THE USE OF GIS FOR DETECTION AND IDENTIFICATION OF OCCURRENCE OF PETROCALCIC AND PETROGYPSIC HORIZONS IN THE CULTIVATED LANDS OF MARYOUT REGION, EGYPT

The present work aims at using GIS, remote sensing and soil data, as a mean for detection and identification of Petrocalcic and Petrogypsic horizons in the cultivated areas of Maryout region, North-Western Coast of Egypt. The area under investigation bounded by longitudes  29°  35` 13.60˝  and  29°  57`  03.25˝  East and latitudes  30°  45`  00.15˝  and 30° 56` 35.47˝  North with a total area of about 757.80 km²  (180428.57 feddans).
Remote Sensing (RS) and GIS are incorporated to execute the soil base map. Results of thirty nine soil profiles located in the studied area were used as a database for the present study. Twenty soil profiles were dug and described to represent the SMUs. Soil samples were collected for the Laboratory analyses according to the differences in the morphological properties and stored as attributes in a geographical soil database linked with the soil map units. Based on the morphological description and analytical data the soils are classified as Typic Haplocalcids; Typic Petrocalcids; Typic Calcigypsids; Typic Haplogypsids; Petrocalcic Petrogypsids; and Typic Petrogypsids. Four dominant diagnostic horizons were observed in the studied soils; Calcic, Gypsic, Petrocalcic and Petrogypsic horizon. Based on the field observations and using RS and GIS we could define the different diagnostic horizons in the studied area.
Spatial interpolation, using exact interpolator [nearest neighborhood (Thiessen polygon)] between the field observations was used to drive the distribution of current diagnostic horizon. Results showed that, Calcic horizon occupies 349.51 km², Petrogypsic horizon occupies 168.36 km², Petrocalcic horizon occupies 63.08 km², and Gypsic horizon occupies 16.77 km². Results also  showed that, there is some factors affect the formation of Petrocalcic and Petrogypsic horizons namely: land use, parent material, land form, slope gradient. From the previous finding it can be concluded that, soils having these horizons need a special management in order to avoied the effect of these horizons. Also we can concluded that GIS with other source of data are a suitable tool for detection, prediction and planning studies and consequently for decision making in the studied area.