Assessment of Soil Degradation in Northwest Nile Delta, a Case Study: El-Bousily District

Abstract

The objective of the current research is to assess soil degradation in northwest Nile Delta, at Edfina governmental farm, El-Bousily region, using linkage between SALTMOD simulation model and spatiotemperol variability.The soil salinity (EC dS/m) ranged from (2.62 to 16.40), (4.68 to 18.60) dS/m and (8.60 to 24.80) dS/m in current time (year 2000), predicted time (year 2005) and predicted time (year 2010), respectively. A coefficient of variance (CV) of soil salinity was 0.46, 0.36 and 0.27 for current and predicted times. These values illustrated the extent of heterogeneity. C.V. values decreased with time according order: current time (year 2000) > predicted time (year 2005) > predicted time (year2010). The water table level ranged from (65 to 118) cm, (40 to 105) cm, and (15 to 85) cm in current time (year 2000), predicted times (year 2005) and (year 2010), respectively. The mean and median values decreased with predicted time, while the variance and C.V. values increased with predicted time. Water table depth became closer to the surface indicating waterlogging to occur in the future. Soil salinity fitted exponential model in current data. While, it fitted gaussian model in predicted data. Data reveal that the nugget variance values of EC increased with time. Its values were (0.60, 1.75 and 2.20 m) for current and predicted data, respectively. This trend indicates their strong spatial dependence and high-inherited variability with change time. The sill variance that illustrated the structural variance values of EC were (15.00, 16.85 and 17.79 m) for current and predicted data, respectively. The range values show that maximum interpolation distances for soil salinity were (588, 826 and 737 m) in current time and predicted times (2005 and 2010). Depth of water table was fitted to gaussian model. Data indicated that water table depth has highest nugget variance (32.2, 47.3 and 103.0 m) which indicates their strong spatial dependence and high-inherited variability. The sill variances of depth of water table (199.4, 255.6 and 379.6 m), for current and predicted times, respectively. The results of range which illustrated spatial dependence over specific lag distance show that maximum interpolations for depth of water table were (1016, 984 and 1481 m) for current and predicted time, respectively.Salinity levels and water table depth shifted from average data (7.86 dS/m, 84 cm) at present to (9.93 dS/m and 65 cm) after 5 years and (14.10 dS/m and 45 cm) after 10 years. The dominant area of soil salinity values are in current time (4-7 dS/m) which represent (74.32 %) from total study area. While its values in prediction year 2005 are (9-14 dS/m) represent (83.46%) and in prediction (year 2010) from (16-24.90 dS/m) which represent (88%) from total study area. The dominant area of water table level values are in current time (65-85 cm), which represent (86.25%) from total study area. While its values in prediction year 2005 are (40-70 cm) which represent (91.62%) and in prediction year 2010 from (15-55 cm) which represe...