Spatial Variation in Groundwater Types in the Mt. Karang (West Java, Indonesia) Volcanic Aquifer System Based on Hydro-Chemical and Stable Isotope (?D and ?18O) Analysis

Abstract

On the island of Java, groundwater use has significantly increased because of population growth and industrial development. Mt. Karang (a volcano in West Java, Indonesia) has the potential to be a significant groundwater source. Samples were collected twice from springs, dug wells and rivers (rainy and dry seasons). We used information about the aquifer system, hydrogeological conditions and hydro-chemical data to investigate groundwater sources and their associated recharge processes. Chemical data showed that samples belonged to the Ca-Na-HCO3 type in both seasons. The dominant Ca²⁺ indicates that this water may have flowed through a rock formation composed of andesitic-basaltic rocks with Ca-plagioclase minerals. HCO₃⁻ originates from either infiltration of rain water that has been equilibrated with CO₂ in the atmosphere, or from CO2 that has been generated by respiration of organic material. Several groundwater samples shows the isotopes values were lighter in the rainy season than in the dry season, which may indicate evaporation during infiltration in the recharge area. There are two types of water isotopically; one is relatively deep circulated water with consistent δD values, the other is of shallow circulated one affected by evaporation. We reconstructed a conceptual model of the groundwater flow systems and recharge mechanisms in Mt. Karang, based on hydrogeological, hydro-chemical and stable isotope data. This model will give an improved understanding of the region's hydrogeological condition.

Geological Trap Controlling the Residence Time of Groundwater in Assessment of Exploitation Zone for Its Sustainable Resources Case Study: The Slope of Karang Mount, Banten Province, Indonesia

“…Geological setting of the studied area were also identified based on the previous geologi- (Santosa, 1991;Rusmana et al, 1991;Endyana et al, 2011;Harada et al, 2014;Alam et al, 2014aAlam et al, , 2014bAlam et al, , 2019, and further surveys carried out in this study. A prominent feature in the studied area is the presence of two volcanoes, namely Karang Volcano (1750 m msl.)…”

“…Syariman and Hendarmawan (2010) presented measurements of the hydrological elements of rainfall to evapotranspiration. Meanwhile, Alam et al (2014a;2014b; and Hartanto et al (2019; reveal hot spring water for geothermal potential. The Serang City is located in the northeast of Mount Karang with developing industrial activities (see Figure 1).…”

Kualitas Air pada Puncak Musim Kemarau di Daerah Rawa Danau Kabupaten Serang

“…Fasies hidrokimia jenis alkali yaitu kalsium-magnesium bikarbonat ini merupakan cerminan dari geologi dan iklim daerah penelitian. Daerah penelitian di susun oleh batuan produk vulkanik yang menyebabkan terjadi interaksi senyawa mineral dalam akuifer antara airtanah dengan batuan yang dilalui (Alam et al, 2014). Selain itu telah Tabel 3.…”