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All Journal INTERNATIONAL JOURNAL OF ENVIRONMENT AND GEOSCIENCES
Takahiro Osawa
Center for Remote Sensing and Ocean Science (CReSOS), Udayana University, PB Sudirman Street, Post Graduate Building, Denpasar, Bali 80232, Indonesia
Agriculture, Biological Sciences & Forestry Earth & Planetary Sciences Environmental Science

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Land Cover Change Detection Using Landsat Data in Giao Thuy District, Nam Dinh Province, Vietnam Nguyen Tuyet Lan; Takahiro Osawa; I Wayan Nuarsa; Ngo The An
International Journal of Environment and Geosciences Vol 1 No 1 (2017)
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.2017.v01.i01.p03

Abstract

Giao Thuy located a coastal area, which has fully the characteristed of microclimate Red River delta. This study was conducted to detect the land cover changes from 2000 to 2015 and the causes. The changes are evaluated using Landsat data by method of land use classification combined with interviews. The results showed that most portion of the land cover class was crops land and land cover change was crops land decreases, forest land rises, aquaculture ponds increase, surface water reduces and unuse flat land area increases. The causes were policy issuses, market, economic, salinity intrusion, climate change and deposits alluvial.
Multi-temporal Analysis for Differential Interferometry Synthetic Aperture Radar (D-InSAR) and Its Application to Monitoring Land Surface Displcements Putu Edi Yastika; Norikazu Shimizu; Tasuku Tanaka; Takahiro Osawa
International Journal of Environment and Geosciences Vol 1 No 1 (2017)
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.2017.v01.i01.p01

Abstract

Land subsidence rate in Semarang has been observed by D-InSAR technique based on ALOS-PALSAR data on ascending orbits, which is processed by GMTSAR and ArcGIS software. Two kind of methods namely single D-InSAR and Multi-Temporal D-InSAR has been done. By employing SRTM3 and ASTER1 DEM data to remove the topography component, total 67 pairs of inteferogram has generated. Northeast area and shoreline area has largest subsidence about 20-32 cm for 4 years or average rate 5-8 cm/year. Since the northwest area and center area has lower subsidence rate and even no remarkable subsidence occurred, this area seems to be stable comparing the northeast area. Removing the topography component phase to get displacement phase from the phase interferogram by using SRTM3 DEM and ASTER1 DEM data respectively, the both results coincided with 0.995 correlation value. The coherence threshold is an important factor to get better accuracy, but if setting the threshold too high, the process of interference will be failed and not be able to obtain the results in a lot of area. The perpendicular baseline and the temporal baseline (time period) is an important factor to determining the coherence threshold. By using many scenes the Multi-Temporal D-InSAR was applied, and by selecting good pairs of the interferograms, accuracy of the results will be improved. The correlation value for GPS data eventually increased from 0.63 to 0.77.
Remote Sensing Application to Estimate Groundwater Recharge in Denpasar and Surrounding Areas I Nyoman Artabudi; Takahiro Osawa; I Wayan Budiarsa Suyasa
International Journal of Environment and Geosciences Vol 1 No 1 (2017)
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.2017.v01.i01.p02

Abstract

Water is one of the most important resources for human life, both to support the daily activities and for irrigation purposes as well as supporting tourism industry. Until now the groundwater is still ranked as the major needs, especially in densely populated areas like Denpasar. Groundwater is renewable natural resources, and plays an important role in the provision of water supplies for various purposes. Understanding the spatial variability of groundwater recharge is very important for proper water resource management. Precipitation measurement by satellite especially Global Satellite Mapping for Precipitation, can be applied to large areas only, it can be stated that use of satellite data always results in an improvement of the spatial precipitation estimate if gauge density is low. The aim of this research was to determine precipitation patterns, precipitation groundwater relationship and to estimate local groundwater recharge rate across the Southern Bali basin using remote sensing. This study considers the direct estimation of recharge using recovery of the groundwater level (?H) and total precipitation (Pt) during the wet period. Groundwater recharge was estimated from these two variables using a simple regression equation. The patterns of precipitation in research area was monsoonal dry season occurred in July to August, wet season occurs during November to April and punctuated by transitional season. Precipitation influence on groundwater oscillation occurred on 1~2 months earlier. The amount of recharge rate in the study area based on the results of the study period 2005~2009, for the precipitation data from Global Satellite Mapping for Precipitation ranges from 218 ~ 220 mm per year or about 26 percent of the annual average of precipitation and 650 ~ 660 mm per year or about 32 percent based on the rain gauge data.
Co-Authors I Nyoman Artabudi I W BUDIARSA SUYASA I Wayan Nuarsa Ngo The An Nguyen Tuyet Lan Norikazu Shimizu Putu Edi Yastika Tasuku Tanaka