Introduction to airphoto interpretation

1
Chapter 3

• Introduction to airphoto interpretation
• Introduction to Remote Sensing
• Instructor Dr. Cheng-Chien Liu
• Department of Earth Science
• National Cheng-Kung University
• Last updated 16 April 2003

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3.1 Introduction

• Airphoto interpretation
• raw data ? human brain processing ? information ?
  communicate
• History
• Balloon photographs (1858)
• WWI ? military reconnaissance tool
• WWII ? CD film
• After WWII ? wide spread

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3.2 fundamentals of airphoto interpretation

• Photo interpreter
• Training
• Experience
• Keen power of observation coupled with
  imagination patience
• Thorough understanding of the phenomenon
• Knowledge of the geographic region
• Supporting materials
• Maps
• Field observations

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3.2.1 elements of airphoto interpretation

• Airphoto interpretation departs from daily image
• The portrayal of features from an overhead, often
  unfamiliar perspective
• l outside visible range
• Unfamiliar scales and resolutions
• Basic characteristics
• Shape
• Size
• Pattern

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3.2.1 elements of airphoto interpretation (Cont.)

• Basic characteristics (cont.)
• Tone
• Texture
• Shadows ? topographic variations ? geologic
  landform
• Site aid in the identification of vegetation
  types
• Association e.g. a ferris wheel ? amusement park

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3.2.2 Photo interpretation strategies

• Direct recognition
• e.g. identification of highway interchange
• Inference of site conditions
• e.g. infer the buried gas pipeline ? light-toned
  linear streals
• e.g. infer the type of crop ? crop calendar
• Detective ? put all evidence ? solve a mystery
• The interpreter uses the process of convergence
  of evidence to successively increase the accuracy
  and detail of the interpretation

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3.2.3 Airphoto interpretation keys

• Help the interpretation in an organized and
  consistent manner.
• Two basic parts
• A collection of annotated or captioned
  stereograms
• A graphic or word descrioption
• Two general types
• Selective key
• Elimination key ? more positive answer but may
  result in erroneous answers.
• Dichotomous key (Fig 3.1)

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3.2.3 Airphoto interpretation keys (cont.)

• More easily constructed and more reliably
  utilized for cultural feature identification than
  for vegetation or landform identification
• Crop , tree identification ? region-by-region,
  season-by-season.

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3.2.4 Film-filter combinations

• Affect the amount of information that can be
  interpreted from the image

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3.2.5 Temporal aspects of photo interpretation

• Vegetative growth, soil moisture ? vary during
  the year
• Observe several time ? better result

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3.2.6 Photo scale

• Table 3.1 typical scales and areas of coverage
• Small150,000medium112,000large
• Small ? reconnaissance mapping, large area
  resource assessment, general resource management
  planning
• Medium ? identification, classification, mapping
  of tree species, agricultural crop type,
  vegetation community and soil type
• Large ? intensive monitoring of the damage caused
  by plant disease, insects or tree blowdown,
  emergency response to hazardous waste sills and
  for the intensive site analysis of hazardous
  waste sites.

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3.2.6 Photo scale (cont.)

• NHAP I
• 19801985, 158,000, 180,000, 13200m, leaf-off
• NHAP II
• 19851987 , leaf-on.
• NAPP
• 140,000, leaf-on, -off

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3.2.7 Approaching the interpretation process

• Photographic materials, interpretation equipment,
  goals of the interpretation ? no single right way
  to do.
• Examples of requirement
• Identify and count
• Identify anomalous conditions
• Delineate discrete areal units
• Classification system or criteria ? separate
  categories
• Minimum mapping unit (MMU) (Fig 3.2)
• From higher contrast one to lower one
• From the general to the specific
• delineate photographic regions. (tone, texture.)

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3.2.8 photo preparation and viewing

• Important factors
• Relevant collateral sources of information (maps,
  field reports, .)
• Good lighting access to equipment
• Systematically labeled and indexed
• Boundary delineations
• Fiducial marles, road intersections ? registration

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3.2.8 photo preparation and viewing (cont.)

• Effective areas
• Definition central, bounded by lines bisecting
  the area of overlap with every adjacent
  photograph
• Advantages
• Cover entire photo without duplicate effort.
• The least relief displacement
• Construction ? transfer points
• Disadvantages of lelineating effective areas on
  each photos ? need twice efforts
• Sometimes, only for every other photo

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3.3 Basic photo interpretation equipment

• 3 purposes
• Viewing
• Making measurements
• Transfer interpreted information to base maps or
  digital databases

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3.3 Basic photo interpretation equipment (cont.)

