Flood is a common disaster affecting the lives and properties of humans. It has a history of causing great damage to infrastructure; disrupt transportation, also, a greater degree of flooding can lead to caving in of the earth causing landslides. Oftentimes, Lagos state, the economic capital of Nigeria has been subjected to flooding owing to heavy rainfall coupled with other causative factors. This study aims to prepare a flood susceptibility map of Lagos state using the frequency ratio model and Geographic Information System (GIS). In this paper, we have considered ten salient contributing factors to flooding, they are; slope, curvature, drainage proximity, drainage density, soil type, average annual rainfall, topographic wetness index, land use & land cover, normalized difference vegetation index, and elevation to delineate the area susceptible to flooding. The flood inventory map was prepared from 100 flood points identified from news reports, and Google Earth Imagery and was further divided into 70 for training and 30 for testing the model. The result shows that 12.54% and 11.62% of the total area of Lagos state have very high and very low levels of flood susceptibility, respectively. The Area Under the Curve has been used to validate the model and was found to perform satisfactorily with a success rate of 64% and a prediction rate of 61%. This work is a necessary input for mitigating flood hazards in the state and will serve a good purpose in making decisions for city planners and the government.

Conversion between space rectangular (X, Y, Z) and curvilinear (?, ?, h) coordinates is an important task in the field of Surveying, geodesy, positioning, navigation, mapping etc. Different techniques which include iterative methods, non-iterative techniques and closed form algebraic methods have been applied over the years to carry out the coordinate conversion. However, the results obtained using these techniques are deficient in one way or the other due to the inherent limitations such as inability to produce results for curvilinear coordinates when the values of X, Y and Z are subsequently or simultaneously equal to zero. Therefore, this study attempts to put forth an optimum coordinate conversion technique between space rectangular and curvilinear coordinates. The data used are coordinates of points which include the space rectangular coordinates and their equivalent curvilinear coordinates. They were observed and processed in Nigeria using Doppler 9 software by African Doppler Survey (ADOS) and they were confirmed to be of first order accuracy and hence of high quality. The data processing involved the design of the optimum techniques equations, coding of the algorithms and necessary computations to obtain results. Analyzing the results obtained, it can be inferred that the designed optimum model has successfully carried out the conversion between space rectangular and curvilinear coordinates. Therefore, the optimum technique model is recommended for use for the conversions from Space rectangular coordinates to Geocentric, Geodetic, Reduced coordinates and vice versa.

This study was carried out to determine 3D-position of selected points within Obafemi Awolowo University. The points were located at Africa Regional Institute for Geospatial Information Science and Technology (AFRIGST), Central Technological and Laboratory Workshops (CTLW), main Bus Stop, Religion ground, New Environmental Design and Management (New EDM), and Spider building. China HuaCe Corporation (CHC) GPS and Promark 3 GPS were used to carry out observation on the selected points. The data gotten were post processed using GNSS solution software for Promark3, Compass software for CHC GPS and the result gotten were compared with the known coordinates of those points. The data was analyzed using Statistical Package for Social Sciences (SPSS) to determine the most accurate instrument between the two. The occupation time for the two instruments on each station was 45 minutes. Analysis of Variance (ANOVA) and Chi square Variance analysis were conducted, the result showed that there is no significant difference between the observations of the two instruments in comparison with the adjusted coordinate. It can be concluded that any of the two instruments can be used for 3D point positioning to obtain accurate result.

This study was carried out to determine 3D-position of selected points within Obafemi Awolowo University. The points were located at Africa Regional Institute for Geospatial Information Science and Technology (AFRIGST), Central Technological and Laboratory Workshops (CTLW), main Bus Stop, Religion ground, New Environmental Design and Management (New EDM), and Spider building. China HuaCe Corporation (CHC) GPS and Promark 3 GPS were used to carry out observation on the selected points. The data gotten were post processed using GNSS solution software for Promark3, Compass software for CHC GPS and the result gotten were compared with the known coordinates of those points. The data was analyzed using Statistical Package for Social Sciences (SPSS) to determine the most accurate instrument between the two. The occupation time for the two instruments on each station was 45 minutes. Analysis of Variance (ANOVA) and Chi square Variance analysis were conducted, the result showed that there is no significant difference between the observations of the two instruments in comparison with the adjusted coordinate. It can be concluded that any of the two instruments can be used for 3D point positioning to obtain accurate result.