Repeated geophysical measurements in dry and wet soil conditions to describe soil water content variability

Abstract. This work addresses the impact of climate change on the hydrology of a catchment in the Mediterranean, a region that is highly susceptible to variations in rainfall and other components of the water budget. The assessment is based on a comparison of responses obtained from five hydrologic models implemented for the Rio Mannu catchment in southern Sardinia (Italy). The examined models – CATchment HYdrology (CATHY), Soil and Water Assessment Tool (SWAT), TOPographic Kinematic APproximation and Integration (TOPKAPI), TIN-based Real time Integrated Basin Simulator (tRIBS), and WAter balance SImulation Model (WASIM) – are all distributed hydrologic models but differ greatly in their representation of terrain features and physical processes and in their numerical complexity. After calibration and validation, the models were forced with bias-corrected, downscaled outputs of four combinations of global and regional climate models in a reference (1971–2000) and future (2041–2070) period under a single emission scenario. Climate forcing variations and the structure of the hydrologic models influence the different components of the catchment response. Three water availability response variables – discharge, soil water content, and actual evapotranspiration – are analyzed. Simulation results from all five hydrologic models show for the future period decreasing mean annual streamflow and soil water content at 1 m depth. Actual evapotranspiration in the future will diminish according to four of the five models due to drier soil conditions. Despite their significant differences, the five hydrologic models responded similarly to the reduced precipitation and increased temperatures predicted by the climate models, and lend strong support to a future scenario of increased water shortages for this region of the Mediterranean basin. The multimodel framework adopted for this study allows estimation of the agreement between the five hydrologic models and between the four climate models. Pairwise comparison of the climate and hydrologic models is shown for the reference and future periods using a recently proposed metric that scales the Pearson correlation coefficient with a factor that accounts for systematic differences between datasets. The results from this analysis reflect the key structural differences between the hydrologic models, such as a representation of both vertical and lateral subsurface flow (CATHY, TOPKAPI, and tRIBS) and a detailed treatment of vegetation processes (SWAT and WASIM).

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Enhancing Soil Water Content for Increased Food Production in Semi-Arid Areas of Kenya Results From an On-Farm Trial in Mwala District, Kenya

Journal of Agricultural Science ◽

10.5539/jas.v6n4p125 ◽

2014 ◽

Vol 6 (4) ◽

pp. 125 ◽

Cited By ~ 3

Author(s):

Anne Karuma ◽

Peter Mtakwa ◽

Nyambilila Amuri ◽

Charles K. Gachene ◽

Patrick Gicheru

Keyword(s):

Soil Moisture ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Water Conservation ◽

Crop Yields ◽

Conservation Tillage ◽

Cropping Systems ◽

Soil Conditions ◽

Tillage Methods

Soil water conservation through tillage is one of the appropriate ways of addressing soil moisture deficit in rainfed agriculture. This study evaluated the effects of tillage practices on soil moisture conservation and crop yields in Mwala District, Eastern Kenya during the long rains (LR) and short rains (SR) of 2012/13. Six tillage systems: Disc plough (MB), Disc plough and harrowing (MBH), Ox-ploughing (OX), Subsoiling – ripping (SR), Hand hoe and Tied Ridges (HTR) and Hand hoe only (H) and, three cropping systems namely, sole maize, sole bean and maize - bean intercrop, were investigated in a split-plot design with four replicates. Data on soil water content was monitored at different weeks after planting and the crop yields at end of each growing season. A three-season average shows that soil water content and crop yields were higher in conventional tillage methods compared to the conservation tillage methods. Long term tillage experiments are thus required at different locations, under various environmental and soil conditions to validate the study findings.

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Obtaining soil hydraulic parameters from soil water content data assimilation under different climatic/soil conditions

CATENA ◽

10.1016/j.catena.2017.12.022 ◽

2018 ◽

Vol 163 ◽

pp. 311-320 ◽

Cited By ~ 4

Author(s):

Javier Valdes-Abellan ◽

Yakov Pachepsky ◽

Gonzalo Martinez

Keyword(s):

Data Assimilation ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Soil Conditions ◽

Hydraulic Parameters ◽

Soil Hydraulic Parameters ◽

Soil Hydraulic

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Field calibration of a capacitance soil water probe in heterogeneous fields

Soil Research ◽

10.1071/sr03051 ◽

2004 ◽

Vol 42 (3) ◽

pp. 289 ◽

Cited By ~ 33

Author(s):

Dieter Geesing ◽

Martin Bachmaier ◽

Urs Schmidhalter

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Soil Samples ◽

Soil Conditions ◽

Site Specific ◽

Field Calibration ◽

Calibration Methods ◽

Significant Difference ◽

Capacitance Probe

Soil water research requires methods to perform accurate measurements. A capacitance probe gauge has characteristics that seem to make it an attractive replacement for neutron scatter gauges to measure soil water content, but there is evidence that capacitance systems should be calibrated for individual soils. Laboratory calibrations and many field calibration methods are costly and time-consuming, and controlled conditions and disturbed soil samples do not always reflect field conditions, and thus, they are inadequate for practical use. The objectives of the present study were (i) to test a simple field calibration method for a recently developed capacitive sensor even under highly variable soil texture conditions, and (ii) to validate this approach under various soil moisture conditions. Soil samples were taken 0.5 m from the access tube of the sensor and a whole field calibration and several site-specific calibrations were developed using 10–142 observations per site under different soil water regimes. A regression of soil water content estimated by sensor reading on water content obtained by core sampling showed no significant difference in the slope and intercept of the 1:1 line when the field calibration was applied. However, the precision of the calibration was only considerably increased if the estimations were based on site-specific calibrations developed on at least 35 observations per site. The precision and accuracy of the calibration equations were not affected when data were obtained only under wet or dry soil conditions. The method presented in this paper is a speedy and cheap way to calibrate capacitance probe sensors.

