BEBERAPA
PENGERTIAN DASAR
I. Geomorphology
is the study of landforms
(Lobeck, 1939)
II. Geomorphology
is the science of landforms
(Thornbury, 1954)
III. Geomorphology
is the study which describes landforms and the process which their
formation, and investigates the interrelationship, of these forms and
process and their special arragement
(Van Zuidam, et. al., 1979)
IV. Geomorphology
• Studi mengenai bentuk bumi (Derbyshire, 1979, p. 15)
• Studi tentang bentuk lahan (landform)
Lingkup studi
• Derbyshire, 1979, p. 17
F = f(P,M) dt
F
f
P
M
dt
:
:
:
:
:
Landform (bentuklahan)
Fungsi dari
Proses
Material
Perubahan menurut waktu
Derbyshire membedakan 4 level dari studi geomorfologi
Level 1 : study of elements of the equation
(studi tentang bentuklahan, proses, dan material, masing-masing
secara terpisah)
Level 2 : Balancing the equation
Mencari hubungan timbal balik antara bentuklahan, proses, dan
material pada suatu daerah tertentu pada saat tertentu pula
Level 3 : Differenciating the equation
Termasuk dalam hal ini pengujian cara-cara mengetahui hubungan
timbal balik antara ketiga elemen tersebut dan variasinya menurut
waktu
Level 4 : Applying the equation
Penggunaan manfaat dari ketiga level tsb di atas untuk maksud
pengelolaaan lingkungan
V. Geomorphology
is the study of landforms, and in particular of their nature,
origin, processes of development, and material
composition.
(Cooke, et. al., 1974)
VI. Geomorphology
Dalam lingkup studi geomorofologi tercakup:
• Bentuk lahan (landform)
• Proses-proses geomorfologi
• Genesis (asal-usul/perkembangan jangka panjang)
(Verstappen, 1977, p. 2)
VII. Geomorphology
is the scientific study of landscapes and the processes that
shape them. The science of geomorphology has two major
goals.
1. One is to organize and systematize the description of
landscapes by intellectually acceptable schemes of
classification.
2. The other is to recognize in landscapes evidence for
changes in the processes that are shaping them and
have shaped them (Arthur Bloom)
http://www.uwm.edu/Course/416-403/geomorph_rs_apps.htm
Karmono Mangunsukardjo (1986) menjabarkan 4 aspek geomorfologi :
1. Studi mengenai bentuklahan, atau disebut dengan morfologi,
mempelajari relief secara umum yang meliputi aspek :
a). Morfologi
Yakni aspek-aspek yang bersifat pemerian suatu daerah, antara
lain teras sugai, beting pantai, kipas aluvial dan plato
b). Morfometri
Yakni aspek-aspek kuantitatif dari suatu daerah seperti
kemiringan lereng, bentuk lereng, ketinggian, beda tinggi,
kekerasan medan, bentuk lembah, tingkat pengikisan dan pola
aliran
2. Studi mengenai proses geomorfologi,
Yakni proses yang mengakibatkan perubahan bentuklahan dalam
waktu pendek serta proses terjadinya bentuklahan yang mencakup
morfogenesa, dengan aspek-aspek :
a). Morfo-struktur pasif
meliputi litologi (tipe dan struktur batuan) yang
berhubungan dengan pelapukan
b). Morfo-struktur aktif
berupa tenaga endogen
c). Morfo-dinamik
berupa tenaga eksogen yang berhungan dengan tenaga
angin, air, es, gerak masa batuan dan volkanisme
3.
Studi geomorfologi yang menekankan pada evolusi pertumbuhan
bentuklahan atau morfo-kronologi, menentukan dan memerikan
bentuklahan dan proses yang mempengaruhinya dari segi umur relatif
dan umur mutlak
4. Geomorfologi yang mempelajari hubungannya dengan lingkungan,
studi ini mempelajari hubungan antara bentuklahan dengan unsurunsur bentangalam seperti batuan, struktur geologi, tanah, air,
vegetasi dan penggunaan lahan
Geomorphology should not be viewed as a product of lithosphere
processes but as part of an integrated earth-surface system of
interacting "sphere": lithosphere, hydorsphere, atmosphere, and
biosphere. Geomorphology is an environmental science as much
as it is a geologic science.
