What is spectral reflectance?

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Hello, I am hydrologist but not an expert in GIS. I want to know what is spectral reflectance?How it is connected with remote sensing and GIS in the anlysis of water quality? Would like to get some expert'sexplanationon the topic.

3 Answers

  1. What I did leave out is heat pollution, infrared scanning can determine deference in temperature in a water body, e.g. a power station releasing hot water into a river, the extent and path of water can be tracked. I know of one proposal where they were going to try and identify groundwater inflow into a water body by looking at temperature difference, might be useful in hydrology!!

  3. A quick one minute answer – let me know if it is as clear as mud. Remote sensing is usually referring to satellite sensor collection of reflected sun light from the earth surface. Reflected light is captured in numerous band, colour bands, infra-red bands etc. Spectral reflection is the intensity number of the ‘light’ band captured in the various bands (spectrum). There are various methods developed that use ratios between bands to identify vegetation and soil types etc. Water usually comes out black i.e. absorbs all light, but if has high sediment load, algae, water plants, shallow depth (might get reflectance from underlying stream sediments) different reflectance values are obtained. With satellites covering the same area every few days one can do change detection on a water body. Amount of moisture in vegetation can be picked up – that’s a little more complicated.