The apparent groundwater age rejuvenation caused by the human activity in Jakarta area, Indonesia
Abstract
The rapid urbanization in Jakarta area has become a serious subsurface environmental issues such as groundwater level decline and land subsidence due to excessive groundwater pumping. These problems began to emerge recently by some hydrological studies. The comparison of 14C activity between 1985 and 2008 shows the apparent groundwater age rejuvenation in the deep aquifer under the DKI Jakarta. We discussed by using a numerical groundwater flow model to evaluate the process of this rejuvenation in the urbanized area. Since the groundwater pumping was not performed intensely, the groundwater discharge flow toward the sea coast was dominant until 1983, however, this outward flux switched to intrusion flux into deeper aquifer after mid-1980s because of over-pumping in the urban area. The most largest flux among six flux directions toward the deep aquifer under the DKI Jakarta became “vertical downward flux” which means the shallower groundwater intrude into the deep one due to the excessive groundwater pumping from mid-1980s and this flux grows about 50% in 2000s. This result is consistent with the detection of chlorofluorocarbon (CFC)-12, which works as an indicator of young groundwater even in the deep groundwater. As the rejuvenation ratio “R” was determined by using 14C activity in the groundwater, R increase with the CFC-12 concentration and boths have good correlation. Besides, we estimated the “vertical downward flux” at each well's screen depth by the model estimation. The result shows that this flux has larger in the urban groundwater depression area and especially at shallower part of the deep aquifer, and it affects the magnitude of the shallow groundwater intrusion. Relationship between R and CFC-12 concentration. The diameter of cube shows the magnitude of the “vertical downward flux”
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2010
- Bibcode:
- 2010AGUFM.H11G0888K
- Keywords:
-
- 1830 HYDROLOGY / Groundwater/surface water interaction;
- 1834 HYDROLOGY / Human impacts;
- 1836 HYDROLOGY / Hydrological cycles and budgets;
- 1880 HYDROLOGY / Water management