COMPARISON OF TWO SOIL-WATER MODELS UNDER SEMI-ARID GROWING CONDITIONS

1988 ◽  
Vol 68 (1) ◽  
pp. 17-27 ◽  
Author(s):  
R. DE JONG
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Distribution ◽  
Water Movement ◽  
Arid Zone ◽  
Absolute Difference ◽  
Long Term Experiment ◽  
Growing Conditions ◽  
Semi Arid

The Versatile Soil Moisture Budget (VSMB) and the Soil-Plant-Air-Water (SPAW) model were compared and tested against soil-water content data from a long-term experiment in which wheat was grown on fallow land in the semi-arid zone of Saskatchewan. Both models were driven by daily air temperatures and precipitation data. At the expense of requiring more detailed soil and crop information, the SPAW model simulated the water balance and its components in greater detail than the VSMB. Predictions of soil-water contents throughout the growing season with either model corresponded very well with the measured data. The overall mean absolute difference in total soil-water content to a depth of 120 cm was 1.5 cm for the VSMB and 1.2 cm for the SPAW model. Predictions of water distribution in the profile were also satisfactory. A choice between the two models, to be used under semi-arid growing conditions, will depend on the availability of input data and the required level of output. Key words: Soil-water movement, modelling, evapotranspiration

scholarly journals Modelling the Impact on Root Water Uptake and Solute Return Flow of Different Drip Irrigation Regimes with Brackish Water

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 425 ◽  
Author(s):  
Fairouz Slama ◽  
Nessrine Zemni ◽  
Fethi Bouksila ◽  
Roberto De Mascellis ◽  
Rachida Bouhlila
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Uptake ◽  
Brackish Water ◽  
Deficit Irrigation ◽  
Root Zone ◽  
Root Water Uptake ◽  
Return Flows ◽  
Semi Arid

Water scarcity and quality degradation represent real threats to economic, social, and environmental development of arid and semi-arid regions. Drip irrigation associated to Deficit Irrigation (DI) has been investigated as a water saving technique. Yet its environmental impacts on soil and groundwater need to be gone into in depth especially when using brackish irrigation water. Soil water content and salinity were monitored in a fully drip irrigated potato plot with brackish water (4.45 dSm−1) in semi-arid Tunisia. The HYDRUS-1D model was used to investigate the effects of different irrigation regimes (deficit irrigation (T1R, 70% ETc), full irrigation (T2R, 100% ETc), and farmer’s schedule (T3R, 237% ETc) on root water uptake, root zone salinity, and solute return flows to groundwater. The simulated values of soil water content (θ) and electrical conductivity of soil solution (ECsw) were in good agreement with the observation values, as indicated by mean RMSE values (≤0.008 m3·m−3, and ≤0.28 dSm−1 for soil water content and ECsw respectively). The results of the different simulation treatments showed that relative yield accounted for 54%, 70%, and 85.5% of the potential maximal value when both water and solute stress were considered for deficit, full. and farmer’s irrigation, respectively. Root zone salinity was the lowest and root water uptake was the same with and without solute stress for the treatment corresponding to the farmer’s irrigation schedule (273% ETc). Solute return flows reaching the groundwater were the highest for T3R after two subsequent rainfall seasons. Beyond the water efficiency of DI with brackish water, long term studies need to focus on its impact on soil and groundwater salinization risks under changing climate conditions.

scholarly journals Relating surface backscatter response from TRMM Precipitation Radar to soil moisture: results over a semi-arid region

2009 ◽  
Vol 6 (5) ◽  
pp. 6425-6454
Author(s):  
H. Stephen ◽  
S. Ahmad ◽  
T. C. Piechota ◽  
C. Tang
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Arid Regions ◽  
Vegetation Index ◽  
Temporal Trends ◽  
Model Parameters ◽  
Precipitation Radar ◽  
Semi Arid

Abstract. The Tropical Rainfall Measuring Mission (TRMM) carries aboard the Precipitation Radar (TRMMPR) that measures the backscatter (σ°) of the surface. σ° is sensitive to surface soil moisture and vegetation conditions. Due to sparse vegetation in arid and semi-arid regions, TRMMPR σ° primarily depends on the soil water content. In this study we relate TRMMPR σ° measurements to soil water content (ms) in Lower Colorado River Basin (LCRB). σ° dependence on ms is studied for different vegetation greenness values determined through Normalized Difference Vegetation Index (NDVI). A new model of σ° that couples incidence angle, ms, and NDVI is used to derive parameters and retrieve soil water content. The calibration and validation of this model are performed using simulated and measured ms data. Simulated ms is estimated using Variable Infiltration Capacity (VIC) model whereas measured ms is acquired from ground measuring stations in Walnut Gulch Experimental Watershed (WGEW). σ° model is calibrated using VIC and WGEW ms data during 1998 and the calibrated model is used to derive ms during later years. The temporal trends of derived ms are consistent with VIC and WGEW ms data with correlation coefficient (R) of 0.89 and 0.74, respectively. Derived ms is also consistent with the measured precipitation data with R=0.76. The gridded VIC data is used to calibrate the model at each grid point in LCRB and spatial maps of the model parameters are prepared. The model parameters are spatially coherent with the general regional topography in LCRB. TRMMPR σ° derived soil moisture maps during May (dry) and August (wet) 1999 are spatially similar to VIC estimates with correlation 0.67 and 0.76, respectively. This research provides new insights into Ku-band σ° dependence on soil water content in the arid regions.

scholarly journals Water Distribution in Reconstructed Soil of Nonmetal Mines and the Ecological Effect in Xinjiang, China

