POLyGONAL KARST MORPHOLOGy OF KARANGBOLONG AREA, JAVA-INDONESIA MORFOLOGIJA POLIGONALNEGA KRASA OBMOČJA KARANGBOLONG, JAVA, INDONEZIJA Eko HARyONO1, Sutanto TRIJUNI PUTRO2, SURATMAN3 & SUTIKNO3 1 Karst Research Group, Faculty of Geography, Gadjah Mada University, North Sekip, Bulaksumur, yogyakarta, Indonesia, Fax. +622746492340, e-mail: e.haryono@geo.ugm.ac.id 2 Faculty of Natural Resources Technology, yogyakarta Institute of Technology, Janti Street Km 4, yogyakarta, Fax +62274566863, e-mail: sutanto0612@gmail.com 3 Karst Research Group, Faculty of Geography, Gadjah Mada University, North Sekip, Bulaksumur, yogyakarta, Indonesia, Fax. +622746492340, e-mail: ratman_woro@yahoo.com, e-mail: sutikno@geo.ugm.ac.id Received/Prejeto: 14.01.2016 COBISS: 1.01 ACTA CARSOLOGICA 46/1, 63–72, POSTOJNA 2017 Abstract UDC 551.435.8(594.5) �ko Haryono, Sutanto Trijuni Putro, Suratman & Sutikno: Polygonal karst morphology of Karangbolong area, Ja�a�In� donesia The Karangbolong karst is situated in the southern zone of Java where Miocene limestone has been uplifted and has experi- enced karstification since the late Pliocene. The research docu- mented here aims at exploring morphological characteristic of the area. Special interest is attributed to differentiation of val- ley or depression morphology, conical karst morphology, and the roles of jointing system and uplift history in their develop- ment. The morphology investigation was mostly undertaken using aerial photograph visual interpretation of panchromatic aerial photograph and analytically shaded DEM, as well as field observations. The results show that the general morphological features of Karangbolong karst are characterized by aligned val- leys and aligned enclosed depression with three different pat- terns. The orientation of the valleys and enclosed depressions coincide with the structural pattern of the area, indicating that the formation of aligned valleys and aligned enclosed depres- sions is preferential dissolution through jointing. The residual hills are typified by conical karst morphology with sharp peaks. It is found that tight joint spacing appears to be the main rea- son for the sharp peak of the conical hills. Asides from jointing system, morphology of the area is likely governed also by topo- graphical position and gravity sliding of the limestone bed dur- ing the uplift. Uplift history has important control on the dif- ferentiation of morphology between plateau part and sloping part. Limitation of this research is that the aerial photograph was not rectified well, because the analyses in this research Izvleček UDK 551.435.8(594.5) �ko Haryono, Sutanto Trijuni Putro, Suratman & Sutikno: Morfologija poligonalnega krasa območja Karangbolong, Ja�a, Indonezija Opravili smo geomorfološko študijo območja krasa Karangbo- long v južnem delu Jave. Miocenski apnenci tu zakrasevajo od dviga območja v pliocenu. Izpostavili smo razlike med odprti- mi dolinami in zaprtimi depresijami, morfologijo stožčastega krasa ter vlogo razpoklinskih sistemov in dvigovanje območja pri geomorfološkem razvoju območja. Metode temeljijo na štu- diji pankromatskih letalskih posnetkov, senčenega digitalnega modela reliefa ter terenskih raziskavah. Morfološke značilnosti območja se odražajo predvsem v linijski razporeditvi dolin in kotanj. Smer dolin in kotanj sovpada s strukturnim vzorcem območja, kar nakazuje, da je njihov razvoj posledica učinko- vitejšega raztapljanja v razpoklinskih conah. Stožčasti vrhovi imajo ostre vrhove, kar je verjetno posledica goste razpoklin- ske mreže. Na morfologijo območja močno vpliva tudi gravi- tacijsko drsenje apnenčastih plasti med dvigovanjem ozemlja. Zgodovina dvigovanja je verjetno pomembna za razlike med morfološkimi značilnostmi na pobočjih in planotah. Slabe rektifikacije letalskih posnetkov ne omogočajo dobre morfo- metrične analize območja, zato smo se omejili predvsem na zaznavanje značilnih