Soil Water Erosion Vulnerability and Suitability under Different Irrigation Systems Using Parametric Approach and GIS, Ismailia, Egypt

Assessment of erosion rate in a rainfed agricultural area on the Northwestern coast of Egypt using 137Cs measurements

In the present work, the use of the fallout radionuclide ¹³⁷Cs as a tracer for estimating soil redistribution rates over the past 60 years was tested in Egypt at an agricultural field with a smooth slope (0-10%) located in Ras El-Hekma on the Northwestern coast. The average annual soil erosion rate was derived from ¹³⁷Cs inventories (Bq m^-2) and by using the conversion Diffusion and Migration Model (DMM). The activity concentrations of ¹³⁷Cs with uncertainty ranging between 7.5 and 20.9% were measured using HPGe gamma spectrometry. Approximately exponential shape for the distribution of ¹³⁷Cs activity concentration was observed within the upper 20 cm of the soil profile associated with the reference site while for the study sites, the ¹³⁷Cs depth distribution profiles indicate generally an increase of activity reaching a maximum peak of ¹³⁷Cs usually at a depth of 10-15 cm followed by an abrupt exponential decrease of ¹³⁷Cs activity concentration with depth. The measured average reference inventory for this area was 697 Bq m^-2 with a coefficient of variation of 23%. This value is close to the estimated reference inventory using the conversion model, which was 744 Bq m^-2. Transect sampling strategy was adopted at the study area where three parallel transects were chosen based on the common slope. The estimated average annual erosion rate for the three transects was found to be 7.5 t ha^-1 y^-1, and sediment delivery ratio was approximately 98%, which shows the moderate vulnerability of the Ras El-Hekma area to water erosion.

An Assessment on the Safety of Drinking Water Resources in Yasouj, Iran

The health of drinking water is an important criterion for developed countries and around half of the world’s population is deprived of sanitary and safe drinking water. By identifying the time of pollution occurrence and the places that are most sensitive to pollution the management of the quality of drinking water can be planned. Since the landfill for Yasouj, a city in Iran, was located in a higher place than the drinking water wells, which were drilled in a karst aquifer, the safety of the drinking water resources (including eight wells) of Yasouj were investigated in the present study. For this purpose, different parameters, comprising the concentration of eight heavy metals and eight ions, alkalinity, total harness, pH, biological oxygen demand (BOD5) and total coliform, were measured over 12 months and the obtained data were compared with the WHO’s and Iran’s drinking water standards. To assess the measured data statistically, SPSS software was applied. From the reported results, the water characterizations of the wells complied with the mentioned standards; however, four of the wells were more prone to supply higher quality water. It is noted that Hg, Cd, and the total coliform of wells were close to the permissible values reported by both the aforementioned standards. Therefore, the water obtained from wells should be disinfected before using and Hg and Cd concentrations need to be monitored regularly to prevent poisoning. Due to the rapid movement of pollutants in karst areas, it is very important to detect their presence in the water resources over time. Consequently, continuous monitoring and sampling is one of the most important protection dealings for karst aquifers.

Long-Term Impact of Wastewater Irrigation on Soil Pollution and Degradation: A Case Study from Egypt

There is consensus on the impact of wastewater irrigation on soil properties and heavy metal accumulation. The studies that show the impact of temporal changes as a result of different long-term additions of wastewater on the heavy metal accumulation and degradation of soil are extremely limited. This study was carried out to assess heavy metal contamination in soils irrigated with wastewater for more than 30 years in Egypt. A total number of 12 irrigation water samples and 12 soil profiles were collected during 2020 and were chemically characterized. The results showed that soils irrigated with wastewater over the long term contained significantly higher concentrations of heavy metals compared to fields irrigated with fresh water. Heavy metal levels in water and soil samples were within the permissible limits, with the exception of Cd concentration in water (0.03 mg L−1). Continuous cultivation for a long period of time (30 years) using raw urban wastewater application has led to the adverse effect of increasingly available Pb concentration (5.44 mg kg−1). Similar temporal behavior was seen for Cd and Fe, which increased by 0.98 and 11.2 mg kg−1, respectively, after 30 years. The heavy metals in wastewater-irrigated soils significantly increased in clayey soils, as compared to sandy soils irrigated from the same source. Our findings provide important information for decision makers in Egypt and similar countries for the development of a strategy for the use of wastewater in irrigation for sustainable agricultural management.