No abstract

The karst hills of Gombong Selatan have abundant potential water resources, especially in locations that have underground springs and rivers. The connectivity between the subsurface passageways that is difficult to know can threaten the potential of water resources, one of which is due to pollution caused by uncontrolled human activities. Therefore, identification of catchment systems and boundaries of water catchment areas in karst aquifers is needed that can contribute to sustainable water resources management policies. This catchment identification needs to be conducted because previous studies have never explored the eastern side of this karst area. This study aims to (1) define the underground river flow connectivity (upstream-downstream) of Banteng Cave; and (2) limiting the water catchment area of Banteng Cave. The method used to determine the subsurface connectivity system was carried out through an artificial tracer test, while the catchment area was delineated using a water balance approach. The results showed that the underground river of Banteng Cave has connectivity with Lake Blembeng, as evidenced by a change in watercolour after the tracer test and breakthrough curve (BTC) analysis of the tracing test results. BTC analysis shows that the Banteng Cave passageway has one main passage and does not have a tunnel branch. The estimated area of the Banteng Cave catchment used a water balance approach, which is 141.73 hectares. The Banteng Cave karst catchment conditions are dominated by the formation of valleys and karst cones accompanied by the appearance of valleys and karst hills that are quite evenly distributed, indicating that the Banteng Cave karst catchment is included in the advanced karst development phase. Furthermore, this research contributes significantly to increase knowledge regarding the characteristics of void karst development in aquifers which in the future are very important for determining water resources management policies.

The connectivity of the Barat Cave underground river system needs to be known to support the implementation of proper environmental management so that water resources can be maintained sustainably. However, the mapping of underground river paths is often hindered by conditions of narrow cave passages, a barrier blocking the flow of water (siphon), deep underground lakes, underground waterfalls, as well as paths filled with water. This research was conducted in Barat Cave, Karangbolong Karst Area. The purpose of this study is to determine the upstream-downstream connectivity system in this underground river and define the characteristics of the passageway based on quantitative analysis of the transport parameters from the tracer test results. This underground river network analysis needs to be done because previous research has never analyzed this underground river network. The research method used in this study is divided into three stages, namely the pre-field stage, the field stage, and the post-field stage. The pre-field step includes determining the location of the study, collecting secondary data, and studying the literature. The field stage consists of a hydrogeological survey to find information on the presence of caves, springs, sinking stream ponors, or luweng in the study area, instantaneous discharge measurements, and tracer tests. The post-field stage includes data processing and analysis. The results showed that the Barat underground river system originated from the Kalimas sinking stream, Mblabak Cave, Pendok Cave, and Pagilangan sinking streams, then merged into a single tunnel without a flow breaker to the Barat Cave, Pengantin Cave, and appeared in the Kalikarak springs to become a surface river, with a tunnel pattern in the form of curvilinear branchwork. The transport parameters for the underground system tracing of the Barat cave have an advection value of 86.528 m/hour, a dispersion of 0.092 m2/second, a dispersivity of 3.38 meters, and a recovery of 63%. The transport value of the tracing test parameter is influenced by the characteristics of the passageway and underground river flow conditions.

Salah satu pilar utama dari UNESCO Global Geopark adalah aspek edukasi yang ditujukan untuk meningkatkan kesadaran dan apresiasi terhadap nilai penting dan keunikan geologis dari suatu kawasan. Salah satu kawasan tersebut adalah Gunung Sewu UNESCO Global Geopark dimana terdapat proses geologi berupa karstifikasi yang masih berlangsung dan menghasilkan bentukan-bentukan unik dan khas dari kawasan karst seperti sistem perguaan. Proses tersebut, selain menghasilkan keindahan juga memiliki nilai ilmiah sebagai gerbang dalam memahami sejarah geologi. Oleh sebabnya, untuk semakin meningkatkan dan memperkuat kesadaran masyarakat terutama pengunjung UNESCO Global Geopark diperlukan pengemasan informasi sedemikian rupa agar semakin menarik minat pengunjung dalam mempelajari proses dan aspek ilmiah tersebut. Penelitian ini secara kualitatif deskriptif mengkaji bagaimana fotogrametri gua dapat menyediakan geoinformasi untuk memenuhi tujuan dan fungsi Geopark. Selain menggunakan metode fotogrametri untuk menghasilkan geoinformasi yang dibutuhkan, penelitian ini juga menggunakan metode pemetaan gua untuk mendapatkan gambaran keruangan dari gua sebagai fenomena kebumian yang dikaji. Lokasi penelitian berada di Goa Tembus, salah satu geosite Gunung Sewu UNESCO Global Geopark yang berada di Geoarea Wonogiri. Sebagai hasilnya, didapatkan fotogrametri menghasilkan gambaran keruangan gua dengan kekuatan visual yang lebih baik dari peta gua biasa. Selain memiliki kekuatan visual yang lebih tinggi, fotogrametri gua juga memiliki tampilan antarmuka yang interaktif sehingga lebih menarik bagi pengunjung. Pengembangan hasil pemetaan 3-dimensi dari fotogrametri juga dapat dipadankan dengan realitas berimbuh atau realitas visual. Secara ilmiah, fotogrametri juga menampilkan fitur-fitur geologis secara lebih rinci yang dapat dimanfaatkan untuk menggali dan menganalisis gejala speleogenesis seperti speleomorfologi fitur-fitur ornamen serta speleogen.