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Spatial based method in determining hydrology component value due to land use change Case Study upstream Citarum river basin Darmawan, S., Sumarto, I., Budiharto, A. Dept. of Geodetic Engineering Bandung Institute of Technology Jl. Ganesha 10, Bandung 40132 - Indonesia Abstract Component hydrology in the form of precipitation, evapotranspiration, run off and infiltration very needed in agricultural, irrigation and mitigation disaster of floods and dryness. Determining hydrology component value can be conducted with the empirical method but still less gives the spatial information. To get the spatial information of component hydrology needed data spatial. Existence of Geographical Information System (GIS) technology as tools expected can visualizing and management data spatial (vector & raster) and data textual. GIS can determine and analysis spatial information component hydrology. Result of analysis obtained land use change during year 1994 till 2001 with added urban area and primary/secondary forest happened gradation. Result analysis in February year 2001 sub basin Ciwidey having highest value run off, sub basin Citarik having biggest value evapotranspirasi, sub basin Cisangkuy having biggest value infiltration. Sub basin Cisangkuy still is good as diffusion area irrigate while sub basin Citarik can be estimated critical area. Introduction Development and resident growth is not supported existing land. Land requirement cause land use change and gradation in citarum river basin. Land use change and gradation are can floods in rains season and dryness in dry season. These conditions influence the production of rice in West Java and destroyed performance installation of water power station saguling, cirata and jatiluhur. To determine the spatial information component hydrology required attribute and spatial data. Used of attribute and spatial data to determine of component hydrology value needed technique to manage spatial and attribute data. Existence of data spatial and technique to manage spatial and attribute data can result spatial information component hydrology value. This information can to analyze furthermore and very good for basin management by holistic, plan and have continuation. Geographic Information System (GIS) represent tools which can be used to assist visualizing and management spatial- attribute data. GIS can determine spatial information component hydrology value. GIS represent system being based on computer which design to collect, compiling, saving, managing, manipulation, analyzing, and visualizing information spatial-textual. Location Location study in up stream river basin citarum west java province Indonesia. Up stream river basin have 5 (five) sub basin that is: Cikapundung, Citarik, Cisarea, Cisangkuy and Ciliwung. Regional of research study show in picture 1.  Picture 1. Location study and LANDSAT Imagery upstream citarum river basin in 1994 and 2001 Methods In the effort to target done step in the form of data collecting, data processing, built Data Bases and analyze textual - spatial data. Thornthwaite method, soil Conversion Service Curve Number ( SCS-CN) and water budget used to determine component hydrology value. Data and method used to be allied for the implementation in GIS. Discussion Result of analysis conclude that in the year 1994 for sub basin Cikapundung of land used for urban area, sub basin Citarik majority land used for the rice field, sub basin Ciwidey land used for the plantation, sub basin Cisangkuy land used for the secondary forest and sub basin Cisarea used for the secondary forest. While for the year of 2001 land use change happened, reportage among other things for the sub basin Cisangkuy and sub basin Cisarea majority land use becomes the plantation. As a whole land use for the urban, farm, industrial and mine area to mounting while for the primary forest, secondary forest, plantation, mixture garden, and rice field is downhill  Picture 2. Land use change upstream citarum river basin 1994 to 2001 Use spatial data give the new paradigm in determining model of component hydrology. Existence of data spatial expected value of component hydrology more realistic and come near fact in field. Spatial data required to be adapted for used model hydrology. Spatial data can be visualizing the attribute data like rainfall and temperature. To assist the visualization and management of spasial-atribut data used geographic information system (GIS). GIS assumed most precise because this is can model the data in the form of rainfall, temperature, earth surface, land use and soil in the form of visualization spatial-textual, can saving, managing and determining component hydrology value from data, and also can analyze the value of component hydrology in sub basin. Determined hydrology component value show in picture 3. Analyze spasial-atribut data with the data model of grid based used spatial analyst. Spatial Analyst model builder represent a module to easy and quicken to build the model of data grid with diagram or flowchart. One of function that easily to conversion of vector data to grid, and point interpolation and process the overlay arithmetic. Description statistical use the spatial analyst summarized zones own the very reliable ability. Spatial analyst summarized zones represent a module for the group of assess the grid in zone of sub basin. To hereinafter can determining statistical component hydrology value in sub basin like max, min, mean and standard defies. Determined mean hydrology component value in statistical with summarized zones show in picture 4. Conclusion Spatial data very assisting to determining spatial component of hydrology values. GIS is a method most precise because this technology can visualizing data of rainfall, temperature, earth surface, land use and soil type with easily, and GIS can saving, managing and determining component of hydrology values and GIS can analyze hydrology component value every sub basin. Land use change influence component of hydrology value, sub basin Ciwidey happened by the process precipitation and run off which higher in January and February, sub basin Cisangkuy very higher in infiltration, sub basin Cikapundung very higher in coefficient run off and lower in infiltration, sub basin Citarik very higher in evapotranspirasi, sub basin Cisangkuy still be good as diffusion area irrigate while sub basin Citarik can be estimated a most critical area compared to other sub basin.  Picture 3 Determined spasial hydrology component value in January 1994 and January 2001  Picture 4. Determined mean hydrology component value in statistical with summarized zones References
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