The saturated hydraulic conductivity of a soil is the main parameter for modeling the water flow through the soil and determination of seepage losses. In addition, hydraulic conductivity of compacted soil layers is cr...The saturated hydraulic conductivity of a soil is the main parameter for modeling the water flow through the soil and determination of seepage losses. In addition, hydraulic conductivity of compacted soil layers is critical component for designing liner and cover systems for waste landfills. Hydraulic conductivity can be predicted using empirical relationships, capillary models, statistical models and hydraulic radius theories [1]. In the current research work the reliability of Kozeny-Carman equation for the determination of the hydraulic conductivity of compacted clayey soils, is evaluated. The relationship between the liquid limit and the specific surface of the tested samples is also investigated. The resulting equation gives the ability for quick estimation of specific surface and hydraulic conductivity of the compacted clayey samples. The results presented here show that the Kozeny-Carman equation provides good predictions of the hydraulic conductivity of homogenized clayey soils compacted under given compactive effort, despite the consensus set out in the literature.展开更多
The present study has been undertaken to depict spatial distribution of different aquifer parameters in the eastern part of Kushtia district through a detailed hydrogeological survey. For this investigation, 119 litho...The present study has been undertaken to depict spatial distribution of different aquifer parameters in the eastern part of Kushtia district through a detailed hydrogeological survey. For this investigation, 119 lithologs and 92 pumping test data have been used. These data have been processed, analyzed, interpreted and krigged for the spatial assessment of the aquifer properties viz. transmissivity, hydraulic conductivity, hydraulic diffusivity, specific yield, radius of influence, and specific drawdown. It is seen from the investigation that the transmissivity and hydraulic conductivity values obtained from the pumping tests of the wells are varying from 1811 m<sup>2</sup>/day to 2568 m<sup>2</sup>/day and 32.5 m/day and 61.5 m/day respectively, the hydraulic diffusivity being ranging from 181,143 m<sup>2</sup>/day to 256,788 m<sup>2</sup>/day. The estimated specific yield of 17.97% - 23.46% supports that the area is dominated with coarse grained sands. This study reveals that the distribution of deep tube wells in the area are not within the radius of influence (638 - 760 m) each other, but few shallow and hand tube wells existed within the radius of influence. The estimated specific draw down is varying from 57 m/cumec to 126.1 m/cumec. From the overall analysis, it is found that the area is favorable for groundwater exploration.展开更多
为了解喀斯特地区树种适应水分亏缺生境的内在机制,选择广西弄岗喀斯特森林9种主要树种,分析树种间水力结构及相关性状的差异及相关性。结果显示:供试9种树种间的最大边材比导率、最大叶片比导率、胡伯尔值、木质部导管直径及木材密度...为了解喀斯特地区树种适应水分亏缺生境的内在机制,选择广西弄岗喀斯特森林9种主要树种,分析树种间水力结构及相关性状的差异及相关性。结果显示:供试9种树种间的最大边材比导率、最大叶片比导率、胡伯尔值、木质部导管直径及木材密度存在极显著(P<0.01)差异,其中,海南椴〔Diplodiscus trichospermus(Merrill)Y.Tang〕的最大边材比导率、最大叶片比导率以及木质部导管直径均最大,但胡伯尔值和木材密度最小。干季和湿季,供试9种树种间木质部导水率丧失百分比(PLC)均存在极显著差异,且金丝李(Garcinia paucinervis Chun et How)的PLC值均最高,分别为44.39%和38.92%。除闭花木〔Cleistanthus sumatranus(Miq.)Muell.Arg.〕、海南椴和淡黄金花茶(Camellia flavida Chang)外,其他6种树种PLC值在干季和湿季间无显著(P>0.05)差异,表明喀斯特地区树种耐干旱能力普遍较强。相关性分析结果表明:单叶叶面积与最大边材比导率、木质部导管直径和叶片净光合速率呈极显著(P<0.01)或显著(P<0.05)正相关,但与木材密度呈极显著负相关。综上所述,喀斯特地区木材密度较大的树种虽然耐旱性较强,但木质部水分运输效率会降低,进而使叶片净光合速率降低;反之,木材密度较小的树种虽然有利于木质部水分运输效率提高及碳固定,但是其耐旱性降低;水力结构功能特征间的关系既存在协同也存在一定的权衡。展开更多
Root distribution of three desert shrubs,Tamarix ramosissima Ledeb.,Haloxylon ammodendron(C.A.Mey.) Bunge and Reaumuria soongorica(Pall.) Maxim.was investigated under co-occurring conditions using a method for excavat...Root distribution of three desert shrubs,Tamarix ramosissima Ledeb.,Haloxylon ammodendron(C.A.Mey.) Bunge and Reaumuria soongorica(Pall.) Maxim.was investigated under co-occurring conditions using a method for excavating the whole root system.Assimilation shoot water potential and transpiration rates were monitored during the wet-dry cycle.Leaf-specific apparent hydraulic conductance and the index of water stress impact for the three species were calculated from shoot water potential and transpiration rate.The results showed that,along the soil profile,the root system of T.ramosissima mainly distributed at 50 to 310 cm interval,with an average total absorbing root-surface area of 30,249.2 cm2 per plant;the root system of H.ammodendraom distributed at 0 to 250 cm interval with an average total absorbing root-surface area of 12,847.3 cm2 per plant;the root system of R.soongorica distributed at 0-80 cm interval,with an average total absorbing root-surface area of 361.8 cm2.The root distribution shows the following:T.ramosissima uses groundwater as its main water source;H.ammodendraom uses both groundwater and rainwater;and R.soongorica uses rainwater only.During the wet-dry cycle,the hydraulic parameters of T.ramosissima showed no responses to precipitation.R.soongorica responded most significantly,and the responses of H.ammodendraom were intermediate.In conclusion,the plant response to rain events is closely related to their root distribution and plant water-use strategy.展开更多
文摘The saturated hydraulic conductivity of a soil is the main parameter for modeling the water flow through the soil and determination of seepage losses. In addition, hydraulic conductivity of compacted soil layers is critical component for designing liner and cover systems for waste landfills. Hydraulic conductivity can be predicted using empirical relationships, capillary models, statistical models and hydraulic radius theories [1]. In the current research work the reliability of Kozeny-Carman equation for the determination of the hydraulic conductivity of compacted clayey soils, is evaluated. The relationship between the liquid limit and the specific surface of the tested samples is also investigated. The resulting equation gives the ability for quick estimation of specific surface and hydraulic conductivity of the compacted clayey samples. The results presented here show that the Kozeny-Carman equation provides good predictions of the hydraulic conductivity of homogenized clayey soils compacted under given compactive effort, despite the consensus set out in the literature.
