Geostatistical analysis of soil moisture variability on Da Nangou catchment of the loess plateau, China

Abstract

To achieve a better understanding of environmental issues related to soil erosion,¯ood-ing, and solute transport, it is necessary to understand the variability of soil moisture under different climatic and geological conditions and at different spatio-temporal scales. Moisture patterns based on ®ve depths (0±5, 15±20, 25±30, 45±50, and 70±75 cm) were determined in the Da Nangou catchment of the loess plateau of China from May to September 1999. Spatial structure of pro®le-averaged and layer-averaged soil moisture was analysed using semivariograms. The results indicated that soil moisture exhibits changing spatial dependence with time and depth. For pro®le-averaged soil moisture, high sills [4.6±14 %(v/v) 2 ] and high ranges (135±160 m) were observed during dry conditions. The sills [2.6±6.3 (%v/v) 2 ] and ranges (140 m) were small during wet conditions. However, soil moisture was described by linear semivariograms without a sill following a signi®cant rain event. For layeraveraged soil moisture, the sills increased with depth, but not for the ranges. The nuggets tended to increase with higher sills. This analysis provides insights into the variability of soil moisture on a large scale and interpolation strategies for extrapolating point measurements across the catchment.

The effects of land use on soil moisture variation in the Danangou catchment of the Loess Plateau, China

“…of soil moisture within upper layers (5, 15, 25 cm) exhibited high levels as reported by many authors (e.g. Anderson and Burt, 1978;Barling et al, 1994;Wang et al, 2001). However, the soil moisture variations in deeper layers were relatively stable with seasonal changes and greatly influenced by land use.…”

“…However, little attention is paid to the influences of land use patterns on soil moisture. Evaluating the effects of land use and its pattern on soil moisture is difficult because the differences in land uses which produce a change in the soil properties and evapotranspiration are likely to increase soil moisture variability across the landscape (Andrew et al, 1998;Wang et al, 2001). Vachaud et al (1985) asserted that soil texture was the main factor that controlled soil moisture, but in semiarid areas, other factors, such as topography, vegetation and land use, may have a major influence on soil water content (Grayson and Western, 1998).…”

Spatiotemporal prediction of soil moisture content using multiple-linear regression in a small catchment of the Loess Plateau, China

“…While powerful geostatistical techniques exist for optimum interpolation of soil moisture from sample grids (Yates and Warrick, 1987;Stein et al, 1988;Western et al, 1998;Wang et al, 2001b), they are appropriate when areas are intensively sampled and there are few, if any, major discontinuities (Webster, 1985). However, the large spatial and temporal variation in soil moisture content and, therefore, the expensive and inefficient survey are preventing the adoption of interpolation and surface fitting methods.…”

Analysis on soil nutrient characteristics for sustainable land use in Danangou catchment of the Loess Plateau, China

“…Furthermore, the European Union has also financed a project, ''A participatory approach for soil and water conservation planning, integrating soil erosion modeling and land evaluation, to improve the sustainability of land use on the Loess Plateau in northern China-EROCHINA'' (Ritsema, this issue). During the first phase, the main efforts were devoted to the understanding of gully erosion processes and soil erosion modelling (Wang et al, 2001b;Qiu et al, this issue). And then research activities were mainly focused on land evaluation and land use planning to improve the sustainability of land use .…”