i think thermal remote sensing will give some clue.. or you can try high resolution data which will provide the detail picture and extract the features by taking separated from others.

pls have a look

http://www.trans-servisgroup.ru/pdf/trans-servis_-_advertising_material_(thermal_remote_sensing).pdf.

or

http://www.netl.doe.gov/kmd/cds/disk37/B%20-%20Native%20American%20Program/NT15453_Final%20Presentation,%20Feb%202004.pdf.

Thanks a million, Bharath Setturu for your answer. It is really resourceful.