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Soil moisture plays a fundamental role in eco-hydrological processes in the semi-arid Loess Plateau. Catchments on the Loess Plateau can be generally divided into the hillslope domain and gully domain. However, the soil moisture variations linked to topographic domains and land use types remain poorly understood. Therefore, in this study, differences in soil moisture among three typical land use types (forestland, native grassland, and farmland) were investigated and compared between the spatial domains of hillslope and gully in the Jiegou catchment on the semi-arid Loess Plateau of China. Additionally, the spatial variations in the soil moisture of the 0–100 cm layers were explored in both wet and dry periods to evaluate the seasonal effects of different spatial domains and land use types. The results showed that including gully soil moisture weakly increased the spatially averaged soil moisture in the catchment but obviously increased the variability during wet periods. In contrast, the spatial means decreased weakly while the variability obviously decreased during dry periods. Soil moisture in forestland was lower than that in native grassland and farmland at all spatial domains during both wet and dry periods. The results also indicated that surface soil moisture (0–10 cm) differs between spatial domains but not land use types, which mainly due to the differences of evapotranspiration on the two topographic domains. In contrast, deep soil moisture (80–100 cm) differs among land use types but not spatial domains, which because of the differences of root water uptake among land use types. In addition, slope aspect played a more important role than slope gradient and elevation in the distribution of soil moisture at the hillslope domain. This was because the slope aspect affected the ground temperature by receiving different solar radiation, and further affected the soil evaporation and vegetation transpiration. Therefore, the results of this study indicates that both topographic domains and land use types should be considered when attempting to characterize soil moisture variability or modelling surface hydrological processes at catchment scale in heavily gullied regions.

The temporal characteristics of soil moisture are critical for the stability and sustainability of rebuilt ecosystems. In China's Loess Plateau (CLP), large areas of unsuitable croplands were restored to forest or grassland in order to control soil and water loss. Thus, knowledge of the temporal pattern and its controlling factors of soil moisture in revegetated areas over long-term is indispensable. In this study, four plots with different land uses (shrubland, grassland, fallow land and cropland) were set up on a loess slope in northern CLP. The profile soil moisture in the 0–4 m soil layer was measured from 2004 to 2015. Semivariogram models were established to analyze the profile temporal characteristics of soil water content (SWC) over 12 years of revegetation. The results suggested that: temporal stability of SWC under cropland was better than that under the three types of revegetated lands. Among the three types of revegetated lands, fallow land had stronger stability and higher value of SWC and was thus recommended as the best revegetation type. Generally, variation of SWC decreased with the increase of soil depth under shrubland, fallow land and cropland. However, under grassland, an inverse trend of SWS variation was observed and huge water absorption by deep grass roots was responsible for this trend. The temporal variation in SWC was under the joint influence of land use, soil depth and slope position, and land use was regarded as the dominant one. The study provided wider insight into scientific and reasonable vegetation restoration strategies in CLP region.

Identifying the controlling factors of streamflow changes across space and time is important for water resources management. This study investigated the streamflow changes and related them to climate and land use in the Jing River catchment on China's Loess Plateau. The spatiotemporal attribution was examined with the Budyko framework through splitting the whole catchment/study period into subbasins/subperiods. The annual mean streamflow significantly decreased by 0.6–1.0 mm yr − 1 ( p w ) in the Budyko framework is well correlated with the accumulative area fraction of forest and grassland, which provides a potential method to develop an empirical form for w .

Over the last decades, the off-site damages caused by muddy floods have been of growing concern throughout much of Western Europe, and particularly in Wallonia (Belgium). A reliable identification of locations with a high muddy flood hazard is thus a key issue in this context. The main objective of this study was therefore to build and evaluate a muddy flood hazard prediction model in order to assess the probability of occurrence of muddy floods at any specific location. A logistic regression approach was used to explain muddy flood occurrence using a database of 442 muddy flood-affected sites and an equal number of homologous non-flooded sites. Explanatory variables were related to geomorphology, land use, sediment production and sediment connectivity in the contributing area. The prediction quality of the model was then validated using an independent dataset composed of 48 pairs of flooded and non-flooded sites. The best muddy flood hazard assessment model required a total of 5 explanatory variables as inputs: the mean slope, a sediment connectivity index, as well as the proportion, spatial aggregation and proximity to the outlet of artificial surfaces. The model resulted in a prediction quality of 76% (calibration dataset) and 81% (validation dataset). Including the characteristics of artificial surfaces substantially improved the model quality (p-values from 10− 11 to 10− 5). All three variables related to artificial surfaces showed negative correlations with the muddy flood hazard. The proportion of cropland was not included in the final model, but this variable was strongly inversely correlated to the proportion of artificial surfaces. Besides the characteristics of artificial surfaces, sediment connectivity also showed significant explanatory power (p-value of 10− 12). A positive correlation between sediment connectivity and muddy flood hazard was found. Future muddy flood hazard models should therefore include both artificial surfaces characteristics and sediment connectivity-related information. Given the good prediction quality, the developed statistical model could be used as a reliable tool to prioritize sites at risk of muddy floods in order to install mitigation measures.

