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Estimation of water retention in Oxisols cultivated with cotton plant in the cerrado of Mato Grosso = Estimativa da retenção de água em Latossolos do Cerrado mato-grossense cultivados com algodão Texte intégral
2014
Junior, José Holanda Campelo | Azevedo, Emilio Carlos de | Alves, Marcelo de Carvalho | Mello, Dimas de | Lobo, Francisco de Almeida | Amorim, Ricardo Santos Silva
In the state of Mato Grosso, the area planted with cotton is mainly concentrated in the plains, where the climate Aw determines an alternation between a rainy and a dry season, and where the soil is predominant Red-Yellow Latosol and Red Latosol (Oxisol). One of the factors that determine success in cultivation of this species is just the prior knowledge of the hydraulic properties of soils which, for various reasons, are not variables of extensive knowledge in the areas of production. This study aimed to verify the adequacy of pedotransfer functions to evaluate the soil water retention capacity in the cotton regions in Mato Grosso, taking into account the bulk density and content of clay, silt and sand soil. For this, soil samples were collected in 21 plots of commercial production of cotton in the state of Mato Grosso to determinate the particle size distribution, bulk density, and water retention curve in soil. In the region of cotton production in Mato Grosso, the pedotransfer functions, 0,334 - 0,0003 Ar and 0,247 - 0,0003 Ar, for estimating the water content in the tensions of 0.033 and 1.5 MPa, respectively, are suitable to evaluate the water retention capacity of the soils of the cotton production plots in this state. = No estado de Mato Grosso, a área de plantio com o algodão está concentrada principalmente nos chapadões, onde o clima Aw determina uma alternância entre um período chuvoso e outro seco, e onde os solos LatossoloVermelho-Amarelo e Latossolo Vermelho são predominantes. Um dos fatores que determinam o sucesso no cultivo dessa espécie é justamente o conhecimento prévio das propriedades hidráulicas dos solos que, por diferentes razões não são variáveis de amplo conhecimento nas áreas de produção. Neste trabalho objetivou-se verificar a adequação de funções de pedotransferência para avaliar a capacidade de retenção de água dos solos de regiões produtoras de algodão em Mato Grosso, levando-se em consideração a densidade aparente e conteúdo de argila, silte e areia do solo. Para isso, foram coletadas amostras de solo em 21 talhões de produção de algodão do Mato Grosso, para determinação da distribuição do tamanho de partículas, da densidade aparente e da curva de retenção de água no solo. Na região de produção de algodão em Mato Grosso, as funções de pedotransferência, 0,334- 0,0003 Ar e 0,247-0,0003 Ar, para estimativas dos conteúdos de água nas tensões de 0,033 e 1,5 MPa, respectivamente, são adequadas para avaliar a capacidade de retenção de água dos solos dos talhões de cultivo de algodão nesse Estado.
Afficher plus [+] Moins [-]The Younger Dryas black mat from Ojo de Agua, a geoarchaeological site in Northeastern Zacatecas, Mexico Texte intégral
2017
Ardelean, Ciprian F. | Israde-Alcántara, Isabel | González-Hernández, Romel | Arroyo-Cabrales, Joaquín | Solis-Rosales, Corina | Rodríguez-Ceja, María | Pears, Ben R. | Watling, Jennifer | Macías-Quintero, Juan I. | Ocampo-Díaz, Yam Zul E.
