Transcript
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Special Training Program for NNRMS officers(5th May-29th June, 2007 @ iirs, Dehradun, India
Visual Interpretation Techniques and Analysis of Remotely Sensed Data for Geological Mapping
Prof. Samir P ParmarAssociate Professor, Dharmasinh Desai University, Nadiad, India
Mail: samirddu@gmail.com
2 DisclaimerThis presentation is on net just for educational purpose only. The person, places, brands mentioned here are not promoted by author. The copyright material might be here but it is expected that the purpose of violation is just educational hence should be waved. Thank You
- Prof. Samir P Parmar
3Photo / Image Interpretation
• Extraction of qualitative and / or quantitative information from photo/ image in the form of a map. Present Context: Geological Map (Lithology + Structure)
• Types of Interpretation:A. Direct Interpretation Based on Grey Levels or Digital Numbers (Digital Image Classification) B. Indirect Interpretation or Deductive Approach
Based on Interpretation Elements (Image Elements & Terrain Elements) coupled with “Convergence of Evidences” criteria.
Since the geologic materials are often covered by a mantle of soil, weatheredzone, land use/ land cover, Indirect (or Deductive) Approach is more useful than Direct Approach.
4Natural Process Vs. Photo / Image Interpretation
Landform Drainage Soil
Shape, Size, Tone, Texture, Pattern, Shadow,
Association
CausativeElements
TerrainElements
Image Elements
PrimaryFactors
SurfaceExpression
Expressionon Images
Sequ
ence
in N
atur
e
Phot
o/ Im
age
Inte
rpre
tatio
n
Rock attributes(Lithology &Structure)
Physical Processes(Weathering, Erosion
& Deposition)Time
(Source: Gupta, 1991)
ErosionVegetation& Land Use
5Deductive Approach
1. Photo / Image Elements• Shape• Size• Tone / Colour• Texture• Pattern• Shadow• Association
2. Terrain / Geotechnical Elements• Landform
• Drainage Pattern, Density & Anomaly
• Vegetation & land Use
• Erosional Pattern
• Soil
Convergence of Evidence
Existing Geological Information & Ground Checks
6 EXISTING GEOLOGICAL MAPS & LITERATURE
PREPARATION OF FINAL LITHOLOGICAL MAP OVERLAY
FIELD VERIFICATION
PREPARATION OF PRE-FIELD LITHOLOGICAL MAP OVERLAY
COORELATION OF IMAGE CHARACTERISTICS & ROCK TYPES
STUDY OF IMAGE & TERRAIN ELEMENTS
VISUAL INTERPRETATION
SATELLITE IMAGERYContd..
Amount of Information Extracted α Amount of Experience
7Image Elements
Shape or Form
- Refers to the geometric aspects of the object in the image.
The river is spontaneously recognized by its characteristic form.
The agricultural lands are defined by the geometric shape and size of the fields.
The gullied bad-land area is recognized by the nature of dissection.
8 Tone - Defined as the relative brightness in a black/white image.
Image Elements
Settlements have a very bright tone.
Agriculture, mainly over clayey rocks, has medium grey tones.
Ultrabasic rocks show up with a dark grey tone.
• Light Tone Arenaceous / Acidic Rocks• Dark Tone Argillaceous / Basic Rocks• Banded Tone Interbedded Rocks• Homogenous Tone Uniform Composition
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Image Elements
Texture- Defined as frequency of tonal change.
Homogeneous grassland - Smooth textureConiferous forests - Coarse texture
- Scale dependent
10Image Elements
Pattern
- Refers to the spatial arrangement of features.- May be Natural (e.g. river terraces) or Man-made (e.g. agriculture
terraces).
Agriculture Fields (Rectangular & terraced patterns).
Banded pattern in the vegetationenhancing different rock types.
11Image Elements
Association - Refers to the occurrence of the object of study in combination with other objects that makes it possible to infer about the object.
Material surrounding the cinder/ volcanic conesshould be volcanic rocks.
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Examples:
Sinkholes / Karst Topography - Limestone CountryDip Slopes - Sedi.mentary TerrainTerrace, Point Bars, Back Swamps, etc. - Unconsolidated Fluvial DepositsCinder Cone – Volcanic RocksDunes, Sand sheets – Unconsolidated Aeolian Deposit
Terrain / Geotechnical Elements
Landform
- Most important element which throws light on the type of rock, geologic structure, and process.