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Zizhao Zhang ◽  
Xiaoli Guo ◽  
Qianli Lv ◽  
Ruihua Hao ◽  
Zezhou Guo ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Distribution ◽  
Land Reclamation ◽  
Observation System ◽  
Neutron Probe ◽  
Matrix Potential ◽  
The Law ◽  
Reconstructed Soil

Because of the arid climate and fragile ecological environment in Xinjiang, China, land reclamation should be carried out after mining. The core of land reclamation is the water content of the surface covering soil. In this paper, the law of water distribution in reclamation reconstructed soil of nonmetal mines in Xinjiang was studied. In order to obtain the law of water distribution in reconstructed soil, we set up an observation system of the neutron probe and tensiometer. The neutron probe was used to monitor the soil water content. The tensiometers were used to obtain the matrix potential of soil for verifying the water distribution in reconstructed soil. Volumetric water content and matrix potential of reconstructed soil during 1-year period of management and irrigation were obtained by long-term monitoring. After one year’s field in situ test, 2424 sets of neutron probe data and 1368 sets of tensiometer data were obtained. By studying the above parameters, we summarized the law of water distribution in reconstructed soil of variable thickness and degree of compaction with nonmetallic waste rock filling. The results showed that covering soil was helpful to retain water content. Whether the soil was compacted or uncompacted, the soil water content at the depth of 10 cm was less than that at other depth of reconstructed soil because it was greatly affected by meteorological factors. The water content of reconstructed soil at 30 cm depth was greater than that at other depths. Under the influence of factors such as the thickness and compaction of the soil, the response time of soil water content and matrix potential to each irrigation infiltration was different. According to the characteristics of reclamation-vegetation such as alfalfa growth in Xinjiang, the thickness of surface reconstructed soil should be not less than 50 cm. Over time, soil that was compacted once was better for the vegetation. The research results could provide a reference for the land reclamation of nonmetallic mines in Xinjiang, China.

scholarly journals Impact of long term fertilization on soil water content in Haploborolls

2010 ◽  
Vol 56 (No. 9) ◽  
pp. 408-411 ◽  
Author(s):  
C.Y. Song ◽  
X.Y. Zhang ◽  
X.B. Liu ◽  
Y.Y. Sui ◽  
Z.L. Li
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Organic Amendments ◽  
Pig Manure ◽  
Fertilizer Treatment ◽  
Total Soil ◽  
Long Term Experiment ◽  
The Impact

Soil water content under no fertilizer (NF), fertilizer (F) (N:30; P<sub>2</sub>O<sub>5</sub>: 45 kg/ha), and fertilizer plus pig manure (FO) (N:30; P<sub>2</sub>O<sub>5</sub>: 45 kg/ha; pig manure 15 000 kg/ha in 2003; and 30 000 kg/ha in 2004 and 2005) treatments was measured using neutron probe instrument for a period three years in a long term field experiment in order to investigate the impact of different fertilization treatments on Haploborolls soil water content. Fertilization had significant effects on the soil water content. FO treatment had greater soil water content in 10 cm depth than F treatment with average 9.9% increase (P &lt; 0.05) but lower than NF treatment; however, in the depth from 30 to 90 cm, there was no water content difference between F and FO treatments. Treatment with organic amendments reduced total soil water content on the long term experiment basis. Across the three years, no fertilizer treatment had total soil water content higher by 1.2% and 3.1% than fertilizer treatment and fertilizer plus pig manure treatment within 10 to 210 cm soil profile in most of the months, respectively.

USE OF TEMPE CELL, MODIFIED TO RESTRAIN SWELLING, FOR DETERMINATION OF HYDRAULIC CONDUCTIVITY AND SOIL WATER CONTENT

1984 ◽  
Vol 64 (2) ◽  
pp. 265-272 ◽  
Author(s):  
T. G. SOMMERFELDT ◽  
G. B. SCHAALJE ◽  
W. HULSTEIN
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Movement ◽  
Clay Content ◽  
Core Sample ◽  
Soil Samples ◽  
The Core ◽  
Silty Loam

The Tempe cell, modified by others to determine saturated hydraulic conductivity (K), was further modified to restrain swelling of the soil and to facilitate air and water movement across the top and bottom of the sample. An apparatus was developed whereby K and water content (θ) could be determined for several soil samples concurrently and suction levels could be varied without disturbing the sample. K and θ were determined for several prepared soil samples by the constant head permeameter method and by the Tempe cell with and without swelling restrained, and for soil cores by the Tempe cell with swelling restrained. With swelling restrained, the K results from the prepared samples did not differ significantly from those of the core samples. For the sandy to silty loam soils at suction levels 0, 10, and 20 kPa, θ of the core sample was less than that from the other samples, whereas for the clay loam soils, θ of the core sample was less than that from the others at suction levels of 0 and 10 kPa. For all methods, θ was correlated to clay content of the soil. These results indicate that the Tempe cell, as finally modified with swelling restraints, can be used to determine K and θ for characterizing the drainability of a nonstructured to weakly structured soil, using either prepared samples or cores. Key words: Hydraulic conductivity, pore volume, soil water content, Tempe cell

Net positive soil water content following cover crops with no tillage in irrigated semi-arid cotton production

2021 ◽  
Vol 208 ◽  
pp. 104869
Author(s):  
Joseph A. Burke ◽  
Katie L. Lewis ◽  
Glen L. Ritchie ◽  
Paul B. DeLaune ◽  
J. Wayne Keeling ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Cover Crops ◽  
No Tillage ◽  
Cotton Production ◽  
Semi Arid
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