Observations and Modeling of Profile Soil Water Storage above a Shallow Water Table

2004 ◽  
Vol 68 (3) ◽  
pp. 719-724 ◽  
Author(s):  
Mahmood Nachabe ◽  
Caroline Masek ◽  
Jayantha Obeysekera
2000 ◽  
Vol 80 (1) ◽  
pp. 43-52 ◽  
Author(s):  
David R. Lapen ◽  
Jonathan S. Price ◽  
Robert Gilbert

Time domain reflectometry (TDR) was used to estimate soil water storage dynamics in several uncultivated blanket bogs and poor fens in southeastern Newfoundland during the summer growing season. The purpose of the research was to evaluate links between surface moisture conditions, evapotranspiration, and recharge processes in order to elucidate factors that govern blanket peat formation in the region. Water storage changes in the peat/Sphagnum above the water table (ΔSWS) were found to be important storage terms in daily water balance estimates. Daily mean ΔSWS values for bog and fen approximated −0.3 and −0.45 mm, respectively. It was also found that, i) fairly high peat water-holding capacities, ii) frequent atmospheric recharge, iii) atmospheric controls on evapotranspiration, and, iv) the transport of water into the unsaturated zone from the shallow water table via capillary and external wicking processes helped to preclude significant de-watering over the bulk of the peatland surfaces. Recharge via groundwater appears to be an important factor governing moisture conditions requisite for peat accrual and the growth of Sphagnum spp., especially in the fens. Key words: Time domain reflectometry, blanket peats, soil water, evapotranspiration, water table depth


1997 ◽  
Vol 1 (2) ◽  
pp. 265-277 ◽  
Author(s):  
M. G. Hodnett ◽  
I. Vendrame ◽  
A. De O. Marques Filho ◽  
M. D. Oyama ◽  
J. Tomasella

Abstract. Soil water storage was monitored in three landscape elements in the forest (plateau, slope and valley floor) over a 3 year period to identify differences in sub-surface hydrological response. Under the plateau and slope, the changes of storage were very similar and there was no indication of surface runoff on the slope. The mean maximum seasonal storage change was 156 mm in the 2 m profile but it was clear that, in the dry season, the forest was able to take up water from below 3.6 m. Soil water availability was low. Soil water storage changes in the valley were dominated by the behaviour of a shallow water table which, in normal years, varied between 0.1 m below the surface at the end of the wet season and 0.8 m at the end of the dry season. Soil water storage changes were small because root uptake was largely replenished by groundwater flow towards the stream. The groundwater behaviour is controlled mainly by the deep drainage from beneath the plateau and slope areas. The groundwater gradient beneath the slope indicated that recharge beneath the plateau and slope commences only after the soil water deficits from the previous dry season have been replenished. Following a wet season with little recharge, the water table fell, ceasing to influence the valley soil water storage, and the stream dried up. The plateau and slope, a zone of very high porosity between 0.4 and 1.1 m, underlain by a less conductive layer, is a probable route for interflow during, and for a few hours after, heavy and prolonged rainfall.


2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Mandana Rahgozar ◽  
Nirjhar Shah ◽  
Mark Ross

Simultaneous measurements of soil moisture profiles and water table heads, along a flow path, were used to determine evapotranspiration (ET) along with other components of the water budget. The study was conducted at a small-scale (~0.8 Km2) hydrologic monitoring field site in Hillsborough County, Florida, from January 2002 to June 2004. Frequency Domain Reflectometry soil moisture probes, installed in close proximity to water table monitoring wells were used to derive changes in the soil water storage. A one-dimensional transect model was developed; changes in the soil water storage and water table observations served as input to determine all vertical and lateral boundary fluxes along the shallow water table flow plane. Two distinct land cover environments, grassland and an alluvial wetland forest, were investigated in this particular study. The analysis provided temporally variable ET estimates for the two land covers with annual totals averaging 850 mm for grassland, to 1100 mm for the alluvial wetland forest. Quantitative estimates of other components of a water budget, for example, infiltration, interception capture, total rainfall excess, and runoff were also made on a quarterly and annual basis. Novelty of this approach includes ability to resolve ET components and other water budget fluxes that provide useful parameterization and calibration potential for predictive simulation models.


