关键词: 土壤盐渍化, 逆向演替, 渭-库绿洲

Abstract:

Based on remote sensing data, and combined with groundwater level observation data, the study do an quantitative research for the relationship between soil salinization and groundwater , and explore the salinization reversal evolvement of Wei-ku oasis. The results show that: 1) the annual ground water lowered 0.05 meters in the study area, with a downward trend from 1997 to 2001 year; there was obviously declined in ground water from 2002 to 2007 year, the rate was 0.175 meters every year, which was mainly caused by human activity, human land cultivation, a lot of drilling and utilization of groundwater resources, and the rise and fall of groundwater caused soil salinization.2) the middle-mild saline land has declined by 63.1 km² from 1989 to 2001 year; while the severe saline land has increased by 342.47 km² ;the total area of salt-affected ??land increased 279.37 km²,the average annual increase of 23.28 km². From 2001 to 2007 year, the middle- mild saline land has decreased by 155.42 km²;the severe saline land area has increased by 70.80 km²; the total saline area was obviously decreased by 84.62 km², at an average annual decrease rate of 14.1 km². 3) the proportion of salinized land area is relatively high when the ground water level is in the range from 2.3 to 2.7 meters, there was a biggish value in 2.4 to 2.5 meters; the proportion is relatively low when the ground water level is in the range from 2.7 to 3.4 meters; 4) Some parts of Wei-ku oasis has already in a reversal evolvement circumstance which is valuable for soil salinization, the ground water table is below threshold(4.66 meters),which would affect the surface salt accumulation, the groundwater mineralization degree is lower than 3 g/L; 5) Salinization reversal evolvement presents temporal and spatial characters ,and gradually occurs from the upper to the lower,and from the inside to the outside of Oasis.

Key words: soil salinization, reversal evolvement, Wei-ku oasis