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•Swales can be surprisingly dry despite conventional expectations of their wetness.•Soil and vegetation characteristics strongly influence soil moisture variations.•Over 50% of soil ...moisture variations are explained by non-topographic factors.•A new index that integrates topographic and non-topographic information is proposed.•This index advances predictability of catchment-scale soil moisture variation.
Concave hillslopes, also known as swales, play a pivotal role in facilitating the transfer of water and nutrients from hillslopes to riparian zones in headwater catchments by serving as pathways for surface and subsurface flow. Swales have long been recognized as hydrologic wet spots that contribute significantly to catchment runoff. However, long-term in situ observations have rarely confirmed this conventional understanding. In this study, we present a comprehensive analysis of three years of daily soil moisture measurements taken at multiple depths across 33 sites within a forested catchment to delineate key determinants of soil moisture variation at the catchment scale. Contrary to conventional understanding, our findings indicate that swales may represent areas of lower soil moisture, with those located on sunny hillslopes experiencing a higher frequency of dry conditions, amounting to 13.31% of the time during the study period, when compared to other topographical features such as slopes, valleys, and ridges. Topography alone accounted for less than half of the variation of soil moisture across the catchment. Whereas non-topographic factors (such as vegetation, soil porosity, soil temperature, and soil depth) strongly influenced soil moisture distribution in time and space. To better capture the nuances of soil moisture dynamics, we propose an enhancement to the Topographic Wetness Index (TWI) through the incorporation of non-topographic variables, which improves the model's representation of soil moisture variations. Our findings elucidate the complex interactions between topographic and non-topographic factors in shaping soil moisture dynamics at the catchment scale, offering valuable insights for refining process-based hydrological models and contributing to a deeper understanding of the spatial and temporal variability of soil moisture in headwater catchments.
•We make an analysis on the seasonal variability of water quality in the Wei River basin.•Land use type in the dry season has a more significant correlation than in the rainy season on both the water ...quantity and quality.•Steeper lands generally have a stronger influence on the stream water quality than flatter lands.•Seasonal variability also occurs in the relationship between topographic characteristics and water quality.•The same land use type plays different, positive or negative, roles on stream water quality in different land use patterns.
The effect of topographic characteristics of land uses on stream water quality must be addressed for a better understanding of the complex relationship between land use and stream water quality. In this study, Geographic Information System (GIS) and Pearson correlation analysis were used to determine whether there were relationship between land use types and stream water quality at the sub-basin scale in the Wei River basin, China, during the dry and rainy seasons in 2012. Temporal variation of these relations was observed, indicating that the relationships between water quality variables and different land uses were weaker in rainy seasons than that in dry seasons. Compared with other land uses, agriculture and urban lands had a stronger relationship with water quality variables in both rainy and dry seasons. Topographic characteristics of land use were employed to further analyze these relationships. The results showed that seasonal variation also occurred in the complex relationship, and land uses in steeper slopes generally had a stronger influence on stream water quality than those in flatter ones. For the riparian zone of each sampling site, the slope coefficients were weaker than those at the sub-basin scale. Land use type near stream water was generally a better indicator for the effectiveness of water quality. These results suggest that the slope and proximity should be taken into account for better land use management.
Fish are some of the most threatened vertebrates in the world due to their often-sensitive response to environmental changes. Major land-use changes in the European Alps have direct and indirect ...impacts on fish communities, and these impacts are expected to increase in the future. Therefore, the identification of factors that are associated with the distribution of fish communities is of great importance to develop guidelines for management, precautions and sustainable use of running waters. In this study, the relationship of various factors – landscape structure and land use, topography, morphology, hydrology, physical and chemical water characteristics, hormonally active substances, pesticides, food availability, fisheries and piscivores birds – with fish assemblages are analysed. Field data from 81 stream sections from 2001 metres above sea level (m.a.s.l.) down to 219 m.a.s.l. are used in the study. The results reveal that the number of fish species has a strong association with topographic characteristics in the catchment area as well as with landscape configuration. Fish abundance and biomass are associated mostly with land-use type, hydrology, morphology as well as topography. In addition, there are indirect connections between fish abundance and biomass through land-use type, topography, water properties and hydromorphology. The results clearly indicate that not a single factor, but a multitude of factors are associated with the fish communities in the Eastern European Alps.
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•Fish population of 81 sites have been analysed in a holistic way.•Land use type, topography and hydromorphology are mostly associated with changes in fish fauna.•Fish catch intensity is negatively correlated with fish species richness and abundance.•Fish abundance is significantly negatively connected with endocrine loads.•Biomass is associated with pesticides, macrozoobenthos, piscivorous birds and water properties.
We used Hori’s EEG stages to quantitatively describe EEG changes during the sleep onset period (SOP). We have also described the significance of psychophysiological approaches to the wake-sleep ...transition period, the topographical characteristics of EEG activities in the SOP, and temporal dynamics of the relationship between the waking period before sleep onset and the progress of sleep onset. We expect helpful information providing insights into the consciousness, emotions, behaviors, and brain functions in the waking and sleeping states from investigating the SOP using EEG stages of sleep onset as the primary index and correlating it with behavioral and subjective indexes.
