Soil moisture variation in relation to topography and land use in a hillslope catchment of the Loess Plateau, China

Abstract

The profile characteristics and the temporal dynamics of soil moisture variation were studied at 26 locations in Da Nangou catchment (3.5 km 2 ) in the loess area of China. Soil moisture measurements were performed biweekly at five depths in the soil profile (0-5, 10-15, 20-25, 40-45 and 70-75 cm) from May to October 1998 using Delta-T theta probe. Soil moisture profile type and temporal variation type and their relationship to topography and land use were identified by detrended canonical correspondence analysis (DCCA) and correlation analysis. The profile distribution of time-averaged soil moisture content can be classified into three types i.e. decreasing-type, waving-type and increasing-type. The profile features of soil moisture (e.g. profile gradient and profile variability) are influenced by different environmental factors. The profile type of soil moisture is only attributed to land use while profile gradient and profile variability of soil moisture is mainly related to land use and topography (e.g. landform type and slope). The temporal dynamics of layer-averaged soil moisture content is grouped into three types including three-peak type, synchro-four-peak type and lagged-four-peak type. These types are controlled by topography rather than by land use. The temporal dynamic type of soil moisture shows significant correlation with relative elevation, slope, aspect, while temporal variance displays significant relation with slope shape. The mean soil moisture is related to both the profile and dynamics features of soil moisture and is controlled by both land use and topography (e.g. aspect, position, slope and relative elevation). The spatial variability of soil moisture across landscape varies with both soil depths and temporal evolution. ᭧

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

“…Land uses comprised cropland, fallow land, grassland, shrub land, orchard land, intercropping land and woodland in the study area (Qiu et al, 2001). Crops were mainly potatoes (Solanum tuberosum), beans (Phaseolus valgaris), maize (Zea mays L.) and millet (Panicum miliaceum).…”

Linking the soil moisture distribution pattern to dynamic processes along slope transects in the Loess Plateau, China

“…Effect of land cover type on soil moisture Many of the factors that influence the spatial and temporal variances of soil moisture have been studied previously (Qiu et al 2001aFu et al 2003;Lin et al 2006;Brocca et al 2007Brocca et al , 2008Chen et al 2007). In this revegetated area, the different land cover types were the main control on moisture distributions.…”

“…An understanding of the coupling responses between land cover types and soil moisture is essential to determine the impact of various land uses on hydrological, ecological, and biogeochemical processes at different spatiotemporal scales (Li 2011). Thus, the complex spatiotemporal patterns and variability of soil moisture content have been widely investigated, at various scales, by hydrologists and ecologists in recent decades Fu et al 2003;Hu et al 2009;Qiu et al 2001aQiu et al , b, 2003Western et al 2004;Gao et al 2011).…”

“…In turn, different land cover types affect the mutually interacting hydrologic processes, especially infiltration and evapotranspiration Wang et al 2012;Wang et al 2013), resulting in various characteristics of soil moisture dynamics (Qiu et al 2001a. Chen et al (2007) evaluated the relationship between land cover types and soil moisture dynamics in the Loess Plateau area for five vegetation types and found that soil water loss occurred during the growing season, and the moisture was not fully replenished from rainfall during the rainy season.…”

“…Chen et al (2007) evaluated the relationship between land cover types and soil moisture dynamics in the Loess Plateau area for five vegetation types and found that soil water loss occurred during the growing season, and the moisture was not fully replenished from rainfall during the rainy season. The soil moisture content for land covered by different vegetation types in the semiarid area of the Loess Plateau has been well studied and documented during the past few decades (Qiu et al 2001a;Fu et al 2003;Chen et al 2007;Wang et al 2012Wang et al , 2013. The studies have indicated that bare soils usually have higher soil moisture content than vegetated soils, and that annual crops and grasses have higher soil moisture content than forests .…”