Composite Goodness of Fit in Reaeration Coeffcient Modeling

Determination of reaeration coefficient is an important factor in surface water quality modeling as it determines the efficiency of the Streeter-Phelps model used for predicting dissolved oxygen deficit of any stream. This study compared the efficiency of Atuwara model with ten other reaeration coefficients models by making use of three data sets obtained from river Atuwara during the prevalent wet and dry seasons using composite goodness of fit test which was developed by quantitatively combining statistical and graphical goodness of fit. The eleven tested models were ranked in order of performance. Results show that the four top ranking models were developed through a process that utilized data from multiple streams while models that were developed from data obtained from the test subject alone performed less competitively. The outcome of the study also suggests that the usual practice of selecting the best model based on statistical analysis alone does not necessarily yield the best result and therefore recommended the incorporation of quantitatively analyzed graphs. The paper concludes that selection of the best performing model among existing reaeration coefficient models using the composite goodness of fit may present a cheaper and better alternative to conventional model development approach

Sustainable groundwater exploitation in Nigeria

In this study, a critical review of the groundwater resources history and management in Nigeria was done. The aim was to identify reasons why groundwater is increasingly being exploited in recent times, and to explore ways through which the exploitation could be done sustainably. This was achieved through literature review. It was observed that an estimated 60% of Nigeria’s population get drinking water from ground resources. This high statistic is mostly the resultant effect of infrastructural decay in the potable water supply sector of the country. In Nigeria, just 14 % of the country’s population get regular water supply through piped sources while the remainder of the country’s 162.5 million people draw their water supply mainly from surface and groundwater sources. Groundwater, in Nigeria, is accessed mainly in form of shallow (hand-dug) and deep (boreholes) wells. Well water withdrawal activities are mostly un-regulated and, therefore, the water sources are often subjected to avoidable abuses and pollutions. In particular, rapid urbanization, agricultural and industrial activities are major contributors of pollutions to groundwater sources. Also, unavailability of data such as geographical information on water quantity, hydrology, state of aquifer and withdrawal limits have contributed to the unsustainable use of groundwater in Nigeria. It was recommended that proper regulation of groundwater resources and its protection under the land use act of 1978 could be instrumental to its sustainable exploitatio

WASTE MANAGEMENT AND WATER QUALITY ISSUES IN COASTAL STATES OF NIGERIA: THE OGUN STATE EXPERIENCE

Waste dumping and inadequate waste management efforts are having adverse impact on the environment and humans in Nigerian coastal cities. Nine of the 36 states in Nigeria border the Atlantic Ocean. Twenty-five percent of the Nigerian population is found in the coastal states. These states, with the exception of Lagos, Ogun and Ondo, are more prone to petrochemical wastes arising from petroleum exploration. Field investigations, surveys and literature searches were conducted in order to accomplish the task of this research. Field studies included testing for dissolved oxygen, biological oxygen demand, nitrates, phosphate, total solids and pH

Water Quality Modelling: Case study of the Impact of Abattoir Effluent on River Illo, Ota, Nigeria