geomorfoloških vzorcev. Ključne besede: Južna Java, kras Karangbolong, poligonalni kras, tropska geomorfologija. ACTA CARSOLOGICA 46/1 – 201764 EKO HARyONO, SUTANTO TRIJUNI PUTRO, SURATMAN & SUTIKNO INTRODUCTION Tropical karst morphology, including areas in Indonesia, has drawn the attention of geomorphologists since the early 1900s. It owes its importance through its outstand- ing residual hill morphology compared to that in other climate zones. High rainfall intensity provides huge dis- solution rates for the prerequisite of karstification and karst morphology development. Due to its uniqueness, textbooks on karst geomorphology (Ford & williams 2007; Sweeting 1972) gave special attention by putting tropical karst morphology in a separate category. The first publication on Indonesia karst was first made by Le- hmann (1936) based on his observation in Gunungsewu karst. His publication then drew several other research- ers to get better understanding of Indonesian karst from different perspective (Balazs 1968; Flathe & Pfeiffer 1965; Haryono & Day 2004; Urushibara & yoshino 1997). However those publications were based on research con- ducted in Gunungsewu karst. Different karst areas have not been explored yet, including the Karangbolong karst, though the area is the same physiographic unit as Gu- nungsewu karst. The Karangbolong karst is situated in the southern zone of Java where the most extensive carbonate rock outcrop in the Java Island is situated. The area is distin- guished by an uplifted fault block forming plateau mor- phology (Bemmelen 1970; Pannekoek 1949). The pla- teau generally is bordered with an alluvial plain in the north by a fault line scarp. Karangbolong karst itself is a small block of the southern zone of Java covering an approximate area of 4,834 hectares. The area is located were more on pattern identification. More accurate rectifica- tion is needed for better morphometric analyses. Key words: Southern Java, Karangbolong karst, polygonal karst, tropical geomorphology. Fig. 1: Geological setting of Karangbolong karst, compiled from Asikin et.al. (1992), Spelman (1979). ACTA CARSOLOGICA 46/1 – 2017 65 POLyGONAL KARST MORPHOLOGy OF KARANGBOLONG AREA, JAVA-INDONESIA METHODS This research mainly employed 1: 20 000 panchromatic aerial photograph interpretations incorporated with DEM-ASTER for slope analyses. Aerial photograph was provided by Bureau of Survey and Mapping Coordina- tion of Indonesia (BIG). Aerial photograph was used for lineaments, closed depression, conical hill peak, and dry valley interpretation. ASTER GDEM with 30 m resolu- tion was used for examining general morphology of the area and for generating slope map. Since closed depres- sion interpretation was only possible conducted stere- oscopically, this research used mirror stereoscope and screen scope interactively for examine the closed depres- sion boundary. The delineation, however, was conducted on screen manually over geometrically corrected scanned aerial photographs using Quantum GIS. Interpretation involved 23 black and white panchromatic aerial photo- graphs. Since aerial photograph has radial errors from the center, only 30 % up to 40 % of the center coverage of the aerial photograph was scanned on 300 dpi and geometri- cally corrected. Delineation was then used the mosaic of those center coverage of scanned aerial photograph. The geometric correction was conducted through two order polynomial transformation with six up to eight tie points from digital topographic map. Average RMS error found during geometric correction was 4.475. Closed depres- sions resulted from interpretation were used to analyze closed depression morphometry, i.e. closed depression area, perimeter, length, shape, and pitting index. between 106o28’ – 109o14’ E and 7o38’ – 7o45’ S. The limestone is composed mainly of packstone and bound- stone from Kalipucang Formation (Brahmantyo 2005). The