Creation of GIS digital land resources database of the Nile delta, Egypt, for optimal soil management

摘要

The National development plans mainly aim to conserve the arable lands in the Nile Valley and Delta, in addition to the Oases and desert fringes. Moreover, increasing land productivity is an important National goal for controlling the gap between food production and consumption. Therefore, providing accurate and integrated information about land resources is a must, especially with the accelerated progress of information technology. Such information would be the base for planning, decision making and research needs.Various available information and database systems were employed (e.g. ArcGIS, ERDAS IMAGINE and ENVI). Data of previous soil survey activities were the bases for the created GIS digital database. Soils survey maps (SCALE 1: 100,000), were prepared as GIS ready maps. Other thematic information layers were imported to the GIS model representing the networks of irrigation and drainage, roads, railways and utilities, each layer includes different categories. Urban settlements were updated using recent ETM+and SPOT satellite images. An intensive field investigation was performed in the study region, with the purpose of representing the soil units and collecting ground control points and soil samples for laboratory analyses. The created digital land resources database was used to figure the distribution of soil units and to evaluate and map land capabilities on the bases of FAO, 1985 [1].It was found that the Entisols soil order characterize most of the alluvial soils of Nile Delta, while Aridisols cover a limited area. The soil orders Entisols and Aridisols were found dominating the western desert fringes of the Delta. The results showed that 41.16% of the Delta soils are classified as highly capable, corresponding with Vertic Torrifluvents soil sub-great group. The moderately capable soils, which correspond to Typic Torrifluvents sub-great groups, exhibit 8.00% of the Delta. The low capable soils, corresponding to sub-great groups Aquic Torrifluvents, Typic Haplocalcids and Typic Quartizipsamments represent 17.59% of the Delta located mainly around its northern lakes. The very low capable soils dominate the soils of lacustrine and desert deposits, representing 35.25% of the Delta.It could be pointed out that achieving such detailed digital land resources database for local administrations is a great step towards the implementation of sustainable development and management programs. It is characterized by its comprehensiveness, geographical accuracy and updatability. In the current Era of distinctive progress in information technology, such data can be handled, enhanced and exchanged by different users and authorities. The most striking findings noticed was the urban encroachment on the account of most fertile soils; hence shrinkage in areas of high agricultural capabilities. On the other hand, urbanization doesn’t extend largely to low capable land. It was also noticed that a common unbalance between irrigation and drainage system networks is often and may lead to progress of salinization and land degradation.