic Reference Network. The seven reverse techniques considered are Simple Iteration, Bowring Inverse equation, method of successive substitution, Paul’s method, Lin and Wang, Newton Raphson and Borkowski’s method. The obtained results were then projected onto the transverse Mercator projection to get the new projected grid coordinates in the Ghana national coordinate system. These results were compared with the existing coordinates to assess their performance. The authors proposed the Paul’s method to be a better fit for the Ghana geodetic reference network based on statistical indicators used to evaluate the reverse methods performance.

Journal of Geosciences and Geomatics. 2016, 4(1), 1-7. DOI: 10.12691/jgg-4-1-1
Pub. Date: January 07, 2016

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