Using Soil Moisture Data to Estimate Evapotranspiration and Development of a Physically Based Root Water Uptake Model

Shah, Nirjhar; Ross, Mark; Trout, Ken

doi:10.5772/18040

Cited by 9 publications

(5 citation statements)

References 33 publications

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“…Many studies, including Schelde et al (2011) and Guderle and Hildebrandt (2015), have shown that highly resolved soil moisture measurements contain a great deal of information that can be used to accurately determine ET and sink term, based on hydrologic balance, when the appropriate approach is used. Rahgozar et al (2012) and Shah et al (2012) extended these methodologies to determine other components of the water budget, such as lateral flow, infiltration, interception capture, storage, surface runoff, and other fluxes. Time domain reflectometry (TDR) has been widely used in many irrigating regions, including the desert oasis of the middle HRB, during the last decade , for automated measurement of soil water dynamics, because of its flexibility and accuracy (Schelde et al, 2011).…”

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confidence: 99%

Estimation of Evapotranspiration and Other Soil Water Budget Components in an Irrigated Agricultural Field of a Desert Oasis, Using Soil Moisture Measurements

Liu

Zhao

et al. 2018

Preprint

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Abstract. An accurate assessment of soil water budget components (SWBCs) is necessary for improving irrigation strategies and optimizing the use of fertilizer in any water-limited environment such as the desert oases in arid northwestern China. However, quantitative information of SWBCs is usually challenging to obtain, because, since the water cycle is principally driven by irrigation (I), drainage (D), and evapotranspiration (ET) in desert oasis settings, none of the drivers can be easily measured under actual conditions. Soil moisture is a variable that integrates the water balance components of land surface hydrology, and the evolution of soil moisture is assumed to contain the memory of antecedent hydrologic fluxes, and thus can be used to determine SWBCs from a hydrologic balance. A database of soil moisture measurements from six experimental plots in the middle Heihe River Basin of China (NT1 to NT6, designed to investigate the long-term effects of cropping systems and agronomic manipulation on soil property evolution in the ecotone of desert and oasis) was used to test the potential of a soil moisture database in estimating the SWBCs. The experimental plots were treated as continuous pasture cropping, maize cropping, maize cropping with straw return, maize-maize-pasture rotation, maize-pasture rotation, and maize-pasture intercropping. We first compared the hydrophysical properties of the soils in the plots, including soil bulk density (ρb), vertical saturated hydraulic conductivity (Ks), and soil water retention features, and then determined evapotranspiration and other SWBCs through a data-driven method that combined both the soil water balance method and the inverse Richards function. Our results showed that although the tillage and planting of the past decade have significantly increased the soils' water-holding ability, the magnitude of increase in most of the parameters was independent of the treatments applied across the plots. Despite the relatively flat topography and consciously uniform irrigation, significant variances were observed among the plots in both the cumulative irrigation volumes (between 652.1 mm at NT3 and 1186.5 mm at NT1) and deep drainages (between 170.7 mm at NT3 and 651.8 mm at NT1) during the growing season of 2016. Obvious correlation existed between the volume of irrigation and that of drained water. However, the ET demands for all the plots behaved pretty much the same, with the cumulative ET values ranging between 489.1 and 561.9 mm for the different treatments in 2016, suggesting that the irrigation amounts had limited influence on the accumulated ET throughout the growing season. This work also confirmed that relatively reasonable estimations of the SWBCs in a desert oasis environment can be derived by using soil moisture measurements, and the results will provide a great potential for identifying appropriate irrigation amounts and frequencies, and thus move toward sustainable water resources management, even under traditional surface irrigation conditions.

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confidence: 99%

Estimation of Evapotranspiration and Other Soil Water Budget Components in an Irrigated Agricultural Field of a Desert Oasis, Using Soil Moisture Measurements

Liu

Zhao

et al. 2018

Preprint

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“…To particularly focus on the rela-tions among the mentioned variables, approximately thirty inter-storm periods, each with a minimum length of five days, were selected from October 2004 to October 2007. For each event, the evapotranspiration volume was estimated using the soil water budget method, which has been widely applied in different climate and vegetation cover contexts (Rana and Katerji, 2000;Wilson et al, 2001;Schume et al, 2004;Shah et al, 2012;Shang, 2012).…”

Section: Aggregated Event Scale Analysismentioning

confidence: 99%

Relating soil moisture and air temperature to evapotranspiration fluxes during inter-storm periods at a Mediterranean experimental site

Longobardi

Khaertdinova

2014

J. Arid Land

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The assessment of the water losses by actual evapotranspiration plays a very important role in water resources management, especially in particular environments suffering soil water stresses and water shortages. The rationales of this study are the scarcity of experimental data, the difficulties in the measurement of direct and continuous evapotranspiration fluxes, and the switching between controls by climate and soil water availability. The temporal patterns of observed soil moisture and air temperature of over three years at an experimental site in southern Italy have been analysed to investigate the relation between them and the actual evapotranspiration volume, estimated using the soil water budget method. To this end, an event-based empirical analysis has been performed, exploring the relation between the mentioned variables. One of the major findings of the explorative phase is the qualitative and quantitative identification of the switching between climate and soil water balance as the controls over actual evapotranspiration at the experimental site. This threshold process has then been modelled at the event and sub-event scale, establishing simple empirical equations to predict actual evapotranspiration losses as a function of soil water content. Multilevel-recorded data also allowed the investigation of the importance of soil depth.

