Study on rainfall infiltration in high groundwater channels

In order to solve the adverse effect that the lining of high groundwater level channels is prone to damage when subjected to heavy rainfall, the response law of internal structural state of high groundwater level channels under different rainfall conditions was studied. Based on the non-seepage seepage theory, the seepage pressure (total water head) in the tunnel under four different rainfall types is analyzed and studied. The results show that the most unfavorable rainfall types for the lining structure safety are the frontal rainfall and uniform type rainfall. Therefore we should pay more attention to the front type and uniform type rainfall from the perspective of seepage. The research results can provide reference for slope and seepage control design of high groundwater level channels.

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Observations on some basal failures in sheeted excavations

Canadian Geotechnical Journal ◽

10.1139/t70-017 ◽

1970 ◽

Vol 7 (2) ◽

pp. 136-144 ◽

Cited By ~ 8

Author(s):

V. Milligan ◽

K. Y. Lo

Keyword(s):

Shear Strength ◽

Ground Water ◽

Groundwater Level ◽

Soil Conditions ◽

Remedial Measures ◽

Factors Influencing ◽

Water Head ◽

The Stability ◽

Made In

In excavations below groundwater level, instability of the base may result from the inflow of water into the excavation. The most important factors influencing the stability are the ground water and detailed soil conditions at the site.Construction problems encountered in excavations in clay strata, underlain by pervious water bearing layers, are described. The remedial measures adopted in each case are also discussed. From a study of the observations made in the case records, it is suggested that excavation in intact clays may be carried out to depths exceeding that limited by the ratio of t/h = 0.5, where t is the distance from the bottom of the excavation to the top of the water bearing stratum, and h is the water head at the top of the water bearing stratum, provided that the clay is not disturbed during construction so that the shear strength of the clay is preserved.

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Assessing Impacts of Climate Extremes and Human Water Use on GRACE Total Water Storage Trends in Major U.S. Aquifers

10.5194/gstm2020-61 ◽

2020 ◽

Author(s):

Bridget Scanlon ◽

Ashraf Rateb ◽

Alexander Sun ◽

Himanshu Save

Keyword(s):

Surface Water ◽

Water Use ◽

Groundwater Level ◽

Water Storage ◽

Climate Extremes ◽

High Plains ◽

Total Water ◽

Groundwater Storage ◽

Grace Data ◽

The U.S

There is considerable concern about water depletion caused by climate extremes (e.g., drought) and human water use in the U.S. and globally. Major U.S. aquifers provide an ideal laboratory to assess water storage changes from GRACE satellites because the aquifers are intensively monitored and modeled. The objective of this study was to assess the relative importance of climate extremes and human water use on GRACE Total Water Storage Anomalies in 14 major U.S. aquifers and to evaluate the reliability of the GRACE data by comparing with groundwater level monitoring (~-23,000 wells) and regional and global models. We quantified total water and groundwater storage anomalies over 2002 &#8211; 2017 from GRACE satellites and compared GRACE data with groundwater level monitoring and regional and global modeling results. &#160; The results show that water storage changes were controlled primarily by climate extremes and amplified or dampened by human water use, primarily irrigation. The results were somewhat surprising, with stable or rising long-term trends in the majority of aquifers with large scale depletion limited to agricultural areas in the semi-arid southwest and southcentral U.S. GRACE total water storage in the California Central Valley and Central/Southern High Plains aquifers was depleted by drought and amplified by groundwater irrigation, totaling ~70 km3 (2002&#8211;2017), about 2&#215; the capacity of Lake Mead, the largest surface reservoir in the U.S. In the Pacific Northwest and Northern High Plains aquifers, lower drought intensities were partially dampened by conjunctive use of surface water and groundwater for irrigation and managed aquifer recharge, increasing water storage by up to 22 km3 in the Northern High Plains over the 15 yr period. GRACE-derived total water storage changes in the remaining aquifers were stable or slightly rising throughout the rest of the U.S. GRACE data compared favorably with composite groundwater level hydrographs for most aquifers except for those with very low signals, indicating that GRACE tracks groundwater storage dynamics. Comparison with regional models was restricted to the limited overlap periods but showed good correspondence for modeled aquifers with the exception of the Mississippi Embayment, where the modeled trend is 4x the GRACE trend. The discrepancy is attributed to uncertainties in model storage parameters and groundwater/surface water interactions. Global hydrologic models (WGHM-2d and PCR-GLOBWB-5.0 overestimated trends in groundwater storage in heavily exploited aquifers in the southwestern and southcentral U.S. Land surface models (CLSM-F2.5 and NOAH-MP) seem to track GRACE TWSAs better than global hydrologic models but underestimated TWS trends in aquifers dominated by irrigation. Intercomparing GRACE, traditional hydrologic monitoring, and modeling data underscore the importance of considering all data sources to constrain water storage changes.&#160; GRACE satellite data have critical implications for many nationally important aquifers, highlighting the importance of conjunctively using surface-water and groundwater and managed aquifer recharge to enhance sustainable development.