Kalipucang Formation is underlain unconformably by the Gabon Formation that comprises mostly volcanic breccia and partly tuff, lava intercalated by sandstone and conglomerate (Asikin et al. 1992). Giving the fact that the Karangbolong karst has been uplifted since the Late Pliocene, the area is geologically considered young. However, karst morphology in the area is already well developed. Cave survey also shows that cave systems have developed very well (Bernard et al. 2003). The geological setting of Karangbolong karst is con- sidered unique compared to the other karst areas in Java Island. Limestone beds of Karangbolong karst are rela- tively thin and cover relatively small area. The thickness of the limestone bed is between 300−350 m (Brahmantyo 2005). Being unconformably overlain on the underlying rocks, the limestone of Karangbolong karst is thin in the southern part and becomes thicker to the north. For this reason, most of the underground drainage system of the area flows to the north. Some other underground river systems flow to the west and east to the sloping part of the plateau (Fig. 1). The mean annual rainfall of Karangbolong area cal- culated from four nearest rain gauge station during the last 50 year is around 3,000 mm/year (Haryono 2008). Having considerably high annual rainfall with unique geological setting, Karangbolong karst has experienced unique karst development. This paper is an endeavor to explore and analyze morphological characteristic of Karangbolong karst. Special interest will be attributed to differentiation of valley/depression morphology, conical karst morphology, and the roles of jointing system and uplift history in their development. RESULTS NEGATIVE FORMS (VALLEyS AND ENCLOSED DEPRESSION) The negative relief form of the Karangbalong karst is typified by aligned valleys. The formation of the aligned valleys coincides with the general structural pattern of the area, of which the major direction is Nw−SE and NE−Sw (Fig. 2). These correspond to conjugate joint sets. These two general structural patterns have resulted from compression stresses driven by the northward movement of the subducting India-Australia plate against the Eura- sia Plate in the north. The subduction zone of those two plates is situated 200 km in the south of the study area. Therefore the formation of these valleys could be ex- plained by preferential dissolution along conjugate joint- ing systems (Fig. 2). The expression of those structural patterns is var- ied in different localities. In some parts, the aligned val- leys are more clearly depicted in the NE−Sw orientation ACTA CARSOLOGICA 46/1 – 201766 (Fig. 3a), whereas in other parts (Fig. 3b), the valleys are depicted prominently in the NE−SE direction. These two different modes are governed by the topographic posi- tion of the two localities. NE−Sw valleys develop in the northeast part of the Karangbolong karst where the slope trend is heading to the northeast. As such, more surface runoff flows to the northeast resulting in deeper valleys in that direction. On the contrary, the area of Fig. 3b is situated in the northwest part of Karangbolong karst where the slope trend is towards northwest. The surface runoff in area of Fig. 3b may have flowed to the north- west direction, in turn forming deeper valley in that di- rection. Beside aligned valleys, curvilinear valleys are also found in the Karangbolong karst. Curvilinear valleys are mostly found in the western slope of the Karangbolong plateau. Their origin seems to be related to the collapse and sliding of the limestone blocks during the uplift, as part of detachment tectonics. This collapse and sliding can be shown by the scarp morphology in the upper part of the western slope. The sliding must have caused an outward curvature of the joints that in turn governed the curving preferential dissolution within this area. From the curvilinear pattern, it is likely