陕西洛川L_5-S_8黄土和古土壤水分特征研究

Study on soil-water characteristics of L_5- S_8 in Luochuan,Shaanxi

通过对洛川L5-S8黄土和古土壤层的原状土进行水分特征曲线的实验测定,分析了L5-S8各层土壤的持水性能和供水性能等土水特征。结果表明:L5-1-S8-2的持水性、供水性均随吸力值的增大而减弱。L5-1-L8-2的持水性在较低压力段强于相邻下部的S5-1-S8-2,在较高压力段弱于相邻下部的S5-1-S8-2。L5-1-L8-2的供水性能比相邻下部的S5-1-S8-2强。L5-S8黄土和古土壤水分特征差异的直接原因是孔隙大小分配及粘粒含量多少,根本原因是土壤发育过程中冷干和温湿的气候变化。

On the base of the determination of the soil - water characteristic curves and field moisture capacity of undisturbed soil samples of L5 - S8 in Luochuan, we analyzed the properties of moisture preserve, supply and storing and effective moisture content, and discussed preliminarily the different causes of soil - water characteristics of L5 -S8. The results indicate that the soil - water characteristic curves of L5 - 1 - S8 - 2 are in well accordance with Van Genuchten model and the values of R2 are all above 0.98. The water - preserved properties of L5 -1 -S8 -2 become weaker with the increase of suction value in 0 - 85KPa. The water -preserved properties of the L5 - 1 - L8 - 2 are stonger than that of the S5 - 1 - S8- 2, and the water - preserved properties of the L5 - 1 - L5 - 2 are weeker than that of the S5 - 1 -S8 - 2. The properties of water supply of L5 - 1 - S8 - 2 become weaker with the increase of suction value in 0 - 85 KPa, and the properties of water supply of the L5 - 1 - L8 - 2 are stonger than that of the S5 - 1 - S8 - 2. The direct reason of properties differences of L5 - Ss is the different pore size distribution and clay content etc, and the underlying reason is the cold - dry and warm - wet climate change in soil development process.