scholarly journals Spatial Heterogeneity and Driving Factors of Soil Moisture in Alpine Desert Using the Geographical Detector Method

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2652
Author(s):  
Zhiwei Zhang ◽  
Huiyan Yin ◽  
Ying Zhao ◽  
Shaoping Wang ◽  
Jiahua Han ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Spatial Heterogeneity ◽  
Water Content ◽  
Driving Factors ◽  
Tibet Plateau ◽  
Interaction Detection ◽  
Geographical Detector ◽  
Detector Method ◽  
Different Depths ◽  
Gravimetric Water Content

Soil moisture is a vital factor affecting the hydrological cycle and the evolution of soil and geomorphology, determining the formation and development of the vegetation ecosystem. The previous studies mainly focused on the effects of different land use patterns and vegetation types on soil hydrological changes worldwide. However, the spatial heterogeneity and driving factors of soil gravimetric water content in alpine regions are seldom studied. On the basis of soil sample collection, combined with geostatistical analysis and the geographical detector method, this study examines the spatial heterogeneity and driving factors of soil gravimetric water content in the typical alpine valley desert of the Qinghai–Tibet Plateau. Results show that the average value of soil gravimetric water content at different depths ranges from 3.68% to 7.84%. The optimal theoretical models of soil gravimetric water content in 0–50 cm layers of the dune are different. The nugget coefficient shows that the soil gravimetric water content in the dune has a strong spatial correlation at different depths, and the range of the optimal theoretical model of semi-variance function is 31.23–63.38 m, which is much larger than the 15 m spacing used for sampling. The ranking of the influence of each evaluation factor on the alpine dune is elevation > slope > location > vegetation > aspect. The interaction detection of factors indicates that an interaction exists among evaluation factors, and no factors are independent of one another. In each soil layer of 0–50 cm, the interaction among evaluation factors has a two-factor enhancement and a nonlinear enhancement effect on soil gravimetric water content. This study contributes to the understanding of spatial heterogeneity and driving factors of soil moisture in alpine deserts, and guidance of artificial vegetation restoration and soil structure analysis of different desert types in alpine cold desert regions.

Soil water contents and displacements monitoring, integrated into a Hydrological-Geotechnical Model for the evaluation of large-scale susceptibility to landslides triggered by rainfalls

2020 ◽  
Author(s):  
Roberto Passalacqua ◽  
Rossella Bovolenta ◽  
Bianca Federici ◽  
Alessandro Iacopino
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Ground Level ◽  
Water Infiltration ◽  
Landslide Monitoring ◽  
Simple Relationship ◽  
Capacitive Sensors ◽  
Different Depths

<p>Soil water content is often a landslide’s trigger factor, in particular the shallow ones. Although there is no simple relationship between the water content into the soil and the hydraulic conditions of the slopes at the depths at which the landslides develop, the knowledge of the actual soil moisture is fundamental for the study of landslides, thus, it should be monitored.<br>The LAMP (LAndslide Monitoring and Predicting) system is employed in the INTERREG-ALCOTRA project called AD-VITAM. LAMP (Bovolenta et al., 2016) was yet formulated for the analysis and forecasting of landslides triggered by rain. It adopts a physically based Integrated Hydrological Geotechnical (IHG) model (Passalacqua et al., 2016) and is implemented in GIS. In this Project, the IHG model is fed by data measured using a Wireless Sensor Network (WSN), this formed by low-cost and self-sufficient sensors. The WSN may gather rainfall, temperature, surface’s displacement data (these by mass-market GNSS receivers in RTK) and, in this case, soil water content (by capacitive sensors).<br>The WaterScout SM100 capacitive sensors were lab-analyzed then, recognized as satisfactory, installed on-site together with their related equipment. These sensors connect to a “Sensor Pup”, which has four available channels; therefore, four sensors are installed at each node, at different depths from ground-level, in order to achieve a vertical soil-moisture profile and the rate of infiltration.<br>The selection of the most suitable spots for the water content soil-sensors’ installations depends on the presence of shallow soil layers and of the radio signal emission-reception’s too.<br>The sensors may be set up both in vertical or horizontal direction. In general, the vertical installation is preferable. This implies the creation of small adjacent vertical holes, each one reaching a different depth, where the sensors are singularly pushed. Alternatively, the horizontal one may be adopted, by the opening of a small trench where the sensors are manually inserted at different depths, along a quasi-vertical vertical line. The full contact between the soil and the sensors is always verified, immediately after the installation, using a directly connected FieldScout reader to any single sensor. Furthermore, it is necessary to protect the emerging cables and to avoid preferential ways for water infiltration along the wiring lines.<br>The monitoring networks, installed at the two Italian sites of Mendatica and Ceriana, are currently providing informations in real-time. The data acquired at five nodes, distributed at each of these two sites (40 sensors in total), are currently relayed on a specific web-portal by a GSM connected Retriever-Modem, marking the evolutions of soil moisture profiles at depths between 10 and 85 cm from ground level: these continuous data allow the analysis of the infiltration and evapotranspiration phenomena. Moreover, a correlation between the soil moisture contents and the local displacements is made possible. Finally, a specific calibration of the SM100 sensors’ in relation to the on-site soil types is in progress.</p>

