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From the 1990s to date, growing deterioration of urban environmental quality, and the developments of squatter settlements and squalors have gradually become the attributes of the development patterns in the Federal Capital City (FCC), Abuja and environs in Nigeria. The FCC, Abuja and the surrounding towns and settlements popularly referred to as 'satellite towns' in Nigeria, are characterized by inadequate urban infrastructure, high rural-urban migration, population pressure, high cost of living, poor economic lifestyle, informal settlements and failing infrastructure. In view of these urban development dynamics and the prevailing economic situations in Nigeria, many citizens have resorted to building and settling in unapproved lands within and around the city. In attempts to maintain the designed land use and master plan of the city and to control the quality of infrastructural developments in the area, the relevant government authorities often employ the use of mass demolition of illegal constructions, and informal settlements; resulting in displacement of many inhabitants. A further repercussion of this process is the emergence of several unplanned settlements dotting the surroundings of the city area assumed to be outside the immediate development interest of the FCC authorities. This paper is therefore aimed at assessing the urbanization of the FCC, Abuja as a catalyst for the emergence of squatter settlements and squalors in and around the city. To achieve this, Landsat satellite images of Abuja in 1987, 2001 and 2006 were used in mapping and analyzing the spatial growth of the city. The results of the study showed that squatter settlements and squalors have sprang up in and around the study area due to poor housing scheme, which made proper accommodation within the city unaffordable for low income residents of the city who were mostly civil servants. It was argued in the paper that, though demolition exercise may be agreed by the Abuja City Administration as a necessity, this could be largely avoided if proper housing infrastructure is included in the planning process.

The spatial and temporal variability of water vapour in the atmosphere influences the earth weather, climate system, quality of spatial positioning and radio waves propagation of communications signals amongst others. It is therefore imperative to periodically monitor and map the water vapour phenomenon over specific areas of interest across the globe. This study therefore investigates the time-series variability of the atmospheric water vapour contents (AWVC) over Nigeria from the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim (ERA-I) and National Centre for Environmental Prediction/National Centre for Atmospheric Research (NCEP/NCAR) reanalysis data. The 2007-2017 daily/monthly mean data sets of ERA-I and NCEP/NCAR were visualised and extracted with Panoply version 4.8.6 and MATLAB 2018b for the 37 states capital in Nigeria. The months of minimum and maximum AWVC for all sampled locations were determined and compared, and the best fit trend equations for six cities (one city from each of the six geopolitical zones) were developed. The monthly means of AWVC over the study area showed spatial heterogeneity trend. The latitudinal variations in both ERA-I and NCEP/NCAR data sets showed that AWVC over Nigeria increases as latitude decreases towards the equator, and vice versa, irrespective of the month or time of the year. The study showed that May-September and November-February of 2007-2017 represent the periods with highest and lowest values of AWVC over Nigeria, respectively, which are the expected wet and dry seasons in the study area, and with peak months of August and January, respectively. The linear regression of the ERA-I and NCEP/NCAR data sets gave a coefficient of correlation of about 96.37%, coefficient of determination (R 2) of about 92.9% and a coefficient of efficiency of 87.83%, which indicate that ERA-I and NCEP/NCAR data sets have close values and the relationship between them in estimating AWVC over any selected location is statistically significant and valid. The coefficient of efficiency (E) of about 87.8% shows high level of internal efficiency of the ERA-I and NCEP/NCAR data sets used in this study. The best line of fit from polynomial models showed a range of the R 2 results for the best line-of-fit determination ranging between 78.36% and 95.75% for ERA-I, and 81.24% and 94.13% for NCEP/NCAR. The models and time-series spatial maps of AWVC produced in the study are recommended for use in the empirical estimation of AWVC and validations of other independent water vapour retrieval solutions such as GNSS and aerospace radiometry over the study area.

Sustainable provision of potable water for domestic, industrial and development purposes in Minna has been elusive over the years due to several factors, including lack of spatial database (locations, depth, area, volume, etc.) and the threat by siltation and land use activities within the corridors of the reservoir area. This paper utilizes the data collected from fieldwork to investigate the volume of sediment accumulated in Tagwai reservoir basin over a period of 31 years since the dam was constructed in 1978. Sediment accumulation study in a dam is one of the useful methods of gathering information needed for its monitoring, maintenance, and sustainability. Leica TC1201 (total station) was used for perimeter survey, while Raytheon DE-119 (echo sounder) was adopted for depth measurement. A comparison was made between the designed reservoir volume (28.3 × 10 6 m 3) and the computed volume (20.4 × 10 6 m 3). A loss of about (7.9 × 10 6 m 3) was recorded. Sediment accumulation gave 0.25 Mm 3 , a spread of about (0.80%) annually. Prediction and error analysis was done using geostatistical methods of Kriging/Co-kriging and Empirical Bayesian Kriging in ArcGIS software. The predicted root mean square errors are 0.0963 and 0.1189 for both methods which presented a good representation while testing with other available methods. It can be concluded that the storage capacity of the reservoir is depleting which has further exacerbated the shortage of water experienced in Minna metropolis therefore, urgent attention for de-silting is highly recommended.

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Geodetic reference frames were established decades ago by classical surveying techniques; however, due to biases caused by poor observation techniques and effects of plate tectonic, the origins are poorly defined and adopted. Due to plate tectonics, the relative position of points changes with time and therefore, datum such as MINNA requires redefinition at regular intervals to be in consonant with geodetic reference frame in use. Therefore, with the Continuously Operating Reference Stations (CORS) network in Nigeria, these biases can be mitigated and a more accurate datum transformation parameter between MINNA datum and ITRF can be developed and adopted. Therefore, this study presents the results of time-dependent datum transformation parameters proposed for Nigeria using 5-years GNSS data (from 2011 to 2015) obtained from the NigNet CORS. GAMIT GNSS scientific processing software was deployed in processing, while GLOBK was used for frame definition and datum transformation parameters development. Statistical assessments show the validity of the transformation parameters. The correlation value was found to be 1, root mean square error 0.00411, normalized mean absolute error 1.267E−10 and reliability index 1.0.

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