GIS Application for Land Capability Unit of Erosion Analysis and Disaster Risk Assessment in Kalikajar District, Wonosobo Regency

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TEKNIK PWK

(Perencanaan Wilayah Kota) http://ejournal3.undip.ac.id/index.php/pwk

E-ISSN: 2338-3526, available online at: http://ejournal3.undip.ac.id/index.php/pwk | 1

LAND CAPABILITY UNIT OF EROSION IN GIS APPLICATION FOR KALIKAJAR DISTRICT, WONOSOBO REGENCY

Armeino Fadhlan Atana¹

aInternational Undegraduate Program of Urban and Regional Planning, Diponegoro University

Abstract: In improving the contigency and readiness of people to face a disaster, It is necessary to analyze the factors and causes to be determined for the identification of the disaster itself. The application of geography information system (GIS) carried advantage in a way to optimizing the analysis in order to know the natural disaster that occurred in Kalikajar District, Wonosobo Regency. The analysis brings a result to improve the people anticipation on knowing the land capability unit of erosion through the implementation of geographical information system in the context of assessing the minimization of casualties from disaster in an urban and regional planning context. The analysis covers from social, demography, and natural physical consideration to produced a good outcome in the end.

1. INTRODUCTION

Kalikajar District is one of the district located in Wonosobo Regency Central Java that is located in the foot of Mt.Sumbing. Due to its location adjacent to the mountain, several of constrain and challenges concerning to disaster has occurred in several ways. The term disaster means a major issue that occurs over a short or long period of time and results in widespread losses of people, property, or the environment that are more than what the affected community or society can reasonably expect to be able to recover from using its own resources. According to Law no. 24 of 2007, a disaster is an event or series of events that threatens and disrupts people's lives and livelihoods, whether caused by natural or non-natural factors and human factors, causing human casualties, environmental damage, loss of property, and psychological impacts. Law No. 24 of 2007 defines disasters into three types, namely natural disasters, non-natural disasters, and social disasters.

In this report, the analysis will cover about the land capability in Kalikajar to the implication of natural disaster. Furthermore, the capability of land to face erosion can be resulted by the analysis conducted.

The purpose of this analysis and study is to know about the erosion natural disaster based on the existing time in Kalikajar District, Wonosobo Regency by implementing the geographical information system to fulfill the analysis.

Article Info:

Received:

Accepted:

Available Online:

Keywords:

Keywords: Natural Disaster, Erosion, Geography Information System

Corresponding Author:

Armeino Fadhlan Atana Diponegoro University, Semarang, Indonesia Email: [email protected]

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2. LITERATURE REVIEW a) Natural Disaster

Natural disasters are disasters caused by events or series of events caused by nature . Natural disasters that often occur in Indonesia include floods, droughts, earthquakes and landslides. Disasters can occur because there are two conditions, namely the existence of events or disturbances that threaten and damage (hazard) and the vulnerability (vulnerability) of the community. If a hazard occurs, but the community is not vulnerable, it means that the community can deal with disturbing events on their own, while if the community's condition is vulnerable, but no threatening events occur, a disaster will not occur. If natural disasters are classified based on their causes, they can be classified into two, namely geological natural disasters and climatological natural disasters. Geological natural disasters are natural disasters caused by forces originating from the earth (endogenous forces), such as earthquakes, volcanic eruptions and tsunamis. While climatological natural disasters are natural disasters caused by wind and rain, such as floods, storms, tornadoes, droughts, and forest fires. Apart from these two, there are also natural disasters caused by human activities, namely erosion, sedimentation, critical land, and shortages of raw water .

In this analysis the LCU will concern about the erosion particularly in Kalikajar District, the aim is to find out areas that are experiencing soil erosion, so that the level of land resistance to erosion can be identified and the impact on downstream areas can be anticipated. This analysis requires input in the form of morphological maps, slope maps, soil type maps, hydrogeological maps, soil texture maps, rainfall maps and existing land use maps with the output of LCU maps for Erosion and their explanations.

b) Erosion Disaster

According to Arsyad (2010), erosion is the loss of soil or land fragments that are moved by water or water to another location. Rainfall-generated water is the primary source of erosion in the humid tropics. According to (Suwardjo., et al 1990), excessive erosion is a result of poor land management and use, which results in low or unproductive soil productivity for agricultural activities. In the Kalikajar District, degraded land is a significant issue for dryland agriculture that has, up until now, been primarily brought on by runoff and erosion as well as in regions with steep slopes.

