Determination of Hydraulic and Hydrological Parameters of Available Streams in Okada Town and Its Environs for Viable Source of Water Supply

摘要

The study area comprises Okada Town and its environs located in the South Western part of Edo State in Nigeria. The study area is primarily, an agricultural and commercial area with prospects of becoming a big town with attendant water supply problems. The study identified viable sources for sustainable community based water supply with the objectives to determine hydraulic parameters of the existing streams. The method used to measure the stream hydraulic parameters was Current - Meter Discharge Method. The mean dry weather widths are: Okada Stream (3.6m and 10.2m at narrow and upstream sections); Iguedo and Okhai Streams (10.6m and 2.8m at typical upstream sections respectively). The corresponding stream stages and discharges are: Okada (0.57m; 100,656m~3/day); Iguedo (1.23m; 117,590m~3/day) and Okhai (0.21m; 8,294m~3/day). From the obtained, and plotted data, the derived stream stage-discharge equations of the form Q = CH_n are: Q = 1.543H_(0.5) for Okada Stream; Q = 1.062H_(1.2) for Iguedo Stream; and Q = 0.1334H_(0.21) for Okhai Stream. This study established only 1-year hydrological frequency. A 5-year or 10-year return period is needed for greater risks from probable worst condition scenarios. The recorded maximum combined discharge was 552,441m~3/day in September 2011 and minimum flow was 226,540m~3/day in January 2012. The reliable yield is estimated at 103,886m~3/day and maximum allowable abstraction is 81,455m~3/day. The results show that the three source streams will be adequate for sustainable water supply for the study area.