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2.4.3. Scenario-based land use modeling by using CLUE-S model
Scenario-based land use modeling is used in this research to understand the phenomena of Upstream Cisadane Watershed dynamic, especially related to land
use change. In order to understand the dynamic of land use in recent and future time, the model will be used as a tool to link between present and future of land use
condition and the scenarios will be built to design different alternative conditions of land use. In order to design the plausible scenarios of highland use in the future,
the most important things are the understanding of relationship between land use and the driving factors and the understanding of pressures that caused by those
driving factors. In CLUE-S model, the demand of land use is specified on yearly basis before
the iteration and used as direct input for the allocation module. The allocation of land use in this framework is based on combination between empirical analysis,
spatial analysis and dynamic modeling in raster base iterative procedure. This procedure allows continuous interaction between macro scale demand and local
land use suitability as derived from logistic regression. Macro scale demand or regional demands influence the actual allocation change together with the local
highest probability derived from logistic regression. Based on the iteration variable, preliminary allocation is created by
considering conversion matrix see Table 6. and the total allocated area is calculated by using land use requirements from the regional demand. The iteration
process is repeated until all of demands are balance and correctly allocated. In this research, four combinations of land use change are designed. These
scenarios have been explained in the section 2.3.3.4, including baseline scenario and increasing population growth scenario. These scenarios are demonstrated to
verify the usability of scenario based modeling to support land use analysis in Upstream Cisadane. Each scenario and the results will be explained in the following
section.
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2.4.2.1. Baseline scenario
In this scenario, it is assumed that land use change in future is the continuity of land use change in the past time. Land use change in the past time has been
calculated in the land use pattern section. In this model, the initial land use is land use map year 1991 created from image interpretation. The demand of land use in
the future until the year 2030 is the continuity of the demand of land use change 2001-2009. Moreover, with no
spatial policies applied, it’s mean that all of areas inside the study area are possible to change to another land use. Simulated maps for
selected years 2000, 2010, 2020, and 2030 can be seen in the following figure.
Figure 8. Simulated land use maps with baseline scenario