Flow Measurement for Ungauged Kakayini and Kodadwen Streams in Support of Local Rice Production in the Ashanti Region of Ghana

Local farmers especially in the Ashanti Region of Ghana depend on many ungauged streams for rice cultivation in the rainy season but are unable to do so during the dry season due to water shortage. This paper concentrated on some hydraulic and hydrological properties of ungauged Kakayini and Kodadwen streams in the Ahafo Ano South District of the Ashanti Region of Ghana. The float and current meter were used to measure stream discharges based on the area-velocity method. Roughness coefficients for the two streams were determined using the Manning’s, Strickler, Limerinos and Jarrett procedures. The Boyer’s procedure was used to derive rating curves for the ungauged streams using the measured streamflow and depth data. Discharges, as expected, were in response to rainfall events and there were some time lags between the rainfall events and the resulting discharges. The Kakayini and Kodadwen streams recorded the highest measured discharges of 0.172 m3s-1 and 0.043 m3s-1 respectively for the period the measurements took place. The hydraulic gradients determined using laser range for the Kakayini and Kodadwen streams ranged between 0.0001- 0. 0003. Derived rating curves were 𠑸 = ð ŸŽ. ð Ÿ ð Ÿ”ð Ÿ (𠑯 − ð ŸŽ. ð ŸŽð Ÿ ) ð ŸŽ.ð Ÿ—ð Ÿ•for Kakayini and 𠑸 = ð Ÿ . ð Ÿ ð Ÿ“(𠑯 − ð ŸŽ. ð ŸŽð Ÿ ð Ÿ‘ð Ÿ•) ð Ÿ .ð Ÿ‘ð Ÿ” for Kodadwen respectively with r values of 0.938 and 0.957 respectively. Farmers could be supported to use water for farming activities in these localities more sustainably based on seasonal flow variability and how much water is potentially available for downstream use.