New explorations in the desert of northeastern Zacatecas, in central-northern Mexico, revealed dozens of archaeological and geoarchaeological sites. One of them, Ojo de Agua, contains the remains of a Pleistocene spring-fed hydrographic system located at the southeastern end of a large elongated endorheic basin. The locality yielded a particularly dark, highly organic stratigraphic layer commonly known in the Americas as Black Mat (BM), exposed on the natural profiles of a creek, but not associated with cultural materials. Several radiocarbon assessments confirmed the formation of the Ojo de Agua Black Mat during the Younger Dryas chronozone, with ten calibrated results clustering between 12,700–12,100 cal BP. This multi-proxy study confirmed the peculiarity of the deposit and found similarities and differences with other contexts of Younger Dryas age. The Ojo de Agua Black Mat (stratum C2) is far richer in charcoal specks than the related strata, but lacks phytoliths, diatoms or ostracods. No further biological remains were found in it, except for intrusive capillary roots. Clearly water-lain in a shallow pond, the stratum qualifies as a clayey silt with an acidic-to-neutral pH. Rich in heavy metals and with high contents of titanium, the Ojo de Agua Black Mat yielded significant indicators of intense wildfires during the Younger Dryas, but produced no carbon spherules or nanodiamonds supposedly linked to the impact theory.
Afficher plus [+] Moins [-]Method to characterize aquitards above leaky aquifers with water supply wells | Une méthode pour caractériser les épontes des aquifères semi-captifs à l’aide de puits de production Un método para caracterizar acuitardos por encima de acuíferos filtrantes con pozos de abastecimiento de agua 利用供水井刻画越流含水层上覆弱透水层参数的方法 Um método para caracterizar aquitardos sobrejacentes a aquíferos semi-confinados utilizando furos de abastecimento de água Texte intégral
2010
Ostendorf, David W. | DeGroot, Don J. | Judge, Aaron I. | LaMesa, Daniel F.
Leaky aquifers provide protected drinking water since the aquifer is overlain by an aquitard, and this study develops a method to estimate hydraulic properties of the latter deposit. Steady pumping, supply well shutdowns, and slug tests generate data in adjacent monitoring well clusters that characterize the aquitard. An existing steady model estimates a site-averaged value of the aquitard permeability k if its thickness is known, and this site-averaged estimate may be compared with local k estimates from conventional and extended slug tests. A shutdown attenuation model estimates a local value of the consolidation coefficient CV, which combines with the local k value to specify the compressibility α of the aquitard. The method is illustrated for the Fowl Meadow Aquifer, a stratified drift deposit used as a drinking water supply in eastern Massachusetts (USA), with an overlying silt aquitard of 10 m thickness. Steady data and theory suggest a site-averaged k of 2.3 × 10–¹⁷ m²for the aquitard, while the shutdown attenuation model generates local CVvalues that vary from 10–⁵to 10–³ m²/s. The slug tests yield a local k variation (10–¹⁷–10–¹³ m²) that brackets the site-averaged value, and an α range of 10–⁹–10–⁷ Pa–¹.
Afficher plus [+] Moins [-]Characterization of land subsidence induced by groundwater withdrawals in the plain of Beijing city, China | Caractérisation de la subsidence induite par les prélèvements d’eaux souterraines dans la plaine de Pékin, Chine Caracterización de la subsidencia del terreno inducida por la extracción de agua subterránea en la planicie de la ciudad de Beijing, China 北京市平原区抽水诱发地面沉降响应特征研究 Caraterização da subsidência do solo induzida por extração de água subterrânea na planície da cidade de Pequim, China Texte intégral
2014
Zhang, Youquan | Gong, Huili | Gu, Zhaoqin | Wang, Rong | Li, Xiaojuan | Zhao, Wenji
The plain of Beijing city in China suffers severe land subsidence owing to groundwater overdraft. The maximum subsidence rate could reach 6 cm/year through the 2000s. An integrated subsidence-monitoring program was designed, including levelling survey, borehole extensometers and multilayer monitoring of groundwater level, with the aim to understand both hydrological and mechanical processes and to characterize the land subsidence. From multilayer compaction monitoring, the major compression layers were identified. The major strata contributing to compression deformation are the second (64.5–82.3 m) and third (102–117 m) aquitards, which contributed around 39 % of the total subsidence. Meanwhile, irrecoverable deformations were also observed in the second (82.3–102 m) and third (117–148 m) confined aquifers; they exhibit elasto-plastic mechanical behavior, which is attributed to the thin beds of silt or silty clay. Stress–strain analysis and oedometer tests were conducted to study the aquifer-system response to pumping and to estimate the specific storage of the major hydrogeologic units. The results reveal the creep behavior and elasto-plastic, visco-elasto-plastic mechanical behavior of the aquitards at different depths. The compressibility of the aquitards in the inelastic range is about one order of magnitude larger than for the elastic range.