that during the up- lift, the eastern slope of the plateau block glided to the Sw direction (Fig. 4a). Radially aligned valleys are also found in the northern slope. This radial pattern is like- ly governed by interplay of lineament and slope where the summit of the area in Fig. 4b is the highest part of Karangbolong karst, and its karst morphology is radially developed from this summit. More detailed interpretation under a mirror stereo- scope revealed that most valleys have already developed into compound enclosed depressions, forming cockpit karst morphology with a polygonal plan view. These po- lygonal enclosed depressions mostly developed in the southern part and western part of the plateau (Fig. 5). In the sloping part, enclosed depressions do not develop very well. This could be explained by limestone dissolu- tion and erosion by surface runoff rather than concen- trated percolation through ponors. Only a few single do- lines are found in the area. Single dolines are also found Fig. 2: Lineament and rose diagram of the study area indicating general structural pattern. box with number are sample areas pre- sented in Fig. 3 and Fig. 4. Fig. 3: Aligned valleys in Karang- bolong karst indicating NE−SW and NW−SE orientation. These two aerial photographs are situ- ated at box 3a and 3b in Fig. 2 (The aerial photograph courtesy of bIG). EKO HARyONO, SUTANTO TRIJUNI PUTRO, SURATMAN & SUTIKNO ACTA CARSOLOGICA 46/1 – 2017 67 in the southern plateau where the limestone is very thin due to shallow underlying volcanic clastic rock. The ratio of closed depression area and limestone area or pitting index (williams 1971) of Karangbolong karst is 0.76, indicating that the area has been severely karstified. Ba- sic parameters for closed depression morphometry of Karangbolong karst is presented in Tab. 1. tab. 1: Closed depression morphometry of Karangbolong karst. Parameter Range Average Area (km2) 0.009 – 0.584 0.137 Perimeter (km) 0.371 − 4877 1.689 Length (km) 0.137 – 1.778 0.615 Shape Index 0.21 – 0.80 0.44 Closer look at the valley networks the Karangbo- long Karst is characterized by multi-basinal and angular drainage pattern (Fig. 6). Compared to that from differ- ent karst areas in the world, however, Karangbolong karst has a lower closed depression density. The reason could be explained by the fact that not all depression/valley are enclosed one. Some of the valleys in the sloping part are first order or second order valleys with no sinkholes. On the other hand, angular drainage pattern must be result- ed from preferential dissolution through jointing system. Different orders of valleys are encountered in the area. Most of the valley networks (12 as of 15) are first order valley. Only three valley networks have second order val- ley, and only one valley network has third order valley. Third order valleys are situated in the northern slope of the area. In term of density, the plateau area has lower drainage density than that in sloping part. Fig. 4: two different valley pat- terns in the western slope (A) and northern slope (b) of Karangbolong karst. In the western slope the val- leys are dominated by curvilinear pattern, whereas in the northern slope is more like radial pattern. Solid line with arrow in the figure A is the sliding direction of the limestone during uplift. (The aerial photograph courtesy of bIG). Fig. 5: Enclosed depression of Karangbolong karst delineated un- der mirror stereoscope. due to dif- ficulty of geometric correction pro- cesses, the enclosed depression does not precisely match with the over- laid aerial photograph (The aerial photograph courtesy of bIG). tab. 2: Comparison of enclosed depression density in several ar- eas. Area Enclosed depression density (depression/ km2) Source Karangbolong, Indonesia 5.78 This study Gunungsewu, Indonesia 6.43 Haryono (2008) New Guinea 13.05−13.50 Williams (1971) Guatemala 13.1 Day (1983) Florida, Suwannee 