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Geomorphological Approach for Natural Disaster Analysisin Karo Highland, North Sumatra Province, Indonesia
Dwi Wahyuni Nurwihastuti, Anik Juli Dwi Astuti, Eni Yuniastuti
Department of Geography, State University of Medan, North Sumatra, Indonesia Email: [email protected]
Outline
Introduction
Research objectives
Methods
Results
Conclusion
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Introduction
The earth surface have different physical characteristics of land between one region and another regions
One concept in geomorphology is "the present is the key to the past", which indicated that the processes occurred in the past will continue until the present and the future despite the different intensity
The natural disasters are geomorphological processes The natural disasters that have occurred in the past will happen again in the present and the future
Understanding of landform units will bring to the understanding of the threat of natural disasters in an area that occurred in the landform units
Research objectives
to analyze landform units in the research area based on interpretation of remote sensing imageries (Landsat and SRTM)
to analyze distribution of natural disaster threats using geomorphological approach
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Research Area
Karo Regency cover 17 district with total area of 2,127.25 Km2
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Methods
Research methods survey, sampling and qualitative
Population All area of Karo Regency, North Sumatra Province
Determination of samples stratified purposive sampling
Methods
The study of geomorphological characteristics was carried out by satellite image interpretation and field surveys.
Image enhancement techniques were applied to clarify geomorphological appearance on Landsat.
Landform unit delineation and data analysis used Geographic Information Systems (GIS). Geological map analysis also was used to obtain the information of constituent materials of landform.
The types of natural disaster threats on every landform unit can be obtained from secondary data and field survey.
Analysis of the research results were conducted descriptively and spatially. Descriptive analysis is used to describe the condition of geomorphological characteristics, landform units, and the threat of natural disasters in Karo. While the spatial analysis is used to describe the spatial distribution of landform units and the threat of natural disasters in Karo.
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Satellite Imageries (Landsat and SRTM) Geological Map
Morphology, Morphogenesis, Morphochronology, and Morphoarrangement
Tentative Landform Mapping
Relief Surface Lithology
Topographic Map
Tabulate, Classify and Analyze
Image Processing and Image Enhancement
Research Results:-Data of geomorphological characteristic and
landform unit-Landform map
-the threat of natural disasters
Results Analysis
Field Verification
Geomorphological characteristic and landform unit in Karo
Results
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Morphology of Karo
Plain area central part of KaroHilly and mountainous area west, north, east, and south of Karo
Karo
Topographic Profile of Sinabung -Tongging
Sinabung Tongging
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Topographic Profile of Kutabuluh -Barusjahe
Kutabuluh Barusjahe
Topographic Profile of Mardinding –Sinabung –Barusjahe
Mardinding BarusjaheSinabung
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Morphology of KaroBased on Landsat 7 ETM+ RGB 457
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Morphology of KaroBased on Landsat 7 ETM+ RGB 457
Morphology of KaroBased on Landsat 7 ETM+ RGB 457
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NO. SYMBOL Lithology MATERIAL Sediment Geologic Age1 MPikt Keteran Granite Intrusive : Felsic : Granitoid Plutonism : Batholith Perm Tengah - Trias Akhir
2 Ppa Alas Formation Metamorphic : PhylliteMetamorphism : regional : low-grad perm awal - karbon akhir
3 Ppal Limestone Members Sediment : clastic limestone Sedimentation : littoral Perm tengah
4 PpblBatumilmil LimestoneFormation
Sediment : Chemical : limestone littoral : reef Perm Akhir
5 Pub Bohorok Formation Metamorphic : meta - sedimentMetamorphism : regional : low-grad Karbon akhir - Perm Awal
6 Puk Kluet Formation Metamorphic Meta-sedimentMetamorphism : regional : Low-grad Karbon Akhir - Perm Awal
7 Qh Young Alluvium Sedimen : clastic fine terestrial aluvial Holosen
