IMPACT OF CLIMATE CHANGE ON INUNDATION IN THE KATINGAN TIDAL AGRICULTURAL LOWLAND, CENTRAL KALIMANTAN

Uncontrolled tidal overflows inundated Katingan's tidal agricultural lowland. Inundation is worsening due to the impact of climate change. This condition will decrease the productivity of paddy fields. Therefore, a study was conducted with several objectives to obtain the area, water level, and duration of inundation in paddy fields as an impact of climate change and proposed sustainable water management. The methods used are tidal measurements and hydrodynamic analysis using HEC-RAS. The highest tide was at +4.52 m, while the elevation of the paddy fields was only +3.40 m; thus, the paddy fields were inundated during the spring tide. Sea level rise and rainfall increase the area, water level, and duration of inundation. During spring tide, the inundation area is 73.42, with a duration of inundation of 3.11 days. Under sea level rises of 25 and 50 years, the inundation area increases to 74.41 and 74.86, while the inundation duration increases to 3.28 and 3.40 days, respectively. Under rainfall with a 5- and 25-year return period, the inundation area reaches 79.19 and 79.21, while the duration is 3.40 and 3.48 days, respectively. Paddy fields are continuously inundated for over three days at elevations of +3.70-3.80 m. Excessive inundation during prolonged periods decreased rice production. Preventive actions due to climate change are needed to control the inundations. Inundation control can be conducted by gates, canal excavation, embankments, and drain pipes. Meanwhile, integration between government sectors and local communities is needed to support the sustainability of the Katingan tidal agricultural lowlands. © 2024 Penerbit UTM Press.