Disigning of a drainage system in a swampy coastal area under influence of tides

Abstract

A preliminary design of the layout of the irrigation and drainage system has been made over the whole area of the Secanggang Polder. Owing to the lack of knowledge concerning the tidal movement, agri- cultural practices in the swampy coastal area relating with the water management, and estimation of a considerable amount of earthen work. for drainage facilities, it is suggested to design in detail. only a part of the area, which is the Secanggang drainage area, as a pilot project, while the rest of the area, which is the Sepuoung drainage area remains in the preliminary design stage. The design has been made on a contour map of scale 1:10,000. Irrigation will be supplied from the Sungai Wanpu via the Kotalama 3 main canal with a total capacity of 4.8 m/sec at the main intake. The main canal will split into three secondary canals, namely, the Marbau secondary canal will supply 1434 ha with a total capacity of 3 2.2 m/sec, the Selotong secondary canal will supply 1112 ha with a 3 total capacity of 1.7 m/sec, and the Pematangtinggi secondary canal will supply 414 ha with a total capacity of 0.6 m m³/sec.