Background

While major public projects, notably those dependent on diversion from major river systems, make up the largest component of irrigation in some regions, elsewhere small schemes provide the greater part of canal irrigation. The area served by individual small schemes range from less than 50 ha to as much 5000 ha, but are generally a few hundreds of hectares. Where a scheme is based on direct diversion from a stream, without storage, construction and operation, in the past, has generally been entirely by the participating farmers. On the other hand where, a small reservoir is involved, as in the "tank" common in India, Sri Lanka and elsewhere, construction is commonly by state agency, with the state also being involved in some cases in operation, although generally to a limited degree. Included in the direct diversion systems are the notable "hill" schemes of Nepal. Although these were originally entirely farmer-constructed, government agencies are now providing assistance in rehabilitation, and are involved in construction of new projects. The manner in which this assistance should be provided and its impact on the previously autonomous character of the hill schemes are much debated.

In view of the attention currently being paid to the ecological costs of major storage projects, international development agencies have increasingly turned to small schemes, particularly those which enlist cultivators in their construction and management. It is noted, however, that although such schemes are conceptually very appropriate from the development point of view, their implementation poses a number of problems, some of which are referred to in the following discussion.