We used Hori’s EEG stages to quantitatively describe EEG changes during the sleep onset period (SOP).We have also described the significance of psychophysiological approaches to the wake-sleep ...transition period, the topographical characteristics of EEG activities in the SOP, and temporal dynamics of the relationship between the waking period before sleep onset and the progress of sleep onset. We expect helpful information providing insights into the consciousness, emotions, behaviors, and brain functions in the waking and sleeping states from investigating the SOP using EEG stages of sleep onset as the primary index and correlating it with behavioral and subjective indexes.
Landscape evolution models (LEMs) are essential tools for analyzing tectonic-climate interactions and reproducing landform-shaping processes. In this study we used a LEM to simulate the evolution of ...the mountains from the central Hexi Corridor in the northeastern Tibetan Plateau, where the climate is arid and the surface processes are relatively uniform. However, there are pronounced differences in the topography between the mountains around the central Hexi Corridor. The East Jintanan Shan, West Jintanan Shan and Heli Shan are located in the northern part of the corridor; and the Yumu Shan in the southern part. Firstly, several representative areas were selected from these mountains to analyze the topographic characteristics, including the uniform valley spacing, local relief, and the outlet number. Secondly, a LEM for these areas was constructed using the Landlab platform, and the landscape evolution was simulated. With uniform valley spacing and other topographic characteristics as the criteria, we compared the realistic and simulated terrain for different model ages. Finally, based on the similarity of the simulated and realistic terrain, we estimated the timing of the initial uplift and the uplift rate of the four mountain ranges. The results are consistent with previous geological and geomorphological records from these youthful stage mountains that have not yet reached a steady state. Our findings demonstrate that LEMs combined with topographic characteristics are a reliable means of constraining the timing of the initial uplift and the uplift rate of the youthful stage mountain. Our approach can potentially be applied to other youthful stage mountains and it may become a valuable tool in tectonic geomorphology research.
The purpose of this study was to evaluate the association between focal lamina cribrosa defect (FLCD) and the topographic characteristics of disc hemorrhage (DH), including area and location.
We ...enrolled a total of 98 primary open-angle glaucoma eyes with DH (98 subjects). In vivo lamina cribrosa (LC) images were obtained by swept-source optical coherence tomography (SS-OCT) immediately following the detection of DH. Two masked graders identified FLCD (laminar holes or disinsertions >100 μm in diameter and >30 μm in depth), defined by a customized protocol using en face images and 12 radial-orientation raster scans of SS-OCT. En face image/stereo-disc photography overlay images were evaluated to determine the spatial relationship between the respective FLCD and DH locations. A method of comparing the disc area and DH area pixel numbers was used to estimate the DH area.
Sixty-eight of 98 eyes with DH (68.4%) had at least one FLCD. Thirty-eight of those 68 eyes with DH and at least one FLCD (55.9%) had a DH corresponding to the FLCD location (within one-half clock-hour distance from the midline). The FLCD-correspondent DHs (39 DHs) showed significantly larger areas (0.092 ± 0.030 mm2; P < 0.001) and more proximally located proximal ends (P < 0.028) than the noncorresponding ones (33 DHs; 0.065 ± 0.024 mm2 of area).
The DHs that correspond to FLCD location tend to have larger areas and to be more proximally located than those without correspondence. This suggests that FLCD might affect the topographic characteristics of DH.
Background and aims - Although soils and topography are reported to be key factors determining vegetation patterns, there are very few studies on this topic in tropical Africa. Given the young nature ...of the soils of Nech Sar National park, we hypothesised that the woody
vegetation would be related to both topsoil and subsoil characteristics. As topography also determines soil characteristics, we investigated whether soil and topography could be considered independently.Methods - Abundance of woody plant species was measured in 19 stratified
randomly selected plots of 20 m × 20 m. At the centre of each plot a soil profile pit was dug and samples were taken from each horizon. Topographic characteristics were derived from a 30 m × 30 m digital elevation model. TWINSPAN and Detrended Correspondence Analysis (DCA) were
used to identify major patterns in species composition. Factor Analysis was used to assess the variability of, and correlation between, the soil characteristics. Differences between the vegetation groups in-terms of stand and environmental characteristics was tested with the Mann-Whitney U
test. DCA axes describing the major variation in vegetation patterns were correlated with soil and topographic characteristics.Results - Forest vegetation was found on Fluvisols and Gleyic Cambisols while bushland was found on Andosols and Vertic Cambisols. The vegetation
gradient from forest to bushland (DCA-1) was correlated with both topsoil and subsoil characteristics reflecting parent material and alkalinity; these could however not be dissociated from topography. In contrast, variation both within the forest and the bushland (DCA-2) was not correlated
with environmental characteristics. We attribute this variation to disturbances such as collection of firewood or logging, and to the absence of large browser or scarcity of wildfires.Conclusions - This study calls for giving equal attention to topsoil and subsoil for elucidating
woody vegetation patterns. Though vegetation patterns vary with topography, a comprehensive understanding requires insights into soils.
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