This report presents results obtained from the investigation and water sampling exercise carried out on the segment of River Illo that passes through Sango in Ado Odo-Ota Local Government Area, Ogun State, Nigeria. The report reveals that while some people used water from the river for domestic, food production and recreation purposes, others discharge their wastes without any form of pre-treatment into it. The multipurpose usage of water from River Illo by local residents thus hinges public health on the self-purification capacity of the river alone. Information on water use and waste disposal practices of the local residents were obtained through direct observation and oral interview of members of randomly chosen households built along the river within a distance of 2km. Single grab samples of water were obtained from the river at the site of an abattoir effluent discharge at distances 0m, 10m, 20m, 30m, 50m and 100m from the point of discharge. A seventh sample was also obtained 10m upstream of the point of effluent discharge to furnish information on ambient conditions of the river prior to pollution while an eighth sample which was prepared by diluting the water obtained at 0m with distilled water (i.e. 25% stream water, 75% distilled water) was included to serve as control sample. All water samples were transported (within 3 hours of isolating them from the river body) to the laboratory for analysis and the results were subjected to graphical, statistical and mathematical analysis. Pollution from the abattoir caused a drop in dissolved oxygen level of the river from an ambient value of 4.6mg/l to 0.01mg/l at the point of discharge. The pollution also caused an increase of 447.5mg/l to 1071.5mg/l in T.S., 0.04mg/l to 4.4mg/l in ammonia, 170mg/l to 670mg/l in BOD, 0.05mg/l to 3.05mg/l in phosphorus, 50mg/l to 1066.7mg/l in alkalinity and 18mg/l to 820mg/l in Acidity. It was also found out that between 30m – 80m downstream of the pollution point, a threat of eutrophication is caused by plants growing in the river path. Despite this obstruction, the river recovered considerably to a D.O. level of 3.9mg/l at 100m downstream. Results from the dispersion modeling shows the self-purification capacity of the river, f, to be 1.1 within 30m distance from the point of discharge and 0.8 between 30m and 100m from the point of discharge. The results from the application of the Streeter-Phelps model showed that the eutrophication occurring between 30m – 80m is interfering adversely with the self-purification processes of the river. The percentage compliance of each of the eight water samples with Guideline Values (GLV) of WHO and FEPA was performed. None of the samples met the minimum requirements for BOD, COD and TSS, which are indicators of pollution. It was concluded that River Illo is being polluted by abattoir effluents discharge thereby exposing the health of local residents who use the water from the river for domestic, recreation and food production purposes to avoidable risks. Suggested actions that could further complement the self-purification capacity of the river were offered

Reaeration Coefficient Modelling: Case study of River Atuwara, Ota, Nigeria

This study was carried out on River Atuwara in Ota, Ogun State, Nigeria with the aim of developing a coefficient of re-aeration model applicable to River Atuwara and other rivers in the Nigerian environment. This was achieved by sourcing for data once every month from 22 sampling locations of interest within a pre-selected segment of the river over a period covering the dry and wet seasons. The data collected include hydraulic data (depth, width, velocity and time of travel) and water quality data such as Dissolved Oxygen (DO) and Biochemical Oxygen Demand (BOD). Excel Spreadsheet and MATLAB were used for data processing. Regression analysis was carried out where stream velocity and depth were the regressors and the re-aeration constant k2 (as a function of BOD, DO and Temperature) was the dependent variable. A coefficient of re-aeration, k2, (Atuwara re-aeration model) was developed and validated statistically. Its performance was also verified by comparing the model with 10 other internationally recognized models. It was found that even though Atuwara model performed better than Agunwamba model and most of the other well cited models, both Atuwara model and Agunwamba model could be safely adopted for future water quality modelling researches in the Nigerian environment. Results of detailed water analysis of samples from River Atuwara shows high level of pollution hence it is unfit for human consumption without adequate treatment. It is recommended that River Atuwara and similar rivers in the country should be regularly monitored for quality control

EVALUATION OF WATER QUALITY MODELLING PARAMETERS: TOWARDS THE EVOLVEMENT OF RE-AERATION COEFFICIENT FOR RIVERS IN THE NIGERIAN ENVIRONMENT

This study was carried out on River Atuwara in Ota, Ogun State, Nigeria with the aim of developing a coefficient of re-aeration model applicable to River Atuwara and other rivers in the Nigerian environment. This was achieved by sourcing for data once every month from 22 sampling locations of interest within a pre-selected segment of the river over a period covering the dry and wet seasons. The data collected include hydraulic data (depth, width, velocity and time of travel) and water quality data such as Dissolved Oxygen (DO) and Biochemical Oxygen Demand (BOD). Excel Spreadsheet and MATLAB were used for data processing. Regression analysis was carried out where stream velocity and depth were the regressors and the re-aeration constant k2 (as a function of BOD, DO and Temperature) was the dependent variable. A coefficient of re-aeration, k2, (Atuwara re-aeration model) was developed and validated statistically. Its performance was also verified by comparing the model with 10 other internationally recognized models. It was found that even though Atuwara model performed better than Agunwamba model and most of the other well cited models, both Atuwara model and Agunwamba model could be safely adopted for future water quality modelling researches in the Nigerian environment. Results of detailed water analysis of samples from River Atuwara shows high level of pollution hence it is unfit for human consumption without adequate treatment. It is recommended that River Atuwara and similar rivers in the country should be regularly monitored for quality contro

