Cairo
I make the same comments about long term sustainability for the city of Cairo, the capital of Egypt, as I have for Dallas-Fort Worth. The contrasts between Cairo and Dallas-Fort Worth are extreme. Nevertheless they share a characteristic - rapid growth - which cannot go on indefinitely.
The city of Cairo lies astride the Nile River at the southern end of the Nile Delta. The Nile Valley and the Nile Delta together comprise some 3% of the total area of Egypt, but they are practically the only permanently habitable areas of the entire country.
Three Landsat FCC images of Cairo, Egypt: May 10, 1973; July 18, 1987; and the 1973-1987 difference image.
Use your browser to open each image in a new window to compare them.
Essentially, the entire population of Egypt, some 60 millions, is dependent upon the flood plains of the Nile to supply food. The rich soils and the availability of water have nurtured human civilisation in Egypt for some 10 000 years. The soil and water resources of the Nile floodplains are the only agricultural resources Egypt has. They are resources, the value of which is increasing in value to Egyptian society as its population grows. It grows at a spectacular and distressing rate.
The population of greater Cairo (including Giza and Imbaba) has increased five-fold since the 1950s; a staggering 10% per year. By far the largest proportion of this population increase is choosing to live in urban areas: in Cairo, Alexandria, the large towns, small towns, and the villages.
The changing extent of the urban areas around Cairo is plainly visible from space. The intensively cultivated agricultural areas of the Nile Valley and Nile Delta change very little between 1973 and 1987. The fields are very, very small. The only large scale imprints of agricultural technology are the canals distributing water from the main channel of the Nile. The desert surrounds of the Nile are completely without vegetation, yet 8 000 ago the Pharaohs hunted gazelle in grasslands where now there are only bare dunes.
Cairo is spatially and spectrally distinct from Dallas-Fort Worth. The spatial pattern of its buildings and roads is much finer than that of Dallas-Fort Worth. It is a city that was definitely not designed for the automobile, yet today its always hot streets are crowded with them and with trucks, donkeys, camels, and myriads of people.
The nature and history of Cairo can be inferred in part from its spectral signature, the light it reflects back to the Landsat MSS sensors 900 km out in space. Cairo is mostly a city built in the desert tradition of concrete and mud buildings huddled with almost no green space. There are very few parks or grassed recreation areas, and certainly no household lawns. The spectral contrast between the red agricultural areas and the grey built up areas is much the same for Cairo as it is for all the very much smaller villages spread throughout the Nile delta to the north.
Bearing these two characteristics in mind, the changes from 1973 to 1987 are readily detected.
The city urban complex of Cairo itself has grown considerably. It has extended right across the Nile Valley in a thick band. Cairo has also spread to the north-east, partly into the sandy deserts, but mostly into the agricultural lands of the Nile Delta.
Compared with Dallas-Fort Worth, the area lost to Urbanisation is much smaller, even though the size of the human population is at least 5 times greater in Cairo than in Dallas-Fort Worth. Cairo is a high-density, compact, but overcrowded city. Cairo swarms with people. Dallas-Fort Worth swarms with automobiles.
The population of Egypt lives in and is dependent on the Nile Valley and the Nile Delta. The obvious encroachment of Cairo into these lands and the irreversible conversion of a productive landcover into the non-productive cover of houses and roads is disturbing. It represents an irretrievable loss of a resource critical to the long term survival of the Egyptian people.
The scope and magnitude of this problem is bigger than just the city of Cairo. The same changes, the growth and expansion of urban settlements at the expense of agricultural landcover, are obvious right through the Nile Delta. From 1973 to 1987, scores of tiny villages have become noticeably larger. The red signature of vegetated cropland has been replaced by the mud grey of urban landcover. My eyeball assessment is that these multiple small scale changes in the Delta in aggregate are much larger than the expansion of Cairo itself.