- Two types: Exogenic (Aggradational or Degradational) Endogenic
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a. DendriticDevelops in homogeneous,uniformly resistant xlline & horizontally beddedsediments; Shows lack ofstructural control; Indicates gentle regional slope.
c. Rectangular
Shows presence ofjoints/ fractures at right angles (structural control).
d. Trellis
Shows structural control;Develops in interbedded(differences in resistanceto erosion), dipping orfolded sedimentary orvolcanic rocks.
b. Parallel
Develops on sloping surfaces underlain by homogeneous rocks
1. Drainage Pattern
Terrain / Geotechnical Elements
Drainage Pattern, Density & Anomalies
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h. Contorted
Develops in areas underlain by metamorphic rocks, dykes, veins, magmatised bands and also around the nose of folds.
f. Annular
Develops in maturelydissected domes,basins and volcanicCones, where erosion has exposed rocks of varying resistance.
e. Radial
Develops in domes,volcanic cones.
g. Multi-basinal
Develops in areas with multiple depressions.
Contd..
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Depends on:
- Resistance of Rocks (Harder rocks – Coarser; Softer rocks – Finer)
- Permeability of Rocks (Permeable rocks – Coarser; Impervious rocks – Finer)
- Topography (Lower Slopes – Coarser, Higher Slopes – Finer)
- Climate
Finer Drainage Density Coarser Drainage Density
2. Drainage Density
Contd..
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Examples
Change in drainage density
Long, rectilinear segment of streams
Compressed / Incised Meanders
Abrupt and Localised braiding
Local widening or narrowing of valley or channels
Anomalous curves or turns in rivers/ streams
Abrupt and localised appearance of meanders
Water falls in river course
Difference in part of a drainage system which does not conform to the overall pattern.
3. Drainage Anomaly
Contd..
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Especially useful for unconsolidated material. Study of cross section of gullies are very important. Sheet, rill and gully erosion varies in different types of materials. Development of gully formation is subject to - - Topography - Amount of precipitation - Degree of consolidation - Density of vegetation - Depth of water table - Human influence, etc.
Erosion
Vegetation type & density are indicative of topography, soil, rock or moisture factors or various combinations of these. Land use gives information about the soil condition.
Vegetation and Land use
Terrain / Geotechnical Elements
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(Source: After Zuidam, 1986).
CARBONATES
COARSE GRAINED CLASTICS
FINE GRAINED CLASTICS
Intermediate LithologiesWith
Mixed Characteristics
Resistant orNon-resistant;
Soluble, Karstificationespecially in humid
regions; Internal or partly internal drainage;
Jointing common; Light or light to medium tones.
Generallyresistant; Porous
& permeabledepending on cement/matrix; Drainage partly
internal & of low density; Frequent jointing; Light
or light to medium tones.
Lessresistant;
Insoluble & impervious;External drainage of high
density; Joints may be present, but difficult to detect, except in the more indurated varieties; Dark to
medium or dark phototones.
Salient Photo / Image Characteristics of Sedimentary Rocks
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ACIDIC INTERMEDIATE BASIC AND ULTRABASICPlutonics Massive and uniform,
frequently strongly jointed; Topography in humid regions and at low altitudes subdued or hummocky, in dry regions or at high altitudes sharp and rugged; Drainage joint-controlled or dendritic; Light and light to medium tones.
Intermediate Massive and uniform, in many respects similar to granite, resistance probably lower and jointing less intensive. Dark tones.
Hypabyssal Generally form linear ridges, sometimes linear valleys with light to dark photo-tones.
Extrusives Strato volcanos and cinder cones, blocky flows predominate; Light and light to medium tones.
Intermediate Wide-spread fissure eruptions, shield volcanoes, ropy flows pre-dominate, frequent columnar jointing; Dark and dark to medium tones.
