The relationship between Paneki River and groundwater at Jono Oge Liquefaction Area, Central Sulawesi, Indonesia Available to Purchase

Liquefaction that occurred on 28 September 2018 in Jono Oge Village, Central Sulawesi Province, one of the causes was the shallow groundwater level. Data from monitoring wells after the liquefaction disaster around Jono Oge shows that the groundwater is very shallow, less than 10 m. To the north of the Jono Oge, the liquefaction area is the Paneki River, which has a porous streambed. The river even coincides with the Jono Oge Liquefaction Area. The upstream of the river, the water flows, and further downstream, the discharge decreases until it dries up. Previous research suggested that the Paneki River likely contributed to the liquefaction avalanche. This study aims to determine the direction of flow from the Paneki River to the groundwater in the Jono Oge Liquefaction Area and to estimate the quantity of the river flow through the aquifer system of shallow groundwater. We use the groundwater level data to create the lines of equal hydraulic head and groundwater flow direction. Borehole data determined geological conditions in the Jono Oge Liquefaction Area. We measured the infiltration rate on the streambed when the river was dried and used it to represent the value of hydraulic conductivity. The aquifer layer is assumed to be homogeneous isotropic. We use the principles of Darcy’s law to calculate discharge. The result showed lithological liquefaction to a 30 m dominated by sand with high water permeability. The infiltration rate on the streambed is very rapid, ranging from 40.35 cm/hour– 372.33 cm/hour. We divide the rivers adjacent to the liquefaction area into three parts, with a total of 3.71 km adjacent to the rivers adjacent to the liquefaction area. Segment A is a losing stream, river water infiltrated through the streambed to the aquifer system. Based groundwater flow direction does not lead to a liquefaction area. Segment B is a losing stream whose stream stage is seated above the groundwater level. River water infiltrates the aquifer in the liquefaction area with a potential recharge discharge of 0.062 m³/sec. In Segment C, losing and gaining streams can occur because the difference between the groundwater level and the river surface is minimal. In conclusion, Segment B overlaid between the Paneki River and the Jono Oge liquefaction area is a type of surface water recharging the aquifer that leads to the aquifer below the liquefaction area. While in Segment C is aquifer boundaries because most of the river receives water from the aquifer. The plan to reduce groundwater for liquefaction mitigation by pumping and dumping it into the Paneki River should be carefully considered. Groundwater to river drainage is ineffective because the drain water is re-entering the aquifer.