2013 ◽  
Vol 49 (3) ◽  
pp. 366-381
Author(s):  
B. BUAKUM ◽  
V. LIMPINUNTANA ◽  
N. VORASOOT ◽  
K. PANNANGPETCH ◽  
R. W. BELL

SUMMARYDeep sowing (15 cm) on sands in the dry season is a practice used in post-rice sowing of legumes without irrigation, designed to increase moisture access for germination, growth and crops yield. However, with such deep sowing there can be a penalty for emergence and growth if there is abundant water stored in the upper soil profile during the growing season. Hence, there is a need to define the soil water regimes under which deep sowing is advantageous for different legumes. To investigate the adaptation of legume crop species to deep sowing, we studied their emergence, growth and yield on three deep soils (3–16% clay) with shallow water tables during two years in northeast Thailand. At site 1 and 2, peanut, cowpea, mungbean and soybean were sown shallow (~5 cm) or deep (~15 cm). At site 3, only cowpea and peanut were shallow or deep sown. Shallow water tables maintained soil water content (0–15 cm) above permanent wilting point throughout the growing season. Deep sowing of all legumes delayed emergence by 3–7 days at all locations. Shoot dry weight of legumes after deep sowing was mostly similar or lower than weight after shallow sowing. Yield and harvest index of legumes did not differ meaningfully among sowing depths. Therefore, deep sowing was not beneficial for dry season cropping without irrigation when there was a shallow water table and sufficient water for crop growth throughout soil profiles in the growing season. Taken together with previous studies, we conclude that shallow rather than deep sowing of legumes was preferred when the soil water content at 0–15-cm depth remained higher than permanent wilting point throughout the growing season due to shallow water table.


2015 ◽  
Vol 63 (1) ◽  
pp. 82-92 ◽  
Author(s):  
Martin Wegehenkel ◽  
Horst H. Gerke

Abstract Weighing lysimeters can be used for studying the soil water balance and to analyse evapotranspiration (ET). However, not clear was the impact of the bottom boundary condition on lysimeter results and soil water movement. The objective was to analyse bottom boundary effects on the soil water balance. This analysis was carried out for lysimeters filled with fine- and coarse-textured soil monoliths by comparing simulated and measured data for lysimeters with a higher and a lower water table. The eight weighable lysimeters had a 1 m2 grass-covered surface and a depth of 1.5 m. The lysimeters contained four intact monoliths extracted from a sandy soil and four from a soil with a silty-clay texture. For two lysimeters of each soil, constant water tables were imposed at 135 cm and 210 cm depths. Evapotranspiration, change in soil water storage, and groundwater recharge were simulated for a 3-year period (1996 to 1998) using the Hydrus-1D software. Input data consisted of measured weather data and crop model-based simulated evaporation and transpiration. Snow cover and heat transport were simulated based on measured soil temperatures. Soil hydraulic parameter sets were estimated (i) from soil core data and (ii) based on texture data using ROSETTA pedotransfer approach. Simulated and measured outflow rates from the sandy soil matched for both parameter sets. For the sand lysimeters with the higher water table, only fast peak flow events observed on May 4, 1996 were not simulated adequately mainly because of differences between simulated and measured soil water storage caused by ET-induced soil water storage depletion. For the silty-clay soil, the simulations using the soil hydraulic parameters from retention data (i) were matching the lysimeter data except for the observed peak flows on May, 4, 1996, which here probably resulted from preferential flow. The higher water table at the lysimeter bottom resulted in higher drainage in comparison with the lysimeters with the lower water table. This increase was smaller for the finer-textured soil as compared to the coarser soil.


Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3351
Author(s):  
Tianxing Zhao ◽  
Yan Zhu ◽  
Jingwei Wu ◽  
Ming Ye ◽  
Wei Mao ◽  
...  

Water storage in unsaturated and saturated zones during the crop non-growing season is one of the important supplementary water resources to meet crop water requirements in arid areas with shallow water table depth. It is necessary to analyze utilization of the soil-ground water storage during the crop growing season and its attribution to irrigation during the non-growing season. To facilitate the analysis, a new method based on measurements of soil moisture content and water table depth is developed. The measurements used in this study include (1) 15-year data of soil moisture content within a depth of 1 m from the land surface and water table depth measured in Jiefangzha, including its four subareas and (2) 4-year data of the same kind in Yonglian, located in arid northern China. The soil-ground water storage utilization is calculated as the difference of water storage between the beginning and end of the crop growing season in the whole computational soil profile. The results of average soil-ground water storage utilization in Jiefangzha and its four subareas and Yonglian are 121 mm, 126 mm, 113 mm, 124 mm, 185 mm and 117 mm, and the corresponding average utilization efficiencies in the non-growing season are 32.2%, 32.5%, 31.5%, 31.6%, 57.3% and 47.6%, respectively. Further, the water table fluctuation method was used to estimate the variation in water storage. The coefficients of soil-ground water storage utilization, soil-ground water storage utilization below 1 m soil depth and ground water utilization are defined, and their average values are 0.271, 0.111 and 0.026 in Jiefangzha, respectively. Then, the contribution of soil-ground water storage utilization to actual evapotranspiration is evaluated, which are over 23.5% in Jiefangzha and Yonglian. These results indicate that the soil-ground water storage plays an important role in the ecological environment in arid areas with shallow water table depth.


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