Effects of spatial and temporal dynamics of soil water and salinity on new oasis stability

Desertification outside the oasis and salinization inside are the main factors threatening the survival of oasis. The severity and extend of desertification and salinization depend on the spatial and temporal dynamics of soil water and salt concentration. A study was conducted to evaluate the effects of soil water and salt concentration on oasis stability near Fukang City, XinJiang, P. R. China. The dynamics of water resources for the region was analyzed using data from 1988 to 1998. Soil water content and salinity, ground water table and salt EC were investigated for months of May to September in 2000 and 2001. Changes of land use in the region were examined from 1987 to 1998 and causes of the changes were explored. There was no salinity difference among oasis, ecotone and sand dune. Ecotone was stable in terms of area and boundary because of the irrigation in the oasis supplied critical water needs for vegetation to the two adjacent systems. There were large salinity differences among oasis, abandoned land and desert grassland. For regions of abandoned land and peripheral desert of oasis, salinization had become a serious problem due to the salt accumulation on the soil surface and root zone from evaporated irrigation water. Because of the same reason, abandoned land increased dramatically from 1987 to 1998 in the lower reaches of Sangonghe River, especially inside of new oasis. Land salinization and second salinization were the major factors that threaten the survival of the oasis. Sound and effective plans for water use with proper irrigation and drainage systems are needed in order to minimize salinization effect and protect stable oasis.