Allogenic River in the Hydrogeological System of Gremeng Cave, Gunungsewu Karst Area, Java Island, Indonesia

Abstract

Allogenic rivers play a pivotal role in the development of the karst area. Their open system creates aggressive conditions that cause more intensive rock dissolution and, therefore, possibly form a primary underground river system in a hydrogeological regime. This study aimed to inventory allogenic rivers in the hydrogeological system of Gremeng Cave. This study also investigates Gremeng Cave typology based on underlying geological conditions by analyzing Indonesian topographic and geologic maps and high-resolution remote sensing imagery. In this study, a detailed geological survey was conducted to determine factors triggering the formation of allogenic rivers at the research site based on geological and geomorphological characteristics. The results showed at least five allogenic river subsystems uniting into one primary system. Allogenic from underlying beds exposed updip was the type of the allogenic rivers emerging exactly at the contact between tertiary volcanic rocks and limestones at the Gunungsewu karst area.

Hydrogeological Characterization of the Gunungsewu Karst Area in the Upper Reach of Gremeng Karst Drainage Basin, Indonesia

“…The contact between Wonosari and Semilir Formations results in two hydrogeological formations: ponors through which allogenic rivers enter the underground river system and springs as the output of underground rivers (Figure 2). The allogenic rivers in question are allogenic streams flowing from underlying beds exposed updip [15,21].…”

“…Cahyadi et al (2019; 2020) [15,16] divide the northern segment of the Ponjong Hydrogeological Subsystem into two karst drainage basins: Beton and Gremeng, but have not discussed it in detail. Therefore, the current research set out to complement previous studies that merely separated the subsystem's northern part from the Bribin Karst Drainage Basin.…”

Temporal Variation of Tropical Karst Groundwater Suitability for Irrigation in Gremeng Resurgence, Gunungsewu Karst Area, Indonesia

“…Electrical conductivity tended to be higher in the dry season (April 2019-October 2019) than in the rainy season. This is possible because, in the dry season, Gremeng Resurgence receives recharge water only from groundwater as allogenic recharge and diffuse flow as autogenic recharge [20]. Meanwhile, in the rainy season, dilution by rain reduces dissolved solids in groundwater; hence, a relatively low electrical conductivity.…”

“…Administratively, this sub-system is located on the border of the Gunungsewu Karst Area that is adjacent to the Wonosari Basin. Gremeng Resurgence, together with Concrete Resurgence, fulfills the irrigation water needs of all agricultural practices in the Beton-Gremeng irrigation system [20]. It receives water from an allogenic recharge area, approximately 13.25 km 2 , in the ancient volcanic region in the northern part of the Gunungsewu Karst Area.…”

Temporal variation of water suitability for paddy irrigation needs at karst springs influenced by allogenic recharge in Gunungsewu Karst Area, Indonesia

“…This study was conducted at Beton Spring (Figure 1). It is a resurgence of karst aquifers within the Gunungsewu Karst Area and has a distinctive characteristic, that is, allogenic recharges from outside the karst area [14,15]. With water discharge varying between 505.9 and 11 111.17 L s -1 , Beton Spring has a vital role in irrigating agricultural fields in its surroundings [16].…”