• Binocular vision ? stereoscopic view ? 3-D view
• Stereopairs, stereograms
• Simple lens stereoscope (Fig 3.3)
• Test stereoscopic vision (Fig 3.4) (Table 3.2) ?
  elevation
• One-weak eyesight
• Cannot get stereoscopic view
• But still can be a good interpreter ? monocular
  view
• Viewing the stereogram without a stereoscope

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3.3 Basic photo interpretation equipment (cont.)

• Lens stereoscopes
• Fig 3.3
• Pros portable, cheap
• Cons cannot view the entire photo
• Lens spacing 4575mm
• Lens magnification typically 2 power

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3.3 Basic photo interpretation equipment (cont.)

• Mirror stereoscopes
• Fig 3.5
• Pros broader view, a pair of 240 mm photos,
  measurable.
• Cons large and costly
• Magnification 24 power

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3.3 Basic photo interpretation equipment (cont.)

• Scanning mirror stereoscope
• Fig 3.6
• Built-in provision
• Magnification 1.54.5 power
• Zoom stereoscope
• Fig 3.7
• Continuously variable magnication of 2.510(520)
  power.
• Image in each eyepiece ? rotate 3600
• Expensive, precision, high resolution

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3.3 Basic photo interpretation equipment (cont.)

• Light table
• Fig 3.8
• For transparency
• Balance the spectral characteristics of the film
  and lamps for optimum viewing condition
• Color temperature 3500k ? black body heat at
  3500k
• Noon daylight5500k
• Indoor tungsten bulb 3200k
• Distance measurement
• Low accuracy ? cheaper
• e.g. a triangular engineers scale or metric scale

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3.3 Basic photo interpretation equipment (cont.)

• Area measurement
• Extremely accurate measurement
• see 4.9, 4.10
• Direct measurement
• Error sources ? measuring device, relief, tilt ?
  better to use vertical photos with low relief.
• Dot grid (Fig 3.9)
• Polar planimeter (Fig 3.10)
• Electronic coordinate digitizer (Fig 3.11)

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3.3 Basic photo interpretation equipment (cont.)

• Interpretation information map
• Different size (map and photo)
• Zoom Transfer Scope (Fig 3.13)
• Color additive viewer (Fig 2.42)

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3.4 Land use/ land cover mapping

• Land cover
• The type of feature present on the surface of the
  earth
• Land use
• Human activity or economic function associated
  with a specific piece of land.
• A knowledge of both land use and land cover can
  be important for land planning and land management

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3.4 Land use/ land cover mapping (cont.)

• USGS land use and land cover classification
  system
• Land use and land cover should not be intermixed
  , but practically, land cover ? land use
• but also need some additional information sources
• Use categories rather than specific information

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3.4 Land use/ land cover mapping (cont.)

• USGS land use and land cover classification
  system (cont.)
• Designed criteria
• 85 accuracy
• Same accuracy for the several categories
• Repeatable from one time of sensing to another
• Applicable over extensive areas
• Infer land use

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3.4 Land use/ land cover mapping (cont.)

• USGS land use and land cover classification
  system (cont.)
• Designed criteria (cont.)
• Use for different time of a year
• Divisible categories
• Aggregation of categories
• Comparison with future data
• Recognize multiple uses of land

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3.4 Land use/ land cover mapping (cont.)

• USGS land use and land cover classification
  system (cont.)
• Table 3.3 level I, II
• Also provide level III IV, but it is intended to
  let the local users to design level III, IV. (Fig
  3.14)
• Reviewing and revising ? more wetland classes
• Table 3.4 Representative image interpretation
  formats for various classification levels.
• General relationship, not restriction.
• Minimum size of land use/land cover units mapped
  at various classification levels.
• The smallest representative area on a map 2.5mm x
  2.5mm.

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3.4 Land use/ land cover mapping (cont.)

• Level I classes
• Urban or built-up land ? take precedence
• Agricultural land ? drained wet lands for
  agriculture
• Rangeland
• Forest land ? tree-crown areal densitygt10
• If has wet land characteristics ? wet land
  category
• Water

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3.4 Land use/ land cover mapping (cont.)

