The Preliminary Study for Increasing the Productivity of Unit Tamban Lowland Irrigation Area based on Fact Findings of Observations

Unit Tamban is a fork system of lowland irrigation areas in Kapuas District. It has three primary canals, and each of them has a settling pond at the end. Most of the 3,506 ha planting area still apply once a year cropping patterns. A quick assessment based on field observations is carried out to determine the existing problems, including water management, water quality, and soil quality. The problem in the water management system is silting in the primary and secondary canals. The settling pond at the primary canal was no longer functioning, and it makes the silting worse because the water flow became uncontrolled. Water quality is measured with pH and TDS, the average pH at canal water was 4,22, and TDS was 71 mg/l. The soil type is mainly acid sulphate with pyritic materials, mostly 70 cm below the surface. Increasing cropping patterns twice a year requires improving the water circulations and increasing the soil pH higher than five. The problem in the secondary canal is expected to solve by changing the flow pattern from two way to 1-way flow is needed to avoid dead spots of water so that the leaching processes can work well.