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Effects of Soil Water Content and Soil Temperature on Efficacy of Metham-Sodium Against Verticillium dahliae

Plant Disease ◽

10.1094/pdis.1997.81.7.773 ◽

1997 ◽

Vol 81 (7) ◽

pp. 773-776 ◽

Cited By ~ 27

Author(s):

I. A. M. Saeed ◽

D. I. Rouse ◽

J. M. Harkin ◽

K. P. Smith

Keyword(s):

Soil Temperature ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Verticillium Dahliae ◽

Soil Column ◽

Early Spring ◽

Soil Conditions ◽

Column Studies ◽

Metham Sodium

Soil column studies were conducted to investigate the influence of soil water content and temperature on the efficacy of metham-sodium and its degradation product methyl isothiocyanate against Verticillium dahliae. The viability of the microsclerotia (MS) of the fungus in the top 30 cm of fumigated and control columns was measured. Temperatures for studies were 2 or 22°C, and the soil water content, expressed as soil matric potential, varied from -23 (wet), -113 (moist), to -2485 J/kg (dry). There was a significant interaction of soil water content and temperature on the efficacy of metham-sodium against V. dahliae MS. For the low soil temperature (2°C) the fumigant was more effective against MS of the fungus in wet than in moist or dry soil Soil water content did not affect fungicidal activity of metham-sodium when the soil columns were maintained at 22°C. These results suggest that the fumigant has a greater efficacy against V. dahliae in wet/cold soil conditions compared to the other conditions tested. Consequently, it was recommended that metham-sodium be applied to fields by chemigation in late fall or early spring to obtain efficacious results.

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Variations in Soil Water Content, Infiltration and Potential Recharge at Three Sites in a Mediterranean Mountainous Region of Baja California, Mexico

Water ◽

10.3390/w10121844 ◽

2018 ◽

Vol 10 (12) ◽

pp. 1844 ◽

Cited By ~ 4

Author(s):

Francisco Del Toro-Guerrero ◽

Enrique Vivoni ◽

Thomas Kretzschmar ◽

Stephen Bullock Runquist ◽

Rogelio Vázquez-González

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Soil Profile ◽

Baja California ◽

Soil Depth ◽

Critical Role ◽

Soil Conditions ◽

Wet Season ◽

Potential Recharge

In this research, we examined temporal variations in soil water content (θ), infiltration patterns, and potential recharge at three sites with different mountain block positions in a semiarid Mediterranean climate in Baja California, Mexico: two located on opposing aspects (south- (SFS) and north-facing slopes (NFS)) and one located in a flat valley. At each site, we measured daily θ between 0.1 and 1 m depths from May 2014 to September 2016 in four hydrological seasons: wet season (winter), dry season (summer) and two transition seasons. The temporal evolution of θ and soil water storage (SWS) shows a strong variability that is associated mainly with high precipitation (P) pulses and soil profile depth at hillslope sites. Results shows that during high-intensity P events sites with opposing aspects reveal an increase of θ at the soil–bedrock interface suggesting lateral subsurface fluxes, while vertical soil infiltration decreases noticeably, signifying the production of surface runoff. We found that the dry soil conditions are reset annually at hillslope sites, and water is not available until the next wet season. Potential recharge occurred only in the winter season with P events greater than 50 mm/month at the SFS site and greater than 120 mm/month at the NFS site, indicating that soil depth and lack of vegetation cover play a critical role in the transport water towards the soil–bedrock interface. We also calculate that, on average, around 9.5% (~34.5 mm) of the accumulated precipitation may contribute to the recharge of the aquifer at the hillslope sites. Information about θ in a mountain block is essential for describing the dynamics and movement of water into the thin soil profile and its relation to potential groundwater recharge.