Salient Photo/ Image Characteristics ofIgneous Rocks
(Source: After Zuidam, 1986)
20Sedimentary Rocks: Summary Chart
SandstoneTopography : Flat Table Rocks, Massive, Steep SlopesDrainage : Dendritic to Modified Dendritic, Medium to Coarse TextureTone : Light, BandedGullies : Few, V-shapedVegetation & Land Use : Forested, Barren
ShaleTopography : Soft, Rounded HillsDrainage : Dendritic, Medium to Fine TextureTone : Mottled to dull, BandedGullies : U-shaped, Steep-sided, Bad landsVegetation & Land Use : Cultivated, Barren
LimestoneTopography : Flat Table Rocks, Karst in humid climateDrainage : Angular Dendritic, Medium to Fine Texture, Internal in KarstTone : Light, MottledGullies : Few to noneVegetation & Land Use : Cultivated, Barren, Forested (Source: After Way, 1973)
21 Flat, Interbedded Sedimentary Rocks
Topography : Terraced hill-sidesDrainage : Dendritic, Coarse to Fine TextureTone : BandedGullies : Vary, V- or U-shapedVegetation & Land Use : Cultivated, Forested, Barren
Tilted, Interbedded Sedimentary RocksTopography : Ridge and Valley Drainage : Trellis, Medium to Fine TextureTone : BandedGullies : VaryVegetation & Land Use : Cultivated, Forested, Barren
Contd..
(Source: After Way, 1973)
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Aerial photograph showing jointed sandstone. Aerial photograph showing sink holes in limestone.
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Aerial photograph showing interbedded, dipping sedimentary strata.
24 IRS-1C WiFS FCC
F----F FAULTFr----Fr FRACTURESF SCARP FACE
IRS-1C LISS-III FCC
F
F
F
FF
F
F
FFF
F F
Fr
Fr
SF
Source: NRSA/DOS
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Landsat TM FCC (432=RGB) of 26.04.2001 showing contact between Middle and Upper Siwaliks..
26Igneous Rocks: Summary Chart
Intrusive Granite (Large Masses)Topography : Bold, Dome-like HillsDrainage : Radial, Annular, Dendritic with curved ends, Medium to Coarse TextureTone : Light, UniformGullies : Few to noneVegetation & Land Use : Barren, Forested, Grass Cover, Cultivated
Topography : Narrow Linear RidgesDrainage : NoneTone : Light or DarkGullies : NoneVegetation & Land Use : Natural Cover
Intrusive Granite (Linear Dykes)
(Source: After Way, 1973)
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Extrusive Basalt FlowsTopography : Level PlainDrainage : Regional Parallel, Coarse to Fine TextureTone : Dark, Flow MarksGullies : U-shapedVegetation & Land Use : Cultivated, Natural Cover, Barren
Topography : Terraced hill-sidesDrainage : Parallel, Dendritic, Coarse to Fine TextureTone : Banded, Light to DarkGullies : VaryVegetation & Land Use : Cultivated, Natural Cover, Barren
Extrusive Interbedded Basalt Flows
Contd..
(Source: After Way, 1973)
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A
B C
A. Irregularly fractured granites.
B, C & D. Lava flows and associated cinder cones.
D
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Basement granitic gneisses intruded by dykes.
30Metamorphic Rocks
Display foliation / schistosity as thin parallel to discontinuous linears.
Generally occur as elongate parallel hills / ridges and and valleys, showing crenulated, wavy patterns.
Display mixed drainage patterns (modified dendritic, trellis, rectangular, parallel).
Quartzites form steep sided strike ridges.
Drainage texture varies from medium to fine.
Tone varies: Light, light grey to grey.
Cultivated, Natural cover, Barren.
(Source: After RGNDWM Manual, 2000; Way, 1973)
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Aerial photograph showing gneisses with foliation trends.
32 Criteria for Establishing Lithologic Contact
Break in Slope
Changes in resistance to Erosion
Drainage Changes
Tonal Changes (Lithologic / Soil / Vegetational)
33 Structural Interpretation
Structural Elements
Attitude of beds
Folds
Joints/ Fractures/ Faults/ Lineaments
Unconformity
34 1. Attitude of Beds
a. Horizontal to Sub-Horizontal Beds
Show tonal / colour banding parallel to topographic contours. Show plateau / mesa / butte type of landforms. Show dendritic / modified dendritic drainage pattern. Resistant beds have steep slopes and non-resistant beds have smaller slopes.
Resistant Bed
Non-resistant Bed
Steeper Slope
Gentler Slope
35 b. Dipping Beds
Asymmetric ridges (Cuesta / Hogback) develop in gentle to moderate dipping beds.