6.06 Denizman (2003) Biokovo, Croatia 44 Telbisz et al. (2009) POLyGONAL KARST MORPHOLOGy OF KARANGBOLONG AREA, JAVA-INDONESIA ACTA CARSOLOGICA 46/1 – 201768 POSITIVE FORM/RESIDUAL FORM The residual form of the Karangbolong karst is typified by cone karst morphology (Fig. 7). Compared to the nearby karst areas in the same southern zone of Java, the cone morphology of Karangbolong karst exhibits sharper peaks instead of rounded cones (Fig. 8). The plan view of the conical hills is more elongated rather than circular. The number of conical karst hills, counted from aerial photographs, is 795 with density of 28 cones/km2. The distribution of conical karst hills in the area is indicated Fig. 6: drainage of the Karang- bolong Kars, black pointers show third order dry valleys. by a nearest neighbor index (R) of 0.7, which is in the transition between clustered and random (Fig. 7). The height of the conical karst hills varies from 12 m up to 72 m with approximately 37 m in average (N = 25). The highest cones are situated in the sloping part of the karst and the lower conical hills are distributed on the plateau. More detailed interpretation from the aerial pho- tographs revealed that there is more complexity in the conical karst morphology. Though in Fig. 7 conical karst hills are depicted as separate peaks, most of the peaks lie Fig. 7: Conical karst hills distri- bution in Karangbolong karst. Conical karst hills are depicted as black triangles, lines are dry val- leys. Numbers in the upper left are nearest neighbor parameters: N for number of conical karst hills, do for mean observed distance (km), de for expected distance (km), R for nearest neighbor index, and z for z score. EKO HARyONO, SUTANTO TRIJUNI PUTRO, SURATMAN & SUTIKNO ACTA CARSOLOGICA 46/1 – 2017 69 on ridges (see Fig. 3 and 4). These elongated hills thus have more than one conical karst peak. Ground view pho- tographs also show more conical hill variation as depicted in Fig. 8. Using further analyses from the 30 m DEM (AS- TER), most of the Karangbolong karst is occupied by flat up to > 65 % slope (Fig. 9). Gentler slopes occupy in the plateau part (0–30 %) and the steeper slope occupies the Fig. 8: Conical karst morphology of the Karangbolong karst. The base of the cones is much higher than the base level erosion of the area (A). The cones are mostly organized on ridges separated by aligned valleys (b) (Photo by E. haryono and S.t. Putro). Fig. 9: Slope distribution in Karangbolong karst. sloping part surrounding the plateau (31–65 %). As such on the western and eastern slopes, the conical karst hills are higher compared to that in the central part of the pla- teau. In the central part of the plateau, the conical karst hills are more widely separated with lower relief. POLyGONAL KARST MORPHOLOGy OF KARANGBOLONG AREA, JAVA-INDONESIA ACTA CARSOLOGICA 46/1 – 201770 The morphology of the Karangbolong karst generally re- sembles the typical karst of high intensity rainfall areas which are typified by cockpit karst with conical residual hills. The results show that the area exhibits slightly dif- ferent morphological characteristics governed by joint- ing system, topographical position, and uplift history and type. There is no evidence that lithological facies has an important role in the morphological differentiation within the area. Previous work by Brahmantyo (2005) suggested that the area is composed of different carbon- ate facies. Nevertheless, the distribution of the facies does not coincide with the different morphological variation of the karst. The joint system of the limestone outcrop seems to be the major control of karst morphology. It governs the depression morphology and spacing of the aligned-chain of conical hills that in turn dictate the overall conical karst morphology. Unlike the general karst depression morphology as reported from Papua New Guinea (wil- liams 1971) or Dinaric Karst (Benac