19
Attribute data used for SWAT simulation are: ‐ Climatic series data
‐ Rainfall data ‐ Water discharge data series
‐ Soil characteristic
3.4 Methodology
The methodology of this study is limited to the condition of the data and SWAT model application. The integration of Geographic Information System GIS,
remote sensing and SWAT model was divided into three major steps, as follows; ‐ SWAT model
‐ Calibration and Validation ‐ Landuse Change analysis
‐ Impact of Landuse change to water yield ‐ Landuse Optimizing.
Figure 3.2 shows the flow chart of methodology. The study started by data preparation where coordinates of all spatial data is appropriate to WGS84 coordinate
system, then landuse data series are definite to SWAT model landuse database and developed soil database, landuse series data is also prepared for crosstab process to
detect landuse change. Next step of study is Simulated MWSWAT model, then calibrating the output of SWAT simulation. After the validation is enough the study
is continued by analysis of landuse change using cross table of landuse series data and then each landuse data is simulated by SWAT model.
Final step of study is optimizing landuse; the process is started by developing the same scenario based on landuse that used for calibration and validation.
Optimizing landuse is a selection process to determine the best landuse composition in upper Cimanuk Catchment Area that has good water availability. The details of
optimizing landuse process are presented in next sub-chapter.
20
Figure 3.2 flow chart of methodology.
21
3.5 Field survey
The field survey is conducted to observe water discharge, sediment load and soil characteristics in the same location. Measurement and sampling required in this
research are: ‐ River profile
‐ Water velocity in several stream segment ‐ Soil sampling to determine characteristic of soil type.
The measurement of river profile is done in several locations based on morphological factor and existence of gauge. This location will be used for
validation of SWAT simulation result. Profile measurement employs terrestrial mapping using digital theodolite. Measurement is done by crossing the river, where
every one meter measures distance and height. The water discharge is obtained by measuring water velocity by current meter.
One of SWAT input model are soil characteristics, hence each soil type will be sampled. The location for soil sampling is selected based on soil map and the
location is recorded by GPS and plotted by GIS. Each type of soil is sampled by ring soil sample Ø 2.5” and 0.5 kg soil. Parameters of soil characteristics to be analyzed
are: ‐ Structure and Texture
‐ Organic content ‐ Permeability
‐ Bulk density ‐ Available water content
‐ Porosity.
3.6 Landuse Change Detection
