Impact of excessive groundwater pumping on rejuvenation processes in the Bandung basin (Indonesia) as determined by hydrogeochemistry and modeling Impact de l’excès de pompage des eaux souterraines sur les processus de renouvellement dans le bassin de Bandung (Indonésie) déterminé par l’hydrogéochimie et la modélisation Impacto do bombeamento excessivo no processo de rejuvenescimento na bacia de Bandung (Indonésia) conforme determinado por hidrogeoquímica e modelagem Impacto del bombeo excesivo de agua subterráneas en los procesos de rejuvenecimiento en la cuenca de Bandung (Indonesia) determinado por hidrogeoquímica y modelado
Taufiq A.a,b,c, Hosono T.a, Ide K.a, Kagabu M.d, Iskandar I.b, Effendi A.J.b, Hutasoit L.M.b, Shimada J.a
a Graduate School of Science and Technology, Kumamoto University, Kumomoto, 860-8555, Japan
b Faculty of Earth Science and Technology, Bandung Institute of Technology, Bandung, 40132, Indonesia
c Research Center for Water Resources, Ministry of Public Work and Housing, Bandung, 40135, Indonesia
d Graduate School of Fisheries and Environmental Science, Nagasaki University, Nagasaki, 852-8521, Japan
Abstract
© 2017, The Author(s).In the Bandung basin, Indonesia, excessive groundwater pumping caused by rapid increases in industrialization and population growth has caused subsurface environmental problems, such as excessive groundwater drawdown and land subsidence. In this study, multiple hydrogeochemical techniques and numerical modeling have been applied to evaluate the recharge processes and groundwater age (rejuvenation). Although all the groundwater in the Bandung basin is recharged at the same elevation at the periphery of the basin, the water type and residence time of the shallow and deep groundwater could be clearly differentiated. However, there was significant groundwater drawdown in all the depression areas and there is evidence of groundwater mixing between the shallow and deep groundwater. The groundwater mixing was traced from the high dichlorodifluoromethane (CFC-12) concentrations in some deep groundwater samples and by estimating the rejuvenation ratio (R) in some representative observation wells. The magnitude of CFC-12 concentration, as an indicator of young groundwater, showed a good correlation with R, determined using 14C activity in samples taken between 2008 and 2012. These correlations were confirmed with the estimation of vertical downward flux from shallower to deeper aquifers using numerical modeling. Furthermore, the change in vertical flux is affected by the change in groundwater pumping. Since the 1970s, the vertical flux increased significantly and reached approximately 15% of the total pumping amount during the 2000s, as it compensated the groundwater pumping. This study clearly revealed the processes of groundwater impact caused by excessive groundwater pumping using a combination of hydrogeochemical methods and modeling.
Author keywords
Indexed keywords
Groundwater age,Groundwater mixing,Indonesia,Numerical modeling,Over-abstraction