• Level I classes (cont.)
• Wetland
• Shallow water with submerged ? vegetation water
  class
• Short-lived wetness or flooding ? wetland
• Cultivated wetlands ? agricultural land
• Uncultivated wetland ? wetland
• Drained wetland for other purposes ? other
  classes
• Barren land vegetation or other cover lt1/3
• Tundra treeless regions beyond the geographic
  limit of the boreal forest and above the
  altitudinal limit of trees in high mountain
  ranges.
• Perennial snow or ice areas

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3.4 Land use/ land cover mapping (cont.)

• USGS land use/land cover classification system
  maps
• 1250,000
• For most categories a minimum map unit 16 ha
• Some ? 1100,000
• Digital data
• vector format
• raster format (grid cell size 4 ha)

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3.5 Geologic and soil mapping

• Complex and variable earth surface
• Topographic relief and material composition
• Reflect the bedrock, unconsolidated materials,
  agents of charge.
• Rock type, fracture, effects of internal
  movement, erosion,
• Bear the imprint of the processes that produced
  them

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3.5 Geologic and soil mapping (cont.)

• Geomorphological principles
• Airphoto interpretation geological and soil
  mapping
• Identify and evaluate materials and structures.
• Geological mapping
• History of development 1913, 1920, 1940..
• Identify landforms, rock types, rock structure,
  portray geological units and structure and
  spatial relationship.
• explore mineral resource.
• Far below the surface and inaccessible region
• R.S. ? potential area ? drill holes

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3.5 Geologic and soil mapping (cont.)

• Geological mapping (cont.)
• Multistage image interpretation
• 1250,000, 1100,000 ? 158,0001130,000 ?
  120,000
• Lineaments regional linear features ? linear
  alignment of regional morphological features ?
  streams, escarpments, mountain ranges, tonal
  features (fractures or fault zones).
• Scales a few hundreds of km
• Important in mineral resource studies ? ore
  deposition
• Detection ? angular relationship. (Fig 3.16)

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3.5 Geologic and soil mapping (cont.)

• Geological mapping (cont.)
• Ronchi grid
• A diffraction grate 78 lines/cm
• grid ? suppressed
• ? grid ? enhanced.
• Lithologic mapping
• The mapping of rock units
• Stereoscopic viewing ? enhance
• See 3.15

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3.5 Geologic and soil mapping (cont.)

• Geological mapping (cont.)
• Geobotany
• The relationship between a plants nutrient
  requirements and 2 interrelated factors the
  availability of nutrients in the soil and the
  physical properties of the soil, including the
  availability of soil moisture indirect indicator
• Distribution of vegetation ? (indirect indicator)
  ?
• composition of the underlying soil and rock
  materials
• Geobotanical approach to geologic mapping ?
  Cooperative effort among geologists, soil
  scientists and field-oriented botanists
• Identification of vegetation anomalies related to
  mineralized areas.

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3.5 Geologic and soil mapping (cont.)

• Geological mapping (cont.)
• Geobotany (cont.)
• Geobotanical anomalies
• Anomalous distribution of species and/or plant
  communities
• Sturted growth and/or decreased ground cover
• Alteration of leaf pigment and/or physiographic
  process that produce leaf color changes.
• Anomalous charges in the phenologic cycle.
• e.g. early foliage change senescence in the
  fall.
• alteration of flowering periods,
  late leaf flush
• Taking photos several times during the year.
• Establishing normal condition ? identify
  anomalous
• Band 1.6 um 2.2 um are important for mineral
  exploration and lithologic mapping.

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3.5 Geologic and soil mapping (cont.)

• Soil mapping
• Soil survey ? resource information ? land use
  planning
• Trained scientists extensive field works
  airphoto interpretation ? identify soil
  delineate soil boundaries.
• Airphoto interpretation ? 1930s Panchromatic
  aerial photos 115,840140,000

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3.5 Geologic and soil mapping (cont.)

• Soil mapping (cont.)
• Agricultural soil survey (Fig 3.17, Table 3.6)
• USDA, 1900s.
• 1957 ? publish
• 1980s ? many counties ? line maps or digital form
• Purposes
• Estimating crops
• Evaluating rangeland suitability
• Determine woodland productivity
• Assessing wildlife habitat conditions
• Judging suitability for various recreational uses
• Judging suitability for various development uses

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3.5 Geologic and soil mapping (cont.)

• Soil mapping (cont.)
• The reflection of sunlight from bare soil
  surfaces
• Soil moisture content
• Soil texture
• Surface roughness
• Iron oxide
• Organic matter content

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3.5 Geologic and soil mapping (cont.)

