الفهرس 
Introduction
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Abstract
Salt-affected soils are formed by excess accumulation of salts, especially in arid and semi arid regions. Salinity may be either primary or secondary salinization and is represented by cations (K+, Na+ Ca++, and Mg++) and anions (Cl- , SO4--, HCO3-). Salt- affected soils are classified as saline, alkaline (high sodium) and saline-alkaline in relation to the values of electric conductivity (EC), pH, and exchangeable sodium percent (ESP) of their saturated past. Water logging is a problem associated with excessive irrigation on poorly drained soils where water can’t penetrate deeply or develop in areas where the groundwater table is close to the surfaces. Traditional methods for mapping salt-affected soils are time consuming, expensive and localized. Instead, remote sensing is widely used in delineation and characterization of salt-affected soils and provides a synoptic view of large ground coverage in multiple spectral bands at low costs. The coastal area of the Nile Delta is characterized by a mild climate. The climate of the northern coastal zone of the Nile delta is typical Mediterranean with fairly cool rainy winter and warm dry summer and small diurnal temperature variations. There are different types of geomorphologic features along the coastal strip of the Nile Delta as: sabkha, salt marshes, agricultural lands and sand dunes. The problem of soil salinization in the Nile Delta was attributed to seawater intrusion; irrigation with low quality water; and inadequate field drainage. In order to map the spatial distribution and change of salt-affected soils in the coastal zone of the Nile Delta, two satellite TM and ETM+ images acquired in 1986 and 2001 with 30 m spatial resolution were used. In addition, a digital elevation model with 90 m spatial resolution and a topographic sheet with a scale of 1:500000 drawn from aerial photographs were utilized. Field work was planned to survey the study area and to collect representative soil and water samples from the different geomorphologic units in the study area using field equipment and GPS. Soil sampling sites included: 1- sand dunes, 2- sand flats, 3- sabkhas, and 4- agricultural lands and water sampling sites included 1- irrigation canals, drainage ditches, 3- flooded low lands and 4- open fish farms. water samples were analyzed to determine the pH, electrical conductivity (E.C.), major cations (K+, Na+, Ca++, and mg++), major anions (HCO3-, SO4--, and Cl-), and sodium adsorption ratio (SAR). The same parameters were analyzed in the soil extract and the SAR and exchangeable sodium percent (ESP) were calculated. The soil grain size and soil color were also determined using the standard sieving method and the Munsell Soil color charts, respectively.