Landform (bentuklahan)
Bentukan alam di permukaan bumi yang terjadi karena proses pembentukan tertentu
dan melalui serangkaian evolusi tertentu pula.
atau
Bagian dari permukaan bumi yang mempunyai bentuk khas sebagai akibat pengaruh
dari proses, struktur geologi, dan batuan selama periode waktu tertentu. Oleh karena
itu bentuklahan ditentukan oleh faktor-faktor topografi, struktur geologi, batuan, dan
proses eksogen.
atau
merupakan bentangan permukaan lahan yang mempunyai relief khas karena
pengaruh kuat dari struktur kulit bumi dan akbibat dari proses alam yang bekerja
pada batuan di dalam ruang dan waktu tertentu. Masing-masing bentuklahan
dicirikan oleh adanya perbedaan dalam hal struktur dan proses geomorfologi,
relief/topografi dan material penyusun/litologi (Strahler, 1983 dan Whiton, 1984).
Misal :
Teras sungai : proses sedimentasi oleh aktivitas sungai dan berkembang
sampai terbentuknya (evolusi)
Landscape (bentanglahan)
Panorama atas suatu hamparan daratan yang terdiri dari berbagai keadaan
alam baik alami maupun buatan manusia (artifisial).
Topografi
Menyatakan ketinggian tempat di permukaan bumi dengan ukuran
satuan ketinggian tertentu
Terrain
Merupakan istilah yang diperuntukkan guna menyatakan keadaan medan
suatu wilayah di permukaan bumi, baik keadaan reliefnya, vegetasi/
penggunaan lahan, adanya sungai-sungai, rawa-rawa, sifat-sifat umum
batuan dan lahan, dll.
Istilah ini digunakan terutama untuk keperluan militer (PD I, II)
The collection, analysis, evaluation, and interpretation of geographic
information on the natural and manmade features of the terrain, combined
with other relevant factors, to predict the effect of the terrain on military
operations. Military Dictionary (DOD, NATO)
Digital Geomorphometry based on the use of DEMs is nowadays covered by
the concept of terrain analysis (Wilson dan Gallant, 2000)
Digital Terrain Analysis
The use of remote sensing satellite data for mapping various aspects of terrain, such as land cover, land
use, and soils. Software may then be utilized to derive terrain parameters, such as aspect, catchment
area, and wetness index, which are then used to describe the morphology of the landscape and the
influence of topography on environmental processes.
C:/Sleman/3_D/m
obil_3D.sxd
Imagery
Digital
Terrain Data
(DEM)
3D
Digital Model
© 2007 Intermap Technologies, Inc. All rights reserved.
D:/Military/
Morphometric parameters
•
•
•
•
•
elevation change gradients (slope)
orientation gradients (aspect, steepest downhill slope, viewshed)
curvature gradients (horizontal or tangent curvature)
vertical or profile curvature (mean curvature
combined gradients (tangential curvature).
3D Analyst
C:/Sleman/3_D/srtm_slm_box
Generic landforms
–
–
–
–
–
Stream channel (Valley bottom) - Locations of water accumulation and transition; high number of upstream elements and
concave shapes.
Ridge (Peak) - Locations of water run-off; lowest upstream contributing area and convex shapes.
Slope - Sloping part with generally higher shape complexity.
Plain (Terrace) - Flat areas of low relief and low shape complexity.
Pit - Conical concave landform.
