Evaluating the Sluice Gate Effectiveness for the Water Level Control in the Danda Besar Tidal Irrigation System, South Kalimantan, Indonesia

Abstract

This study evaluates the effectiveness of sluice gates in controlling water levels in the Danda Besar Swamp Irrigation Area (SIA) in South Kalimantan, Indonesia. Hydrodynamic simulations were conducted using the Hydrologic Engineering Center’s River Analysis System (HEC-RAS) version 6.5 with a onedimensional unsteady flow scheme. Scenario analysis was performed for the period of July 18–20, 2024, with hourly outputs. A sluice gate of 1 m height, 3 m width, and +4 m invert elevation was introduced at the entrance of 20 tertiary canals, operated by a simple tidal rule: open during high tide and closed during low tide. The results indicate that, under baseline conditions, the average inundated area was only 914.24 ha, while in the gate scenario this increased to 1173.3 ha, representing a 17% reduction in dry area. The gates successfully retained water during low tide, maintaining inundation that otherwise would be lost under baseline conditions. These findings demonstrate that simple sluice gate operation can effectively control water levels, reduce soil exposure, and provide a practical strategy for sustainable water management in tidal irrigation systems.