基金supported by the National Science Foundation.of United States of America (CREST HRD-1547784 supporting R.B.P.,A.L.J.,J.C.F.and V.C.)a Fulbright Fellowship for ME (Fulbright Visiting Scholar Program 2018).
文摘The present study has been undertaken to depict spatial distribution of different aquifer parameters in the eastern part of Kushtia district through a detailed hydrogeological survey. For this investigation, 119 lithologs and 92 pumping test data have been used. These data have been processed, analyzed, interpreted and krigged for the spatial assessment of the aquifer properties viz. transmissivity, hydraulic conductivity, hydraulic diffusivity, specific yield, radius of influence, and specific drawdown. It is seen from the investigation that the transmissivity and hydraulic conductivity values obtained from the pumping tests of the wells are varying from 1811 m<sup>2</sup>/day to 2568 m<sup>2</sup>/day and 32.5 m/day and 61.5 m/day respectively, the hydraulic diffusivity being ranging from 181,143 m<sup>2</sup>/day to 256,788 m<sup>2</sup>/day. The estimated specific yield of 17.97% - 23.46% supports that the area is dominated with coarse grained sands. This study reveals that the distribution of deep tube wells in the area are not within the radius of influence (638 - 760 m) each other, but few shallow and hand tube wells existed within the radius of influence. The estimated specific draw down is varying from 57 m/cumec to 126.1 m/cumec. From the overall analysis, it is found that the area is favorable for groundwater exploration.
文摘为了解喀斯特地区树种适应水分亏缺生境的内在机制,选择广西弄岗喀斯特森林9种主要树种,分析树种间水力结构及相关性状的差异及相关性。结果显示:供试9种树种间的最大边材比导率、最大叶片比导率、胡伯尔值、木质部导管直径及木材密度存在极显著(P<0.01)差异,其中,海南椴〔Diplodiscus trichospermus(Merrill)Y.Tang〕的最大边材比导率、最大叶片比导率以及木质部导管直径均最大,但胡伯尔值和木材密度最小。干季和湿季,供试9种树种间木质部导水率丧失百分比(PLC)均存在极显著差异,且金丝李(Garcinia paucinervis Chun et How)的PLC值均最高,分别为44.39%和38.92%。除闭花木〔Cleistanthus sumatranus(Miq.)Muell.Arg.〕、海南椴和淡黄金花茶(Camellia flavida Chang)外,其他6种树种PLC值在干季和湿季间无显著(P>0.05)差异,表明喀斯特地区树种耐干旱能力普遍较强。相关性分析结果表明:单叶叶面积与最大边材比导率、木质部导管直径和叶片净光合速率呈极显著(P<0.01)或显著(P<0.05)正相关,但与木材密度呈极显著负相关。综上所述,喀斯特地区木材密度较大的树种虽然耐旱性较强,但木质部水分运输效率会降低,进而使叶片净光合速率降低;反之,木材密度较小的树种虽然有利于木质部水分运输效率提高及碳固定,但是其耐旱性降低;水力结构功能特征间的关系既存在协同也存在一定的权衡。
基金supported by National Natural Science Foundation of China (Grant No. 40725002)
文摘Root distribution of three desert shrubs,Tamarix ramosissima Ledeb.,Haloxylon ammodendron(C.A.Mey.) Bunge and Reaumuria soongorica(Pall.) Maxim.was investigated under co-occurring conditions using a method for excavating the whole root system.Assimilation shoot water potential and transpiration rates were monitored during the wet-dry cycle.Leaf-specific apparent hydraulic conductance and the index of water stress impact for the three species were calculated from shoot water potential and transpiration rate.The results showed that,along the soil profile,the root system of T.ramosissima mainly distributed at 50 to 310 cm interval,with an average total absorbing root-surface area of 30,249.2 cm2 per plant;the root system of H.ammodendraom distributed at 0 to 250 cm interval with an average total absorbing root-surface area of 12,847.3 cm2 per plant;the root system of R.soongorica distributed at 0-80 cm interval,with an average total absorbing root-surface area of 361.8 cm2.The root distribution shows the following:T.ramosissima uses groundwater as its main water source;H.ammodendraom uses both groundwater and rainwater;and R.soongorica uses rainwater only.During the wet-dry cycle,the hydraulic parameters of T.ramosissima showed no responses to precipitation.R.soongorica responded most significantly,and the responses of H.ammodendraom were intermediate.In conclusion,the plant response to rain events is closely related to their root distribution and plant water-use strategy.
