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Figure 3.2 Digital Elevation Model of Palu Catchment Area Sources: SRTM
3.1.2 Climate Condition
Rain falls throughout the year, the heaviest period occurrs from April to July and October to December. The spatial variation of rainfall amount in the area
indicated a decreasing trend from north to south part of the catchment area, where the north side is urban with high population and south part is mountain with high
vegetation. The averages rainfall on the study area is varying depend on the location with range from 1,000 mmyear – 3,500 mmyear; generally the rainfall
becomes heavier on the southern part of the catchment. According to Palu-Poso Watershed Management Agency BPDAS Palu-Poso, generally February is the
driest month while May and November are the wettest months during wet season. Temperatures vary only a few degrees over the course of the year.
Daytime temperatures in lowland areas of the catchment area range from 26° C – 32° C. Highland areas are significantly decreased, as air temperature drops about
6° C with every 1,000 m rise in altitude.
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3.1.3 Land Cover Condition
Based on the topographic map which is issued by the National Coordinating Agency for Surveys and Mapping BAKOSURTANAL now is
Geospatial Information Agency BIG, in 1991 the land cover composition of Palu Catchment is dominated by the forest, which is covered more than 70 of total
watershed area, followed by the shrub land, and agricultural land. The forests are mainly found on the southern part of the catchment, since this area is part of the
Lore-Lindu National Reserves. The main populations were concentrated on the northern part of the catchment, which is the capital of Central Sulawesi namely
Palu City.
3.1.4 Geological Condition
The geology condition of Palu River Watershed is almost the same for the overall area. Generally, alluvial soil, innocuous intrusive rocks, metamorphosed
rocks, and sediment compose the geology structures. The mountainous areas generally consist of acid rock such as gneisses,
schist and granite possessing sensitive to the erosion. The other rock formation, lacustrine formation can be found on the east side of the study area. On the west
side, alluvium rock that derived from metamorphosed rocks and granite can be found.
3.1.5 Demography Condition
Demography is important aspect that leads to land cover change in a catchment area. Most of the changes of the land use are influences by population.
Increasing of the human population means that the needs to the space are increasing also. Palu Catchment with wit area about 3,050 km
2
consists of 13 sub-districts that intersect on the whole catchment area. Where mostly of the
population works as a farmer, which is are utilize a space to farming. Based on the statistical bureau, the total population that settled in those 13 sub-districts is about
187,535 or 88,763 of households. The demography conditions of study area are shows in Table 3.1.
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