Technical efficiency of sprinkler irrigation in Swaziland: a case study of the Lusip Phase 1 in Lubovane area
Magagula, Celinhlanhla, Derrick
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The purpose of this study was to assess the technical efficiency of sprinkler irrigation of smallholder sugarcane scheme in the Lubovane area of Swaziland in terms of design parameters, frequency of water application, adequacy of irrigation and irrigation uniformity. The study was done in Imbali Yamadlenya, Nxutsamlo and Ziyanhle irrigation schemes. Data were collected from each scheme using both primary and secondary data sources between June and September 2013. Primary data included informal interviews and field measurements about operations of the schemes while secondary data included literature review and design documents. Data were analyzed using Microsoft Word and Microsoft Excel. All the schemes were under-performing in terms of the frequency of irrigation, adequacy and irrigation uniformity. Both Imbali Yamadlenya Farmers Association (FA) and Nxutsamlo FA had their emitters discharging more water than the designed specifications while at Ziyanhle FA the discharge was below the design specification. The flow variations for Imbali Yamadlenya, Nxutsamlo FA and Ziyanhle FA were 9.3%, 18.6% and -38.4% respectively. The operating pressure variations were found to be 10%, 8.6% and -40% for Imbali Yamadlenya FA, Nxutsamlo FA and Ziyanhle FA respectively. The first two schemes were over-irrigated while Ziyanhle FA was under-irrigated. The farmers in all the schemes had no systematic irrigation scheduling. They used the “feel” method to determine soil moisture content with one irrigation pattern adopted for the entire season. The calculated CWRs were 4.1mm/day, 11.1mm/day and 1.7mm/day for Imbali Yamadlenya FA, Nxutsamlo FA and Ziyanhle FA respectively. The observed basic infiltration rates for Nxutsamlo, Ziyanhle and Imbali Yamadlenya irrigation schemes were 19.8mm/h, 31.8mm/hr and 10.2mm/hr respectively which meant the soil could absorb water from the sprinklers without experiencing surface runoff. The calculated CUs for Nxutsamlo FA, Ziyanhle FA and Imbali Yamadlenya FA were 55%, 45% and 70% respectively while the DUs calculated were 33.3%, 50% and 60% for all the schemes respectively. The project management need to develop technical interventions for capacity building of the smallholder farmers to better manage their irrigation schemes in order to achieve the project’s goal of reducing poverty and improving their livelihoods and that of their communities.