GIS application to identify the potential for certain irrigated agriculture uses on some soils in Western Desert, Egypt

The study area lies to the western side of the Nile Delta in El Behira Governorate, with latitudes of 30°30′–30°45′N and longitudes of 29°45′–30°00′E, covering about 670,881 km2. Landsat ETM+ image (path 177-raw 39), DEM map and data verification by in situ observations aided by GPS were used for delineating the main physiographic units. The main physiographic units in the study area are: plain, pediplain, terraces, foot slope and table land. Forty-four soil profiles were allocated, exposed and morphologically described to represent the main physiographic units. A total of one hundred and one soil samples were collected from the profiles of the study area for laboratory analyses. The soil suitability maps are produced for three land utilization types of irrigation (LUTs): surface irrigation (LUT1), drip-irrigated vegetables (LUT2) and drip-irrigated trees (LUT3). The considered land suitability criteria for the aforementioned LUTs are: slope gradient, soil depth, soil erosion, soil drainage, soil infiltration rate, available water holding capacity (AWHC), surface stoniness (gravel, stones and boulders), stones in surface horizon, rock outcrop, soil salinity (EC), exchangeable sodium percent (ESP) and calcium carbonate content. The suitability maps for each of the above criteria and the final land suitability maps of the study area for different LUTs were developed by multiplying the reclassified factors map and adding them by Raster calculator technique in spatial analyst module of Arc GIS 9.3 software. The values which are obtained from the result are classified into three classes. These classes were converted to suitability classes: moderately suitable (S2), marginally suitable (S3), and not suitable (NS). The most soil limiting factors in the study area for LUT1 are soil depth and drainage followed by slope gradient, salinity and AWHC. However, the most limiting factors for LUT2 and 3 are surface stones and soil depth followed by stone content of surface horizon and soil salinity. Land improvements are required to improve or reduce the severity of limitations exited in the study area.