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The effects of drainage on substrate water content at several forested Alberta peatlands

Canadian Journal of Forest Research ◽

10.1139/x26-006 ◽

1996 ◽

Vol 26 (1) ◽

pp. 53-62 ◽

Cited By ~ 30

Author(s):

R.L. Rothwell ◽

U. Silins ◽

G.R. Hillman

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Water Table ◽

Tree Growth ◽

Soil Conditions ◽

Drainage Ditch ◽

Sampling Locations ◽

Soil Water Conditions ◽

And Performance

Hydrologic drainage criteria that describe the position of the water table between adjacent ditches are commonly used to assess the initial effectiveness of peatland drainage projects for tree growth improvement. However, these criteria do not reflect the soil conditions that regulate tree growth and performance after drainage. The effect of three drainage ditch spacings (30, 40, and 50 m) on the spatial variability of soil water conditions at three drained boreal Alberta peatlands was studied. Soil water content (0–30 cm depth) was found to be insensitive (p = 0.686) to drainage ditch spacing several years after drainage. Greater variation was observed between different sampling locations (p = 0.024) relative to the position of the ditch edge within similar ditch spacings. Spatial distribution of soil water in the unsaturated zone was found to be inversely related to the degree of water table lowering. Spatial patterns of soil water content were strongly associated with changes to substrate bulk density resulting from post-drainage peatland subsidence.

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Estimating Midday Leaf and Stem Water Potentials of Mature Pecan Trees from Soil Water Content and Climatic Parameters

HortScience ◽

10.21273/hortsci.47.7.907 ◽

2012 ◽

Vol 47 (7) ◽

pp. 907-916 ◽

Cited By ~ 9

Author(s):

Sanjit K. Deb ◽

Manoj K. Shukla ◽

John G. Mexal

Keyword(s):

Water Stress ◽

Water Potential ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Soil Conditions ◽

Silty Clay ◽

Stem Water Potential ◽

Stem Water ◽

Two Parameter

Diurnal and temporal patterns of stem water potential (ψstem) and leaf water potential (ψleaf) were determined during June to Sept. 2010 and 2011 at lower (2.5 m tree height), mid- (4.6 m), and upper (7.6 m) canopy positions for two flood-irrigated, mature pecan [Carya illinoinensis (Wangenh.) K. Koch] orchards near Las Cruces, NM. Diurnal measurements of ψstem and ψleaf at three canopy heights were correlated under both dry and wet soil conditions. However, although soil water contents at Site 2 (silty clay loam texture) remained higher compared with Site 1 (sandy loam), ψstem and ψleaf values, particularly under dry soil conditions at Site 2, were consistently lower, showing the effect of clayey soil texture on pecan water stress. Diurnal patterns of ψstem and ψleaf indicated that measurements of ψstem and ψleaf should be made close to early afternoon (between 1400 and 1500 hr Mountain Standard Time) to evaluate mature pecan water stress, which also corresponded to maximum climatic stress conditions. Midday ψstem and ψleaf measured at three canopy heights over several irrigation cycles during the 2010 season were correlated with one another, midday soil water content at different depths, and atmospheric vapor pressure deficit (VPD). Multiple regression analysis [between midday ψstem or ψleaf and midday θavg (soil water content at 0 to 40 cm), air temperature (Tmd), and relative humidity (RHmd)] during the 2010 season revealed that two-parameter regression models [ψstem or ψleaf = f (midday θavg and Tmd)] were the most significant for the interpretation of midday ψstem or ψleaf at both sites. Using the two-parameter model, predictions of ψstem and ψleaf measured on the both shaded and sunlit sides of trees at three canopy heights for 2011 showed good agreement between measured and predicted ψstem and ψleaf (R2 ranged from 0.70 to 0.98). Two-parameter models derived in an earlier study generally underpredicted ψstem both in 2010 and 2011, which further supported the importance of the time of midday ψstem and ψleaf measurements suggested in this study.

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The role of fluctuations in soil water content on the regulation of dormancy changes in buried seeds of Polygonum aviculare L.

Seed Science Research ◽

10.1079/ssr2005234 ◽

2006 ◽

Vol 16 (1) ◽

pp. 47-59 ◽

Cited By ~ 35

Author(s):

Diego Batlla ◽

Roberto Luis Benech-Arnold

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Field Conditions ◽

Soil Conditions ◽

Potential Range ◽

Moist Soil ◽

Polygonum Aviculare ◽

Buried Seeds ◽

Fluctuating Temperatures

It has been hypothesized that fluctuations in soil water content may affect the dormancy status of weed seed banks under field conditions. In this paper, we present results showing that fluctuations in soil water content affect the dormancy status of buried seeds ofPolygonum aviculareL. stored at dormancy-releasing temperatures. Effects of fluctuations in soil water content on the dormancy status ofP. aviculareseeds were evaluated by comparing changes in the range of temperatures and water potentials permissive for germination, and in the sensitivity to fluctuating temperatures, between seeds subjected to a moist soil regime (MS) or to a fluctuating soil water content regime (FS). In comparison to the dormancy release pattern observed for seeds subjected to MS, seeds subjected to FS generally showed an increase in their dormancy level after periods of storage under dry soil conditions, and a decrease in their dormancy level after periods of storage under moist soil conditions. These effects were more pronounced during early stages of the storage period, producing larger changes in the thermal and water potential range for seed germination than in the sensitivity of seeds to fluctuating temperatures. Seeds subjected to FS generally exhibited a lower mean low-limit temperature, lower mean thermal time and hydrotime requirements for germination, and a higher proportion of the seed population with the capacity to germinatein situ, than seeds subjected to MS. The results obtained suggested that fluctuations in soil water content could be an additional factor affecting dormancy and weed emergence patterns under field conditions.

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