The root cause of erosion is identified, and it includes the following:

1. Loss of fertile topsoil that promotes plant growth.

2. Lessened soil's capacity to take up and retain water.

3. The transported soil will be dumped somewhere, such as in lower lakes, rivers, or reservoirs.

Siltation and eurofication of water bodies are further effects of erosion. Sequential erosion will affect the scene and the area downstream where the erosion is deposited.

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c) Urban Floods & Erosion

The main cause of urban floods occurs due to the increase in population growth in large urban centers in a disorderly manner. Urban development reduces vegetation cover, and so causes the imbalance of the natural hydrological cycle. The predominant reasons for this intensification of rainfall events are soil sealing, heat islands, and waste disposal.

The greatest influence of urban floods is justified by the sealing of the soil. The paving of the streets and the cementation of the ground prevents the infiltration of surface water into the soil, which contributes to the increase of the speed of surface runoff, the increase of the maximum rainfall flows in less time, and the elevation of the rivers. It is estimated that with each increase of 10% of impermeable area, the flow of runoff from surface water doubles.

3. RESULT & DISCUSSION

a) Land Capability Unit Analysis in Erosion Result

The existence of these various negative impacts results in adverse effects for an area, both for the present and for the future. These adverse impacts can be minimized with land capability and suitability analysis. Analysis of land capability and suitability can be carried out based on the physical factors of the land which function as land capability parameters. Analysis of land capability has reference to Regulation of the Minister of Public Works No.20/PRT/M/2007 concerning Technical Guidelines for Physical and Environmental Analysis. The analysis of land capability in this report focuses on the study area, namely Kalikajar District, which is in Wonosobo Regency.

Therefore, to determine the capability of the sub-district's / villages land, an analysis of LCU Morphology, LCU Slope Stability, and LCU Erotion was carried out using the QGIS software.

b) Morphology LCU

Morphology LCU analysis serves to sort out the shape of the landscape or morphology in an area or planning area that is capable of being developed according to its function and potential.

SKL morphology has the aim of obtaining an overview of the level of land capability to be developed as an urban area in terms of its morphology, and to determine the potential and constraints of an area for development. The input needed for the morphological SKL is the largest scale morphological map available, the slope map if any, the morphological map if similar studies have been carried out and the results of field observations.

Figure 1 LCU Morphology

c) Erosion LCU

The purpose of the LCU analysis on erosion is to find out areas that are experiencing soil erosion, so that the level of land resistance to erosion can be identified and the impact on downstream areas can be anticipated. This analysis requires input in the form of morphological

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E-ISSN: 2338-3526, available online at: http://ejournal3.undip.ac.id/index.php/pwk | 4 maps, slope maps, soil type maps, hydrogeological maps, soil texture maps, rainfall maps and existing land use maps with the output of LCU maps for Erosion and their explanations. Before conducting an LCU analysis for Erosion, you must first know the explanation of The data involved in the analysis is the type of soil.

Figure 2 LCU Erosion

Erosion LCU can be finished by gathering and collecting data from the current condition of morphological, slopes, and land use. By this the aim is to know the level of soil erosion in the planning area and/or area as well as to obtain an overview of the limits on each level of ability to erosion.

Looking from a brief and quick scan from the map and figure table, it can be seen that the area that is near to the top of Mt.Sumbing has the highest risk on getting erosion. This because the terrain, slopes, and plant that is there has the tendency to cause erosion.

High Quite High Low Very Low

Bowongso 434,65374 0,18361 250,86192 0,49142 686,19069

Butuh 306,72365 0 290,01529 68,73297 665,47191

Butuh Kidul 40,03771 0 346,52191 10,14546 396,70508 Kalikajar 9,48943 165,88475 182,16422 15,08557 372,62397

