Agus Riyanto, Indra
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Hydrogeology of Mangsri Cave, Gunungsewu Karst Area, Java Island, Indonesia Cahyadi, Ahmad; Reinhart, Hilary; Wahyu Ristiawan, Angga; Dwi Putra, Rakhmat; Labib, M. Ainul; Naufal, Muhammad; Agus Riyanto, Indra; Ramadhan, Fajri; Dwi Laksono, Angga
Sumatra Journal of Disaster, Geography and Geography Education Vol 5 No 1 (2021): Sumatra Journal of Disaster, Geography and Geography Education (June Edition)
Publisher : Sumatra Journal of Disaster, Geography and Geography Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (264.522 KB) | DOI: 10.24036/sjdgge.v5i1.356

Abstract

The Gunungsewu karst area is not only known for its unique landscape but also its recurring drought events. To meet the water supply, the local population utilizes several water potentials, namely doline pond, spring, and underground river. This study was designed to analyze the hydrogeological conditions of Mbangsri Cave, following its accidental discovery by the community at the end of 2018. The hydrogeological analysis was conducted by geological surveys, which consisted of rocks collection and structural measurements, cave mapping, and recharge area delineation based on remote sensing images acquired by unmanned aerial vehicles. The results showed that Mbangsri Cave, in the hydrogeological perspective, had low water resources potential. It is believed to be the result of (1) relatively small catchment area, (2) a fault in the southern part of Mbangsri Cave, creating a small groundwater basin, and (3) the thin epikarst layer, limiting the water storage.
RAINFALL VARIABILITY IN GUNUNGSEWU KARST AREA, JAVA ISLAND, INDONESIA Cahyadi, Ahmad; Haryono, Eko; Nugroho Adji, Tjahyo; Widyastuti, Margaretha; Agus Riyanto, Indra; Taufiq Nur Muhammad, Dzakwan; Fattah Tastian, Naufal
Indonesian Journal of Forestry Research Vol. 8 No. 1 (2021): Indonesian Journal of Forestry Research
Publisher : Association of Indonesian Forestry and Environment Researchers and Technicians

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.59465/ijfr.2021.8.1.23-35

Abstract

Karst area is highly susceptible to changes to climate parameters. One of the parameters is rainfall variability. In addition to shaping the condition of water resources, rainfall in the Gunung Sewu karst area determines the nature of crop and livestock of the agriculture sectors―the local population's main economic activities, warranting the significance of the rainfall variability studies. Rainfall variability in karst areas also affects disaster conditions such as drought and floods. However, due to insufficient meteorological data in quality and quantity, there has been no rainfall variability studies conducted in this locality. The research intended to analyze rainfall variability in the Gunung Sewu karst area in 1979‒2013 by utilizing rainfall predictions from satellite images that many scholars had tested in different locations and recognized as having good quality. In the analysis, mean monthly rainfall was calculated, and the trends of annual rainfall and average rainfall intensity, dry and rainy seasons, the number of rainy days, and the effect of ENSO (El Niño Southern Oscillation) on rainfall were analyzed. The research data were 35 years of daily rainfall records derived from the National Centers for Environmental Prediction (NCEP) Climate Forecast System Reanalysis (CFSR). The analysis results showed that the mean rainfall, number of rainy days, and rainfall intensity had an increasing trend. Also, El Niño quantitatively influenced the rain in the Gunung Kidul karst area.