Geospatial Analysis of Soil Characteristics and Sensitivity to Desertification of Some Alluvial Deposits, El Behira Governorate, Egypt
Aly A. Gaafar, Ihab M. Morsy, Haytham M. Yehia
Geostatistical analysis was carried out to map the spatial distribution of the soil characteristics in GIS environment. The present study aimed to use quantitative method to assess land sensitivity to desertification and produce maps for the study area through coupling geostatistical analysis and Geographic Information System (GIS) for some Alluvial deposits, Kafr El Dawar District, West Delta, Egypt. The study area is located between 31o 00\ and 31o 14\ N and 29o 56\ and 30o 14\ E with total area of 36370.9 ha. The agricultural land covers about 30953.1 ha., and the urban area occupy about 5417.8 ha. To categorize soil properties, eighty five surface soil samples were collected, and soil samples were prepared and analyzed for chemical and physical characterization. The results of spatial variability and dependence indicated that the best fitted semi-variogram models were the gaussian model for soil salinity and soil depth, and the spherical model for sodium adsorption ratio and clay content. The Environmental Sensitivity Area Index (ESAI) was calculated using the overlaying technique of the different quality indices maps, which allow identifying the links between those indices and their spatial patterns. ESA analysis showed that 3.24% of the study area was critical to desertification, 3.12% was fragile to desertification, where most of the study area (92.72%) was Non-affected to desertification. The low quality classes of the ESAI were located at the southwestern part of the study area. The results elucidate that the distribution of ESAI matches the distribution of soil characteristics which were used to calculate the soil quality index. Moreover, irrigation water quality, and management dramatically impact desertification processes. Finally, the study recommended that: i) choosing the suitable spatial and temporal scales, as well as identifying the appropriate parameters, and using appropriate models are essential for correctly identifying and monitoring the ecosystem over long periods of time, to assess the sensitivity to desertification; ii) the assessment of environmental sensitive areas to desertification by coupling geostatistical analysis with modeling in geographic information system is a tool to use by decision-makers involved in the planning of sustainable land uses to identify and resist the desertification hazards.
Key words: Desertification, Geostatistical analysis, Environmental sensitive area Index, and Soil quality.