Rainfall Runoff Model for Calabar Metropolis Using Multiple Regression

Mathematical analyses were used to develop model that predicts the influence of some hydraulic and hydrologic parameters on the perennial flooding of some parts of the Calabar Metropolis. The parameters were obtained from ten sampling locations all within Calabar metropolis. An empirical model was developed to predict discharge based on the independent variables of cross sectional area of drains, degree imperviousness, gradient, sum of channel length, and basin area. The model developed gave a good multiple regression coefficient of 0.982with a standard error of 0.709at a significance level of 0.10. The R2 value of the regression model shows that 96.4% of the total variation in the storm water discharge is accounted for by the five regressors. Incorrect sizing and spread of drains as well as the existing slopes employed in the generation of the drainsb invert during construction have been seen as some of the key factors that foster flooding in the Metropolis. Designers are encouraged to employ the model developed for drains design and analysis for Calabar Metropolis.http://dx.doi.org/10.4314/njt.v33i4.1

Evaluation of Bamboo Porous Pipe as Line Source Emitter in Trickle Irrigation System

This paper attempts to evaluate the use of bamboo as porous pipe (line source) emitter in trickle irrigation at the Cross River University of Technology Teaching and Research Farm Obubra. Two sets of bamboo laterals: opened and plugged ends were used for the trial. The experiment was conducted using four different pressure heads calibrated by pressure gauge. The volume of water discharged from each emitter and pressure drops along the respective laterals were recorded. The results showed that the mean values for the emitter discharge increased as the operating pressure head increases for the respective laterals. However, the overall mean discharge for plugged end lateral significantly (P ≤ 0.05) differed from the opened end lateral. Pressure drops decreased as the emitter distance increases along the respective laterals. The pressure drop overall mean values did not significantly (P > 0.05) vary between the laterals, but the value recorded for the opened end lateral was about 17.99% higher than the plugged end lateral. The emission exponent (X) and proportionality constant (K) were also computed for the respective laterals. There was a significant difference between the laterals with respect to the overall mean values of X and K. The relationship between operating pressure and discharge, emitter distance and pressure drops were also established. A highly positive significant value of “r” (0.97**) for opened end and non significant “r” value (0.96) for plugged end were obtained in relating discharge and operating pressure. For the pressure drops and emitter distance, a strong negative significant “r” values of -0.98** and -0.99** were obtained for opened and plugged ends, respectively. These findings are observed to be in accordance with the principle of trickle irrigation and suggest that the use of bamboo as line source emitter might be possible, if appropriate measures such as environmental, socio-economic and technical issues could be considered.Keywords: Trickle irrigation, Bamboo, emitter, Porous-pip