The Simple Grid Method in GIS Application for Delineation of Erosion Grade...

The Simple Grid Method in GIS Application for Delineation of Erosion Grade Zone at Bandung Basin

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Mega F. Rosana
Lecturer
University of Padjadjaran
Email: [email protected]

Djadjang Soekarna
Head of Geological Survey Institute
Ministry of Energy and Mineral Resources, Rep. of Indonesia.

Lobo M. Balia
Senior Advisor to Minister of Energy & mineral Resources, Rep. of Indonesia .
Ministry of Energy & Mineral Resources, Rep. of Indonesia.

GIS software usually manages vector data. When the facility for raster data is available, it usually used for display and it is not used for analysis. So, it is need the additional method to be used for geo-spatial analysis with many variables. The simple grid method with calculation of numerical info can applied for many purposes of geo-spatial analysis. This method is work by creating grids on map of area that will be analyze, creating data structure with variables have specified, filling this fields data with criteria numbers for analysis, and calculating that record data with statistic method. Finally, that grids have contain numeric data ready for analysis with various mathematical operator, i.e. add, devide, subtract, etc.

Some variables are used for applied this method, i.e. lithologic type, geological structure, slope degree, weathering grade, land use, and rain fall intensity. Result of analysis shows Bandung Basin area can be divided into five zones; very strong erosion, strong erosion, moderate erosion, low erosion, and very low erosion. Areas with very strong erosion are covering Wangisagara, Ciramose, Cicangkuang, Citarik, Cikeruh, etc. Areas with strong erosion are identified at Cimanggung, Cijagra, Barugbug, etc. Areas with moderate erosion are indicated at Cijoho, Cirasea, Ujungberung, etc. Areas of low erosion are at Cikitu, Wayang Mount, Rancakole, etc. Areas with very low erosion are identified at upper Cikapundung, upper Cimulu, upper Citarik, etc.

The data of result analysis and field survey are verified using t-test. The test shows no significant difference among them, where “tcalculation < ttable". That phenomenon shows the simple grid method can be used for analysis of geo-spatial data related with GIS application for delineation of erosion grade zone.

Key-words: The simple grid method, geo-spatial analysis, and erosion grade zone.