• Soil mapping (cont.)
• Plate 8 different appearance of one field during
  one growing season
• Soil parent materials glacial meltwater deposits
  of stratified sand and gravel overlain by 45150
  cm of loess (wind-deposited silt)
• (a), (b), (c)
• corn plants 10 cm
• 2.5 cm rain fall
• uniform ? patchiness
• dry ? high infiltration slight mound
• wet ? low infiltration receive runs off

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3.5 Geologic and soil mapping (cont.)

• Soil mapping (cont.)
• Plate 8 (cont.)
• (d), (e), (f)
• corn plants 2m
• little rain fall
• dry ? leaves and stalks drying out and turn
  brown.
• wet ? continuing to grow and still green
• Soil scientist ? four classes. (Fig 3.18 Table
  3.7)
• Certain times of the year are better suited to
  aerial photography for soil mapping purposes than
  others.

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3.6 Agricultural applications

• Big picture direct application
• Crop type classification (and area inventory)
• Spectral response and photo texture? identify
  crop type
• Require a knowledge of the developmental stages
  of each crop in the area to be inventoried?
  crop calendar
• Use photographs taken on several dates during the
  growing cycle for crop identification
• Color infrared films are better than
  panchromatic film

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3.6 Agricultural applications (cont.)

• Crop type classification (cont.)
• Stereoscopic coverage ? plant height ?
  discrimination
• Table 3.8 dichotomous airphoto interpretation
  key? use single-date panchromatic photography ?
  only broad classes of crops are to be
  inventories.
• Fig 3.19 demonstrate the importance of date of
  photography, photo tone and texture, and
  stereoscopic coverage.

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3.6 Agricultural applications (cont.)

• Crop condition assessment
• Large scale airphotos ? documenting deleterious
  conditions ? crop disease, insect damage, plant
  stress, disaster damage.
• Table 3.9 typical crop management information
  potentially obtainable from large scale color
  infrared aerial photographs.

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3.6 Agricultural applications (cont.)

• Crop condition assessment (cont.)
• Detailed within field interpretations of soil and
  crop condition? fertilizer spreaders and
  irrigators? crop management activities ?
  fn(geolocation)
• Detected plant diseases
• detected insect damage
• other detected damage
• A difficult task ? finer differences in spectral
  response

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3.6 Agricultural applications (cont.)

• Crop yield estimation
• Simple straightforward ? area yield/area ?
  yield
• Complex ? soil moisture, soil fertility, air and
  soil temperature, disease, insect stress,..
• Crop yield prediction ? climatic meteorological
  conditions.
• Traditional approach area yield/area
• (airphoto interpretation) (field
  inspection)
• Direct approach ? historical information ?
  deviation

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3.6 Agricultural applications (cont.)

• Other applications
• Determine areas ? erosion control, weed control
  fertilizing, replanting, fencing or other
  remedial measures
• Taxation real estate purposes
• Assessment of irrigation systems
• Farm livestock surveys

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3.7 Forestry applications

• 1/3 of the worlds land area
• Tree species identification
• More complex than crop identification.
• Complex mixture ? more uniform
• Forest understory
• Step 1 elimination
• Step 2 establish groups
• Step 3 identify individual species
• Shape size
• Fig 3.20 Silhouettes of forest trees
• Fig 3.21 Aerial views of tree crowns.
• Pattern Shadows

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3.7 Forestry applications (cont.)

• Tree species identification (cont.)
• Tone ? relative tones
• Texture ? tufted, smooth, billowy
• Fig 3.22, Fig 3.23
• Black spruce
• coniferous, slender crowns, pointed tops.
• even height or change gradually
• carpetlike appearance
• Aspen
• deciduous, rounded crowns
• widely spaced, variable in size and density
• Balsam fir
• symmetrical coniferous, sharply pointed tops
• thicker than black spruce
• erratic changes in size ? uneven and irregular
  pattern

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3.7 Forestry applications (cont.)

• Tree species identification (cont.)
• Fig 3.22, Fig 3.23 (cont.)
• Fig 3.22 Black spruce ? Aspen
• Fig 3.23 Balsam fir ? Black spruce (mixture)
• Art
• Scale does matter
• Table 3.10, 3.11? Airphoto interpretation key
• Phenological correlations
• Changes in the appearance in the different
  seasons of the year
• e.g. separation of deciduous and evergreen trees
• e.g. difference in the time at which species leaf
  out

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3.7 Forestry applications (cont.)

• Timber cruising
• Objective determine the volume of timber that
  might be harvested from an individual tree of a
  stand of trees
• To be successful ? skilled interpreter aerial
  and ground data
• Photo measurements
• Tree height or stand height ? measuring relief
  displacement or image parallax.
• Tree-crown diameter ? distance measurements
• Density of stocking
• Stand area

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3.7 Forestry applications (cont.)

