The expansion of agriculture into adjoining desert areas can be studied with the help of satellite images obtained from Landsat. You can find the satellite images of the environmental change here:

http://earthshots.usgs.gov/Nile/Nile

http://earthshots.usgs.gov/Nile/Nile1987

An investigation procedure for the students can be found here:

http://edmall.gsfc.nasa.gov/inv99Project.Site/Pages/trl/inv1-5.abstract.html

http://edmall.gsfc.nasa.gov/inv99Project.Site/Pages/trl/inv1-5.abstract.html

USGS Satellite Images for 1973 and 1987 show the dramatic urban growth within the Nile River delta and the expansion of agriculture into adjoining desert areas.[