Iron-manganese (Fe-Mn) concentrations are common morphological indicators of soil oxidation-reduction reactions and are widely used to infer soil hydrology. The factors determining occurrence and distribution of Fe-Mn concentrations at the continental scale have been rarely studied. The objective of this study was to explore the distribution of Fe-Mn concentrations in upland loess soils and identify their favorable environment conditions in the mid-continental North America. A total of 3966 soil profiles were collected from the National Soil Information System database (NASIS). A decision tree (DT) model was used to analyze the spatial relationships between Fe-Mn concentration formation and its relevant environmental factors (climate, soil properties, and land use/land cover), and to identify key factors of Fe-Mn concentrations distribution and occurrence in upland loess soils. The DT model was evaluated with 25% validation dataset with an accuracy of 79%. Results showed that Fe-Mn concentrations were more likely to occur in mesic areas with large precipitation and low internal soil drainage rates, compared to frigid and thermic areas with low precipitation and large internal soil drainage rates. Annual precipitation and temperature were identified as the most important climatic factors influencing the occurrence of Fe-Mn concentrations and showed a complex interaction with soil properties at multiple scales. Soil properties related to potential wet to saturated soil conditions were also important for the occurrence of Fe-Mn concentrations. Results demonstrated the importance of using knowledge of pedogenesis in the selection of environmental covariates and the interpretation of DT model results. Understanding where Fe-Mn concentrations tend to form in the landscape will contribute to improving decisions about proper use of soil that may be limited by wetness and possible inferences about climate influences.

Prehistoric land use at the Guobei site and its relationship with the local environment are examined by applying OSL dating, micromorphological examination and geo-physical analysis. The majority of the OSL dates are of early to middle Holocene ages and are thus comparable to many OSL dates derived from other studies in the same region. According to the particle size analysis, silt-sized particles (2–60 μm) were predominant throughout the profiles examined. However, there are spatial and temporal variations of different size groups of particles throughout the profiles, which provide complementary information for the micromorphological interpretation. The total organic component of the samples examined through LOI is relatively high (all > 2%), with those of the overlying Holocene deposits higher than those of the underlying Malan loess by about 0.2%. Moreover, in all three profiles, the highest organic contents appear in the palaeosols, confirming that there was greater organic accumulation during soil formation periods. The groundmass of most slides collected from the early to middle Holocene horizons displays a very homogeneous pattern, while the abundance and distribution of different kinds of pedo-features, mainly including clay textural, calcitic, iron/Mn and crustal features, vary greatly temporally and spatially. These different lines of information demonstrate diversified pedo/sedimentary processes due to variations in micro-environmental conditions and cultural activities. We discuss the importance of a palaeo-ecological perspective, allowed by the geoarchaeological study, to an improved understanding of the relationship between loess, changing hydrology, prehistoric farming practice and land use, and long-term landscape change in the Chinese Loess area. This will thus contribute to a comparison on the dynamic relationship between loess and prehistoric farming in other regions of the world such as Europe and North America.

The socio-economic effect of the occurrence of specific forms of relief, is a significant research problem in applied geomorphology. The objective of this study was to assess the impact of permanent gullies on land cover and agriculture within the loess areas of Eastern (E.) Poland. We analyzed the relationships between an area consisting of gullies and selected environmental and socio-economic indices. We used the following statistical methods: Pearson's linear correlation, ANOVA, PCA and cluster analysis. It was found that districts with a similar gully density are characterized by the occurrence of a similar set of economic characteristics found within agriculture (cluster analysis). The most distinct impact of the occurrence of gullies on the potential of agriculture was observed when gullies covered more than 2% of the district. We identified the relationships between the area covered by gullies and present-day forest cover (Pearson correlation index 0.5), changes in the forest cover in the 20th century (0.7), the area of landscape parks and reserves (0.8) and the share of big farms (−0.5). Weak negative correlations occurred between the gully area and the economic aspects of agriculture (indices from −0.2 to −0.4). The correlations between the area of gullies, area of forests and share of farms larger than 20ha were confirmed by ANOVA. The PCA method showed a negative correlation between the area of gullies, the share of arable lands and the share of farms with good prospects. A positive correlation was found in the case of protected areas, steep slopes and forests. In the future, gullies may turn out to be a challenge to the development of efficient agriculture; they are an obstacle to land consolidation and farm enlargement. Areas characterized by a high density of gullies require special spatial management to reduce negative economic effects.