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A critical desertification problem facing the Egyptian government is the expansion of urban centers onto productive agricultural lands. Timely and accurate information is needed by national planners to identify the rate of urban growth. In this study, the rate of urban expansion and corresponding loss of agricultural lands is evaluated for two cities in the Nile Delta. The extent of urban areas identified on SPOT images acquired in 1987 and 1995 is compared to areas identified on a topographic map published in 1950. For both cities, the rate of urban growth was much greater during the more recent 1987-1995 period than during the earlier 1950-1987 period.

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Tel. : 980137 Senior Researcher Senior Researcher Soil dnd Water Hesearch In�ti tute, Gamaa St., Giza, Egypt. The u�e of portable ground-based sensors for measuring crcp reflectance has created a need for comparable and reliable measurements procedures capable of providing caliberated and reproducible canopy reflectance data.It could be said that the mea�urement of spectral characteristics of the main field crop�, using hand-held radiometer, i� a suitable means for their identification on satellite images.Also, it will help in understanding thei.r spectral �eperability which, in-turn, could assist computer-aided classi.fication of crops on satellite digital data. Spectral signature is one of the useful tools in the analy�is'of LANDSAT digital data as it forms the basis of identification alld discrimination between variuos field crops and features on earth.The objective of the current study aims at correlating ground bidirectional spectral reflectance data of cotton and rice field crops throughout their growing seclson with high altitude remotely sensed data. Using hand-hel" spectrol-adiometer having four wavelength bands of the LANDSAT multispectral scanner .(MSSJ, enables us to collect in situ temporal spectral measurements of cotton and rice field crops.Green, red and infrared reflectances are closely related to the agronomic and physiological properties of both crops �uch a� plant heigi