8 Qpk Kutacane Formation Sediment : clastic : aluviumSedimentation : terestrial : fluvial Plistosen
9 QTvk Takur-Takur Unit Extrusive : intermediate : lava Volcanism subaerial Pliosen Akhir - Plistosen Awal10 QTvm Mentar Unit Extrusive : Mafic : Polymict Volcanism subaerial Pliosen - Plistosen11 Qvba Sibayak Unit Extrusive : intermediate : lava vulcanism subaerial plistosen - holosen
12 Qvbj Binjai UnitExtrusive : intermediate : Pyroclastic Volcanism subaerial Plistosen
13 Qvbr Barus Volcanic Extrusive : intermediate : lava Vulcanism subaerial Plistosen14 Qvbs Singkut Unit Extrusive : Intermediate : lava Volcanism subaerial Plistosen15 Qvsn Sinabung Volcanic Extrusive : intermediate : lava volcanism subaerial plistosen - holosen16 Qvss Sipiso piso Volcanic Extrusive : intermediate : lava Volcanism : subaerial Plistosen Akhir - holosen17 Qvt Toba Tuffs Extrusive : Felsic : Pyroclastic Volcanism: Subaerial Plistosen18 Qvtsu Sibutan Toba Unit Extrusive : felsic : Polymict volcanism subaerial Plistosen akhir - Holosen19 Tlbu Butar Formation Sediment : clastic : fine : shale terestrial : fluvial Oligosen akhir - Miosen Awal20 Tmvh Haranggaol Formation Extrusive : intermediate : lava Volcanism : aerial Miosen Tengah - Miosen Akhir
Source: Data Analysis Results (2014)
Lithological of Karo
Geological Map of Karo
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Sinabung Volcanic (Qvsn)
Limestone Members(Ppal)
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Formasi Butar(Tlbu)
BatumilmilLimestone
Formation (Ppbl)
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Sibayak Unit (Qvba)
Singkut Unit (Qvbs)
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Toba Tuffs (Qvt)
Landform Units of Karo
1. Volcanic landform
2. Structural landform
3. Denudational landform
4. Solutional landform
5. Fluvial landform
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No Landform Symbol Area (Km2) Percentage (%)Volcanic Landform
1 Sinabung Volcano of Andesites, Dacites, and Pyroclastics V1.1 46.96 2.21
2 Sibayak Volcano of Andesites, Dacites, and Pyroclastics V1.2 11.63 0.55Structural Landform
3 Butar Denudation Structural Mountain S1.1 176.42 8.29
4 Bohorok Denudation Structural Mountain S1.2 32.42 1.52
5 Alas Denudation Structural Mountain S1.3 38.48 1.81
6 Metamorphosed Limestone Denudation Structural Mountain S1.4 125.29 5.89
7 Limestone Members Denudation Structural Mountain S1.5 80.60 3.79
8 Slope of Toba Tuffs Denudation Structural Mountain S2 7.83 0.379 Toba Tuffs Highland S3 259.11 12.18
Denudational Landform10 Toba Tuffs Denudational Mountain D1.1. 64.51 3.0315 Takur-takur Denudational Mountain D1.2 88.69 4.1716 Singkut Denudational Mountain D1.3 25.85 1.2217 Sibutan Denudational Mountain D1.4 36.40 1.7118 Mentar Denudational Mountain D1.5 50.71 2.3819 Binjai Denudational Mountain D1.6 3.68 0.1720 Keteran Granite Denudational Mountain D1.7 12.87 0.6021 Kluet Denudational Mountain D1.8 172.49 8.11
22 Haranggaol Volcano Denudational Mountain D1.9 5.91 0.2811 Butar Denudational Mountain D1.10 8.31 0.3912 Bohorok Denudational Mountain D1.11 57.64 2.7113 Sipiso-piso Volcano Denudational Mountain D1.12 7.85 0.37
14 Barus Volcano Denudational Mountain D1.13 5.73 0.27
23 Slope of Singkut Denudational Mountain D2 249.84 11.7424 Butar Denudational Hill D3 182.58 8.5825 Slope of Toba Tuffs Denudational Hill D4 209.73 9.8626 Takur-Takur Isolated Hill D5.1 5.84 0.2727 Limestone Metamorphosed Isolated Hill D5.2 4.69 0.22
Solutional Landform
28 Batumilmil Limestone Karst Hill K 40.54 1.91Fluvial Landform
29 Alluvial Plain of Young Alluvium F1.1 89.97 4.2330 Kutacane Alluvial Plain F1.2 24.70 1.16
Total 2127.25 100.00
Landform Map of Karo
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Volcanic Landform
Landforms result of volcanic activity, both of which are composed of volcanic material that has come out to the earthsurface or extrusion, as well as frozen beneath the earth's surface or intrusion.
Volcanic landform in the research area consist of:
Sinabung Volcano of Andesites, Dacites, and Pyroclastics
Sibayak Volcano of Andesites, Dacites, and Pyroclastics
Both volcanoes are Pleistocene -Holocene
Sinabung Volcano
Sinabung and Sibayak Volcano on Landsat 7 ETM+ band 457
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Structural Landform
Structural landforms formed by the endogenous process are called tectonic processes. This process includes the uplift, downlift, and folding of the earth's crust, forming a geological structure that folds and faults.
