scholarly journals Contributions of precipitation, irrigation and soil water to evapotranspiration in (semi)-arid regions

2014 ◽  
Vol 35 (6) ◽  
pp. 1079-1089 ◽  
Author(s):  
Juana Paul Moiwo ◽  
Fulu Tao
Keyword(s):  
Soil Water ◽  
Arid Regions ◽  
Semi Arid

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 Redistribution process of precipitation in ecological restoration activity of Pinus sylvestris  var. mongolica in Mu Us Sandy Land, China

2021 ◽  
Author(s):  
Yiben Cheng ◽  
Hongbin Zhan ◽  
Wenbin Yang ◽  
Yunqi Wang ◽  
Qunou Jiang ◽  
...  
Keyword(s):  
Pinus Sylvestris ◽  
Soil Water ◽  
Sap Flow ◽  
Arid Regions ◽  
Moisture Distribution ◽  
Sandy Land ◽  
Mu Us Sandy Land ◽  
Shallow Soil ◽  
Semi Arid ◽  
Horizontal Area

Abstract. Precipitation was the most important water resource in semi-arid regions of China. The redistribution of precipitation among atmospheric water, soil water and groundwater are related to the land surface ecological system sustainability. The study took widely replanted Pinus sylvestris var. mongolica (PSM) in Mu Us Sandy Land (MUSL) as a research object and monitored precipitation, soil moisture, sap flow, and deep soil recharge (DSR) to find out moisture distribution in shallow soil layer. Results showed that the restoration process of PSM in MUSL changed the distribution of precipitation. Precipitation was intercepted in shallow soil, evapotranspiration increased, and DSR significantly decreased, resulting in up to 466.94 mm of precipitation returning to the atmosphere through evapotranspiration in 2016. Vegetation increased soil water storage (SWS) capacity, with maximum SWS in PSM plot and bare sandy land (BSL) being 260 mm and 197 mm per unit horizontal area, respectively in 2016. DSR decreased from 54.03 % of precipitation in BSL to 0.2 % of precipitation in PSM in 2016. Infiltration was not only intercepted by PSM ecosystem, resulting in a time lag, but was also affected by soil temperature, and the infiltration rate in the BSL plot was 11 times of that in the PSM plot from August to September in an annual base. SWS decreased 16 mm and 7.58 mm per unit horizontal area over a one-year period (from March to October) in 2017 and 2019, respectively. The PSM annual sap flow was maintained at a relatively constant level of 153.98 mm/yr. This study helps understand the role of precipitation-induced groundwater recharge in the process of vegetation restoration in semi-arid regions and explains the possible causes of PSM forest degradation. It is necessary to reduce PSM density to allow adaptation to extreme drought in the future.

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

2010 ◽  
Vol 14 (2) ◽  
pp. 193-204 ◽  
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 the 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 the Variable Infiltration Capacity (VIC) model and 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 a 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 Effect of Irrigation Water Regimes on Yield of Tetragonia Tetragonioides

Agriculture ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 22 ◽  
Author(s):  
Gulom Bekmirzaev ◽  
Jose Beltrao ◽  
Baghdad Ouddane
Keyword(s):  
Soil Water ◽  
Irrigation Water ◽  
Arid Regions ◽  
Total Yield ◽  
Soil Salinization ◽  
Soluble Carbohydrates ◽  
Water Regimes ◽  
Irrigation Regimes ◽  
Semi Arid ◽  
Tetragonia Tetragonioides

The main purpose of this experiment was to study the effect of several irrigation water regimes on Tetragonia tetragonioides (Pall) O. Kuntze in semi-arid regions. During the experiment period, it was measured that several irrigation regimes were affected in terms of growth, biomass production, total yield, mineral composition, and photosynthetic pigments. The experiment was conducted in the greenhouse at the University of Algarve (Portugal). The study lasted from February to April in 2010. Three irrigation treatments were based on replenishing the 0.25-m-deep pots to field capacity when the soil water level was dropped to 70% (T1, wet treatment), 50% (T2, medium treatment), and 30% (T3, dry treatment) of the available water capacity. The obtained results showed that the leaf mineral compositions of chloride and sodium, the main responsible ions for soil salinization and alkalization in arid and semi-arid regions, enhanced with the decrease in soil water content. However, the minimum amounts of chlorophyll, carotenoids, and soluble carbohydrates in the leaf content were obtained in the medium and driest treatments. On the other hand, growth differences among the several irrigation regimes were very low, and the crop yield increased in the dry treatment compared to the medium treatment; thus, the high capacity of salt-removing species suggested an advantage of its cultivation under dry conditions.

