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Efficient transformation parameters are key to effective geodetic operations between any systems. With the advancement in technology, an improved interaction between geodetic reference frames has been noticed irrespective of their inherent heterogeneous deformations and the intermittently present oversight that exist as a result of the conversion methodology.The spatial data captured using the Global Navigation Satellite System (GNSS) has a reference datum based on the World Geodetic System 1984 (WGS84) ellipsoid. These data usually require a transformation to a local projection with its ellipsoid and datum and vice versa. These geodetic operations are unavoidably vulnerable to data loss due to distortion, especially if the applied model is unsuitable for the transformation between reference frames. Therefore, the main aim of this study is to authenticate the existing set of parameters for the local and geocentric systems in Nigeria by assessing the efficacy of the Bursa Wolf (BW) and the Molodensky Badekas (MB) models. To this end, both models (BW and MB) are compared in this study and used in the development of the Helmerts seven transformation parameters between Minna datum (Clarke 1880) and WGS84 reference ellipsoids for a large region in Southern Nigeria. Results show that the sets of datum shift transformation parameters for both models (a scale factor with three sets of translational and rotational parameters) derived from the exercise of the BW and the MB models revealed a high degree of correlation between the expected and derived set of coordinates during the validation/testing phase using each set of models. The validation exercise was carried out on a total of seven points, which were not part of the original computations. These points were distributed across the region to provide a better framework anda higher confidence level. Overall, an improvement of 68% is observed in terms of the correlation between expected and derived coordinates in the validation pointsand from the obtained root mean square values. Ultimately, the MB model is preferred to the BW model evidently because the transformation involves a global-local reference frame. .

In large freshwater river basins across the globe, the composite influences of large-scale climatic processes and human activities (e.g., deforestation) on hydrological processes have been studied. However, the knowledge of these processes in this era of the Anthropocene in the understudied hydrologically pristine South Central African (SCA) region is limited. This study employs satellite observations of evapotranspiration (ET), precipitation and freshwater between 2002 and 2017 to explore the hydrological patterns of this region, which play a crucial role in global climatology. Multivariate methods, including the rotated principal component analysis (rPCA) were used to assess the relationship of terrestrial water storage (TWS) in response to climatic units (precipitation and ET). The use of the rPCA technique in assessing changes in TWS is warranted to provide more information on hydrological changes that are usually obscured by other dominant naturally-driven fluxes. Results show a low trend in vegetation transpiration due to deforestation around the Congo basin. Overall, the Congo (r2 = 76%) and Orange (r2 = 72%) River basins maintained an above-average consistency between precipitation and TWS throughout the study region and period. Consistent loss in freshwater is observed in the Zambezi (−9.9 ± 2.6 mm/year) and Okavango (−9.1 ± 2.5 mm/year) basins from 2002 to 2008. The Limpopo River basin is observed to have a 6% below average reduction in rainfall rates which contributed to its consistent loss in freshwater (−4.6 ± 3.2 mm/year) from 2006 to 2012.Using multi-linear regression and correlation analysis we show that ET contributes to the variability and distribution of TWS in the region. The relationship of ET with TWS (r = 0.5) and rainfall (r = 0.8) over SCA provides insight into the role of ET in regulating fluxes and the mechanisms that drive precipitation in the region. The moderate ET–TWS relationship also shows the effect of climate and anthropogenic influence in their interactions.