The Leaching Process of Acid Sulphate Soil by One-and Two-Way Flow Systems in the Katingan Swamp Irrigation Area

Department of Civil and Environmental Engineering, Faculty of Engineering, Universitas Gadjah Mada, Indonesia

^* Corresponding author: endita.prima.ari.pratiwi@ugm.ac.id

Abstract

The Katingan Swamp Irrigation Area, established in 1980, has an important role in supporting food security in Indonesia. It needs to be reclaimed to increase agricultural production, especially for leaching acid sulphate soil. The swamp irrigation area was expanded and rehabilitated so that the two-way flow became a one-way flow system to support the leaching process. This study aims to assess the discharge and water quality alterations in the Katingan main channel after the change of flow system. The aim is achieved by comparing the outcomes obtained from one-way and two-way flow simulations. The simulation used a mathematical model based on water level, water quality, and land topography data collected in the field. According to the findings, the two-way system demonstrates that fresh water from the river has not been able to improve water quality (pH) at the end of the primary channel, thereby leading to extreme acidity in those regions. Meanwhile, a one-way flow facilitates efficient circulation and delivers fresh water to the farthest service regions. Effective water circulation is important to enhance water quality in agricultural areas that have recently expanded. The current study focuses on mid-irrigation. Future research may cover the entire irrigation network for in-depth analysis.