Settlement Arrangement based on Landslide Mitigation (Case study: Capagallung, west Bacukiki District, City of Parepare)

Jayanti Mandasari, Mimi Arifin, Mukti Ali

Department of Urban and Regional Development, Faculty of Engineering, Hasanuddin University

 

1. Introduction

The increasing of population growth has a linear affect with the land needed which is residential areas. This case affects to the land used as residential area on unfeasible land from the perspective of security against the disasters. It seems in Parepare City with around 80% wide area are hilly areas/high morphology, due to the limited land also the high price of land, the residents prefer to live in the hillside.

In general, residential development in contour land are applicable but it must balance with the special technique rules if the slope already around 8-15% (Permen PU No.22/PRT/M/2007). However, we can easily to found the residential areas in the 15% slope without any special treatment and unconsidered the mitigation aspect thus susceptible on the landslides.

These regions are one of the prone landslides area which decided on Local Regulation (Peraturan Daerah) No.10 in 2011 about Spatial Plans (Rencana Tata Ruang Wilayah) Parepare City 2011-2031 such as Cappagalung District, Bacukiki BaratDistrict, with various considerations like classification of class slopes until >45%, irregularity of buildings, and not completed with a standard drainage system thus almost in every year in the raining season, the landslides always happen.

This study aims to identifying the physic and non-physic characteristics also the building structure and the environment of residence in Cappagalung District, Parepare City. Then, create the draft of settlement arrangement based on the consideration of mitigation landslides aspect

 

2. Methods

The method of collecting data are consists of several parts, such as:

Field Observation

To see the phenomenon in case of some issues and potential areas through the direct observation.

Literature Study

To collect the secondary data related with the supporting data like statistic data and policies, map, concept of theory or standardize of plans which used for analyzing primary data.

Interviews and Questionnaires

To find out the information from the interviewees and related parties.

The method used are descriptive qualitative and quantitative also the comparative method with spell out the primary data with aims to be arranged and take comparison from available data with the similar problems, as the input in an effort to rearranged the region through the analysis study literature

 

3. Results and Discussions

To create a concept plans for settlements based mitigation landslides, it carries out an analysis in three areas,

such as physic and non-physic condition also the building structure and environment.

 

a. Physic Character

Slope

The topography variable affected the insecurity level of landslides, due to on Permen PU No.22/PRT/M/2007 that greater the slopes area means the potential of landslides become greater as well, it is could be conclude that Cappagalung District is fulfill the criteria of insecurity areas from disaster based on the RTRW policy in Parepare City.

Table 1. Slopes Percentage in Cappagulang District

Slopes

Classification

Wide Area

Percentage

0-8%

Flat

21,77

25,95

>8-15%

Sloping

12,08

14,40

>15-25%

Heel

22,38

26,67

>25-45%

Steep

24,20

28,84

>45%

Very Steep

3,47

4,14

Total

83,9

100

 

Geological Condition

Based on Verhoef (1996:115) in AriefHartadi (2010:57) about the provisions of rock strength values, said that rock mountain has the compressive strength about 100-200 mpa thus classified as strong qualification. On the other hand, sedimentary rock alluvium has the compressive strength below 100 mpa thus classifies as strong enough category.

On the other side, variance of soil in Cappagalung District are land of regosol, based on the Decision of the Minister of Agriculture No: 837/Kpts/Um/11/1980, regosol land are qualified into very sensitive to erosion category. In the nutshell, a special technology is needed to build buildings on the regosol land.

 

Climatological Condition 

The average of annual rainfall in Parepare city is 2.275 mm/year or 189 mm/month whereas the highest rainfall was happened in the wet month, that is in December about 378 mm/month. By looking he rainfall conditions in Parepare City nowadays, due to the Decision of the Minister of Agriculture No: 837/Kpts/Um/11/1980 and Spatial Planning Guidelines for Area Prone to Landslides Permen PU No.22/PRT/M/2007 that Parepare City is a regional with high rainfall condition.

The air temperature in Parepare City in the last 3 years between 2012-2014 was 28,50C and it was quite high from the comfortable standard for human which is on 200-250C (Norfaeni, 2003 in AriefHartadi, 2010). The average of wind velocity in the research sites were from the West going to the East during in November until April around 2,45 m/second or 21,6 km/hour, qualified into normal category from the general average wind velocity is 19-35 km/hour.

Vegetation Condition

From the agriculture and plantation data which collected, Cappagalung District is dominant by mixed garden which scattered at a height 8-40%. The types of vegetation are shrubs, teak trees, mango trees, coconut trees, banana trees, and bamboo. In general, all of the plants are potential to prevent the erosion. However, needs to do some efforts to increase the vegetation quantity which has potential to prevent the erosion like teak trees and productive plants whether in the home space or in the neighborhood, especially in the slope area with notice on the space and cropping patterns.

