Water availability evaluation towards land extensification potency in Belanti II Swamp Irrigation Area, Central Kalimantan

Belanti II Swamp Irrigation Area has 3976 Ha total area with 2630 Ha or 66,15 land used as paddy area, 462 Ha or 11,62 land used as residential area, and 884 Ha or 22,23 land used as shrubs that uncultivated yet. However, there are no water availability analysis yet in shrubs area. Through this study, water availability in that area will be searched towards land extensification potency. Method used in this study is analysis of river tidal pattern by modelling it in HEC-RAS. Through this method, water availability and affordability can be seen in the uncultivated area by comparing water level and elevation of the land. Based on simulation, river tidal pattern can irrigate 603,36 Ha of 884 Ha uncultivated area which is closer to the source of tide and mean that water level are higher than the land elevation, meanwhile the rest 280,64 Ha of uncultivated area which is farther from the source of tide cannot be irrigated mean that the land elevation are higher than the water level. Water availability in the uncultivated area will affects land extensification potency in Belanti II Swamp Irrigation Area. Through this result, optimization steps of water management can be determined, so that land extensification can be done impacted to productivity enhancement of paddy harvest and followed by increasing of farmers income.