PEMODELAN 2D VLF-EM SUNGAI BAWAH TANAH DENGAN MENGGUNAKAN GUIDE MATLAB DI DAERAH KARST HARGOSARI KECAMATAN SEMANU KABUPATEN GUNUNG KIDUL; 2D MODELING VLF-EM OF HARGOSARI KARSTIC UNDERGROUND RIVER USING GUIDE MATLAB IN SEMANU DISTRICT GUNUNG KIDUL REGENCY

UMAM, ROFIQUL, Sismanto

2016 | Disertasi | FMIPA

Mapping underground river on the karst area can be conducted by using geophysical methods. To map the underground patterns, it can be done by mapping the contrast of the electrical conductivity of the rocks clie fluid on the limestone pores, required an appropriate geophysical methods include VLF-EM (Very Low Frequency Electromagnetik). This research aims to develop a system of data processing tilt into a programming and 2D modeling using Matlab Guide (Matrix Laboratory). Interpretation of the results obtained little noise, so the apparent anomaly compared with the conductive objects with softwere by Markku Pirttijärvi. By adding a Horizontal Contour interpretation correlated with the interpretation Karous Hjelt, it can be determined more clearly the direction of the river, flow depth, and the width of the river. The location of the study area is in Hargosari, Timunsari, Mojosari, and Peyuyon, Semanu, Gunung Kidul with coordinates 8,020oLS and 110,36oBT.The results show that the direction of flow of the underground river crosses the village Hargosari, Timunsari, Mojosari , and Peyuyon, where there and branching underground river on line 3 in Mojosari. With each river heading nortwest and south west the village Peyuyon. The underground river and has an estimated depth of ± 100 meters, then the line 2 has an estimated depth of ± 120 meters. At both ends of the branches have an estimated depth of ± 130 and ± 160 meters.

Kata Kunci : VLF, fraser filter, moving average filter, filter Karous Hjelt, current density equivalent, Guide Matlab