The effects of oasis ecosystem hydrological processes on soil salinization in the lower reaches of the Tarim River, China

Abstract

ABSTRACTOn the basis of the characteristics of the oasis hydrological recycling processes in the lower reaches of the Tarim River, the impacts of surface water and groundwater on soil salt content were analyzed to determine how these processes affect soil salinization. The results showed that the relationship between surface water quality and soil salt content in the 0–50 cm layer of soil was significantly positive, with soil salt content declining as groundwater depths increased. However, there was no clear correlation between surface water and salt content in the 50–100 cm layer of soil. When the groundwater depth was <6 m, the soil salt content showed a high‐surface concentration, exhibiting a ‘T’ distribution and decreased with increasing soil depth in the order of 0–20 cm > 20–50 cm > 50–100 cm. However, with increasing groundwater depth (>6 m), soil salt loads were reduced and showed a ‘rhombus’ distribution, mainly accumulating in the middle layer in the order of 20–50 cm > 0–20 cm > 50–100 cm. When groundwater depth was greater than 6 m, the hardness, total dissolved solids (TDS), and conductance of the groundwater underwent a radical change. Thus, the critical threshold groundwater depth for condensing salt content in groundwater and changing soil salt load distributions was deemed to be 6 m. Salt accumulation in the 0–50 cm layer of soil was determined by the TDS volume in the groundwater when groundwater depth was shallow, which accounted for more than 90% of salt accumulation. However, salt accumulation was determined by the volume of TDS in irrigation water when groundwater depth increased. Copyright © 2013 John Wiley & Sons, Ltd.