Afficher plus [+] Moins [-]Estimation of groundwater flow from temperature monitoring in a borehole heat exchanger during a thermal response test | Estimation des écoulements d’eau souterraine par un suivi de température dans une sonde géothermique verticale, pendant un test de réponse thermique Estimación del flujo de agua subterránea a partir del monitoreo de temperatura en un intercambiador de calor en un pozo durante un ensayos de respuesta térmica 热响应试验期间根据钻孔热量交换器的温度监测估算地下水流 Estimativa do fluxo de águas subterrâneas a partir do monitoramento de temperatura em tubos permutadores de calor durante um teste de resposta térmica Texte intégral
2018
Yoshioka, Mayumi | Takakura, Shinichi | Uchida, Youhei
To estimate the groundwater flow around a borehole heat exchanger (BHE), thermal properties of geological core samples were measured and a thermal response test (TRT) was performed in the Tsukuba upland, Japan. The thermal properties were measured at 57 points along a 50-m-long geological core, consisting predominantly of sand, silt, and clay, drilled near the BHE. In this TRT, the vertical temperature in the BHE was also monitored during and after the test. Results for the thermal properties of the core samples and from the monitoring indicated that groundwater flow enhanced thermal transfers, especially at shallow depths. The groundwater velocities around the BHE were estimated using a two-dimensional numerical model with monitoring data on temperature changes. According to the results, the estimated groundwater velocity was generally consistent with hydrogeological data from previous studies, except for the data collected at shallow depths consisting of a clay layer. The reasons for this discrepancy at shallow depths were predicted to be preferential flow and the occurrence of vertical flow through the BHE grout, induced by the hydrogeological conditions.
Afficher plus [+] Moins [-]Experimental study on the vertical deformation of aquifer soils under conditions of withdrawing and recharging of groundwater in Tongchuan region, China | Etude expérimentale de la déformation verticale des sols d’aquifère en conditions d’exploitation et de recharge des eaux souterraines dans la région du Tongchuan, Chine Estudio experimental sobre la deformación vertical de suelos de acuíferos bajo condiciones de extracción y recarga del agua subterránea en la región de Tongchuan, China 中国铜川地区地下水开采和补给条件下含水层土壤垂直变形实验研究 Estudo experimental da deformação vertical de solos aquíferos sob condições de bombeamento e recarga de águas subterrâneas na região de Tongchuan, China Texte intégral
2017
Wei, Ya-ni | Fan, Wen | Cao, Yanbo
Land subsidence due to aquifer-system compaction accompanying groundwater extraction is a global hazard. Rising urban construction and groundwater demand necessitate increased awareness and better understanding of the geological problem. Motivated by the lack of laboratory-scale studies on this issue, an experimental investigation on the newly developed Tongchuan region, China, is presented. The study addresses the deformation behaviors of three soil samples, with the lithology of silty clay, silt, and fine sand, under the conditions of groundwater withdrawal and recharge using the GDS Consolidation Testing System. Results indicate that all three samples were characterized by elastic–plastic deformation under the conditions of withdrawing and recharging. The vertical deformation of the silty clay in the aquitard above the first confined aquifer was larger than those of the other two samples, and its deformation is a gradual and long process; thus, considerable attention should be paid to deformation in this aquitard due to the apparent creep effect and tiny rebound deformation. However, the settlement of the fine sand in the second confined aquifer cannot be ignored due to the great thickness of the aquifer. For the same soil, as the pore-water pressure declined, the unit rate of vertical deformation decreased gradually, whereas the creep effect of deformation in the later declining stage of pore-water pressure was more apparent than that in the former declining stage. These observations are highly important to the local government, which is developing measures to prevent and control subsidence.
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