Abstract:
Water resource economists and policy makers have suggested that by 2030 one third
of the world's population will be based along river basins, and the scarcity of water
for agriculture will have a tremendous impact on their livelihood. In many parts of
the country, the productivity of paddy is below the potential level due to insufficient
irrigation water, and in the dry season (Yala season), only 30 percent of cultivable
irrigated paddy land could be used for growing due to lack of water. In Sri Lanka,
Dry-Zone is the main paddy zone, and some parts of this area will face an absolute
scarcity of water by 2025. This study attempts to determine the actual usage of
irrigation water at different water risks in the dry and wet seasons in the large-scale
irrigation schemes in the dry-zone of Sri Lanka. Primary data were obtained from 360
paddy farm plots from Rajanganaya, Nachchaduwa and Huruluwewa irrigation
schemes covering upstream and downstream farmers. Actual daily water usage at the
plot level was measured through the volumetric method. Under this method, water is
collected in a container of known volume, and the time taken to fill the container is
recorded. According to our study, on average, in the wet season (Maha season),
upstream farmers of Rajanganaya have used 4.8 acre-feet (5921 cubic meters) and
Huruluwewa upstream farmers 4.2 acre-feet (5181 cubic meters) for paddy farming.
Though the water usage of Raganganaya farmers was 14% higher than that of
Huruluwewa farmers in the wet season, the productivity variation was insignificant
between the two farmer groups. However, the downstream disparity of water usage
in the dry season is much higher than in the wet season. In the dry season, downstream
farmers of Rajanganaya have recorded 5.7 acre-feet, and Huruluwewa downstream
farmers have managed 3.2 acre-feet due to the scarcity of water in the dry season.
The present study has suggested that collectivism is the most suitable way of common
pool resource management rather than individualism, which is incorporated with the
market mechanism.
