Determination of water requirements for producing irrigated rice and other crops in the Afram river valley bottom at Aframso, Ghana

English

The Valley Bottom Rice Development Project (VBRDP) was started in Ghana in 1990 under the Agricultural Sector Rehabilitation Programme of the Ministry of Food and Agriculture. To assess the quantity and quality of water for rice irrigation at the Aframso project site (from 1993-1996), three methods were applied. Firstly, the Nathan's (1997) effective precipitation index (EPI) was used to evaluate rainfall recharge of the Afram River. Secondly, basic statistical parameters (1986 -1995) were used to evaluate river flow characteristics. Finally, the river water quality was assessed on the basis of Ayers and Westcot (1985) water quality guidelines for irrigation. Both the EPI and river flow characteristics revealed sufficient quantity of surface water for irrigated rice at Aframso throughout the growing season.Again, the mean values of essential parameters of river water, e.g. total dissolved solids (73.00mg I"), conductivity (0.094 dS em"), adjusted sodium adsorption ratio (0.32),pH (6.5), HCOl(0.60 meq I") and N-NOl (1.06 mg I") showed that the Afram River water has no immediate quality problems that are likely to adversely affect irrigated rice-based cropping in the area.

Opoku-Duah, S.; Kankam-Yeboah, K.; Mensah, E. K.