荒漠草原产流产沙过程及养分运移特征

Process of Runoff and Sediment Yield and Nutrient Transport Characteristics in Desert Steppe

[目的]荒漠草原夏季降雨强度大且集中性强,水力侵蚀危害严重,明确荒漠草原区产流产沙过程及养分运移规律对该地区开展水土保持工作有重要意义。[方法]试验基于天然降雨观测和人工模拟降雨的方法,研究荒漠草原区产流产沙过程及养分运移规律,并通过对植被进行不同处理研究植被对产流产沙的影响。[结果](1)不同植被处理方式的水土保持效果不同。3种不同处理方式中天然草地的水土保持效果最好,减流率与减沙率分别为11.37%和49.67%。(2)产流产沙过程改变地表土壤物质组成,使地表土壤粗粒化,还对土壤养分产生影响。降雨后砂粒含量增加5.97%~15.71%,土壤速效N、P及有机质分别减少40.84%,27.08%,33.49%。(3)坡面产流产沙量随坡度和降雨强度的增加而增加,幂函数能较好地拟合降雨历时与产流量和产沙量的关系。随降雨强度增加,坡度为5°~25°的峰值产流量平均增加6.70 L;降雨强度0.6~2.0 mm/L时,产沙量增长速度加快的拐点出现在坡度15°~20°。[结论]研究结果可为荒漠草原区水土流失的综合防治提供理论参考,有助于改善荒漠草原区生态环境,有利于该地区开展水土保持工作。

[Objective]The summer rainfall intensity in the desert steppe is strong and concentrated,and the harm of hydraulic erosion is serious.It is of great significance for soil and water conservation in this area to clarify the process of runoff and sediment yield,as well as the law of nutrient transport.[Methods]The experiment is based on natural rainfall observation data and artificial rainfall simulation methods,studying the runoff and sediment production processes,nutrient transport patterns in the desert steppe area,and investigating the impact of vegetation on runoff and sediment production through different vegetation treatments.[Results](1)Different vegetation treatments had different effects on soil and water conservation.Among the three different treatments,the soil and water conservation effect of natural grassland the best,and the runoff reduction rate and sediment reduction rate were 11.37%and 49.67%,respectively.(2)The process of runoff and sediment production would change the material composition of surface soil,make the surface soil coarse-grained,and also affect soil nutrients.After rainfall,the sand content increased by 5.97%~15.71%,and the soil available N,P and organic matter decreased by 40.84%,27.08%,33.49%,respectively.(3)The runoff and sediment yield increased with the increase of slope and rainfall intensity,and the power function can better fit the relationship between rainfall duration and runoff and sediment yield.With the increase of rainfall intensity,the peak runoff yield increased by 6.70 L on average when the slope was 5°~25°.When the rainfall intensity is 0.6~2.0 mm/L,the inflection point of the sediment yield increase rate will appear between the slope of 15°~20°.[Conclusion]The research results can provide a theoretical reference for the comprehensive prevention and control of soil and water loss in desert steppe areas,which is helpful in improving the ecological environment of desert steppe regions and carrying out soil and water conservation efforts in this area.