et al. 2013), aligned valleys are readily recognized from aerial photographs or other high resolution remotely sensed imagery. Enclosed depression from aerial photography can really only be recognized under a stereoscope. Joint spacing appears to be the reason for the sharper cone karst compared to neighboring well-known Gunungsewu karst discussed in previous publication (Balazs 1968; Flathe & Pfeiffer 1965; Haryono & Day 2004; Lehmann 1936; Tjia 2013; Haryono et al. 2016; widyastuti and Haryono 2016). Both areas have the same general physiography, climate and carbonate facies. However, the major joints in the Karangbolong area are more closely spaced than that in the Gunungsewu karst. Elongated dolines as described in previous works (Petrović & Veselinović 2012; Segura et al. 2007) are also very common in the Karangbolong karst. Topographical position in the area takes an impor- tant role in governing the relief magnitude of valleys and conical karst. Higher conical hills, deeper valleys, and steeper slope in the sloping parts can be explained mainly by a higher energy of surface runoff during tor- rential rainfall. High potential erosional energy during torrential rainfall was also reported by Sweeting (1995) in tropical karst areas of China. Quite often a flash flood takes place in the carbonate outcrops in Indonesian karst where ponors have not yet developed. In this circum- stance, mechanical erosion must have played an impor- tant role in landform processes. Dissolution processes, though present to some extent, is less prominent than in the plateau part. Surface water generally dries out within an hour after the end of rainfall. Short residence time at the water-rock interface during the torrential rainfall should deter dissolution processes in the sloping part. The dissolution rate, furthermore, significantly increases when the karst valleys are already covered by soils into which slow percolation takes place. As described from different places (Phillips et al. 2004; Segura et al. 2007), hence, the interplay of mechanical erosion and dissolu- tion in sloping part is a considerably more important process in the Karangbolong karst. Lower conical hills with a wider corrosion plain in the plateau part can be explained by two different pos- sibilities. The first explanation is likely accounted for by a planation process during long periods of limestone ex- posure during the earliest stage of the uplift history. The second explanation appears to be the reduced erosional and corrosion processes in the upper plateau in contrast to the sloping parts. However the first explanation seems to have more logical basis, since the area has experi- enced different phases of uplifting. It has been suggested by previous works (Brahmantyo 2005; Haryono 2013; Pannekoek 1949; Urushibara & yoshino 1997) that the southern zone of Java in which the Karangbolong karst is situated had experienced uplift in the early Pleistocene continued by prolonged stable tectonic setting. Abrupt uplift then happened in the late Pleistocene giving rise to the present situation and made possible the development of deeper valley in the sloping part through a coupling of backward erosion and corrosion. The other unique characteristic of morphology differentiation within Karangbolong karst is the mor- phology inherited from gravity sliding of the limestone beds during uplift. This valley morphology seems to be the first report of such a karst valley pattern. The gravity sliding seems to bend the linear jointing to a curvilinear form that in turn results in curvature depression. with respect to karst development, the morpho- logical characteristics of Karangbolong karst appear to be in the stage of mature karst. The morphology of the area resemble mature stage development suggested in karst development model (Ahnert & williams 1997; Aref et al. 1987; Lehmaann 1936) where karst develop- ment starts from