Kalikuning 0 0 152,36565 3,05965 155,4253

Karangduwur 0 5,97718 188,362 16,33641 210,67559

Kedalon 30,89279 391,48332 0,08268 3,89307 426,35186

Kembaran 0 0 213,49695 6,36404 219,86099

Kwadungan 372,6542 0,09415 992,96318 3348,58191 4714,2934

Lamuk 95,62405 0,00467 338,48608 1,06671 435,18151

Maduretno 0 0 233,84532 30,90554 264,75086

Mangunrejo 4,29425 343,73932 6,26126 1,03643 355,33126 Mungkung 14,99548 246,4171 36,41008 2,14715 299,96981 Perboto 21,65997 339,6478 402,70794 14,24098 778,25669

Purwojiwo 253,90808 0 305,12615 2,52818 561,56241

Rejosari 16,00557 60,33789 346,73347 16,43476 439,51169

Simbang 0 2,72225 229,96232 16,54471 249,22928

Tegalombo 0 0 174,3482 2,68007 177,02827

Wonosari 44,33232 0 281,73791 0,81921 326,88944

Total 1645,27124 1556,49204 4972,45253 3561,09424 Classification

Area Ha Sub-District /

Villages

Figure 3 Erosion Table Classification

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E-ISSN: 2338-3526, available online at: http://ejournal3.undip.ac.id/index.php/pwk | 5 While we can see in the middle part of Kalikajar district, it has a low risk of erosion, even tho the possibility and chance of getting erosion is still open. Lastly , in the western part of Kalikajar district, it can be seen that there are several villages that is categorized into having a quite high risk of erosion. This because the area that is mark by the yellow color has a steep hills and an intense forest.

4. CONCLUSION & RECOMMENDATION a) Conclusion

The result of analysis in terms of natural disaster especially erosion in Kalikajar district Wonosobo Regency has a lot to be considered and anticipated based on the analysis conduct earlier using the GIS application. The natural disaster in Kalikajar has a high risk both on the erosion and land capability unit for the area. Judging to it’s location on the foot of mountain, the possibilities of natural disaster occurance is high. Erosion, landslide, earthquake etc are the natural disaster that need to be anticipated and keep an eye on for the people and communities who lived around Kalikajar District.

Looking from a brief and quick scan from the map, it can be seen that the area that is near to the top of Mt.Sumbing has the highest risk on getting erosion. This because the terrain, slopes, and plant that is there has the tendency to cause erosion. While we can see in the middle part of Kalikajar district, it has a low risk of erosion, even tho the possibility and chance of getting erosion is still open. Lastly , in the western part of Kalikajar district, it can be seen that there are several villages that is categorized into having a quite high risk of erosion. This because the area that is mark by the yellow color has a steep hills and an intense forest.

Map 1 LCU Erosion

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E-ISSN: 2338-3526, available online at: http://ejournal3.undip.ac.id/index.php/pwk | 6 b) Recommendation

Urbanization also produces rising temperatures. With the replacement of green cover by paving, asphalting and construction, there is a decrease in evapotranspiration of foliage and soil. The impermeable surfaces absorb part of the solar energy and thus increase the temperature of the environment. However, with air movements, heat promotes the growth of precipitation. Therefore, some urban centers tend to have higher rainfall than in their periphery.

With urbanization, constructions and new occupations are observed the significant increase of sediments in the watershed, and with it the siltation of the drainage sections (erosion). Thus the production of sediments is deposited in the channel, and with this there is a reduction of its flow capacity during floods. These concept suitable to be implemented in Kalikajar District, since the area has a high risk of floods, landslide, and erosion.

The result of analysis has shown that Kalikajar District has a high risk from natural disaster of erosion. Judging from the existing condition, a contigency plan to minimize the casualties from disaster is key to reduce the victims of people who get affected from the disaster. Particularly for natural disaster, local government such as village office could have the ability to have an emergency plan to rescue the people if there is a disaster that occur on their location. An integration of all stakeholders to work together to keep the community save and to built the community resilience is an important factor to raise the awareness of people around Kalikajar to always stay ready and steady.

5. REFERENSI

IGA FFR. (2020). “NATIONAL PARTNERSHIP ON DISASTER RISK REDUCTION.”

Arsyad, S., (2010). Konservasi Tanah dan Air. Cetakan ke-2, Penerbit IPB Press, Bogor.

Suwardjo. (1981). Peranan sisa-sisa tanaman dalam konservasi tanah dan air pada usaha tani tanaman semusim. Disertasi. Fakultas Pascasarjana Institut Pertanian Bogor.

Figure 4 Watershed Runoff ( Schueler 1987)