Land Cover Interpretation and Mapping

1. Land Cover Interpretation and Mapping Supplemental Material Lecture 1 prepared by R. Lathrop 8/03

2. Land Cover vs. Land Use • Land Cover (LC): the biophysical material covering the earth’s surface • Land Use (LU): how humans are using the land surface • Examples land cover: impervious surface land use: parking lot land cover: grass land use: recreational field

3. LU/LC Classification systems • Classification system: systematic categorization of LU or LC types • Often hierarchical progressing from the general to the specific, e.g., level I --> level II --> level III • Examples: USGS LU/LC (Anderson et al., 1976) Coastal Change Analysis Program (CCAP) USF&WS NWI (Cowardin et al., 1979)

4. Existing USGS Land Cover Products National Land Cover Dataset 1992 (NLCD 92) A U.S. land cover classification product based primarily on 1992 Landsat Thematic Mapper (TM) data. MRLC2000 (Multi-Resolution Land Characteristics 2000) Selected ETM+ and TM scenes (Landsats 7 and 5) from the National Land Cover Characterization 2000 project. Land Use and Land Cover Data (LULC) Historical U.S. land use and land cover data derived from 1970`s and 1980`s aerial photography. Global Land Cover Characterization (GLCC) A global land cover database primarily derived from 1992 to 1993 1-km AVHRR data. For more info: http://edc.usgs.gov/products/landcover.html

5. Photo Interpretation Keys • Selective: made up of typical illustrations and descriptions of objects in a given category • Elimination: hierarchical, requires the user to follow a step-by-step procedure, working from the general to the specific

6. Mapping Considerations • Uncontrolled maps: prepared at photo scale by direct tracing. Area measurements no more accurate than from the photos directly, depends on flatness of the terrain • Controlled maps: transfer onto planimetric base map of uniform scale. Needed for precise measurement of area. • Minimum Mapping Unit: smallest area of land that is mapped as a separate unit or entity, depends on scale & user requirements

7. Visual Interpreting Land Cover • Remember the 7 photo recognition elements • Shape • Size • Shadows - shape & height • Tone/Color • Texture • Pattern • Site • Association

8. More on color: remember image color is a function of the spectral reflectance pattern of the object

9. A color example-plant leaves • Chlorophyll absorbs large % of red and blue for photosynthesis- and strongly reflects in green (.55um) um • Peak reflectance in leaves in near infrared (.7-1.2um) up to 50% of infrared energy per leaf is scattered up or down due to cell wall size, shape, leaf condition (age, stress, disease), etc. • Reflectance in Mid IR (2-4um) influenced by water content-water absorbs IR energy, so live leaves reduce mid IR return • In a CIR photo, Hi NIR ------------> Hi Red Very Lo Red ------------> Very Lo Green Very Lo to Lo Green -----------> Very Lo to Lo Blue As a result due to the additive color processes, the color would be Red to Magenta

10. Spectral reflectance characteristics are both spatially and temporally variable. For example, each leaf is different and can change

11. Photo Interpreting Natural Vegetation Communities • Site is important determinant of the vegetation community type due to differences in microclimate and soil characteristics (e.g. texture, moisture status). I.e., certain community types are associated with certain site types. • Topoclimate: north-facing aspects have a colder microclimate than south-facing aspects • Soil Catena: ridge-tops are drier than valley bottoms

12. Photo Interpreting Natural Vegetation Communities • To identify trees to species type, often need to identify by crown shape - either from a vertical perspective or shadowed silhouette • Photo interpretation keys available for this purpose • Remember as scale changes from large to small the crown shape of individual trees eventually merges to form the overall texture of the forest canopy

13. Vegetation Mapping Applications • Forest stand mapping for timber evaluation - species identification - timber volume: density, canopy closure, tree height • Plant vigor, disease and stress detection • Wildlife habitat mapping • Outdoor recreation capability surveys

14. Cultural Features Identification • Building size, shape and associated features • Major transportation routes: highways and rail-lines, canals/ports, airports • Street pattern and density • Open/green spaces: vegetation type and cover

15. Major categories of urban land use • Industrial • Commercial/service • Transportation/utilities • Institutional (schools, government) • Residential • Recreational

16. Industrial Classification Key • Extraction: characterized by excavations, piles, ponds, tanks, earth-moving equipment • Processing: characterized by bulk material storage, large processing equipment, power plant/smokestacks, waste piles/ponds • Fabrication: characterized by few facilities for storing bulk materials, 1 story warehouse type buildings, rail/truck transportation

17. Urban-Cultural applications • Parking and transportation studies • Residential development analysis indicators of housing quality real estate evaluation • Brown-fields location/evaluation • Open space location/evaluation

18. Engineering Applications • Large projects site location/evaluation • Transportation route location/selection • Construction material surveys • Natural hazard investigations • Post-disaster damage surveys • Monitoring disturbed land • Water pollution investigations