joint-controlled dissolution within the plateau. The mature development of Karangbolong karst is also shown by the development of the karst aquifer and mapped cave passages in the area. A well-developed karst aquifer is characterized by the occurrence of dif- fuse infiltration, internal runoff, sinking streams, and conduit flow found in the area (Haryono et al. 2013). Five major cave systems and underground rivers were found in the area where a conduit aquifer has developed (Bernard et al. 2003; Haryono et al. 2013). However, in DISCUSSION EKO HARyONO, SUTANTO TRIJUNI PUTRO, SURATMAN & SUTIKNO ACTA CARSOLOGICA 46/1 – 2017 71 CONCLUSIONS The morphology of the Karangbolong karst is typified by a combination of aligned valleys with conical hills. Though the area is already in a mature stage of karst development, not all of the karst area is occupied by enclosed depres- sions (cockpits). Differentiation of morphological char- acteristics in the area was found to be governed by joint- ing, topographical position, and detachment tectonics during the uplift. The jointing system in the area not only governs the development of aligned valleys and elongate enclosed depressions, but also governs the morphology of conical karst morphology. Tight joint spacing has re- sulted in the sharp peaks of conical hills. Topographical position governs the differentiation of relief magnitude in the karst morphology. The geological events during the uplift are also found to give some morphological variation in the area. Further attempts should be made to ascertain the control of joint spacing in conical karst morphology by involving more karst areas from different countries and climatic zones. contrast with mature karst in different areas from Papua New Guinea (williams 1971) and Croatia (Telbisz et al. 2009), the Karangbolong karst areas does not exhibit ideal cockpit karst morphology. Not all of the karst area is occupied by enclosed depressions (cockpit), but some portion of the karst area is occupied by aligned valleys. The aligned valleys are generally encountered in sloping parts of the plateau. ACKNOwLEDGEMENTS Thanks are due to the editor Dr. Nadja Zupan Hajna, for the English correction and anonymous reviewers for the very constructive comments and suggestion. REFERENCES Ahnert, F.A. & P.w. williams, 1997: Karst Landform Development in a Three-Dimensional Theoretical Model.- Z. Geomorphologie, Supplementbände, 108, 63–80. Aref, E.M.M., Kadrah, A.M. & Z.H. Lotfy, 1987: Karst Topography and Karstification Processes in the Eocene Limestone Plateau of El Bahariya.- Z. Geo- morphologie NF, 31, 1, 45–64. Asikin, S., Handoyo, A., Pratistho, B. & S. Gafur, 1992: Geological map, banyumas Quadrangle, java. 1:100 000.- Bandung. Balazs, D., 1968: Karst Regions in Indonesia.- Karszt-es Barlangkutatas, 5, 3–61. Bemmelen, R.w. Van, 1970: The Geology of Indonesia. 2nd ed.- Martinus Nijhoff, pp. 732, The Hague. Benac, Č., Juračić, M., Matičec, D., Ružić, & I.K. Pikelj, 2013: Fluviokarst and Classical Karst: Examples from the Dinarics (Krk Island, Northern Adriatic, Croatia).- Geomorphology, 184, 64–73. DOI: http:// dx.doi.org/10.1016/j.geomorph.2012.11.016 Bernard, L., Josiane, L., Locatelli, C., Robert, G., Set- iawan, R., Sitepu, I. & F.E.A. winarto, 2003: Expé- dition Spéléologique Sur Le Karst de Karangbolong (java, Indonésie).- Fédération Française de Spéléol- ogie, Report Number: 61. Brahmantyo, B., 2005: Perkembangan bentangalam Karst Gombong Selatan, dengan Geologi Sebagai Faktor Kendali.- PhD thesis. Institut Teknologi Bandung, pp. 182. Day, M, 1983: Doline Morphology and Development in Barbados.- Annals of the Association of American Geographers, 73, 2, 206-219. DOI: http://dx.doi. org/10.1111/j.1467-8306.1983.tb01408.x POLyGONAL KARST MORPHOLOGy OF KARANGBOLONG AREA, JAVA-INDONESIA ACTA CARSOLOGICA 46/1 – 201772 Denizman, C.A.N., 2003: Morphometric and Spatial Distribution Parameter of Karstic Depression, Low- er Suwannee River Basin, Florida.