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Noise from transportation systems is unavoidable in urban areas and can be harmful to human health. The noise generated by selected transportations systems in Ilorin, an urban area in central Nigeria, was studied by direct measurements and the use of questionnaires. Measurements were taken at the airport, train station and different locations for vehicular traffic. Questionnaires were also administered on residents of these areas to elicit information on the perception of transportation noise in the areas. The results show that all the studied locations produced maximum noise levels in excess of the 85-dBA acceptable tolerable limit for humans. The train station produced the highest stepwise noise levels due to the motion and horning of the locomotive engines. The study also established distances in which the sound level is safe over a specific period of time for each of the studied noise sources. These are of 18.84 m, 161.21 m, 13.85 m and 15.08 m for aircraft take-off, movement and horning of railway locomotive engine and vehicular traffic inside and outside town respectively. Suggested solutions were that residential buildings, academic areas and hospitals should not be located too close to sources of transportation noise and the need for enforcement of relevant noise control laws is to be pursued. Keywords: Noise pollution, sound pressure level, equivalent sound level, acceptable noise level, noise perception

This study presents the impact of global warming on precipitation patterns in Ilorin, Nigeria, and its implications on the hydrological balance of the Awun basin under the prevailing climate conditions. The study analyzes 39 years of rainfall and temperature data of relevant stations within the study areas. Simulated data from the Coupled Global Climate model for historical and future datasets were investigated under the A2 emission scenario. Statistical regression and a Mann-Kendall analysis were performed to determine the nature of the trends in the hydrological variables and their significance levels, while a Soil and Water Assessment Tool (SWAT) was used to estimate the water balance and derive the stream flow and yield of the Awun basin. The study revealed that while minimum and maximum temperatures in Ilorin are increasing, rainfall is generally decreasing. The assessment of the trends in the water balance parameters in the basin indicates that there is no improvement in the water yield as the population increases. This may result in major stresses to the water supply in the near future.

Optimization models have been developed to maximize annual energy generation from the Doma dam, subject to the constraint of releases for irrigation, ecological purposes, the water supply, the maximum yield from the reservoir and reservoir storage. The model was solved with LINGO software for various mean annual inflow exceedence probabilities. Two scenarios of hydropower retrofitting were considered. Scenario 1, with the reservoir inflows at 50%, 75%, and 90% probabilities of exceedence, gives the total annual hydropower as 0.531 MW, 0.450 MW and 0.291 MW, respectively. The corresponding values for scenario 2 were 0.615 MW, 0.507 MW, and 0.346 MW respectively. The study also considered increasing the reservoir’s live storage to 32.63Mm3 by taking part of the flood storage so that the maximum draft increases to 7 Mm3. With this upper limit of storage and draft with reservoir inflows of 50%, 75% and 90% probabilities of exceedence, the hydropower generated increased to 0.609 MW, 0.540 MW, and 0.347 MW respectively for the scenario 1 arrangement, while those of scenario 2 increased to 0.699 MW, 0.579MW and 0.406 MW respectively. The results indicate that the Doma Dam is suitable for the production of hydroelectric power and that its generation potential is between 0.61 MW and 0.70 MW.

Hydrological models are very useful for predictions in many ungauged basins across the world. There are many hydrological models available for discharge data generation with different complexities and varied input parameter requirements. Studies have shown that models with many input parameters do not necessarily perform better than those with few input parameters. Basin morphometric parameters play significant roles in the conversion of rainfall to runoff and obtaining good estimates of these parameters for use in runoff models is sometime challenging as Inaccurate input into models can propagate errors and make the models to perform poorly. This study employs the method of principal component analysis to reduce the number of morphometric parameters required to run a runoff model without losing any major information. Parameters for five selected study basins in central Nigeria were measured and analysed. The result shows that three morphometric parameters (Fitness Ratio, Ruggedness Number and Watershed Eccentricity) can adequately represent other parameters as an input into a runoff model for the basins. This reduces significantly the time and effort needed to compute all the parameters which in actual fact may not improve the quality or efficiency of the runoff model.

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In this study, probability analysis was performed on peak daily rainfall data in order to predict rainfall interval values and to determine the best fit functions in some parts of Nigeria. The selected towns are Kaduna, Kano, Yola, Jos, Damaturu and Maiduguri. The obtained peak daily rainfall values were subjected to Gumbel, Log-Gumbel, Normal, Log-Normal, Pearson and Log-Pearson probability distributions. Mathematical equation for probability distribution functions were established for each town and used to predict peak rainfall. The predicted values were subjected to goodness of fit tests such as Chi-square, Correlation Coefficient, Coefficient of Determination and Errors of Estimates to determine how best the fits are. The model that satisfies the tests adequately was selected as the best fit model. The study revealed that the peak rainfall at Kaduna, Jos, Kano, Yola and Damaturu are best fitted by log-Gumbel, while log- Pearson distribution is suitable for predicting peak rainfall in Maiduguri. The result also shows that the occurrences of peak daily rainfall depth of 100 mm and above are rare in the selected areas. Keywords: Peak rainfall, Probability distribution models, Return period, Probability interval and goodness of fit tests

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This study focused on the evaluation of willingness-to-pay (WTP) for sustainable household water use in Ilorin, Nigeria. The study involved assessment of the existing water supply situation particularly considering water use indicators such as demography, adequacy of existing water supply system and WTP for reliable supply. Field work involved the use of structured questionnaire to obtain data on household water use and WTP for a reliable water supply of the sampled houses consisting three land use patterns. Stata/SE 8.0 and Microsoft EXCEL software were employed to evaluate the variables that affect WTP for improved household water use while ccontingency Valuation Method was adopted to evaluate the WTP for reliable and sustainable service delivery. The findings of the study revealed that: approximately 70 % of total sampled households were connected to municipal supply out of which 13 % indicated satisfaction in terms of sufficiency and 87 % used alternative sources to augment water supply; consumers are willing to pay an average sum of N 737.22 per month for improved water supply services and; gender, water quality and household income level have significant impact on WTP at 5% level of significance. There is the need to put in place a framework to enhance improvement of system reliability and sustainability. Keywords : Evaluation, willingness, reliability, sustainability, household, water