D:/military/tinkrsb_ras
Topographic attributes: elevation (meters), slope (degree) aspect (degree), planform
curvature, topographic wetness and stream power
Topographic wetness and stream power indices were used to quantify flow
intensity and accumulation potential. Topographic wetness (also known as Compound
Topographic Index [CTI] or topographic moisture index) at a particular point on the
landscape is the ratio between the catchment area contributing to that point and the slope
at that point (Wilson and Gallant, 2000). Higher positive values are wetter and lower
negative values are drier and values are calculated as:
The Stream Power Index (SPI) is closely related to the topographic wetness index and is
used to estimate the erosive power of the terrain. Areas with large stream power
indices have a great potential for erosion. If total stream power is greater than that
required to transport the sediment available (supply limited), then there will be a net loss
in sediment and the stream will erode. If stream power is less (transport limited) than that
required, then there will be a net gain in sediment and the stream will aggrade. Values are
calculated as:
Stream power index
= Catchment areaxtan β (Moore et al., 1993)
where β
= Slope in degrees
GIS-Based Automated Landform Classification and Topographic, Landcover
and Geologic Attributes of Landforms Around the Yazoren Polje, Turkey
Perencanaan dan Operasi Militer
Drop Zone 1
Target Objective
Drop Zone 2
Pemahaman karakteristik medan menentukan akses yang efektif
RELIEF
a. Relief
Bentuk wilayah : keadaan tinggi rendah suatu wilayah di permukaan
bumi ditinjau dari segi perbedaan tinggi dan kemiringannya (lereng)
atau
Bentuk ketidakteraturan secara vertikal, baik dalam ukuran besar
maupun kecil dari permukaan litosfer.
Misal :
datar, landai , berombak, bergelombang, berbukit kubah
(humocky), berbukit, bergunung.
RELIEF :
1.
2.
3.
4.
5.
6.
7.
datar (D)
landai (L)
berombak (B)
bergelombang (Gb)
berbukit kubah (humocky)/Bk
berbukit (Bt)
bergunung (Gn)
HUBUNGAN RELIEF LERENG DAN BEDA TINGGI (US Soil Survey)
Relief
Datar/hampir datar
Berombak/Topografi landai
Berombak-bergelombang, topografi
miring
Bergelombang-berbukit, topografi
dengan lereng sedang
Perbukitan/topografi terjal
Pegunungan/topografi sangat terjal
Pegunungan sangat curam
Lereng (%)
0-2
3-7
8-13
Beda tinggi (m)
<5
5-50
25-75
14-20
50-200
21-55
56-140
>140
200-500
500-1000
>1000
HUBUNGAN RELIEF LERENG DAN BEDA TINGGI (Sunardi J., 1985)
Relief
Datar
Landai/berombak
Landai/Miring
Lereng (%)
0-3
5-8
8-15
Beda tinggi (m)
<5
5-10
10-25
Miring/berbukit
15-25
25-100
Miring terjal/ berbukit terjal
Terjal (berbukit terjal)
Sangat terjal (bergunung)
25-45
45-100
>100
100-200
200-500
>500
Panjang LERENG (US Soil Survey)
Panjang Lereng (m)
0 - 15
25 - 50
50 - 250
250 - 500
> 500
Keterangan
Sangat pendek
Pendek
Panjang menengah
Panjang
Sangat Panjang
Landforms evolve through the slow erosional removal of weaker rock, leaving the more
resistant rock standing as ridges or mountains. (Drawn by A. N. Strahler.)
Komponen dari relief yaitu :
a. amplitude (beda tingggi antara lembah dan puncak)
b. bentuk punggung
c. bentuk lereng
d. bentuk lembah
Aspek relief yang lain :
1. hubungan antara unit reliief kemiringan lereng dan
perbedaan tinggi relief
2. kepadatan aliran
3. pola aliran sungai
The concept of slope gradient. (a) How slope is measured on the landscape and the two ways in which it
can be expressed (degrees and percent). (b) Limits and definitions of slope classes used by the Natural
Resources Conservation Service. Map units with complex slopes require the use of more than one term,
e.g., “steep and moderately steep.” The overlap of ranges allows them to be specifically set for each
survey area. After the Soil Survey Division Staff (1993).