Quantification of driving factors on NDVI in oasis-desert ecotone using geographical detector method

2019 ◽  
Vol 16 (11) ◽  
pp. 2615-2624 ◽  
Author(s):  
Yu Zhang ◽  
Ke-cun Zhang ◽  
Zhi-shan An ◽  
Yan-ping Yu
Keyword(s):  
Driving Factors ◽  
Geographical Detector ◽  
Detector Method

Soil-specific calibration of capacitance sensors considering clay content and bulk density

Soil Research ◽  
2016 ◽  
Vol 54 (1) ◽  
pp. 111 ◽  
Author(s):  
Nargish Parvin ◽  
Aurore Degré
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Bulk Density ◽  
Precise Measurement ◽  
Clay Content ◽  
Limited Range ◽  
Soil Profiles ◽  
Soil Hydrology ◽  
Soil Columns ◽  
Different Depths

Soil hydrology research requires the accurate measurement of soil water content. Recently, less expensive capacitance sensors (CS) have become popular for the measurement of soil moisture across soil profiles, but these sensors need to be calibrated for precise results. The purpose of the present study was to determine the effect of clay content and bulk density (ρb) on the calibration of CS. Two different CS (10HS and 5TM) were considered for the study. Clay content and ρb of the soils were determined from two different sites and from three different depths (0–5, 25–30 and 50–60 cm) of an experimental field in Gembloux, Belgium. Custom calibration (CC) equations were developed using packed soil columns following the same ρb at sequential volumetric water content (θ) levels. The factory-supplied calibration (FSC) showed an overestimation of θ (0.04–0.07 m3 m–3) with the 10HS sensor, and an underestimation of θ (0.06–0.077 m3 m–3) with the 5TM sensor for the entire calibration range. The variance in raw sensor outputs for different ρb and clay content of soil depths was not highly significant because the soil had limited range of variability in ρb and clay content. However, the CC is recommended in parallel with FSC for the precise measurement of soil moisture with CS.

scholarly journals Driving factors and their interactions of carabid beetle distribution based on the geographical detector method

2021 ◽  
Vol 133 ◽  
pp. 108393
Author(s):  
Xueqin Liu ◽  
Hui Wang ◽  
Xinpu Wang ◽  
Ming Bai ◽  
Dahan He
Keyword(s):  
Carabid Beetle ◽  
Driving Factors ◽  
Geographical Detector ◽  
Detector Method

A carbon-based method for estimating the wetness of forest surface soil horizons

2007 ◽  
Vol 37 (4) ◽  
pp. 846-852 ◽  
Author(s):  
Donald S. Ross
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Field Capacity ◽  
Least Squares Regression ◽  
Soil C ◽  
Soil Calcium ◽  
The Relationship ◽  
Water Holding ◽  
Soil Moisture Retention ◽  
Gravimetric Water Content

