Imagery

Satellites & Aerial Photos


Satellite Image

Source

The satellite image used here is from 1993 Thematic Mapper Satellite Images. Several images are placed together in a mosaic to make one image, with the edges smoothed digitally by the graphic cartographer. The map was obtained from the LDEQ, and USGS. These agencies prepared the map by:

1) Georectifying it: giving it a scale and orienting it to known reference points (latitude and longitude).

2) Classifying it: making all similar areas on land have a similar colors on the map. For example all the agricultural fields are one color and all of the urban areas another color.

This website makes use of the image through the work of geographic information systems personnel at the South Central Planning and Development Commission who digitally cut out the area within the Barataria-Terrebonne watershed and superimposed smaller watershed boundaries on the image.

Interpretation

 

The piece of the image above is from the Barataria Basin. It shows forested areas in green, water in colors ranging from blue to black and marsh in gray to green. While these seem very realistic, an urban area across the Mississippi River from New Orleans is shown in the top center of the image above. Notice it is pink to silver. Urban areas tend to be silver in this image and agricultural fields are generally pink.

Look closely at this image to see how much detail it shows versus the aerial photos. Which shows more detail?


Aerial Photos

Source

The aerial photos used in this web site are not actually even aerial photos - they are digital orthophoto quarter quadrangles, or more simply DOQQs. DOQQs are different from aerial photographs in that they are Georectified to remove distortions and add scale. The scale of each DOQQs used on this web site is shown on the image.

The source of the DOQQs is the US Geological Survey. Click here to find out more about DOQQs of this area and other area: http://geography.wr.usgs.gov/doq/

As with the Satellite Image, the DOQQs were cut to the outlines of specific small watersheds in Barataria and Terrebonne Basins by the geographic information systems personnel at South Central Planning and Development Commission.

Interpretation

 

 

Many of the features you can see on the DOQQs show natural features and evidence of human activity. Sometimes you can see evidence of activity that can lead to pollution.

For example, natural features in the image above left include an ox bow lake parallel to ridges (highlands) and swales (lowlands) and the occasional linear lake. Forested areas are green. Human-made features in this image are primarily agricultural fields, which are various shades of pink. Another human feature in this image is an industrial plant, which has ponds for cooling or pollution control.

Above right the natural features include freshwater marshes, marsh ponds, and a small area of forested wetland (pink). Human-made features include canals dredged for access into the marsh, probably for oil and gas production.

Features to look for on all images include: roads, canals (very straight, linear bodies of water), agricultural fields (adjoining squares or rectangles in shades of green and pink), urban areas tiny adjoining, industrial areas, roads and canals. Sometimes you can see square water bodies: These may be 1) marshes that were surrounded with levees for agricultural use, and that later subsided (sank) from lack of sediment input; 2) industrial plant pollution control or cooling ponds; 3) city sewage treatment. Sometimes the city sewage treatment has circular water bodies.

© BTNEP: Barataria Terrebonne National Est all Rights Reserved