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| Spatial variation of soil moisture on the grass and shrub land under simulated rainfall in Loess area |
| Zhao Pengyu1,2,Xu Xuexuan1,2,Liu Puling1,2,Shi Xinhe1,2,Chen Tianling3,Liao Xin2,Li Bo2 |
| 1.Institute of Soil and Water Conservation,Chinese Academy of Science and Ministry of Water Resources,712100,Yangling,Shaanxi;2.College of Resource and Environment,Northwest A&F University,712100,Yangling,Shaanxi;3.Gansu Institute of Soil and Water Conservation Science,730020,Lanzhou: China |
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Abstract Based on the observation data of soil moisture under forty-two simulated rainfalls in Yangou watershed of the Loess Area,responses of soil moisture to the simulated rainfalls on grass land and shrub land under two slopes with different management(undisturbed,cutting,plowing) were studied.The results were as follows: Under five supplementary rainfalls(accumulation presipitation 291.2-357.7 mm),according to the standard deviation and variation coefficient of soil moisture,the effect of land management on soil moisture in the 0-100 cm soil layers showed that: the soil moisture in undisturbed grassbush land could be divided into active layer(0-10 cm),relatively steady layer(10-70 cm) and sub-active layer(70-100 cm);the whole soil profile of cutting land(0-100 cm)was a relatively steady layer;plowing land was divided into active layer(0-10 cm)and relatively steady layer(10-100 cm).Under a single rainfall(presipitation range 46-85 mm),the active and relatively steady layers would become thinner gradually or disappear with the increase of precipitation,while the sub-active layer increased,changes of the moisture content in the whole soil profile tended to be uniform.It was suggested that more sensitive descrimination sandards which were standard deviation(s) and variation coefficient(Cv) should be used to divide the soil layer according to moisture variability under high intensity supplementary rainfall: active layer,s more than 1.4,Cv more than 0.12;sub-active layer,s changes from 0.9 to 1.4 and Cv changes from 0.08 to 0.12;relatively steady layer,s less than 0.9 and Cv less than 0.08.Soil moisture was increased with the slope decreasing.Slope had a more siganificant effect on soil moisture in undisturbed land and cutting land compared to plowing land,and the effect of slope on soil moisture in 50-100 cm soil layer was more siganificant than that in 0-50 cm soil layer.In conclusion,soil moisture in depth of 0-100 cm gradually increased after a single rainfall,and soil moisture of the profile became gradually stable.Land management as well as slope had siganificant effects on both the change intensity of soil moisture and changes of that in different soil depth.
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Received: 06 May 2008
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