• Timber cruising (cont.)
• Photo volume tables
• Multiple regression (extracted data, ground data)
• Volume of individual trees fn(species, crown
  diameter, height)(Table 3.12)
• For large scale photos, scattered trees in open
  areas.
• Table 3.13 stand volume table

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3.7 Forestry applications (cont.)

• Assessment of disease and insect infestations
• Panchromatic photos ? often used
• Medium and large scale color and color infrared
  photos ? most successful surveys
• Tree disease
• Insect damage
• Forest damage
• Plate 9 gypsy moth defoliation of hardwood trees.

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3.7 Forestry applications (cont.)

• Additional applications
• Success ? high quality reference data

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3.8 Rangeland applications

• Definition see 2.4
• Provide forage, support land use (agriculture,
  recreation housing)
• Range managers use air photos in much the same
  way as do foresters.
• Main concern vegetation change over time
• Forage yield estimation.

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3.9 Water resource applications

• Water resources irrigation, power generation,
  manufacturing, recreation,
• Airphoto ? monitor ? quality, quantity,
  distribution
• Interaction of sunlight and water
• Absorptionfn(l)
• near-infrared ? a few tenths of a meter ? dark
  tone
• 0.480.6um ? best penetration (1520m) ?
  underwater haze
• red ? few meters

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3.9 Water resource applications (cont.)

• Analysis of underwater features
• White sand bottoms
• normal color film ? blue-green
• color infrared (yellow filter) ? blue
• Fig 3.24 color and color infrared photos for
  Hanauma Bay

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3.9 Water resource applications (cont.)

• Water pollution detection
• Polluted water ? impurities ?? limit its use
• Natural sources of pollution
• e.g. minerals leached from soil and decaying
  vegetation
• Point source
• e.g. industrial outfalls
• Non-point source
• e.g. fertilizer and sediment runoff.

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3.9 Water resource applications(cont.)

• Water pollution detection (cont.)
• Materials (excessive amounts) ? water pollution
• Organic wastes
• Infections agents
• Plant nutrients
• Synthetic-organic chemicals
• Inorganic chemical and mineral substances
• Sediment
• Radioactive substances
• temperature

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3.9 Water resource applications(cont.)

• Water pollution detection (cont.)
• Air photo
• ? type and concentration?
• ? discharge point dispersion
• in some instances ? it is possible to make valid
  observations about sediment concentrations using
  quantitative photographic radiometry coupled with
  the laboratory analysis of selective water
  samples.
• Fig 3.25 dispersal plume of silt-laden water
  flowing into a lake
• Air photos ? enforcement of antipollution law
• Oil film on water (Fig 3.26)
• Oil slicks
• Oil sheens
• Oil rainbows

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3.9 Water resource applications(cont.)

• Lake eutrophication assessment
• Trophic state
• Eutrophic state (nutrient rich)
• Oligotrophic (low nutrient, high Oxygen)
• Eutrophication the general process by which
  lakes age
• Different people ? different levels of
  eutrophication that can be accepted
• Air-photo ? mapping aquatic macrophytes
• Table 3.14 interpretation key
• Algae concentration ? good indicator of a lakes
  trophic status

63
3.9 Water resource applications(cont.)

• Flood damage estimation
• Fig 3.27 multi-date sequence and aftereffects.
• A. normal appearance
• B. peak of a flood.
• C. 3 weeks after flooding
• D. 6 weeks after flooding
• Crop damage
• Streaked pattern of light-toned lines ? direction
  of flood flow.
• Fig 3.28
• For flood damage assessment
• B is clean than a
• Refer to Fig 6.12b for satellite image

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3.9 Water resource applications(cont.)

• Other Applications
• Vegetation index
• Ground water location
• Groundwater discharge areas ? well
• Groundwater recharge zone ? protect
• Hydrologic watershed assessment
• Reservoir site selection
• Shoreline erosion studies
• Snow cover mapping
• Survey of recreational use of lakes and rivers

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3.10 Urban and regional planning applications

• Timely, accurate and cost-effective sources of
  data (requirement)
• Population estimates.
• Air-photo ? dwelling units of housing type
• Housing quality studies
• Statistical analysis of a set of environmental
  quality factors. e.g. house size, lot size,
• Traffic and parking studies
• Traditional on-the-ground vehicle count
• Air-photo ? shows distribution ? area of
  congestion

66
3.10 Urban and regional planning applications
(cont.)