Geomorphic components of slopes in a landscape with an open drainage system.
After Ruhe (1975b).
(b) Two-dimensional components, i.e., the five elements of “fully developed” slopes.
Examples of
Simple (S),
Compound (C),
Complex (Cx)
hillslope profiles,
slope breaks (Br),
as viewed in cross-section.
After Ahnert (1970).
The nine basic geometric forms of hillslopes, with flowlines illustrating
how water and debris (theoretically) moves on them.
After Ruhe (1975b) and Huggett (1975).
Tallus adalah fragmen batuan yang terakumulasi sebagai tumpukan didasar bukit atau tebing.
Pediment adalah lapisan tanah dasar / batuan dasar yang sangat landai (kemiringan sekitar 5°).
• Morfologi Positif:
– Gunung (Mountain)
– Bukit (Hill)
– Kubah (Dome)
– Punggungan (Ridge)
• Morfologi Negatif
– Lembah (Valley)
– Cekungan (Basin)
Komponen dari relief yaitu :
a. amplitude (beda tingggi antara lembah dan puncak)
b. bentuk punggung
c. bentuk lereng
d. bentuk lembah
Aspek relief yang lain :
1. hubungan antara unit reliief kemiringan lereng dan
perbedaan tinggi relief
2. kepadatan aliran
3. pola aliran sungai
: Mountains
: Alluvial fans
: Valleys
: Wash drainage areas
(Reprinted with permission, Leighty (2004)
http://www.sciencedirect.com/science/article/pii/S0016706110003976
Studi tentang drainase pada foto udara atau data PJ meliputi 3
aspek :
1. tekstur drainase (drainage texture) atau kerapatan aliran
2. bentuk lembah (valley shape)
3. pola drainase (drainage pattern)
Pola aliran merupakan cerminan dari struktur dan tipe/ komposisi
batuan. Sedangkan kerapatan aliran mencerminkan resistensi dan
kekedapan batuan.
1. Tekstur Drainase (drainage texture) atau Kerapatan Aliran
tekstur drainase merupakan kerapatan drainase (rasio
total panjang sungai dalam sebuah DAS) dan frekuensi
drainase (jumlah aliran sungai dalam DAS dibagi
dengan luas DAS).
Tekstur drainase atau Kerapatan Aliran terutama dipengaruhi oleh tiga
faktor :
a) Iklim,
b) Relief
c) Karakter dari batuan dasar atau tanah (yaitu porositas dan
permeabilitas).
Kerapatan aliran mencerminkan resistensi dan kekedapan batuan.
Ex : Batuan beku/volkanik: gabro. granite
Kerapatan aliran dapat dideskripsikan sebagai:
• sangat halus (ultra fine),
• halus (fine),
• sedang (medium),
• kasar (coarse)
Drainage textures: (i) Coarse and (ii) fine
Kerapatan aliran
 Batuan kompak dan permeabel
 Kerapatan aliran jarang
 Batuan lunak dan impermeabel
 Kerapatan aliran rapat
Drainage density
The interpretation of DD varies with map scale. Typically its measured on a scale of
1:24,000.
Texture
Coarse (low)
Medium
Fine (high)
Ultra fine
DD (km/km sq.) Conditions
<8
8-20
20-200
>200
• Permeable or resistant
• Humid and well vegetated
• Permeable rksh.
• Rainfall
• well vegetated
• Impermeable surface
• Low rainfall
• Little vegetation
•
•
•
•
Impermeable surface
Low rainfall
easily erodible rocks
little vegetation
http://w3.salemstate.edu/~lhanson/gls210/gls210_streams3.htm
C = clayshale
SC = sandy or silty clay
Ss = sand or sandstone
Texture
Coarse
Medium
Fine
Common
gravel(ly)
sand(y)
clay(ey)
Drainase dikatakan internal ketika beberapa garis drainase terlihat di
permukaan dan sebagian besar di bawah permukaan (sub-surface),
misalnya batugamping (limestone) dan kerikil (gravel).
