【作者】 程艳涛；

【导师】 王根绪；

【作者基本信息】 兰州大学 ， 水文学及水资源， 2008， 硕士

【摘要】 入渗是水文循环过程中一个重要环节,在长江源区,土壤水分入渗对径流的影响很大,也是高原生态系统重要的影响因素。本文通过对长江源区进行连续三年的土壤水分入渗试验,分析了典型多年冻土区高寒草甸生态系统中影响土壤水分入渗的主要因素:地温,土层深度,植被类型,植被盖度,土壤初始含水率及地表土壤结皮。得出以下结论:(1)在相同植被盖度和土壤状况下,当地温大于4℃时,土壤饱和导水率与地温相关性明显。(2)应用考斯科加夫公式和霍顿公式来模拟长江源区土壤水分入渗过程。模拟结果显示:在高寒草甸生态系统的水分入渗模拟中,考斯科加夫公式优于霍顿公式。下渗初期,下渗速率较大,随下渗量的增加而递减,最后趋于稳定;而高寒沼泽生态系统,土壤水分入渗速率大于高寒草甸生态系统,变化快,稳定需要的时间更长。(3)随土层深度增加,土壤饱和导水率总体呈现下降趋势,从大到小各土层顺序为0～10cm、20～30cm、10～20cm和30～40cm。在植被盖度小于70%情况下,植被很难影响到30cm以下的土壤饱和导水率;而当植被盖度大于70%,30cm以下的土壤饱和导水率与植被存在一定相关性。(4)0～10cm,10～20cm,20～30cm三层土壤中,随着植被盖度的增大,土壤饱和导水率增大,饱和导水率与植被盖度变化具有显著相关性(R~2≥0.6)。土壤水分入渗过程模拟结果显示:考斯科加夫公式比霍顿公式能更好的模拟长江源区流域不同植被盖度下的土壤水分入渗过程,植被盖度越大,Kostiakov模型模拟得越好。(5)土壤的初始含水率只影响土壤水分的入渗过程,不会影响到土壤水分入渗的结果。初始含水率高的土壤,初始入渗速率小,稳定较快;初始含水率低的土壤,初始入渗速率大,稳定较慢。(6)土壤结皮大大削弱了土壤的入渗能力,降低了水分的入渗效率,对水分的入渗与涵养存在不利影响。结皮层土壤水分入渗速率变化趋势为小-大-小,最后趋于稳定。更多还原

【Abstract】 Infiltration is an important process in hydrologic cycle,in the source region of Yangtze River,infiltration of soil moisture has impact in runoff and plateau ecology. Basing on the measured data in infiltration,ground temperature and vegetation during three years,we studied the main facts on infiltration in the area of alpine ecological system:soil temperature,depth,vegetation type and cover degree,original soil water concentration,and soil crustation.The main conclusions are as follows:(1)The correlation coefficient between saturation conductivity and soil temperature is high as ST＞4℃under the same vegetation cover degree and soil construction.(2)We simulate the infiltration process using Kostiakov and Horton model,and find that Kostiakov infiltration model is better for meadow grassland in cold region.The infiltration rate is higher at the beginning of infiltration,and the infiltration rate has a timly decreasing trend..The infiltration rate of swamp is higher than the infiltration rate of meadow.(3)In profile,the sequence of saturation conductivity coefficient was soil layers 0～10cm,20～30cm,10～20cm and 30～40cm below the surface from max.to min. In vegetation cover less than 70 percent of cases,the impact of vegetation it is very difficult to 30 cm below the soil saturated hydraulic conductivity.When the vegetation cover more than 70%,30 cm below the soil saturated hydraulic conductivity and vegetation There is a certain correlation.(4)Through analysis,0～10 cm,10～20cm,20～30cm of soil in the three-tier, with the increase of vegetation cover,soil saturated hydraulic conductivity increased, saturated hydraulic conductivity and vegetation cover in a significant correlation(R~2≥0.6).Soil moisture infiltration process simulation results showed that:Kostiakov infiltration model is better for meadow grassland in cold region.The greater vegetation cover,Kostiakov a simulation model The better.(5)The initial soil moisture content of soil moisture affects only the infiltration process,will not affect the results of soil water infiltration.Initial high moisture content of the soil,the initial rate of infiltration of small,fast and stability;initial low moisture content of the soil,the initial infiltration rate,slower stability.(6)Soil encrustation greatly weakened the capacity of the soil infiltration, reducing the efficiency of water infiltration,the infiltration of water conservation and the existence of adverse effects.Guitar cortex soil water infiltration rate trends for small - big - small,finally stabilizing.更多还原