• Various factors RS photo ? data ? GIS Analysis
• Transportation route location
• Sanitary landfill site selection
• Power plant sitting
• Transmission line location
• Fig 3.29 urban change detection

67
3.11 Wetland mapping

• Significance of wetland
• Retain water
• Reduce flood level
• Trap suspended solids and attached nutrients ?
  clear lake
• For wildlife (drinking and stopping)
• Species diversity and food web.
• Biological record
• recreation

68
3.11 Wetland mapping (cont.)

• Purpose (multi-or single-) ? inventory
• 3 basic elements for identifying wetland
• Hydrophytic vegetation
• Hydric soils
• Wetland hydrology
• Fig 3.30 color infrared photo for wetland mapping
• Fig 3.31. Wetland vegetation map
• Table 3.15 airphoto interpretation key.

69
3.12 wildlife ecology applications

• Wildlife
• Wildlife ecology
• Wildlife conservation
• Wildlife management

70
3.12 wildlife ecology applications (cont.)

• Wildlife habitat
• Combination of climate, substrate and vegetation
• Niche
• All mapping techniques are applicable
• edges delineation
• GIS
• Fig 3.32 Wildlife habitat types in Sheboygan
  Marsh
• 9 vegetation classes ? 5 wildlife habitat types
• Muskrat hut ? in AV area, 100 white spots

71
3.12 wildlife ecology applications (cont.)

• Wildlife censusing
• Ground survey aerial visual observation
• Problems of counting
• Quick decision?
• Aggregation?
• Low-flying aircraft ? disturb
• Best method vertical aerial photography
• Accurate counting
• Normal patterns of spatial distribution
• Permanent record
• Prolonged study ? more information
• Only valid for those open areas during daytime

72
3.12 wildlife ecology applications (cont.)

• Wildlife censusing
• Scalefn(animal size)
• Film-filter ? high contrast (Fig 2.18)
• Digitize ? computer-aid counting
• Fig 3.33 Prairie dog colony
• Fig 3.34 Beluga whales
• Calve
• Number length
• Bachelor group

73
3.13 Archaeological application

• Airphotos ? locate sites whose existence has been
  lost to history
• Both surface and subsurface features
• Surface features
• Visible ruins e.g. Stonehenge, castles, Indian
  dwelling.
• Mounds e.g. bird-shaped and serpent-shaped
  Indian mounds.
• Rock structures e.g. Bighorn Medicine Wheel,
  mounds
• Fig 3.35 Nazca lines

74
3.13 Archaeological application (cont.)

• Subsurface features
• e.g. buried ruins of buildings, ditches, canals,
  roads
• Tonal anomalies in soil moisture, crop growth,
  ephemeral difference in frost patterns
• Fig 3.36 ancient city of Spina
• A city of canals and waterways.
• Dark-toned linear feature ? dense vegetation ?
  wet location ? former canals
• Light-toned rectangular areas ? sparse vegetation
  over sand ? brick foundation
• Light-toned linear feature ? present-day drainage
  ditches.

75
3.13 Archaeological application (cont.)

• Subsurface features
• Fertile loess soils over the white chalk bedrock
  (foundation)
• Fig 3.37 deep winter plowing ? scraped the
  foundation ? brought up chalk
• Fig 3.38
• recent conversion from pasture to cropland ? few
  fertilizer
• over the foundation ? light toned.

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3.14 Environmental assessment

• Human activities ? adverse environmental effects.
• U.S. NEPA (1969)
• Environment impact statements
• Key items
• Environmental impact
• Cannot-avoided impact
• Alternatives
• Relationship(short- long-term)
• Irreversible and irretrievable commitments

77
3.14 Environmental assessment (cont.)

• Principal biophysical effects of human activity
  on environment
• Change natural drainage conditions
• Change water turbidity temperature
• Chemical pollutants
• Change in vegetation
• Change wildlife population and distribution
• US. RCRA

78
3.14 Environmental assessment (cont.)

• Airphotos
• EPAs principal remote sensing tools
• e.g. emergeray response photography to the
  spillage of hazard materials
• e.g. site analyses of waste sites
• Historical photos
• Drainage conditions
• e.g. site analyses of waste sites
• Historical photos
• Drainage conditions
• e.g. locate potential sites for drilling and
  sampling of hazardous wastes
• e.g. identification of failing septic systems

79
3.15 Principles of landform identification and
evaluation

• Significance of terrain characteristics
• Airphotos ?
• Bedrock type
• Landform
• Soil texture
• Site drainage conditions
• Susceptibility to flooding
• Depth of unconsolidated materials over bedrock
• Slope of land surface.