Drainase eksternal di mana jaringan drainase terlihat baik di permukaan.
Kerapatan drainase rendah pada batuan permeabel, seperti: tanah liat
(clays), serpih (shales).
argillaceous = “berlempung”
untuk menentukan batu di mana mineral lempung merupakan komponen
sekunder tapi signifikan. Misalnya, batugamping berlempung (argillaceous
limestones ) adalah batugamping yang terdiri sebagian besar dari kalsium
karbonat, tetapi termasuk 10-40% dari mineral lempung: batugamping
tersebut, ketika lembut, sering disebut napal. Demikian pula, argillaceous
sandstones (batupasir berlempung) adalah batupasir yang terutama terdiri
dari biji-bijian kuarsa, dengan ruang interstitial penuh dengan mineral
lempung.
Calcareous = “berkapur”
Berkapur adalah kata sifat yang berarti sebagian besar atau sebagian
terdiri dari kalsium karbonat, dengan kata lain, mengandung kapur atau
menjadi kapur.
Arenaceous = “berpasir”
batuan klastik sedimen dengan ukuran butir pasir antara 0,0625 mm
(0,00246 in) dan 2 mm (0,08 in) dan mengandung kurang dari 15% matriks.
2. Bentuk lembah (valley shape)
Bentuk lembah dapat bervariasi terkait dengan batuan dasar atau tanah.
• Bentuk V sering berkembang di pasir (sands) dan kerikil (gravels),
• Bentuk U berkembang di tanah lanau (silty soils).
• Bentuk lembah yang panjang dengan penampang membulat
menunjukkan tanah lempung (clayey soils) .
Typical valley cross-sections : (i) V-shaped, (ii) U-shaped and (iii) gently rounded
3. Pola drainase (Drainage pattern)
adalah “spatial arrangement” dari sungai (streams).
Pola aliran merupakan cerminan dari struktur dan tipe/ komposisi
batuan.
 Batuan miring
 pola aliran pararel
 Batuan yang landai dan homogen
 pola aliran dendritik
 Batuan dengan struktur kekar dan sesar intensif
 pola aliran rektanguler
 Struktur lipatan
 pola aliran trellis
DENDRITIC
• Tree
• Uniform Rock
TRELLIS
• Alternating
layers of hard
and soft rock
• Parallel
streams
RADIAL
• From highest central
point (butte/conical hill)
RECTANGULER
• Bends 90o
• Tributaries 90o
• Joint and faults
Dendritic drainage pattern.- Also called trees like or arborescent. Most common
basic pattern. F is fine texture; C is coarse texture. No structural control. Occurs
on fine textured impervious material.
Von Bandat, “Aerogeology”
Anak sungai acara urutan
keempat dan ketiga bentuk
melengkung
Modification- of dendritic pattern. Tributaries of fourth and third order show Pincer-like
curved forms. Occurs on igneos intrusions.
Subparallel-dendritic pattern. Coastal plain type. Flat bottomed broad short channels of limited
extent. Elongated tributaries at the right developed due to tilt of the surface (arrow). Broad channels
develop in fine sandy material.
Von Bandat, “Aerogeology”
Dendritic-pinnate pattern.
There is no structural control. P is a plain surface: The material is sandy and clayey silt.
(Ripley Cy., Indiana, U. S. Dept. of Agriculture)
Von Bandat, “Aerogeology”
Dendritic-pectinate pattern. Featherlike design typical with loess. Parallel gullies with
pearshaped headwater basins. Main stream in flat bottomed valley. P is a loss surface
(After Belcher).
Von Bandat, “Aerogeology”
Modifications of dendritic pattern. Different designs develop in clayshale (C), sandy or silty clay
(SC), and sand or sandstone (Ss). The different is in shape, ramification, type, texture and length
of gullies. C is most ramified, tree-like, fine textured. S is more wide spaced, less ramified with
short straight gullies. SC is finer textured with longer ramified gullies; a type between C and S
(Sweetwater Cy., Wyoming, USGS)
Von Bandat, “Aerogeology”
Angular drainage pattern. This basic type is also called a trellis pattern. A and B.
are two tilted sandstone blocks. The pattern is fault controlled. It is found on fractured
granular deposits or intrusives.