scholarly journals Soil Salinity Type Effects on the Relationship between the Electrical Conductivity and Salt Content for 1:5 Soil-To-Water Extract

2021 ◽  
Vol 13 (6) ◽  
pp. 3395
Author(s):  
Amin I. Ismayilov ◽  
Amrakh I. Mamedov ◽  
Haruyuki Fujimaki ◽  
Atsushi Tsunekawa ◽  
Guy J. Levy
Keyword(s):  
Electrical Conductivity ◽  
Soil Water ◽  
Soil Salinity ◽  
Arid Regions ◽  
Clayey Soil ◽  
Salt Content ◽  
Water Extract ◽  
Soluble Salts ◽  
The Relationship ◽  
Semi Arid

Soil salinity severely affects soil ecosystem quality and crop production in semi-arid and arid regions. A vast quantity of data on soil salinity has been collected by research organizations of the Commonwealth of Independent States (CIS, formerly USSR) and many other countries over the last 70 years, but using them in the current international network (irrigation and reclamation strategy) is complicated. This is because in the CIS countries salinity was expressed by total soluble salts as a percentage on a dry-weight basis (total soluble salts, TSS, %) and eight salinity types (chemistry) determined by the ratios of the anions and cations (Cl−, SO42−, HCO3−, and Na+, Ca2+, Mg2+) in diluted soil water extract (soil/water = 1:5) without assessing electrical conductivity (EC). Measuring the EC (1:5) is more convenient, yet EC is not only affected by the concentration but also characteristics of the ions and the salinity chemistry. The objective of this study was to examine the relationship between EC and TSS of soils in a diluted extract (1:5) for eight classic salinity types. We analyzed extracts (1:5) of 1100 samples of a clayey soil (0–20 cm) collected from cultivated semi-arid and arid regions for EC, TSS, soluble cations (Na+, Ca2+, Mg2+), and anions (HCO3−, Cl−, SO42−). Results revealed that (i) the variation in the proportional relationships (R2 ≥ 0.91–0.98) between EC (0.12–5.6 dS m−1) and TSS (0.05–2.5%) could be related to salinity type, and (ii) the proportionality coefficient of the relationships (2.2 2–3.16) decreased in the following order of salinity type: SO4 < Cl(SO4)–HCO3 < Cl(HCO3)–SO4 < SO4 (HCO3)–Cl < Cl. The findings suggest that once the salinity type of the soil is established, EC (1:5) values can be safely used for the evaluation of the soil salinity degree in the irrigated land in the context of sustainable soil and crop management.

Improvement of evapotranspiration estimates over arid and semi-arid regions with a physically based water stress constraint scheme

2020 ◽  
Author(s):  
Kun Zhang ◽  
Donghai Zheng ◽  
Yunquan Wang ◽  
Gaofeng Zhu
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Soil Water ◽  
Arid Regions ◽  
Bare Soil ◽  
Stress Constraint ◽  
Near Surface ◽  
Soil Water Stress ◽  
Physically Based ◽  
Semi Arid

&lt;p&gt;In the arid and semi-arid regions, the bare soil evaporation dominates the total evapotranspiration (ET). To date, in most of the process-based ET models, the constraint on the actual evaporation from bare soil due to water stress is either related to an empirical function of near-surface humidity or represented by a water stress factor linked with surface soil moisture. However, the relative humidity (RH) shows a hysteretic effect on the ET event, and the relationship between soil water stress and soil moisture is nonlinear, usually leading to the overestimation of ET in arid and semi-arid regions. In this study, we plan to improve the ET estimates on dry land by implementing a physically-based water stress constraint method, which is developed by parameterizing the Buckingham-Darcy&amp;#8217;s law and yielded an excellent performance with laboratory data. The physically-based water stress constraint scheme is further incorporated into two different ET models (i.e. PT-JPL, MOD16) to generate the global ET estimates, whereby the latest ERA5-land reanalysis data and MODIS NDVI\LAI is adopted as model inputs. We not only validate the simulated ET with available flux observations but also intercompare the performances of different schemes in estimating ET in the arid and semi-arid regions. This study will provide a new way to characterize the regional soil water stress on the ET estimates especially in the arid and semi-arid conditions.&lt;/p&gt;

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