The degree of wetness in forest surface soils has an effect on chemical and biological processes but is not easily measured. The high spatial variability in carbon (C) concentration creates high variability in water-holding capacity, and gravimetric water content is not informative. Local hydrology can create patchiness in soil moisture, with saturated soils often found near well-drained ones. When sampling to measure such factors as nitrification potential, it would be advantageous to have a simple metric that reflects the relative wetness of the soil. The relationship between C concentration (range 51.5–520.8 g·kg–1) and gravimetric water content was found to be linear for a set of 113 H- and A-horizon samples assumed to be at field capacity. The wetness ratio is defined as the actual water content of a sample divided by the water content predicted by the least squares regression equation based on C concentration (soil water content (kg·kg–1) = 0.080 + 0.0057 soil C concentration (g·kg–1)). Soil moisture retention curves were developed for a small number of samples in the range of 0 to about –10 kPa and showed that the equation predicted that water would be held at relatively high potential. In samples taken from 10 watersheds in the northeastern USA, wetness ratios between 1.25 and 3.1 were associated with soils identified in the field as ranging from wet to boglike. A median ratio of 0.49 was found in a watershed sampled after an extended dry period. At the Sleepers River Research Watershed, high wetness ratios were associated with a high soil calcium concentration, presumably from enriched groundwater. The ratio should be a useful measurement in watershed studies.

scholarly journals Effects of soil water content on carbon sink strength in an alpine swamp meadow of the northeastern Qinghai-Tibet Plateau

2021 ◽  
Author(s):  
Junqi Wei ◽  
Xiaoyan Li ◽  
Lei Liu ◽  
Torben Røjle Christensen ◽  
Zhiyun Jiang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Climate Warming ◽  
Ecosystem Respiration ◽  
Saturated Soil ◽  
Tibet Plateau ◽  
Sink Strength ◽  
Qinghai Tibet Plateau

Abstract. Predicted intensified climate warming will likely alter the ecosystem net carbon (C) uptake of the Qinghai-Tibet Plateau (QTP). Variations in C sink/source responses to climate warming have been linked to water availability; however, the mechanisms by which net C uptake responds to soil water content in water-saturated swamp meadow ecosystems remain unclear. To explore how soil moisture and other environmental drivers modulate net C uptake in the QTP, field measurements were conducted using the eddy covariance technique in 2014, 2015, 2017, and 2018. The alpine swamp meadow presented in this study was a consistent and strong C sink of CO2 (−168.0 ± −62.5 gC m−2 y−1, average ± standard deviation) across the entire 4-year study period. A random forest machine-learning analysis suggests that the diurnal, seasonal, and annual variations of net ecosystem exchange (NEE) and gross primary productivity (GPP) were controlled by temperature and solar radiation. Ecosystem respiration (Re), however, was found mainly regulated by the variability of soil water content (SWC) at different temporal aggregations followed by temperature, the second contributing driver. We further explored how Re is controlled by nearly saturated soil moisture and temperature comparing two different periods featuring identical temperatures and significantly differences on SWC and vice versa. Our data suggest that, despite the relatively abundant water supply, periods with a substantial decrease of SWC or increase of temperature produced higher Re lowering the C sink strength. Our results reveal that nearly saturated soil conditions during the warm seasons can help to maintain lower ecosystem respiration rates and thus enhance the overall C sequestration capacity in this alpine swamp meadow. We argue that changes in soil hydrological conditions induced by a warming climate near permafrost (or seasonal frozen layers) may affect the C sink magnitude of wet and cold ecosystems through changes in soil hydrology and the subsequent effect on respiration losses.

scholarly journals Performance of Soil Moisture Sensors in Florida Sandy Soils

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 358 ◽  
Author(s):  
Rhuanito Soranz Ferrarezi ◽  
Thiago Assis Rodrigues Nogueira ◽  
Sara Gabriela Cornejo Zepeda
Keyword(s):  
Water Management ◽  
Soil Moisture ◽  
Water Content ◽  
Sandy Soils ◽  
Irrigation Scheduling ◽  
Management Efficiency ◽  
Soil Moisture Sensors ◽  
Citrus Production ◽  
Gravimetric Water Content ◽  
Calibration Equations