- Dip slopes are gentler and obsequent slopes (or back slopes) are steeper.
- Drainage density is coarser on dip slope, and finer on obsequent slope.
- Tributaries are longer on dip slopes, and shorter on obsequent slopes. Symmetric ridges (Strike Ridges) develop in steep dipping beds. Flatirons or dip facets develop wherever interbedding of hard and soft rocks exists. Open end of flatirons or dip facets indicate direction of dip. Rule of “Vs” can be used to infer the direction of dip if topographic slope is less than the dip amount. “Vs” point in the down-dip direction.
(Source: Block Diagrams after Miller, 1961)
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Aerial photograph showing flatirons or dip facets in sedimentary strata. Observe the relationship betweentopographic slope and dip of beds.
Dip Slope
Obsequent Slope
Flatiron
Flatiron
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Symmetric ridges (strike ridges) indicating steep dips.
38 c. Folds Can be identified by: - Tracing the marker horizons / beds - Establishing the dips - Drainage characteristics.
Simple or Non-plunging folds produce parallel outcrops of beds.
Plunging folds have V or U shaped outcrop pattern.
Major streams curve around the nose of fold (contorted drainage).
Aerial photograph showing a plunging anticline.
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Enlarged photograph of a part of plunging anticline.
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Photograph showing plunging anticline and syncline.
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Landsat MSS FCC (321=RGB) of 1973.
42 d. Faults / Fractures / Joints / Lineaments
Expressed on the photo / image by: - Mismatch in the rocks on opposite sides of a linear feature - Straight segments of rivers - Abrupt stream diversions - Stream offsets, ridge offsets - Alignment of vegetation, lakes, ponds and springs - Abrupt termination of topographic features, landforms, drainage pattern, geologic structure, etc. - Presence of scarps and triangular facets - Alignment of water falls across streams - Tonal/ Textural (erosional/ vegetational/ drainage) changes on opposite sides of a linear feature.
Faults:
Aerial photograph showing faults.
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Linear to curvilinear features of geological significance.
Presumably reflect sub-surface phenomenon.
Joints / Fractures:
Surface expression same as Faults.
Joints are shorter, many in number and more or less parallel.
Lineaments:
Unconformity: Angular unconformity & Non-conformity are easily recognisable.
Unconformable contacts are mainly irregular.
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Aerial photograph showing a major cutting across sedimentary strata and younger unconsolidated sediments.
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Landsat TM FCC (432=RGB) of 21.11.1989. Landsat ETM+ FCC (432=RGB) of 29.10.2001.
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Landsat TM FCC (432=RGB) of 21.11.1989.
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Landsat TM FCC (432=RGB) of 21.11.1989.
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Landsat TM FCC (432=RGB) of 21.11.1989.
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Landsat TM FCC (432=RGB) showing Yamuna Tear Fault, western part of Doon valley.
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Kynshi Fault in Granitic Gneisses, East Khasi Hills District, Meghalaya
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Prominent lineaments south of Laitlyngkot, East Khasi Hills District, Meghalaya
52 Aerial photograph showing a strike-slip fault.
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Satellite image showing a neotectonic fault in Doon valley.
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Ground water irrigated area (over exploited zones)
IRS-LISS-III Standard FCC of part of Precambrian basement, South India.
Hydrologic information( Surface water bodies)
Conduits for G.W.movement(Fractures / Lineaments)
Barriers for G.W.movement(Dolerite dykes)
Run-off zones(Residual Hills)
Source: NRSA / DOS
55 Landsat TM
Cartosat-1 QuickBird
Landsat TM
MULTIRESOLUTION SATELLITE IMAGES - ADVANTAGES
56 Landsat TM
Cartosat-1 QuickBird
Landsat TM
MULTIRESOLUTION SATELLITE IMAGES - ADVANTAGES
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Base flow in Song R. near Satyanarayana
SATELLITE IMAGE SHOWING DISCHARGE ZONE Landsat TM
Landsat TM Landsat TM
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SATELLITE & GROUND VIEWS
Location: Kaja, Spiti Valley
IRS LISS-III Image
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Special Thanks to Faculty members and Management who provided me excellent expert level training in NNRMS course in 2007, IIRS, Dehradun, Uttaranchal, INDIA
Thank You !
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