Adaptive water management in response to tidal inundation and sea level rise on tidal agricultural lowlands of Katingan, Central Kalimantan

Abstract

Abstract Decreased water management systems and sea level rise cause inundation in the Katingan tidal agricultural lowland. Excessive and prolonged inundation can decrease rice production or even loss of rice land. A study was conducted to provide adaptive water management for controlling water levels in canals and rice crop fields inundation. For this purpose, a combined one- and two-dimensional unsteady flow method was used in HEC-RAS. The scenario of water level control uses sluice and flap gates in secondary canals. Under spring tide conditions, water level control with gates decreases the inundation area by 95.62%. Likewise, in the 25 and 50-year sea level rise scenarios, inundation decreased by 88.51% and 82.25%. In the spring tide condition, the duration of inundation is decreased from 3.5 to 0.9 days. Under 25 and 50-year sea level rise scenarios, the duration of inundation was decreased from 3.7 to 3 days and from 4.3 to 4.1 days. The use of gates significantly decreases inundation in the spring tide condition, but under sea level rise in 25 and 50-year, the depth and duration of inundation are still dangerous for rice crops; therefore, it is necessary to advance water management control for the sustainability of rice fields.