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5 CHAPTER V
ANALYSIS
5.1 Watershed Delineation
Watershed delineation in this study used the combination of Basin 3.1, Global Mapper 12, and Arcview 3.3. Each application has its own advantage in achieving best
results. The data used are Digital Elevation Model DEM data or Landsat. These data can be downloaded from the internet or others sources. DEM year 2006 is used in this study,
and though the study itself has been started since 2010, it could be assumed that there is no major change on Buper watershed elevation as the determining parameter of watershed
boundary. This assumption will be evaluated on land use change analysis. Watershed delineation is focused on the approximation of watershed position
according to Google Earth‘s streaming, previous study report, and field observation. They are all done in 2010 in order to gain fine data according to the similarity of occurring year.
Figure 5.1 Buper Watershed Approximation by Google Earth A, Field Observation B and Previous Study Report Before Watershed Delineation C
Primary step of watershed delineation is using Basin 3.1 and produce drainage outlets, streams, sub basin, and basin boundary according to the data from DEM. Basin 3.1
application automatically gives the watershed boundary based on stream and outlet we choose. In this study, the outlet position chosen is similar to the of small dam planning from
B
C A
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DPU. This position is taken because the study site is a watershed that will going to be conservated to give sustainable water supply to the embung will be build by the government.
Figure 5.2 Basin 3.1 Operation for Watersehed Delineation around Buper
Data and stream overview on Basin 3.1 operation reveal information about surface water flow direction on chosen watershed, and outlets on Basin 3.1 operation gives
information about water output on Buper Watershed and each sub basin within. Generally, Basin 3.1 operation will give useful information about Buper Watershed as inputs for next
analysis in this study. Watershed delineation can also be done using Global Mapper 12. This application
also provides automatic watershed delineation feature to study site neighborhood. The result is smoother and it‘s easier to use, but cannot give information about flow location and
preferred outlets. Global Mapper cannot make watershed boundary according to the stream
we pick. The data needed for Global Mapper 12 is Land Sat data or DEM. The result of this operation can be used as reference to Basin 3.1 operation result.
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Figure 5.3 Global Mapper 12 Operation Watershed Delineation around Buper
Both through Basin 3.1 and Global Mapper 12, don‘t have good layout yet, thus that it needs re-digitalization using Arcview 3.3 to repair the results from previous applications and
make geographical information system from it. This information system is crucial for the next analysis that need spacial analysis. After the editing using arcView 3.3 we get Buper
watershed boundary of 12,6 km
2
as a result of watershed delineation. In order to syncronize out the watershed delineation with the actual condition, the
watershed boundary is exported to Google Earth and compared with the field observation result within the same coordinates.
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Figure 5.4 Buper Watershed Map and Google Earth Plotting
WATER FLOW
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5.2 Topography Analysis
Kategori