IN SIWA OASIS, situated in Egypt, secondary salinization of irrigated lands is a crucial problem. The results found that the Siwa shallow groundwater (SGW) and high summer evapotranspiration is considered the main cause of soil salinization, however, the irrigation water sodicity is considered the main causes of soil sodicity. The SGW depth generally decreased in winter and increased in summer seasons. A high correlation was found between the soil EC (dS m-1) and soil SAR and Cl (meq L-1) (R2 = 0.89 and 0.91 for SAR and Cl, respectively), consequently, the dominant ions in Siwa soil solution are Na and Cl. The results also emphasise good correlation between soil available nitrogen and SGW contamination with nitrate (r2 = 0.80 and 0.73, winter and summer, respectively). The eutrophication is expected in the study area especially in winter seasons due to nitrate concentrations increase. A conceptual, daily, semi-distributed hydrologic Saltmed model was found to be successful under Siwa climatic conditions. The model recorded that the quantity of irrigation water used in traditional irrigation is more than requirement. The traditional irrigation applies 300 L/m2/14 days, however, the quantity of 50 L/m2/14 days is adequate for olive crop water requirement and soil salinity removal. The results of this research could be applicable to similar situations worldwide.