- Journal of Cave and Karst Studies, 65, 1, 29–35. Flathe, H. von & D. Pfeiffer, 1965: Grundzuge Der Mor- phologie, Geologie and Hydrogeologie in Karstge- beit Gunung Sewu/Java Indonesia.- Geol. JB, 83, 533–562. Ford, D.C. & P.w. williams, 2007: Karst hydrogeology and Geomorphology.- John wiley & Sons Ltd, pp. 562, Chicester. Haryono, E., 2008: Kajian morfometri jaringan Lembah Karst dan Perkembangan Karst di Kawasan Karst Karangbolong, Karst Gunungsewu, Karst blam- bangan, dan Karst Rengel.- PhD thesis. Fakultas Geografi UGM, pp. 158. Haryono, E., 2013: Uplift Evidence from Karst Morphol- ogy: Preliminary Evidence from Blambangan Pen- insula Karst, Indonesia.- In: M. Filippi & P. Bosák (eds.) Proceedings of the 16th International Congress of Speleology, 21st−28th July 2013, Brno, Czech Re- public. Czech Speleological Society, 3, 90–93, Pra- ha. Haryono, E. & M.J. Day, 2004: Landform Differentiation within the Gunung Kidul Karst, Java-Indonesia.- Journal of Cave and Karst Studies, 66, 2, 62–68. Haryono, E., yulianto, B., Putro, S.T. & F. Nucivera, 2013: Studi hidrogeologi Kawasan Karst Karangbolong.- Fakultas Geografi UGM, Report. Haryono E., D. Danardono, S. Mulatsih, S.T. Putro & T.N. Adji, 2016: The Nature of Carbon Flux in Gunungsewu, Java-Indonesia.- Acta Carsologica, 45, 2, 173−185. DOI: http://dx.doi.org/10.3986/ ac.v45i2.4541 Lehmann, H., 1936: Morphologische Studien auf Java.- Geographische Abhandlungen, 3, 9, 1–114. Pannekoek, A.J., 1949: Outline of The Geomorphology of java.- E.J. Brill, pp. 57, Leiden. Petrović, A.S. & R. Veselinović, 2012: The Genesis and Evolution of Uvalas in Gajina Mlaka Paleovalley on the Kucaj Mountains.- Glasnik Srpskog geograf- skog drustva, 92, 1, 91–104. DOI: http://dx.doi. org/10.2298/gsgd1201091p Phillips, J.D., Martin, L.L., Nordberg, V.G. & w.A. An- drews, 2004: Divergent Evolution in Fluviokarst Landscapes of Central Kentucky.- Earth Surface Processes and Landforms, 29, 7, 799–819. DOI: http://dx.doi.org/10.1002/esp.1070 Segura, F.S., Pardo-pascual, J.E., Rosselló V.M., & J.J. Fornós, 2007: Morphometric Indices as Indicators of Tectonic, Fluvial and Karst Processes in Cal- careous Drainage Basins, South Menorca Island, Spain.- Earth Surface Processes and Landforms, 32, 13, 1928–1946. DOI: http://dx.doi.org/10.1002/ esp.1506 Spelman, H., 1979: Final Report. Geology, hydrogeology and engineering geological features of the Serayu Riv- er basin, Central java, Indonesia.- Netherlands Uni- versities Foundation for International Cooperation, Serayu Valley Project: Volume 4. Sweeting, M.M., 1972: Karst Landforms.- Macmillan, pp. 362, London. Sweeting, M.M., 1995: Karst in China: Its Geomorphology and Environment.- Springer, pp. 265, Berlin. Telbisz, T., Dragušica, H., & B. Nagy, 2009: Doline Mor- phometric Analysis and Karst Morphology of Biokovo Mt (Croatia) Based on Field Observations and Digital Terrain Analysis.- Hrvatski Geografski Glasnik, 71, 2, 5–22. Tjia, H.D., 2013: Morphostructural Development of Gu- nungsewu Karst, Jawa Island Perkembangan Mor- fostruktur Kars Gunungsewu Di Pulau Jawa.- Indo- nesian Journal of Geology, 8, 2, 75–88. DOI: http:// dx.doi.org/10.17014/ijog.v8i2.157 Urushibara, y.K. & M. yoshino, 1997: Palaeoenviron- mental Change in Java Island and Its Surounding Areas.- Journal of Quarternary Science, 12, 5, 435– 442. DOI: http://dx.doi.org/10.1002/(sici)1099- 1417(199709/10)12:5<435::aid-jqs325>3.0.co;2-e widyastuti, M. & E. Haryono, 2016: water Quality Char- acteristics of Jonge Telaga (Doline Pond) as water Rerources for the People of Semanu District Gu- nungkidul Regency.- Indonesian Journal of Geogra- phy, 48, 2, 157-167. DOI: https://doi.org/10.22146/ ijg.17595 williams, P.w., 1971: Illustrating Morphometric Analy- sis of Karst with Example from New Guinea.- Z. Geomorphologie, 14, 40–61. EKO HARyONO, SUTANTO TRIJUNI PUTRO, SURATMAN & SUTIKNO