Alternative techniques of supplementary irrigation for the rain-fed paddy schemes in Brunei Darussalam: A case study of the Kg. Junjungan paddy scheme

Abstract

Brunei Darussalam is a hot and humid country in the equatorial region of Asia. Located on the island of Borneo, Brunei Darussalam enjoys moderate seasonal rainfall. It is green, rugged and hilly in the upland areas and fairly flat with valleys and swamplands near the coastal belt. Some areas are ideal for paddy cultivation. Emerging from the national urgency and "Grow More Food" crash program campaign, the Kg. Junjungan scheme presents a proposal to convert from rain-fed paddy cultivation to fully irrigated paddy. The scheme area is nearly flat and suitable for paddy with a non-perennial stream flowing nearby. The scheme area also experiences flash flow after heavy rainfall events in the catchment. This water resource, valuable and scarce at times, flows down the stream untapped, while a nearby paddy scheme suffers for lack of water during a drought situation between two periods of rainfall events. With a study at pre-feasibility level, this paper investigates the possibility of tapping the flash flow for the abstraction and diversion alternatives of surface water for irrigation by gravity or pump, or a combination of both. Findings suggest that a pump station and a head works could be the best alternative of water abstraction from the stream. There would be an intake channel to the pump station and a conveyance canal from the pump station to the scheme area to ensure sufficient full supply level. If the drought situation worsens, another option is sub-irrigation by controlled drainage using the irrigation and drainage network for retention and control of ground water table in the scheme area. This option will sustain crops during periods of extreme drought from wilting. © 2011 WIT Press.