80
3.15 principles of landform identification and
evaluation (cont.)

• Soil characteristics
• Definition
• e.g. 10m deposit (C) 9m unaltered (B) 1m
  weathered (A)
• Engineering ABC
• Soil science (pedological) AB
• Soil horizon
• A horizon surface soil topsoil
• 060cm, 1530cm
• Weathered horizon
• Most organic matter
• B horizon subsoil
• 0250cm, 4560cm
• Fire-textured particles from A horizon
• C horizon parent material

81
3.15 principles of landform identification and
evaluation (cont.)

• Soil characteristics (cont.)
• Three origins of soil materials
• Residual soils
• Transported soils
• Organic soils
• Table 3.16 soil particle size designations.
• Siltclay 50fine texture
• Sandgravelgt 50 coarse texture
• For residual soil texture ? BC
• For transported soil texture ? parent material
• USDA soil drainage classes (7 classes) ? natural
• Artificial drainage

82
3.15 principles of landform identification and
evaluation (cont.)

• Land use suitability evaluation
• Topographic characteristics
• For subdivision development
• 26
• Steep enough for good surface drainage
• Flat enough ?no site development problems
• 02 ? may have some drainage problems
• 612 ? more interesting but more costly
• gt12 ? problem in street and lot design, as well
  as domestic sewage disposal
• gt20 ? severe limitation
• For industrial park and commercial site ? lt 5
• Soil texture and drainage conditions
• Well-drainedcoarse texture soils ? few limitation

83
3.15 principles of landform identification and
evaluation (cont.)

• Land use suitability evaluation (cont.)
• Groundwater tables
• Shallow ? problems in septic tank
• At least 2m
• Depth of bedrock
• Prefer gt 2m
• 12m may be feasible in some cases
• Soil-slope condition
• Slope stability analysis ? not discussed
• Incipient landslide failure ? detectable using
  airphoto

84
3.15 principles of landform identification and
evaluation (cont.)

• Elements of airphoto interpretation for landform
  identification and evaluation
• Topography
• A distinct topographic change at the boundary
  between two different landforms.
• Drainage pattern and texture
• Indicators of landform, bedrock, soil, drainage
  conditions
• Fig 3.39 six basic drainage patterns ? destruct
  ional from erosion
• Dendritic
• Rectangular
• Trellis
• Radial
• Cantripetal
• Deranged

85
3.15 principles of landform identification and
evaluation (cont.)

• Elements of airphoto interpretation (cont.)
• Drainage pattern and texture (cont.)
• Fig 3.40
• Coarse-textured?good internal drainage
• Fine-textured?poor internal drainage
• Erosion
• Gullies
• The smallest drainage feature from airphotos
• A meta wide and a hundred meters long
• Formation rainfall?not percolate
  ?rivulets?runoff?enlarge
• Fig3.41
• V-shape sand gravel
• U-shape silty soils
• Long with gently rounded silty clay, clay

86
3.15 principles of landform identification and
evaluation (cont.)

• Elements of airphoto interpretation (cont.)
• Photo tone
• Brightness
• Use relative tone values
• Fig 3.54
• Lighter tone ? higher position
• Varying soil moisture content ? different
  sunlight reflection ? mottled tonal pattern
• Capillary action ? tonal gradients ? boundary
  sharpness
• Color or color infrared ? same principle

87
3.15 principles of landform identification and
evaluation (cont.)

• Elements of airphoto interpretation (cont.)
• Vegetation and land use
• Indicator, but in many cases, they are obscured
• The airphoto interpretation process
• Initially ? consider all elements
• After some experience ? subconsciously
  instantaneously
• Humid climates ? gt50 cm rainfall per year
• Arid climates ? lt50 cm rainfall per year
• Airphoto interpretation ? field operation
• Verify
• suggestion

88
3.16 Bedrock landforms

• Horizontally bedded sandstone
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.43

89
3.16 Bedrock landforms (cont.)

• Horizontally bedded shale
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.44

90
3.16 Bedrock landforms (cont.)

• Horizontally bedded limestone
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.45

91
3.16 Bedrock landforms (cont.)

• Horizontally bedded granitic rocks
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.46

92
3.16 Bedrock landforms (cont.)

