The drainage component of the water balance equation

Soil Research ◽  
1965 ◽  
Vol 3 (2) ◽  
pp. 95 ◽  
Author(s):  
CW Rose ◽  
WR Stern
Keyword(s):  
Water Balance ◽  
Water Content ◽  
Bulk Density ◽  
Balance Equation ◽  
Clay Soils ◽  
Swelling Clay ◽  
Water Balance Equation ◽  
Field Crops

A method is presented for determining the drainage term in the water balance equation, which may then be used to solve for evaporation from field crops. Questions concerning accuracy in determination of the drainage term are considered. Two special problems that arise in this context with swelling clay soils are discussed, namely, the variation of bulk density with water content, and the inference of in situ soil water suction from volumetric water content measurement.

Field calibration of ThetaProbe (ML2x) and ECHO probe (EC-20) soil water sensors in a Black Vertosol

Soil Research ◽  
2007 ◽  
Vol 45 (3) ◽  
pp. 233 ◽  
Author(s):  
J. L. Foley ◽  
E. Harris
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Clay Soils ◽  
Deep Drainage ◽  
Swelling Clay ◽  
Field Calibration ◽  
Volumetric Measurements

Past studies have shown that soil-specific calibrations are required to attain a higher level of accuracy when measuring soil water content with ThetaProbe and ECHO probe soil water sensors, particularly in swelling clay soils. Both probes were assessed for their capacity to accurately monitor soil water in a deep drainage study on a Black Vertosol. Probes were trialled in situ and calibrated against hand-sampled volumetric measurements. The generic calibrations given by the manufacturers resulted in significant errors in water content estimates for both probes. Using the generic calibration, ECHO probes under-estimated water content by 0.10–0.2 m3/m3, whereas ThetaProbes under-estimated by 0.04 m3/m3 at the wet end and over-estimated by 0.08 m3/m3 at the dry end. The soil-specific calibrations significantly improved the accuracy of both probes. ThetaProbes were chosen for the drainage study. The calibration allowed for accuracy across the full wet–dry range to within 0.001–0.004 m3/m3 of volumetric measurements. ECHO probes were less accurate at the wet end, but still determined soil water content to within 0.02–0.05 m3/m3 of volumetric measurements.

Water balance in swelling materials: some comments

Soil Research ◽  
1997 ◽  
Vol 35 (5) ◽  
pp. 1143 ◽  
Author(s):  
D. E. Smiles
Keyword(s):  
Water Balance ◽  
Water Content ◽  
Material Balance ◽  
Physical Space ◽  
Clay Soils ◽  
Acid Sulfate ◽  
Retention Ponds ◽  
Material Space ◽  
Semi Arid

Materials ranging from wet tailings in retention ponds through potentially acid sulfate sediments in humid marine environments to clay soils in semi-arid climates shrink and swell with change in water content. This paper discusses the formulation and determination of material balance in such swelling and cracking materials. Significant errors and their likely magnitudes are identified when these estimates are based in physical space, as opposed to material space. Ways in which this problem might be dealt with are discussed.

scholarly journals Improved Mekong Basin Runoff Estimate and Its Error Characteristics Using Pure Remotely Sensed Data Products

2021 ◽  
Vol 13 (5) ◽  
pp. 996
Author(s):  
Hok Sum Fok ◽  
Yutong Chen ◽  
Lei Wang ◽  
Robert Tenzer ◽  
Qing He
Keyword(s):  
Water Balance ◽  
Balance Equation ◽  
Remotely Sensed ◽  
Water Balance Equation ◽  
Water Balance Component ◽  
Mekong Basin ◽  
Data Products ◽  
Terrestrial Water ◽  
Published Result

Basin runoff is a quantity of river discharge per unit basin area monitored close to an estuary mouth, essential for providing information on the flooding and drought conditions of an entire river basin. Owing to a decreasing number of in situ monitoring stations since the late 1970s, basin runoff estimates using remote sensing have been advocated. Previous runoff estimates of the entire Mekong Basin calculated from the water balance equation were achieved through the hybrid use of remotely sensed and model-predicted data products. Nonetheless, these basin runoff estimates revealed a weak consistency with the in situ ones. To address this issue, we provide a newly improved estimate of the monthly Mekong Basin runoff by using the terrestrial water balance equation, purely based on remotely sensed water balance component data products. The remotely sensed water balance component data products used in this study included the satellite precipitation from the Tropical Rainfall Measuring Mission (TRMM), the satellite evapotranspiration from the Moderate Resolution Imaging Spectroradiometer (MODIS), and the inferred terrestrial water storage from the Gravity Recovery and Climate Experiment (GRACE). A comparison of our new estimate and previously published result against the in situ runoff indicated a marked improvement in terms of the Pearson’s correlation coefficient (PCC), reaching 0.836 (the new estimate) instead of 0.621 (the previously published result). When a three-month moving-average process was applied to each data product, our new estimate further reached a PCC of 0.932, along with the consistent improvement revealed from other evaluation metrics. Conducting an error analysis of the estimated mean monthly runoff for the entire data timespan, we found that the usage of different evapotranspiration data products had a substantial influence on the estimated runoff. This indicates that the choice of evapotranspiration data product is critical in the remotely sensed runoff estimation.

scholarly journals Retention time of lakes in the Larsemann Hills oasis, East Antarctica

2020 ◽  
Author(s):  
Elena Shevnina ◽  
Ekaterina Kourzeneva ◽  
Yury Dvornikov ◽  
Irina Fedorova
Keyword(s):  
Water Balance ◽  
Retention Time ◽  
Balance Equation ◽  
Water Exchange ◽  
Warm Season ◽  
East Antarctica ◽  
Water Balance Equation ◽  
Larsemann Hills ◽  
Lake Volume ◽  
Field Campaigns