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Characteristics of Groundwater Response to Precipitation for Landslide Prevention at Kiyomizu-Dera

Journal of Disaster Research ◽

10.20965/jdr.2017.p0993 ◽

2017 ◽

Vol 12 (5) ◽

pp. 993-1001

Author(s):

Toru Danjo ◽

Tomohiro Ishizawa ◽

Masamitsu Fujimoto ◽

Naoki Sakai ◽

Ryoichi Fukagawa ◽

...

Keyword(s):

Groundwater Level ◽

Heavy Rainfall ◽

Slope Failure ◽

Field Measurements ◽

Scale Model ◽

Slope Failures ◽

Wet Season ◽

Soil Failure ◽

Groundwater Response ◽

Typhoon Season

Every year in Japan, slope failures often occur due to heavy rainfall during the wet season and typhoon season. The main reasons for soil failure are thought to be the increase of soil weight from infiltrated precipitation, the decrease in shear strength, and effects of the increase groundwater elevation. It is therefore important to consider to characteristics of groundwater behavior to improve slope disaster prevention. Kiyomizu-dera experienced major slope failures in 1972, 1999, and 2013, and a large slope failure occurred nearby in 2015. The two most recent events occurred since observation of precipitation and groundwater conditions began at the site in 2004. In this research, we determine the relationship between rainfall and groundwater level using both a full-scale model experiment and field measurements. Results indicate strong connection between rainfall intensity and the velocity of increase in groundwater level, indicating that it is possible to predict changes in the groundwater level due to heavy rainfall.

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Numerical Calculation and Safety Evaluation of Impervious Effects of the Reinforced Dyke

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.255-260.1092 ◽

2011 ◽

Vol 255-260 ◽

pp. 1092-1095

Author(s):

Yu Zhao ◽

Jian Wei Zhang ◽

Tie Cheng Wang ◽

Xue Jun Huo

Keyword(s):

Cross Section ◽

Safety Evaluation ◽

Calculated Data ◽

Performance Parameters ◽

The Finite Element Method ◽

Total Water ◽

Seepage Velocity ◽

Water Head ◽

Impermeable Wall ◽

Technical Specifications

Based on the finite element method, the seepage field of reinforced dykes of a reservoir is analyzed from hydro geological nature and characteristics of the impermeable wall. According to the typical cross-section of the reinforced dyke, performance-parameters of the dyke such as total water head, seepage velocity, seepage gradient are compared with the counterparts of the original dyke. Results in steady seepage are obtained. Generally seepage quantity decreases 45% from the original dyke. Permeability coefficients and defects of the impermeable wall are the most factors of affecting effectiveness of dyke reinforcement. Because piezometric tubes work well, measured dada are reliable, both measured and calculated data also coincide with each other well. The results show that the impervious reinforcing plan of the dyke is fit, the reinforced dyke can reach predeterminate impervious effects and meet the technical specifications. Safety of the reservoir is guaranteed.

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A multilayer soil approach for seepage process analysis in earthen levees

10.5194/egusphere-egu21-11038 ◽

2021 ◽

Author(s):

Bianca Bonaccorsi ◽

Tommaso Moramarco ◽

Leonardo Valerio Noto ◽

Silvia Barbetta

Keyword(s):

