Soils and Water use Dept., National Research Center, Dokki, Cairo, Egypt.

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1 Scientific registration n : 2459 Symposium n :36 Presentation : poster Problem of urban encroachment in some areas of great Cairo (Egypt) Problème de l expansion urbaine dans quelques zones autour de l agglomération du Caire ( Egypte) RASHEED Mohamed Abbas, ABD El-RAHMAN Mohamed Soils and Water use Dept., National Research Center, Dokki, Cairo, Egypt. Remote sensing is used thoroughly in urban analysis, urban planning and urban development. Aerial photographs were used since 1940 s for defining the urban areas. However, the first large scale systematic use of such photographs to identify land dereliction started in the 1960 s (Collins and Bush 1969a, 1969b, 1971 and 1974). The current investigation aims to study the urban enchroachment against the fertile land and the desert in 3 locations of great Cairo Governorate, Egypt using the Aerial photographs as an article of remote sensing techniques. Location and Environmental Condition of Study Areas: Since urban enchroachment represents a great loss of arable land, thus the study sites were chosen within and outside the Nile Valley in Great Cairo Governorate (Figures 1,2 and 3). A number of 3 locations were undertaken to represent different spatial extension and environmental conditions. The remote sensing data used in studing each site was selected in accordance with the area of the site and the resolution of remote sensing data. Methodology: Monitoring and measuring of urban areas: Aerial photographs at scale 1:10,000 dated in 1956 and 1985 were manually interpreted to monitor urban areas. The spatial disarray (image texture) of component land covers gives the urban areas their physical recognizability. The interpretation scheme of aerial photographs was followed according to Gad (1988), as a process, divided into a number of phases (i.e. photo reading, classification and deduction). The boundaries were exactly delineated on transparent papers. A series of copy magnification was performed in order to bring the boundaries of study sites to the same scale on the corresponding aerial photographs. Digital planimeter (PLACOM, KP-90N) was used to measure the area of each study site. Soil analyses A number of selected soil profiles were studied to represent the areas which are encroachment by urbanization. The evaluation of these soils was based on the 1

2 morphological description of the profiles and on some physico-chemical properties of soil samples. Evaluation of urbanization The provisional methodology of FAO/UNEP and UNESCO, 1993 was taken as a guideline. It was modified on the assumption that the accepted increase in urban areas is <1% per year. This assumption is based on the usual rate of population growth in most developing countries as 1:2% per year. Thus the suggested rating values for different aspects of urbanization is shown in Table (1). Table(1): Class Limits Suggested for Assessing Different Aspects of Urbanization Desertif. Assessment Class Limits Aspect Factor Slight Mod. Severe V. Severe Status Loss of fertile land < >50 within ten yrs. (% of inhabited areas) Rate Increase in urban area 1-1.5% >5 per year Risk Population growth < >3 RESULTS AND DISSUSSION Aerial photo interpretation: Three sites have been studied using aerial photographs (1956 &1985) compared together. It was possible to delineate the boundaries of each study site (Figures 1,2 and 3 ). The high resolution of the photographs and the stereoscopic view were quite helpful for exact delineation of these boundaries. The use of digital planimeter, (PLACOM, digital planimeter KP-90 N ), resulted in measuring the urban area of each study site in two different times Table (2). Table (2) :Acreage of urban areas mentioned from aerial photographs Area Name Time of photograph Acreage *Feddan Increase of Urbanization (Fed.) Rate of increase per year El-MAADI and DAR El-SALAM KHANKA Dokki and Mohandeseen * Feddan = 4200m 2 The measurements make it possible to notice a significant increase of urbanization with respect to the time interval. The rate of increase ranges between per year. (El-Maadi and Dar El-Salam and Khanka), Table (2). The results reveal that the aerial photographs, with a satisfactory resolution are capable to insinuate the insight of very small areas 2

3 Soil characteristics and classification : A great number of soil profiles, representing urbanized areas, were studied. The soils are characterized by a good structure and non saline to slightly affected. The soil profiles can be classified as Vertisols, typic torrerts. These soils occupy the alluvial flood plain and fall within class I and II according to their suitability for cultivation. The soils of El-Maadi and Dar El- Salam occupied the western fringe of the Eastern desert. Evaluation of urbanization: The obtained results from the aerial photographs were employed in the modified FAO/UNEP provisional methodology (1983) to evaluate the magnitude of urbanization. It was possible to estimate classes of status, rate and risk of urbanization (Table3). The results show that the study areas are almost exposed to a very severe status and rate of urbanization, all the study areas face severe risk. These measures are based on the assumption that all urban expansion happened on cultivated fertile land. The new communities are the hope now to save the remaining fertile land from being lost. 3

4 Table (3): Evaluation of Different aspects of urbanization (1956 to 1985). Area Name Status Rate Risk 1 Class 2 Class 3 Class El Maadi & Dar El - 79 V. Severe 79 V. Severe 2 3 Severe Salam Khanka 110 V. Severe 11 V. Severe 2 3 Severe Dokki & 180 V. Severe -- V. Severe 2 3 Severe Mohandeseen The estimation of the risk is based on a population increase of 1:200,000 people per year, which represent 2-3% in a population of about 56 million people. Following a more civilized population policy may reduce the future risk of urbanization. This can come through a detailed study of people s socio- economic behavior. Conclusion and recommendations The cultivated areas in the Nile Valley and Delta are suffering from a serious problem of urbanization. This problem has caused an irretrievable loss of very fertile suitable soils. The problem is characterized by a very severe status and rate while the risk is severe. The Government has reached against the problem and issued several laws to control the land utility. These laws also prohibit any other activities to scrape or derelict the agricultural lands. Remote sensing techniques have been used in detection, monitoring and evaluation of urbanization in the study areas. The aerial photographs have offered the advantage of stereovision large scale, good resolution and restricted manipulation of image interpretation. The use of the photographs made it possible to zoom on the small urban areas. It is strongly recommended to plan the new urban in the desert regions in order to attract people out of the Nile valley and Delta. It is very important to stress on the decentralized authorities and to re-distribute the administrations all over the different governorates. The law system has to be very strict against invasion, of any form in the agricultural land It goes without saying that in order to establish stable new communities in desert areas, they must be supported by sustainable economic projects. These can be based on agricultural, industrial or touristic projects according to the condition of the sites and its relative advantages REFERENCES COLLINS, W.G. AND BUSH, P.W. (1969a). The definition and classification of derelict land, Journal of the town planning institute, COLLINS, W.G. AND BUSH, P.W. (1969b). The use of aerial photographs in the study of derelict land, Journal of the town planning institute, 55, COLLINS, W.G. AND BUSH, P.W. (1971). Aerial Photography and Spoiled Lands in Yorkshire The Planner, 57, COLLINS, W.G. AND BUSH, P.W. (1974). The application of aerial photography to surveys of derelict land in UK, in E.C. Barratt and L.E. Curtis (eds.), Environmental Remote Sensing, Arnold. London, FAO/UNEP (1983). A provisional Methodology for Soil Degradation Assessment. FAO: Rome (1983). 4

5 GAD, A. (1988). The study of desertification processes and soil conditions in the transition zones between the desert and the Nile Valley, using remote sensing (lower Nile Valley, Egypt) 427 p. Gent: Rijks Universiteit, international Training Center for post graduate soil scientists (Thesis s Ph. D. ). Key words: Urban Encroachment, Remote sensing-aerial Photographs, Risks- Monitoring. Mots clés : Expansion urbaine, télédétection, photographie aérienne, gestion des risques 5

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