Managing Irrigation Sediment Barriers in a Tropical Volcanic Basin through Mathematical Model

Volcanic eruptions transport substantial amounts of sediment into river systems. It damages irrigation structures that depend on the nearby river for water delivery, reducing the conveyance efficiency. This study aims to propose an efficient approach for the management of sand traps as the main sediment barriers in irrigation networks within the Progo-Opak-Serang (POS) Volcanic Basin. It is accomplished by a measurable approach: a mathematical framework executed with the Hydrologic Engineering Center’s River Analysis System (HEC-RAS). This study focuses on selected sand traps: Badran, Blawong, and Pengasih. The results show that the calibrated and validated Manning’s coefficients of Badran, Blawong, and Pengasih Sand Traps are 0.014, 0.020, and 0.025, respectively. The combination of Thomas as a sorting method, Rubey as a fall velocity method, and Laursen as a transport function can represent the transport parameters of the sand traps within the POS Basin. The recommended flushing discharge and duration for Badran, Blawong, and Pengasih Sand Traps are 4, 4.4, and 1.9 m³/s and 150, 50, and 45 min, respectively, while the flushing frequency is 4, 3, and 3 times a year. The existing sand trap performance in Badran is less effective, while that of Blawong and Pengasih is less efficient. This study assists in improving food production and security by promoting sustainable irrigation systems.