• Horizontally bedded lava flows
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.47

93
3.17 Aeolian landforms

• Sand dunes
• Formation
• Fig 3.48

94
3.17 Aeolian landforms (cont.)

• Sand dunes (cont.)
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.49

95
3.17 Aeolian landforms (cont.)

• Loess
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.51

96
3.18 Glacial landforms

• Formation
• Repeated advances of glacial ice over 30
• Glaciation forms
• Valley glaciation
• Continental glaciation
• Ice move ? abrade and pluck
• Glacial drift
• Materials deposite by glaciation

97
3.18 Glacial landforms (cont.)

• Till landforms
• Repeated advances of glacial ice over 30
• Glaciation forms
• Valley glaciation
• Continental glaciation
• Ice move ? abrade and pluck
• Glacial drift
• Materials deposite by glaciation

98
3.18 Glacial landforms (cont.)

• End moraines
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.53

99
3.18 Glacial landforms (cont.)

• Basal ground moraine area
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.54

100
3.18 Glacial landforms (cont.)

• Drumlins
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.55

101
3.18 Glacial landforms (cont.)

• Eskers
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.56

102
3.18 Glacial landforms (cont.)

• Outwash sediments
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.57

103
3.18 Glacial landforms (cont.)

• Glacial lakebeds
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.58

104
3.18 Glacial landforms (cont.)

• Beach ridges
• Airphoto identification
• Topography
• Drainage and erosion
• Photo tone
• Vegetation and land use
• Fig 3.59

105
3.19 Fluvial landforms

• Formation
• Flowing water ? erosion transportation
  deposition
• fn(water velocity, particle size)
• Stream competence the maximum-size particles a
  stream can transport at a given velocity
• Stream capacity the maximum amount of materials
  the stream can transport and is related to stream
  volume

106
3.19 Fluvial landforms (cont.)

• Alluvial fans
• Airphoto identification
• Topography fan shape
• Drainage and erosion
• excellent internal drainage
• limited surface drainage with few gullies
• Numerous distributary channels
• Photo tone
• Generally light, but distributary channels may be
  darker
• Vegetation and land use
• Lack of vegetation
• May be heavier vegetation at base

107
3.19 Fluvial landforms (cont.)

• Alluvial fans (cont.)
• Fig 3.60
• Slope apex (10) ? valley (12) ? base (8)
• Darker tone and vegetation near the base of fan

108
3.19 Fluvial landforms (cont.)

• Floodplain
• Airphoto identification
• Topography
• Generally level with small downstream gradient
• Natural levees slightly higher position
• Slack water deposits in lowest position
• Drainage and erosion
• Principal stream flow
• Wide floodplain ? second stream
• High groundwater table
• Photo tone
• Point bar deposits, natural levee ? light tone
• Slack water deposits ? darker tone
• Oxbow ? uniform gray tone
• Vegetation and land use
• Often agricultural use

109
3.19 Fluvial landforms (cont.)

• Alluvial fans (cont.)
• Fig 3.61
• Present channel (PC)
• Abandoned channel (AC)
• Point bar deposits (PB)
• Oxbow lake (OX)
• Slack water deposit (SW)

110
3.19 Fluvial landforms (cont.)

• Delta
• Type
• Arcuate delta e.g. the Nile Delta
• Birdfoot delta e.g. the Mississippi Delta
• Fig 6.13

111
3.20 Organic soils

• Formation
• Continuous water saturation ? limit the
  circulation of O2 ? decomposition of organic
  matter? ? accumulation ? organic matter gt
  mineralization ? muck or peat
• Characteristics
• Typically begins in lakes or ponds
• Poor foundations for construction activities
• If over drain ? irreversible hardening
• If too dry ? fire hazard

112
3.20 Organic soils (cont.)

• Airphoto identification
• Found
• Topographic depressions (moraine, ground moraine,
  floodplain, oxbows)
• Depression between sand dunes, beach ridges
• Limestone sinkhole
• Kettle hole
• Topography
• Very flat, often sharp contrast with surrounding
  material

113
3.20 Organic soils (cont.)

• Airphoto identification (cont.)
• Drainage and erosion
• Poorly drain, few gullies
• Farm ? artificially drain
• Photo tone, vegetation and land use
• Bare soil ? dark tone
• Drained agricultural areas ? distinctive pattern

114
3.20 Organic soils (cont.)

• Fig 3.62
• Organic soils
• Glacial till, drumlin
• Well drained, cultivated
• 2m 5m Fibrous peat in a former glacial lakebed
• 8095 organic matter, 520 mineral matter