Hydraulic Conductivity ◽

Water Table ◽

Groundwater Level ◽

Process Analysis ◽

The Body ◽

Soil Parameters ◽

New Approach ◽

Soil Hydraulic Conductivity ◽

Water Head ◽

Soil Hydraulic

Earthen levees protect flood-prone areas during severe flood events. In most cases, however, flooding is the result of the collapse of the embankments due to the seepage through and under the levee body. The description of the seepage line is difficult mainly because of the uncertainty on the hydraulic parameters, first of all the soil hydraulic conductivity. Barbetta et al. (2017) proposed a practical method for the seepage analysis based on the Marchi&#8217;s equation for the estimation of the probability of occurrence of the levee seepage which provides a vulnerability index under the assumption that the groundwater level coincides with the ground. Recently, the method has been tested also considering the groundwater level below the ground pointing out that such a condition has a high impact on the levee vulnerability to seepage. However, it does not consider the interactions between seepage process in the levee body and in the foundation.In this context, this work proposes a new approach for the analysis of the infiltration line through the body and the foundation, considering a multilayer soil and assuming a different soil hydraulic conductivity for each layer. The new equation is obtained starting from the continuity equation and the flow equation.The saturation line estimated through the Marchi&#8217;s equation and the one derived through the new multilayer model equation are compared. The analysis is first addressed to identify a threshold of the ratio between water head and water table beyond which the Marchi&#8217;s equation is no longer applicable. Indeed, the Marchi&#8217;s equation is valid when the river water head is lower than the water table. Different values of these two variables are analyzed and a threshold ratio equal to 0.57 is identified.Furthermore, the levee vulnerability to seepage estimated with the two approaches is compared and the levee is found more vulnerable when the new approach is applied. The results indicate that the difference between the two vulnerability approaches decreases as the distance between the groundwater table and the ground level tends to zero. The proposed approach is an attempt to quantify the seepage probability with more realistic levees characteristics, hydraulic and soil parameters.&#160;Barbetta, S., Camici, S., Bertuccioli, P., Palladino, M. R., & Moramarco, T. 2017. Refinement of seepage vulnerability assessment for different flood magnitude in national levee database of Italy. Hydrology Research, 48(3), 763&#8211;775. https://doi.org/10.2166/nh.2017.101.

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Experimental Study on the Carrying Capacity of Lining Structure of Hydraulic Tunnel

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.361-363.1593 ◽

2011 ◽

Vol 361-363 ◽

pp. 1593-1597

Author(s):

Wei Shen ◽

Shi Lang Xu

Keyword(s):

Large Scale ◽

Water Pressure ◽

Concrete Lining ◽

Outer Side ◽

Total Water ◽

Deformation Properties ◽

Lining Structure ◽

External Water Pressure ◽

External Water ◽

Stress And Deformation

In this paper, a large-scale indoor model test with water pressure is conducted in order to investigate the stress and deformation properties of reinforced concrete lining structures with circular cross-sections.Under internal water pressure, the water pressure carried by lining structure is about 20%~40% of total water pressure before cracking and less than 30% after cracking.Under external water pressure, without drainage of outer side of lining, the water pressure carried by lining structure is only less than 40% of total water pressure.

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An assessment of water footprint for irrigated rice in Punjab

Journal of Agrometeorology ◽

10.54386/jam.v23i1.84 ◽

2021 ◽

Vol 23 (1) ◽

pp. 21-29

Author(s):

B.S. SIDHU ◽

RAKESH SHARDA ◽

SANDEEP SINGH

Keyword(s):

Heavy Rainfall ◽

Water Footprint ◽

Irrigation Management ◽

Economic Security ◽

Green Water ◽

Crop Evapotranspiration ◽

Total Water ◽

Irrigated Rice ◽

On Farm ◽

Agroclimatic Zones

Water scarcity has become one of the highest risks for environmental and economic security worldwide. The water footprint for rice production, i.e., the total volume of freshwater consumed to produce a unit quantity rice has been estimated for three different agroclimatic zones of Punjab for the years 2000 to 2017. The results revealed that effective rainfall (Peff) improved in later years due to a change in crop calendar,legally enforced by an Act prohibiting the transplanting of paddy before a specified date. During the period of study, minimum crop evapotranspiration (ETc) was 4645 and maximum was ETc of 9511 m3ha-1 during 2014 and 2011, respectively. The green water footprint (WFgreen) for rice varied from 646litreskg-1of rice during low rainfall years (2012) to 1149 litre kg-1 of rice during heavy rainfall (1192 mm) during 2011.Out of a total water footprint (WFtotal) of 2650 litre kg-1, the share of blue water footprint (WFblue) was higher 1804 litre kg-1 (68%), indicating a need to improve on-farm irrigation management to conserve water resources.

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The Resolution and Contrast in Biological Sections Determined by Inelastic and Elastic Scattering

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071569 ◽

1973 ◽

Vol 31 ◽

pp. 224-225

Author(s):

D. L. Misell

Keyword(s):

Electron Microscopy ◽

Adverse Effect ◽

Elastic Scattering ◽

Inelastic Scattering ◽

Amorphous Carbon ◽

Polymeric Materials ◽

Chromatic Aberration ◽

Image Resolution ◽

Quantitative Estimates ◽

Elastic Ratio

In the electron microscopy of biological sections the adverse effect of chromatic aberration on image resolution is well known. In this paper calculations are presented for the inelastic and elastic image intensities using a wave-optical formulation. Quantitative estimates of the deterioration in image resolution as a result of chromatic aberration are presented as an alternative to geometric calculations. The predominance of inelastic scattering in the unstained biological and polymeric materials is shown by the inelastic to elastic ratio, I/E, within an objective aperture of 0.005 rad for amorphous carbon of a thickness, t=50nm, typical of biological sections; E=200keV, I/E=16.

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