Abstract. The study gives first estimates of water transport scale for five lakes located in the Larsemann Hills oasis (69º23' S, 76º20' E) in the East Antarctica. We estimated the lake retention time (LRT) as a ratio of the lake volume to the income and outcome terms of a lake water balance equation. The LRT was evaluated for lakes of epiglacial and land-locked types, and it was assumed that these lakes are monomictic with water exchange existing during a warm season only. We used hydrological observations collected in 4 seasonal field campaigns to evaluate the LRT from the outcome and income terms of the water balance equation. For the epiglacial lakes Progress/LH57 and Nella/Scandrett/LH72, the LRT was estimated of 12–13 and 4–5 years, respectively. For the land-locked lakes Stepped/LH68, Sara Tarn/LH71 and Reid/LH70, our results show a big difference in the LRT calculated from the outcome and income components of the water balance equation. The LRT for these lakes vary depending on the methods and errors inherent to them. We suggested to rely on the estimations from the outcome surface runoff since they are based on the hydrological measurements with better quality. Lake Stepped/LH68 exchange water within less then 1.5 years. Lake Sara Tarn/LH71 and Lake Reid/LH70 are the endorheic ponds with the water exchange through mostly evaporation, their LRT was estimated as 21–22 years and from 8–9 years, respectively. To improve the estimates of the LRT, the hydrological observations are needed to monitor the lakes and streams during the warm season with the uniform observational program.

The Effectiveness of Evapotranspiration Systems in Disposing of Wastewater in Remote Aboriginal Communities in Northwest Australia

1991 ◽  
Vol 23 (10-12) ◽  
pp. 1825-1833
Author(s):  
D. R. McGrath ◽  
G. E. Ho ◽  
K. Mathew
Keyword(s):  
Water Balance ◽  
Water Loss ◽  
Balance Equation ◽  
Eucalyptus Camaldulensis ◽  
Bare Soil ◽  
Pan Evaporation ◽  
Aboriginal Communities ◽  
Water Balance Equation ◽  
Northwest Australia

The potential usage of Evapotranspiration (ET) systems in remote Aboriginal communities was investigated. ET system sizing requirements were determined from the water balance equation. Water loss from lysimeters planted with trees (Eucalyptus camaldulensis) or lawn grass and from bare soil and gravel was monitored over several months and compared to pan evaporation measured during the same period. It was found that ET from bare soil and grass followed similar trends to pan evaporation, ranging from 30-60% of pan evaporation for soil and from 60-80% of pan evaporation for grass. ET rates increased in the tanks planted with trees as the plants grew and exceeded pan evaporation rates. Evaporation from gravel-filled lysimeters was low, being as little as 10% of pan evaporation.

scholarly journals Global evapotranspiration over the past three decades: estimation based on the water balance equation combined with empirical models

2012 ◽  
Vol 7 (1) ◽  
pp. 014026 ◽  
Author(s):  
Zhenzhong Zeng ◽  
Shilong Piao ◽  
Xin Lin ◽  
Guodong Yin ◽  
Shushi Peng ◽  
...  
Keyword(s):  
Water Balance ◽  
Balance Equation ◽  
Empirical Models ◽  
Water Balance Equation ◽  
The Past

scholarly journals TLS and SfM Approach for Bulk Density Determination of Excavated Heterogeneous Raw Materials

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 174 ◽  
Author(s):  
Peter Blistan ◽  
Stanislav Jacko ◽  
Ľudovít Kovanič ◽  
Julián Kondela ◽  
Katarína Pukanská ◽  
...  
Keyword(s):  
Bulk Density ◽  
Laser Scanning ◽  
Large Scale ◽  
Raw Materials ◽  
Terrestrial Laser Scanning ◽  
Mineral Resources ◽  
Point Clouds ◽  
Raw Material

A frequently recurring problem in the extraction of mineral resources (especially heterogeneous mineral resources) is the rapid operative determination of the extracted quantity of raw material in a surface quarry. This paper deals with testing and analyzing the possibility of using unconventional methods such as digital close-range photogrammetry and terrestrial laser scanning in the process of determining the bulk density of raw material under in situ conditions. A model example of a heterogeneous deposit is the perlite deposit Lehôtka pod Brehmi (Slovakia). Classical laboratory methods for determining bulk density were used to verify the results of the in situ method of bulk density determination. Two large-scale samples (probes) with an approximate volume of 7 m3 and 9 m3 were realized in situ. 6 point samples (LITH) were taken for laboratory determination. By terrestrial laser scanning (TLS) measurement from 2 scanning stations, point clouds with approximately 163,000/143,000 points were obtained for each probe. For Structure-from-Motion (SfM) photogrammetry, 49/55 images were acquired for both probes, with final point clouds containing approximately 155,000/141,000 points. Subsequently, the bulk densities of the bulk samples were determined by the calculation from in situ measurements by TLS and SfM photogrammetry. Comparison of results of the field in situ measurements (1841 kg∙m−3) and laboratory measurements (1756 kg∙m−3) showed only a 4.5% difference in results between the two methods for determining the density of heterogeneous raw materials, confirming the accuracy of the used in situ methods. For the determination of the loosening coefficient, the material from both large-scale samples was transferred on a horizontal surface. Their volumes were determined by TLS. The loosening coefficient for the raw material of 1.38 was calculated from the resulting values.

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