Using simulation modelling to improve the design and management of furrow irrigation in small-holder plots

Over 70 % of all irrigated land in Sub-Sahara Africa is currently under surface irrigation. However, the performance of surface irrigation in this region is often low resulting in significant deep drainage losses and sustainability concerns. This is of a particular concern for tenant based large scale irrigation scheme located in arid and semi-arid areas which are prone to salinity and drainage problems. Field design and irrigation management practices have a significant impact on performance but have received only limited consideration to date. Externally funded irrigation projects in the region are usually constructed using generic design parameters with limited or no analysis of local soil and operational conditions. Similarly, irrigation design and management guidelines for in-field irrigation management are generally lacking due to the high cost and time involved in obtaining data for traditional evaluations. This paper uses data collected from small-holder irrigation plots in the Tana River Basin to demonstrate the benefits of using the simulation program SIRMOD to evaluate the performance of surface irrigation practices. It also discusses the benefits of simulation modelling for identifying irrigation performance indices and guidelines for improving the design and management practices of small-holder irrigation plots.