Soil moisture sensors can improve water management efficiency by measuring soil volumetric water content (θv) in real time. Soil-specific calibration equations used to calculate θv can increase sensor accuracy. A laboratory study was conducted to evaluate the performance of several commercial sensors and to establish soil-specific calibration equations for different soil types. We tested five Florida sandy soils used for citrus production (Pineda, Riviera, Astatula, Candler, and Immokalee) divided into two depths (0.0–0.3 and 0.3–0.6 m). Readings were taken using twelve commercial sensors (CS650, CS616, CS655 (Campbell Scientific), GS3, 10HS, 5TE, GS1 (Meter), TDT-ACC-SEN-SDI, TDR315, TDR315S, TDR135L (Acclima), and Hydra Probe (Stevens)) connected to a datalogger (CR1000X; Campbell Scientific). Known amounts of water were added incrementally to obtain a broad range of θv. Small 450 cm3 samples were taken to determine the gravimetric water content and calculate the θv used to obtain the soil-specific calibration equations. Results indicated that factory-supplied calibration equations performed well for some sensors in sandy soils, especially 5TE, TDR315L, and GS1 (R2 = 0.92) but not for others (10HS, GS3, and Hydra Probe). Soil-specific calibrations from this study resulted in accuracy expressed as root mean square error (RMSE) ranging from 0.018 to 0.030 m3 m−3 for 5TE, CS616, CS650, CS655, GS1, Hydra Probe, TDR310S, TDR315, TDR315L, and TDT-ACC-SEN-SDI, while lower accuracies were found for 10HS (0.129 m3 m−3) and GS3 (0.054 m3 m−3). This study provided soil-specific calibration equations to increase the accuracy of commercial soil moisture sensors to facilitate irrigation scheduling and water management in Florida sandy soils used for citrus production.

scholarly journals Effects of Rainfall Manipulation on Ecosystem Respiration and Soil Respiration in an Alpine Steppe in Northern Tibet Plateau

2021 ◽  
Vol 9 ◽  
Author(s):  
Xueqin Li ◽  
Yan Yan ◽  
Lijiao Fu
Keyword(s):  
Climate Change ◽  
Soil Moisture ◽  
Soil Respiration ◽  
Water Content ◽  
Ecosystem Respiration ◽  
Tibet Plateau ◽  
Climate Change Scenarios ◽  
Regional Patterns ◽  
Northern Tibet ◽  
Alpine Steppe

The response mechanism of ecosystem respiration (Re) and soil respiration (Rs) to different water conditions is of great significance for understanding the carbon cycle under future changes in the precipitation patterns. We used seven precipitation treatments to investigate the effects of precipitation on Re and Rs on a typical alpine steppe in Northern Tibet. Precipitation was captured and relocated to simulate the precipitation rates of −25, −50, −75, 0 (CK), +25, +50, and +75%. The soil moisture was influenced by all the precipitation treatments. There was a positive linear relationship between the soil moisture and Re, Rs in the study area during the experiment (July–October). Soil volumetric water content (VWC), absolute water content (AWC), soil temperature (ST), aboveground biomass (AGB), bulk density, soil total nitrogen (TN), and alkaline hydrolysis nitrogen (AHN) were the predictors of Re and Rs. The multiple linear regression analysis showed that ST and AWC could explain 90.6% of Rs, and ST, AWC, and AHN could explain 89.4% of Re. Ecosystem respiration was more sensitive to the increased precipitation (+29.5%) whereas Rs was more sensitive to the decreased precipitation (−23.8%). An appropriate increase in water (+25 and +50%) could improve the Re and Rs, but a greater increase (+75%) would not have a significant effect; it could have an effect even lower than those of the first two. Our study highlights the importance of increased precipitation and the disadvantage of decreased precipitation on Re and Rs in an arid region. The precipitation changes will lead to significant changes in the soil properties and AGB, and affect Re and Rs, to change the climate of the alpine steppe in Northern Tibet in the future. These findings contribute to our understanding of the regional patterns of environmental C exchange and soil C flux under the climate change scenarios and highlight the importance of water availability to the regulating ecosystem processes in semi-arid steppe ecosystems. In view of these findings, we urge future researchers to focus on manipulating the precipitation over longer time scales, seasonality, and incorporating more environmental factors to improve our ability to predict and model Re and Rs and feedback from climate change.

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