Von Bandat, “Aerogeology”
http://www.asu.edu/courses/gph111/Hydrology/Trellis.jpg
Angulate pattern, a modification of the angular pattern. The minor tributaries are parallel,
joining the main tributaries at obtuse angles. The pattern is fracture controlled and is found
mostly in granular sediments, like sandstones in near horizontal attitudes.
Von Bandat, “Aerogeology”
Contorted drainage pattern. The streams show reversed flow (arrows). The material is
sandstone. The control is structural.
Von Bandat, “Aerogeology”
Parallel patterns. This basic pattern develops on fine textured material with steep slopes.
Also along laminated formations of diffrent resistance, e.g., sand stone-shale belts, or on
tilted valley fills. It is most common along steep clay scarps with obsequents streams.
Von Bandat, “Aerogeology”
Subparallel pattern. The parallel tributaries join the main stream at an angle. This type is
common coastal plains in fine material, or on lava streams.
Von Bandat, “Aerogeology”
Radial drainage Pattern. The consequent streams flow from a central area in a radial design. The
design is from an Indonesian volcano. The material is fine textured tuff and granular tuff at G. This
basic pattern can be centrifugal (positive) on domes or uplifts and centripetal (negative) in basins.
Von Bandat, “Aerogeology”
Annular drainage pattern. The rather rare design occurs on domes with concentric hard and
soft upturned beds, or basins of similar composition.
Von Bandat, “Aerogeology”
Radial, pincerlike-dendritic and annular drainage pattern on a small granite dome.
Dashed lines with arrow are hard upturned bedded sediment, ridges. The central
granite ridge with apex is at G. (Meade Cy., South Dakota)
Von Bandat, “Aerogeology”
Sinkhole pattern develops on soluble rocks like limestone, gypsum, dolomite. Sink are usually
roundish or oval shaped. Only short rudimentary surface channels develop. The shallow
basins are filled with residual clay.
Von Bandat, “Aerogeology”
Drainage pattern in tropical Karst. Three different types of limestones (A, B, C) show three types of
sinkholes and dissolved fractures. The dry surface channel is fracture controlled. The angular
boundary between the limestone types suggests fault contacts. ( After a Bataafsche Petroleum
Maatschappij photograph)
Von Bandat, “Aerogeology”
Dichotomic pattern. The streams radiating from a common point in a fan shaped manner
depositing granular material by branching and multiple bifurcation (dichotomy). This
design is found on alluvial fans and deltas.
Von Bandat, “Aerogeology”
Anastomotic drainage pattern with meandering stream. Oxbow lakes (O) and
meander scars ( M) are on abandoned channels. Because of the collateral
commuting food channels, the pattern is called anastomotic. This depository pattern
in common on floodplains may be, in part, structure controlled.
Von Bandat, “Aerogeology”
This photograph shows a __________ stream channel
a.
b.
c.
d.
e.
meandering
undercut
gradient
straight
braided
This image shows an area in the Appalachian Mountains in Pennsylvania. The type of
drainage pattern that generally characterizes this region is __________
a.
b.
c.
d.
e.
annular
Trellis
rectangular
dendritic
deranged
This photograph shows part of the Kalahari Desert [Africa]. The drainage pattern is evident as a series
of dark and light stripes that follow patterns of fossil sand dunes from an ancient desert. Parallel
channels intersect a larger stream following a fault on the left side of the image. Together, these
geologic controls create a __________ drainage pattern.
a.
b.
c.
d.
e.
trellis
rectangular
annular
radial
dendritic
This karst region in Slovenia represents which type of drainage pattern?
a.
b.
c.
d.
e.
f.
rectangular
radial
deranged
annular
dendritic
trellis