Wind Energy Study and Energy Cost of Wind Electricity Generation in Nigeria: Past and Recent Results and a Case Study for South West Nigeria

The study assessed the wind energy potential of ten selected sites in the south western region of Nigeria and carried out a cost benefit analysis of wind power generation at those sites. Twenty four years’ (1987 to 2010) wind speed data at 10 m height obtained from the Nigerian meteorological agency were employed to classify the sites wind profiles for electricity generation. The energy cost analysis of generating wind electricity from the sites was also carried out. The outcome showed that sites in Lagos and Oyo States were adequately suited for large scale generation with average wind speeds ranged between 2.9 and 5.8 m/s. Those from other sites may be suitable for small scale generation or as wind farms, with several small turbines connected together, to generate large enough wind power. The turbine matching results shows that turbines cut-in and rated wind speeds of between 2.0 and 3.0 m/s, and between 10 and 12.0 m/s respectively will be very suited to all the sites, particularly those in locations outside Lagos and Oyo States. The energy cost analysis shows that generation cost can be as low as 0.02 €/kWh and as high as 5.03/kWh, depending on the turbine model employed

Reaeration Coefficient Modeling: A Case Study of River Atuwara in Nigeria

A study of the self purification capacity of River Atuwara was done with the aim of developing a reaeration coefficient model, k2, for the river. The k2 model was evaluated and validated by comparing its performance with the Streeter-Phelps and Agunwamba models. Atuwara model was developed using non-linear regression while its performance was checked by the use of statistical and graphical parameters. The model gave the best dissolved oxygen predictive capacity in comparison with other models when used with the modified Streeter-Phelps equation in spite of the limitations imposed on it by the sinusoidal shape of the dissolved oxygen recovery curve caused by frequent interruptions in the recovery processes of the river system. It is also of note that due to its importance to human and aquatic life sustenance, the natural recovery processes of River Atuwara from frequent pollution loads could only be enhanced through an effective monitoring and regulation of effluent discharges into it by the Ogun State Environmental Protection Agency

People Perception of Domestic Water Supply Situation in Ogun State, Nigeria

Right or wrong, public perception impacts directly on environmental issues. Thus, the past two decades have seen an increase in the analysis of the human-environment relationship. This study assesses sources and providers of water to residents of Ogun state, Nigeria. Public perception, with respect to government performance in terms of water provision and, the willingness to pay for water services rendered, were gauged using stratified sampling technique. A total of 1,500 questionnaires were distributed to the sampled population spread in five out of the twenty local government areas of the state. Results indicated 81% of the residents obtained water from groundwater resources while only 14.9% receive water from public utilities. Also, over 75% of the respondents provide water for themselves while 65% indicated that they will prefer not to pay for water services even if the government makes the services available. The study showed that water agencies cannot be sustainably operated when public attitude to protection of same is not favorable. It was recommended that advocacy programs aimed at educating residents on inherent benefits of sustainably patronizing state water utilities rather than dependence on self-made efforts would prove helpful to both residents and government

Study of Auto Purification Capacity of River Atuwara in Nigeria

The aim of this paper was to study and predict the self-purification capacity of River Atuwara. This was done primarily by measuring the Dissolved Oxygen (DO) downstream of a pre-selected pollution discharge point on River Atuwara and then predicting the same using the modified Streeter-Phelps equations. Other data gathered from each of the 17 sampling stations on River Atuwara and used in the analysis included Biochemical Oxygen Demand, (BOD), pH, stream velocity, stream depth and distance. Predicted DO deficit trend lines were first fitted by retaining the original re-aeration coefficient component, k2, of the modified Streeter-Phelps equation (USGS equation) and subsequently by substituting it with Atuwara reaeration coefficient model. It was found that the latter displayed better predictive capacity. Results also demonstrated that the auto-purification capacity of the river which is already limited by the relatively low DO saturation level is further threatened by the wastes being discharged into it at varying intervals. Some of the wastes which are non-biodegradable and acidic were also found to be interrupting the auto-purification processes of the river. Water from River Atuwara requires treatment before it can be considered safe for consumption by its current users