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“…So far, however, relatively few studies have been published on testing the potential of using a soil moisture database as a method to systematically estimate the SWBCs of farmland in dryland regions, where the principal soils are coarse (Grayson et al, 1999;Yang et al, 2019) and tend to have low water retention capacity and high drainage (Lal, 2004) and the plant roots are very diverse and complex because of the harsh environments in which they grow. As frequently occurring soil aridification and nutrient leaching present major threats to food security and sustainable development of regional communities in these environments (Crosbie et al, 2009), the development of a reliable farmland SWBC estimation method, which can make the most of the vast amounts of soil moisture data, is crucial for irrigation management optimization (Musters and Bouten, 2000;Sharma et al, 2017), especially for arid regions with coarse-textured soils. This work used the TDR measurements of soil moisture collected from a long-term field experiment in the ecotones of desert and oasis, which was originally designed to test the accumulative impacts of different cropping systems (i.e., maize and alfalfa) and agronomic manipulation (i.e., succession cropping, crop rotation, row intercropping) on soil property evolution.…”

Section: Introductionmentioning

confidence: 99%

Quantification of soil water balance components based on continuous soil moisture measurement and the Richards equation in an irrigated agricultural field of a desert oasis

Li¹,

Liu²,

Zhao³

et al. 2019

Hydrol. Earth Syst. Sci.

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Abstract. An accurate assessment of soil water balance components (SWBCs) is necessary for improving irrigation strategies in any water-limited environment. However, quantitative information on SWBCs is usually challenging to obtain, because none of the components (i.e., irrigation, drainage, and evapotranspiration) can be easily measured under actual conditions. Soil moisture is a variable that integrates the water balance components of land surface hydrology, and the evolution of soil moisture is assumed to contain the memory of antecedent hydrologic fluxes, and can thus be used to determine SWBCs from a hydrologic balance. A database of soil moisture measurements from six experimental plots with different treatments in the middle Heihe River basin of China was used to test the potential of a such a database for estimating SWBCs. We first compared the hydrophysical properties of the soils in these plots, such as vertical saturated hydraulic conductivity (Ks) and soil water retention features, for supporting SWBC estimations. We then determined evapotranspiration and other SWBCs using a method that combined the soil water balance method and the inverse Richards equation (a model of unsaturated soil water flow based on the Richards equation). To test the accuracy of our estimation, we used both indirect methods (such as power consumption of the pumping irrigation well and published SWBCs values at nearby sites) and the water balance equation technique to verify the estimated SWBCs values, all of which showed good reliability with respect to our estimation method. Finally, the uncertainties of the proposed methods were analyzed to evaluate the systematic error of the SWBC estimation and any restrictions regarding its application. The results showed significant variances among the film-mulched plots in both the cumulative irrigation volumes (652.1–867.3 mm) and deep drainages (170.7–364.7 mm). Moreover, the un-mulched plot had remarkably higher values in both cumulative irrigation volumes (1186.5 mm) and deep drainages (651.8 mm) compared with the mulched plots. Obvious correlation existed between the volume of irrigation and that of drained water. However, the ET demands for all of the plots behaved pretty much the same, with the cumulative ET values ranging between 489.1 and 561.9 mm for the different treatments in 2016, suggesting that the superfluous irrigation amounts had limited influence on the accumulated ET throughout the growing season due to the poor water-holding capacity of the sandy soil. This work confirmed that relatively reasonable estimations of the SWBCs in coarse-textured sandy soils can be derived by using soil moisture measurements; the proposed methods provided a reliable solution over the entire growing season and showed a great potential for identifying appropriate irrigation amounts and frequencies, and thus a move toward sustainable water resources management, even under traditional surface irrigation conditions.

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Using Soil Moisture Data to Estimate Evapotranspiration and Development of a Physically Based Root Water Uptake Model

Cited by 9 publications

References 33 publications

Estimation of Evapotranspiration and Other Soil Water Budget Components in an Irrigated Agricultural Field of a Desert Oasis, Using Soil Moisture Measurements

Estimation of Evapotranspiration and Other Soil Water Budget Components in an Irrigated Agricultural Field of a Desert Oasis, Using Soil Moisture Measurements

Relating soil moisture and air temperature to evapotranspiration fluxes during inter-storm periods at a Mediterranean experimental site

Quantification of soil water balance components based on continuous soil moisture measurement and the Richards equation in an irrigated agricultural field of a desert oasis

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