Geological structures are visible in the area of research in the field and imagery in the form of fault.
A fault in the Landsat image is characterized by the appearance of straightness (lineaments), a straight line or curved in the form of vegetation alignment and straightness of hills, valleys, and rivers
The structural landforms that occur in the study area have experienced the denudationalprocess.
Denudational processes that occur include: the process of weathering, erosion, and mass movement, mainly due to local climatic conditions (rainfall) and the force of gravity.
Structural landform of Karo on Landsat 7 ETM+ RGB 457
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Lineaments on Landsat 7 ETM+ RGB 457
Denudational Landform
The processes that occur in denudational landform consist of weathering, erosion, mass movement and sedimentation.
Rocks weathering are caused by rupture of the cooperation of all processes on both rock mechanics (disintegration) and chemical (decomposition) that resulting rock fragments into smaller rocks. Due to the gravitational force acting on the results of weathering rock fragments, then there is a mass movement of rock that can be in free fall, avalanche (slides), roll, creep, and flow of the fragment. The fragments move down the slope, then the fragment having the deposition at a lower place. The deposited material due to the gravity of the heterogeneous rock fragments called colluvium.
Generally, the denudational landforms are found in areas with topography: wavy, undulating, hilly or mountainous that have soft rocky due to weathering processes and wet climates. Consequently, the structure form does not appear because of the mass movement.
Denudational landform in Karo consist of Isollated hill, denunadtional hill, and denudational mountain from various lithology
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Location: Road of Medan –Berastagi (Doulu) (E 98º32’37.79” N 03º13’42.62” )
Debris Fallon denudational landform
Landslide Type: Debris Fall in denudational landform of Toba Tuffs
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Type of landslide: Soil Rotational Slideon the denudational hill
(N 03º04’35.4” E 98º06’39.68”)
Soil Creep occurred on denudational landform Location: Road of Tiga Binanga - Kutacane N 03º03’24.5” E 98º08’21.07”
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Soil Slide occurred on denudational landform
Location: Tiga Binanga
Soil Slide occurred on denudational landformLocation: Road of Merek - Dairi
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Soil Slide occurred on denudational landformLocation: Road of Merek - Dairi
Topple occured on the denudational -
structural landformLocation: Sipiso-piso
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Rock Fall occurred on denudational landform
Solutional landform in Karoconsist of BatumilmilLimestone Karst Hill.
The area of is 40.54 Km2 or 1.91% of BatumilmilLimestone Karst Hill total area.
Located in Kutabuluh and Tiganderket.
Solutional Landform (karst)
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Solutional processes that form stalactites and stalagmites in the cave of Liang Dahar Kutabuluh
Fluvial Landfom
Fluvial landform in Karo consist of alluvial plain in Mardinding and
Merek
The area of alluvial plain is 114,67 Km2 or 5,39% of total area.
Alluvial plain has flat topography as a result deposition of alluvium on both sides of the river. Sediment is the result of flood water carrying sediment in the river during the floods. Thus, the structure of alluvial deposits is layered horizontal in the area with lower elevation
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Alluvial plain
Fluvial Landfom
Fluvial Landfom
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Threat of Natural Disasters in Karo
The potential of natural disasters on every landform units in the research area are as follows:
Volcanic landform is an area prone to volcanic eruptions, lahar flow, and pyroclastic flow.
Denudational, structural, and solutional landform are areas prone to landslide and erosion.
Fluvial landform is an area prone to flash flood and landslide in the river bank.
All of landforms in the research area are prone to earthquakes.
NoLandform
Unit
Type of Disaster
Volcano Eruption
Lahar Flow
Pyroclas-tic Flow
Land-slide Erosion
Flash Flood
Earth-quake
1 Volcanic √ √ √ √ √
2 Structural √ √ √
3 Denudational √ √ √
4 Solutional √ √ √
5 Fluvial √ √ √
Types of natural disasters on each landform unit
Sources: Data Analysis Result (2014)
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Conclusion
Geomorphological information can be obtain from
interpretation of Landsat 7 ETM+ and SRTM. The research
area consist of volcanic, structural, denudational, solutional,
and fluvial landform.
The information of morphogenesis can be used to analyze
the potential of natural disasters in the research area.
The landform unit can be used as a mapping unit in the
mapping of the threat of natural disasters
Thank you…
