Hydraulic Study on The Use of Gates to Improve Drainage Performance of Dadahup Lowland Irrigation Area

Abstract

Dadahup lowland irrigation area, known in Bahasa as Daerah Irigasi Rawa (DIR) Dadahup, is one of the Ex-PLG areas that has been now included in the food estate program. It has been experiencing low productivity, producing only 1.7-2.9 ton/ha/year of paddy. Farming on lowland areas is often hindered by inundation during rainy season. Such problems were observed at Blok A5 of DIR Dadahup where inundation might last for a long time. Drainage was hindered since the water level in the channel, being at +1.4 to 1.6 m, was higher than the ground level whose elevations were +1.30 m for the right area and +1.00 m for the left area. Flow simulation by employing HEC-RAS is proposed to obtain a drainage system that can overcome this inundation problem. The use of gates in the secondary and tertiary channels was analyzed to improve drainage performance. The results show that by using gates and pumps can reduce the inundation area and maintain the water level in the channel according to cultivation needs. Such as in tertiary channel, the water level in the right tertiary channel can be maintained at +1.30 m ~ +1.46 m, and that in the left tertiary channel can be maintained at +1.12 m.