Land Using Condition

Due to the calculation results, Cappagalung District is dominant by the open space around 48,75 ha or 58,11% from the overall width, settlement is 20,75 Ha or 24,73% and the infrastructure is 14,40 ha or 17,16%. It means, this site is fulfill the standardize of RTH public and private.

b. Determining The Danger Level Of Erosion Based On The Physic Character

To determine the danger level of erosion, it used quantitative method USLE (Universal Soil Loss Equation),consists of 5 things such as climate (R=erosion), soil properties (K=Erodibility), topography (LS = length and slope),land using factors (CP), and the level of soil depth (TSL). Below is the formula: government in term of the rules of building permit (IMB).

 

c. Social Economic Condition

On the social economic condition, analysis the level of education, livelihood, and income per capita in Cappagalung District are measured.

The level of education in Cappagalung District were below standard, it shows from the alumni percentages SLTA, SLTP, SD and not completed SD were higher than graduates.

However, in the livelihood, about 80% from all the societies are working in transport and service skills areas, they also have additional job such as farming in terms of using the free land.

Due to the observation, almost 50% of the population does not have any fix income. It shows the income of Cappagalung District are low. The low income also evidenced due to prosperous family stage, Cappagalung District become one of the district with the biggest pra-prosperous family in Bacukiki Barat District, which 475 families in total. A huge number of population who has double job as a farmer or gardener would more intensive to cultivate their farmland, then as a result it is possible to do extension from the farmland become protected area in the slopes with high qualification.

By seeing this condition, it is necessary to decide a local regulation about urban design environment with a detail spatial protected

There is a stage of interaction relations among the societies in Cappagalung District could be said as quite good, this things characterized from the opinion of societies in Cappagalung District from the interviews which partially from the population still cultivate mutual aid system. On the other fact, based on the understanding related with the environment condition, almost the whole of respondent do not know if their location of residence is one of the areas prone to landslides, thus most of people utilize the free land without thinking about the disaster risk.

A low education and economic level in general, but supported with a highly sense of togetherness, therefore models of socialization approach about the rules of building structure and environment is community based approach so that the societies could easily understand and they realize that the rules are given for common interest.

 

d. Building Structure and Environment Condition

The average of building density in Cappagalung District is 15 unit/ha. The buildings classification are below from the standard which decided on KeputusanMenteri PU No. 378/KTSP/1987.

From the calculating process, the value of basic building coefficient (KBD) in average is 19%, building floor coefficient in average is 0,96 and KDH in average is 81,2%.

Based on Kepmendagri No.59/1998 and Regional Regulation on Spatial Planning (RTRW) Parepare City, the value of KDB, KLB and KDH in Cappagalung District are qualified the minimum standard qualification.

The quality of building in Cappagalung District are defied into 2 kinds of building such as the permanent building and the semi-permanent. The settlement in the slope 0-8% are dominantly by permanent buildings, in the slope >8-15% partially are permanent buildings and others are semi-permanent buildings, and the settlement in slope >15%-45% are dominantly by semi-permanent buildings. Below are the analysis map of transect settlement condition which formulated on Figure 4.

There are types of road in Cappagalaung District such as irregular system, it can be seen from irregularity road system, regarded from the width or the direction of the road. In the drainage networks, most of them are following the road network where the network system defied into two kinds such as artificial drainage which consists of the open and close drainage, and the natural drainage which some parts still could be watering and other parts can notcause already closed by soil.

Few of the people in the research location still using the wells as the clean water resource and manage the waste by burning or throw it in canal. Below are the analysis map of transect infrastructure condition which formulated on figure 5.

e. The Concept of Non-Structural Layout Direction

  1. The increasing of the capacity from the societies in terms of community empowerment through trainings and non-formal education therefore the knowledge and understanding of the environment would increasing and have skills to protect the settlement.
  2. The effort to minimize the vulnerability of communities to land use in disaster-prone areas with the intensive socialization of mitigation disaster activities by the government.
  3. The approach based on community to the societies who already utilizing the land use in the protected area to be willing to reallocated and location provision like realignment due to the more safety to live on it and doing the economic activities in the societies.
  4. A strict regulation like a law fines directed to everyone who build the building without any build permit (IMB) so that it could help to controlling the space used and to avoid the activities/overload land use especially in conservative areas.

 

CONCLUSION

Due to the identification result for the physic and non-physic characteristic, Cappagalung District is the region which vulnerable to the landslides, however in terms of the buildings environment are below standard yet to become as the settlement in general views. Therefore, the planning of the settlement based on the disaster mitigation are needed to minimize the disaster happens in someday. The concept of structural arrangement in the form of the settlement arrangement with terasering system followed by the infrastructure improvements and non-structural such as the increasing of the population capacity in the research location and the regulation related with the development control for the settlement with a community based approach system.

 

References

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Keywords:

Settlement, landslides, cappagalung subsdistrict, arrangement concept, disaster mitigation

 

Source:

Mandasari, Jayanti, dkk. 2016.  Settlement Arrangement based on Landslide Mitigation (Case study: Capagallung, west Bacukiki District, City of Parepare)CITIES 2015 International Conference, Intelligent Planning Towards Smart Cities, CITIES 2015, 3-4 November 2015, Surabaya, Indonesia.

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