Spatial variability of surface soil moisture under different landscape units in the Heihe Oasis
Guo Deliang, Hu Wei, Fan Jun, Wang Li
1. College of Resources and Environment, Northwest A&F University, 712100, Yangling, Shaanxi; 2. Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 100101, Beijing; 3. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and the Ministry of Water Resources, 712100, Yangling, Shaanxi: China)
Abstract：By using statistical and geostatistical methods, spatial structure characteristics of surface soil moisture were studied, including gobi, woodland and agricultural land in the oasis area of the midstream of the Heihe River between August and October. The results showed that: 1) soil moisture of the three landscapes units decreased from August to October and represented moderate variation. The relative variation (the coefficient of variation) of soil water was smaller under dry soil condition and the absolute variation (the standard deviation) of soil water was higher under wet soil condition; 2) the soil surface moisture of the three landscape units had obvious spatial structure and seasonal variations, which represented patch shape distributions. The optimal fitting was achieved using the exponential model. The variation tendency of sill, range and water content was similar and there was a moderate and strong relationship between soil moisture and spatial correlation. The spatial autocorrelation in October was significantly greater than that in August and September; 3) Land use,mean soil water moisture, soils,landform, climate and human activities were the major factors leading to obvious time and space differences of surface soil moisture in the study area. Further study indicated that average soil water content had longer effects.
2013, Vol. 11 
