PERFORMANCE EVALUATION OF IRRIGATION SCHEMES IN THE TRANSITION AGRO-ECOLOGICAL ZONE OF GHANA

Abstract

The study assessed the performance of irrigation schemes in the Transition Agro-ecological Zone of Ghana using a set of comparative performance indicators. The study was conducted on two (2) functioning schemes and two (2) defunct schemes. It was carried out in Akumadan, Tanoso, Kaniago and Subinja irrigation schemes in the Transition Agro-ecological zone of Ghana. The performance of the functioning schemes (Akumadan and Kaniago) spanning the years of 2018 – 2022 were evaluated using selected comparative indicators categorized into five (5) groups, namely; water delivery, physical structures, financial, environmental condition and agricultural production performance. The challenges of the schemes were also identified through the study. Data collection sources included literature reviews, interviews, field measurements and laboratory analysis. The study revealed that the main pipe at Akumadan had 100 % maximum flow length whilst the canal system at Kaniago recorded a flow length of 64 % due to low gravity flow in the downstream of the canal. The developed irrigable areas in Akumadan and Kaniago were under-utilised with irrigation rates ranging from 15 – 36 % and 18 – 57 % respectively. The sustainability indices of the irrigated areas in Akumadan and Kaniago were low with recorded values of 31 % and 28 % respectively. Irrigation service charges recovery was poor in the Kaniago scheme with recovery efficiency ranging from 25 – 59 % whereas the recovery was good in the Akumadan scheme with efficiency ranging from 82 – 88 %. A low degree of financial autonomy (25 %) was recorded in Akumadan whereas a high degree of financial autonomy (100 %) was recorded in Kaniago. Some irrigation structures in the Akumadan and Kaniago schemes were in poor working condition as they recorded poor structure indices of 27 % and 14 %. The road network in the Akumadan scheme was in good working condition as roads passability efficiency of 100 % was achieved whereas Kaniago had no major road construction in the scheme. Both schemes recorded 100 % environmental stability indices indicating stable and resilient irrigable areas with regards to pH, salinity and sodicity problems. Production in the schemes was gradually in decline due to the constant reduction in size of the cultivable area of the schemes. Poor agronomic practices, inadequate sprinklers and laterals and low gravity flow were major causes of the low production performance in the schemes. The Impact-sprinklers located at the up-stream and down-stream areas of the Akumadan scheme recorded Distribution Uniformity (DU) values of 73 % and 83.3 % respectively. At the same time, the Uniformity Coefficient (UC) values of the sprinklers were found to be 85.2 % at the up-stream and 90.8 % at the down-stream. At Kaniago, the water conveyance efficiencies measured in the up-stream, mid-stream and down-stream of the canal system were found to be 100 %, 93 % and 36 % respectively. The Tanoso and Subinja schemes had been abandoned for years because of their defunct state. Hence, these schemes required rehabilitation so as to improve performance and promote irrigated agriculture in the transition agro-ecological zone of Ghana.