Earth Science

Groundwater chemical behaviors in various locations are one of the most dynamic fields of research in the present world. In the present study, groundwater sampling was conducted with an aim to assess the groundwater chemistry and to compare the water types using piper and Chadha´s plots. Groundwater chemistry was assessed and natural processes are identified as the controlling factors of hydrochemistry. Piper and Chadha´s diagram was created for comparing the results of water types. Majority of the samples were behaved in more or less same way except few samples. The prominent type was Ca-Mg-Cl type of water in both methods. However, a slight variation was observed in the Na-Cl type of water. Easily accessible software’s to plot is the Chadha´s diagram major advantage observed

Gravity data were acquired along two profiles in some parts of the Njaba River sub-basin located in Southeastern Nigeria. Profile A-A’ runs for about 30 kilometers from Ogbaku to Oguta lake and Profile B-B’ (covers about 12km) runs from Mgbidi to Oguta lake with the end of the two profiles meeting at the lake. The corrected data is interpreted to prove the petroleum potentiality of the study area. The Bouguer gravity anomaly along Profile A-A’ revealed an initial positive gravity values (+50 to +10 g.u.) to a wavelength (distance) of about 21km and then followed by a sudden drop of the observed gravity showing a significant gravity minimum to a value of about -150 g.u. Profile B-B’ showed an alternating gravity highs and lows which was followed by a sharp drop in the observed gravity (-140 g.u.) when getting close to Oguta lake where the ends of the two profiles (A’ and B’) met. Further investigation showed that the structure modeled is graben (gravity low) and horsts (gravity high) bounded by two normal faults. The gravity high observed is due to the lesser density contrasts between the sediments and the basement, that is, the basement is closer to the surface (when compared with the areas showing negative anomaly) which could be explained to have resulted from the upwarping of the crust. The area showing gravity low shows thick sedimentary accumulation of recently deposited alluvium deposits deposited in the subsided area bounded by these two faults. The structural framework of the parts of the Njaba River sub-basin studied in particularly the northwestern part of the sub-basin in which structural faults and thick sediment pile were observed suggests an environment favorable for large-scale entrapment of hydrocarbons. This is justified by the ongoing exploration and exploitation of petroleum resources in the area and its environs (Oguta, Izombe, and Ossu oil fields). Further geologic and geophysical (3D seismic survey) studies is recommended to accurately map and obtain more information on the subsurface geological structures and stratigraphy of the sub-basin.

Ogbum-nu-Abali Creek of Port Harcourt metropolis was undertaken to assess the impact of human activities in relation to physico-chemistry between March – May, 2006. Results of physico-chemical parameters showed that most of the parameters were higher than the maximum permissible limits for surface waters and discharge of wastewaters into surface waters. Results further showed that pH ranges from 6.20 – 6.70 with a mean value of 6.54 mean values of parameters included: conductivity (1602.03 ?s/cm), TSS (174.78mg/L), TDS (5187.577mg/L), Turbidity (8.12NTU), BOD5 (27.95mg/L), DO (4.51mg/L), Oil and Grease (5.77mg/L), Phosphate (0.443mg/L), Lead (0.3mg/L), Fe (2.74mg/L), Manganese (11.54mg/L), Chromium (0.33mg/L) and Temperature (28.170C) respectively. The creek was transparent, foamy, slimy, slightly smelly and no animal life was sighted in it due to deterioration of water quality as evident by high BOD and low oxygen content. It is pertinent to state that anthropogenic activities in and around the creek have given rise to alteration of the physico-chemical characteristics of the water quality rendering it unfit for recreational exercise, therefore, the abattoir at Ahiamakara leading to Nkpogu community should be discontinued to avoid water pollution. Keywords: Anthropogenic activities, pollution, discharge, creek, and rivers.

Weather Generators (WGs) are widely used in water engineering, agriculture, ecosystem and climate change studies because observed climatic series have deficiencies related to length, completeness and spatial coverage. WG models can simulate daily temperature data in a few parametric ways. One way is to simulate daily minimum (Tmin) and maximum (Tmax) temperatures using an autoregressive model. Another way consists of the simulation of daily average temperature (Tav) and daily temperature range (R) and then the calculation of Tmin and Tmax indirectly. In this study, four different algorithms were assessed for daily temperature in combination with a well-tested weather generator. M1 and M2 algorithms simulated the daily Tav and R values directly and Tmin and Tmax indirectly. M3 algorithm simulated Tmin and Tmax and M4 algorithm simulated Tmin and Tav directly and the other variables indirectly. The results showed that each algorithm could perform better in simulating primary variables (which are simulated directly). This issue was more considerable in relation to daily R values. M2 overestimated the cross-correlation coefficients of this variable because of the assumption of a strong autocorrelation structure between primary variables in the WG model. M3 and M4 outperformed the other algorithms in relation to most studied indices. This study showed the importance of choosing the best temperature generation algorithm according to the requirements.