Optimization of Water Resources in the Northern Province River Basins for Irrigation Schemes Used for Food Production in Sri Lanka

Abstract

Sri Lankan consumes rice as the main source of food. Hence most of the area of the country has been used for paddy cultivation. Therefore improving the paddy cultivation will lead to a positive impact on the society in every aspect. Northern Province of Sri Lanka is divided into two distinct geographic areas: Jaffna peninsula and the Vanni. Jaffna peninsula is irrigated by underground aquifers fed by wells whereas the Vanni has irrigation tanks fed by nonperennial rivers. Major rivers include: Akkarayan Aru, Aruvi Aru, Kanakarayan Aru, Kodalikkallu Aru, Mandekal Aru, Nay Aru, Netheli Aru, Pali Aru, Pallavarayankaddu Aru, Parangi Aru, Per Aru, Piramenthal Aru, Theravil Aru. During dry seasons most of the irrigation schemes in this area become dry. Hence the command area of those irrigation schemes cannot be irrigated successfully for two seasons. As a consequence cultivated crops fail and farmers are affected heavily. This study includes collection of field data, estimation of water availability in the river for diversion, inflow to tanks from catchments by hydrologic modelling, estimation of water demand for cultivation using crop water management model and estimation of the potential improvement of the cultivation areas and cropping intensity. Based on the preliminary study we suggest to improve the irrigation system in the study area, and proposes to construct diversion canal/feeder canals and anicuts across the rivers, by considering these river basins, the final aim can be achieved at investigating the improvement in irrigated areas and cropping intensity by the diversion canal proposed.