RECHARGE ANOMALY ON TRANSFER ZONE OF CIKAPUNDUNG FLUVIAL SYSTEM, , WEST

Zamzam A.J. Tanuwijaya1 Hendarmawan2 and Ajat Sudrajat2 1 Department of Geodetic and Geomatic Engineering, ITB 2Faculty of Geology Padjadjaran University

Abstract Cikapundung fluvial system divided into three zones; production, transfer and deposition. The production zone is a recharge area that forms the drainage basin which flows into Maribaya outlet. In the southern part of this production zone is a northward facing fault scarp which hinders the groundwater flow to Bandung. The transfer zone is a segment of Cikapundung River extending from Maribaya outlet to Curug Dago. This transfer zone is characterized by presence of basaltic lava flows that covers the river bed. The deposition zone is a segment from Curug Dago to , where water flows above an alluvial fan. This fan was formed due to the activities of the Sunda Volcanic Complex. This deposition zone ends up as sediment in ancient Bandung Lake. According to daily stream discharge data over 63 years (1952-2014) there were indications of water loss between Maribaya and Gandok outlet. This study focus on recharge mechanism of transfer zone segment. The transfer zone is a segment of Cikapundung River which has effluent type, marked by a line of spring waters out from the cliff, whilst in this zone is influent. The transfer zone is located within the Palasari Block, where all the regional lineaments within the block were controlled by the tectonic activities of Lembang Fault. Generally, these regional lineaments tend to have radial orientation and converge to the west of the fault. These lineaments can be indicated of the weak zones which serve as conduit for groundwater to flow into the aquifer. The result study can be concluded that the water loss within the transfer zone occur within the river segment that have the lowest gradient slope and high lineaments density. The recharge mechanism within the transfer zone occurs through the river pools that have no basaltic bed due to eroded or they have basaltic bed with high fracture density. Keywords: fluvial system, effluent, influent, recharge anomaly

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