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All Journal INTERNATIONAL JOURNAL OF ENVIRONMENT AND GEOSCIENCES
Takahiro Osawa
Regional Satellite Applications Center for Disaster Management (RSCD), Japan Aerospace Exploration Agency (JAXA), 4-1-1 Industrial Technology Institute Asutopia, Ube, Yamaguchi 7550195, Japan
Agriculture, Biological Sciences & Forestry Earth & Planetary Sciences Environmental Science

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Land Subsidence Monitoring From ALOS/PALSAR Data By Using D-InSAR Technique In Semarang City, Indonesia I Nyoman Sudi Parwata; Kakuji Ogawara; Tasuku Tanaka; Takahiro Osawa
International Journal of Environment and Geosciences Vol 3 No 1 (2019)
Publisher : Graduate Study of Environmental Sciences, Postgraduate Program of Udayana University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/ijeg.2019.v03.i01.p01

Abstract

This research was focused to estimate land subsidence in Semarang City by using DInSAR Method during 2007-2010 which is based on ALOS-PALSAR data. Three pair of SAR images were processed to detect land subsidence during 2007-2010. On the other hand, three pairs of SAR images (with small perpendicular baseline and very short interval time observation) were processed to generate Digital Elevation model (DEM). This DEM used to remove topographic phase in DInSAR processing. The land subsidence in Semarang City mostly appears in Northern area (main city), with maximum subsidence value which is derived by using DInSAR Method is about -4.8 cm/year (2007-2008), -8.1 cm/year (2008-2009), and -9.9 cm/year (2009-2010). The average is 7.6 cm/year (2007-2010). The subsidence result by using DInSAR technique was compared with GPS data which was available during 2008-2011. The coefficient determination between DInSAR and GPS method is about 0.65 for 2008-2010. Its mean DInSAR method has a good accuracy and reliable to use for land subsidence monitoring in wide area. The main causes land subsidence in Semarang City is probably due to load of building structure and over extraction of ground water. The number of registered drilled wills increased rapidly during early 1990s especially is industrial areas. The total drilled wells are 1050 units in 2000s.
Characteristics of Diurnal Rainfall Cycle Over Java as seen by the TRMM Precipitation Radar I Dewa Gede Agung Pandawana; Tasuku Tanaka; Takahiro Osawa; Abd. Rahman As-syakur; Made Sudiana Mahendra
International Journal of Environment and Geosciences Vol 3 No 1 (2019)
Publisher : Graduate Study of Environmental Sciences, Postgraduate Program of Udayana University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/ijeg.2019.v03.i01.p03

Abstract

Precipitation is one element of climate that mostly studied in Indonesia because it has a very high diversity both temporal (time) as well as spatial (place). The diurnal cycle is one of the important factors in the occurrence of rain in the islands of Indonesia that have an impact on regional rainfall patterns in Indonesia. The diurnal cycle of precipitation is an essential component of the tropical climate and one of the predominant components of atmospheric variations. The aims of this research were to determine and analyze the spatial patterns and the characteristics of rainfall diurnal cycle in Java Island and the surrounding areas (Java Island, Java Sea and Indian Ocean) using remote sensing data. In this study, data from Tropical Rainfall Measuring Mission satellite (TRMM) Precipitation Radar level 2A25 and wind data from National Centers for Environmental Prediction (NCEP) for 5 years period from 2007 to 2011 are used. The results of this research are the spatial patterns of daily rainfall in Java Island and the surrounding areas are different between land and sea. In the land, rain generally occur in the afternoon (12.00 to 18.00 LT), whereas in the ocean (the Java Sea and Indian Ocean) generally occur at midnight and noon (00.00 to 12.00 LT). The characteristics of rainfall diurnal cycle in Java Island and the surrounding areas are effected by land-sea physical properties, day-night cycle and by land-sea location.
Evaluation of GSMaP Precipitation Estimates Over Indonesia Agit Setiyoko; Takahiro Osawa; I Wayan Nuarsa
International Journal of Environment and Geosciences Vol 3 No 1 (2019)
Publisher : Graduate Study of Environmental Sciences, Postgraduate Program of Udayana University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24843/ijeg.2019.v03.i01.p04

Abstract

Generally, observation of the rainfall in Indonesia are still conventionally using rain gauge over Indonesian region. The rain gauge network are still the most reliable source over Indonesia, however this network is not as dense as in the other major continents. The aim of this research were validation and evaluate the annual rainfall periodicity and to obtain the correction factor of the GSMaP rainfall estimation data in Indonesia. Data used in this research are daily rainfall derived from GSMaP_MVK Ver.5 and in-situ data from rain gauge measurement by BMKG from March 2000 to November 2010. The validation showed that the satellite estimate gave an underestimated condition in all of three dominant rainfall characteristics region in Indonesia. The pattern of monthly rainfall time series average based on 40 stations from March 2000 – November 2010 showed quite similar than rain gauge pattern. The relationships of monthly rainfall average showed very good agreement with rain gauge data giving very high correlation (r=0.82 – 0.92) MBE and RMSE was less than 100 mm/month. The result of spectral analysis using DFT also showed a good agreement with rain gauge spectral analysis data on monthly.
Co-Authors Abd. Rahman As-syakur Agit Setiyoko I Dewa Gede Agung Pandawana I Nyoman Sudi Parwata I Wayan Nuarsa Kakuji Ogawara M. Sudiana Mahendra Tasuku Tanaka