Assessment of design practices and performance of small scale irrigation structures in south region

Uneven distribution of rainfall in the country in general and in South region in particular makes irrigation the best way to enhance food production. Development of smallscale irrigation schemes is the best alternative as they require minimum investment & their gestation period is comparatively low. The southern region as part of the country has been implementing such schemes. Despite remarkable achievements, some of the implemented schemes have totally failed and some are performing below their capacity. A case study considering 26 existing small scale irrigation works (about 1/3rd of the total schemes) in the south region is carried out for this research work and attempt is made to understand the causes of the major problems that are related to the design consideration of the different components of the structure and identify the gap in knowledge between the current design practices and performance of the structures. The pre and post construction institutional aspects, planning aspects, social aspects, economic aspects, operation & utilization aspects are also given due attention. Some of the physically observed problems of the existing irrigation structures considered for analysis are: main canal siltation (50%), sedimentation of the headwork (42%), problem of seepage through foundation (4%), main canal seepage (33%), scouring of downstream bank (8%), drying of rivers (12%), damage on impervious and flexible apron(19%), change of river course(12%), damage of under sluices(27%) and damage on CD works(4%). Likewise, some of the planning, institutional & operation problems are lack of adequate community participation, water right conflict among up streamers and down streamers (12%), market outlet problems (8%), proper handing over problem (31%), lack of proper training and the like. During the time of the study, 18 % the irrigation schemes of the region were not operational because of aforementioned and related reasons.