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Mapping groundwater reserves in northwestern Cambodia with the combined use of data from lithologs and time-domain-electromagnetic and magnetic-resonance soundings | Cartographie de réserves d’eaux souterraines au nord-ouest du Cambodge avec une utilisation combinée de données de logs lithologiques, de sondages électromagnétiques dans le domaine temporel et de résonance magnétique Mapeo de las reservas de agua subterránea en el noroeste de Camboya con el uso combinado de datos de litológicos y sondeos electromagnéticos en el dominio del tiempo y de resonancia magnética 利用岩性记录数据及时间域电磁和磁共振测深绘制柬埔寨西北地区地下水储量图 Mapeamento de reservas de águas subterrâneas no noroeste do Camboja com uso combinado de dados litológicos e sondagens eletromagnéticas de domínio de tempo e por ressonância magnética Полный текст
2018
Valois, Remi | Vouillamoz, Jean-Michel | Lun, Sambo | Arnout, Ludovic
Mapping groundwater reserves in northwestern Cambodia with the combined use of data from lithologs and time-domain-electromagnetic and magnetic-resonance soundings | Cartographie de réserves d’eaux souterraines au nord-ouest du Cambodge avec une utilisation combinée de données de logs lithologiques, de sondages électromagnétiques dans le domaine temporel et de résonance magnétique Mapeo de las reservas de agua subterránea en el noroeste de Camboya con el uso combinado de datos de litológicos y sondeos electromagnéticos en el dominio del tiempo y de resonancia magnética 利用岩性记录数据及时间域电磁和磁共振测深绘制柬埔寨西北地区地下水储量图 Mapeamento de reservas de águas subterrâneas no noroeste do Camboja com uso combinado de dados litológicos e sondagens eletromagnéticas de domínio de tempo e por ressonância magnética Полный текст
2018
Valois, Remi | Vouillamoz, Jean-Michel | Lun, Sambo | Arnout, Ludovic
Lack of access to water is the primary constraint to development in rural areas of northwestern Cambodia. Communities lack water for both domestic and irrigation purposes. To provide access to drinking water, governmental and aid agencies have focused on drilling shallow boreholes but they have not had a clear understanding of groundwater potential. The goal of this study has been to improve hydrogeological knowledge of two districts in Oddar Meanchey Province by analyzing borehole lithologs and geophysical data sets. The comparison of 55 time-domain electromagnetic (TEM) soundings and lithologs, as well as 66 magnetic-resonance soundings (MRS) with TEM soundings, allows a better understanding of the links between geology, electrical resistivity and hydrogeological parameters such as the specific yield (Sy) derived from MRS. The main findings are that water inflow and Sy are more related to electrical resistivity and elevation than to the litholog description. Indeed, conductive media are associated with a null value of Sy, whereas resistive rocks at low elevation are always linked to strictly positive Sy. A new methodology was developed to create maps of groundwater reserves based on 612 TEM soundings and the observed relationship between resistivity and Sy. TEM soundings were inverted using a quasi-3D modeling approach called ‘spatially constrained inversion’. Such maps will, no doubt, be very useful for borehole siting and in the economic development of the province because they clearly distinguish areas of high groundwater-reserves potential from areas that lack reserves.
Показать больше [+] Меньше [-]Mapping groundwater reserves in northwestern Cambodia with the combined use of data from lithologs and time-domain-electromagnetic and magnetic-resonance soundings | Mapeo de las reservas de agua subterránea en el noroeste de Camboya con el uso combinado de datos de litológicos y sondeos electromagnéticos en el dominio del tiempo y de resonancia magnética | Cartographie de réserves d’eaux souterraines au nord-ouest du Cambodge avec une utilisation combinée de données de logs lithologiques, de sondages électromagnétiques dans le domaine temporel et de résonance magnétique | Mapeamento de reservas de águas subterrâneas no noroeste do Camboja com uso combinado de dados litológicos e sondagens eletromagnéticas de domínio de tempo e por ressonância magnética Полный текст
2018
Valois, Rémi | Vouillamoz, Jean-Michel | Lun, Sambo | Arnout, Ludovic | Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes (EMMAH) ; Avignon Université (AU)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | Institut des Géosciences de l’Environnement (IGE) ; Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Observatoire des Sciences de l'Univers de Grenoble (Fédération OSUG)
International audience | Lack of access to water is the primary constraint to development in rural areas of northwestern Cambodia. Communities lack water for both domestic and irrigation purposes. To provide access to drinking water, governmental and aid agencies have focused on drilling shallow boreholes but they have not had a clear understanding of groundwater potential. The goal of this study has been to improve hydrogeological knowledge of two districts in Oddar Meanchey Province by analyzing borehole lithologs and geophysical data sets. The comparison of 55 time-domain electromagnetic (TEM) soundings and lithologs, as well as 66 magnetic-resonance soundings (MRS) with TEM soundings, allows a better understanding of the links between geology, electrical resistivity and hydrogeological parameters such as the specific yield (Sy) derived from MRS. The main findings are that water inflow and Sy are more related to electrical resistivity and elevation than to the litholog description. Indeed, conductive media are associated with a null value of Sy, whereas resistive rocks at low elevation are always linked to strictly positive Sy. A new methodology was developed to create maps of groundwater reserves based on 612 TEM soundings and the observed relationship between resistivity and Sy. TEM soundings were inverted using a quasi-3D modeling approach called ‘spatially constrained inversion’. Such maps will, no doubt, be very useful for borehole siting and in the economic development of the province because they clearly distinguish areas of high groundwater-reserves potential from areas that lack reserves.
Показать больше [+] Меньше [-]Well-bore clogging of a pumping well in hydraulic interference with an ambient groundwater flow: the Strack-Kostitsina refraction problem in an annular composite redux | Colmatage d’un puits de pompage en interférence hydraulique avec un écoulement d’eau souterraine environnante: le problème de réfraction de Strack-Kostitsina dans un redux composite annulaire Obstrucción de perforaciones de un pozo de bombeo en interferencia hidráulica con un ambiente de flujo de agua subterránea: el problema de refracción de Strack-Kostitsina en un compuesto anular redux 泵送井的井筒堵塞与环境地下水流动的水力干扰:环形复合材料还原中的Strack-Kostitsina折射问题 Colmatação do furo do poço de um poço de bombeamento na interface com um ambiente de fluxo de águas subterrâneas: o problema da refração Strack-Kostitsina em uma redução complexa anualar Полный текст
2018
Kacimov, A. R. | Obnosov, Yu. V.
Explicit expressions for the vector fields of specific discharge and scalar fields of stream functions and piezometric heads in a Darcian steady-state essentially two-dimensional (2-D) flow through a three-component composite representing a vertical or horizontal well with a gravel pack and annular skin are obtained and analysed. The refraction conditions along two concentric circles, which represent interfaces between three porous media of contrasting hydraulic conductivities, are exactly satisfied. Flow nets, isotachs, the locus of the stagnation point bounding the capture zone of the well, and functionals quantifying area-averaged hydraulic characteristics are found. The flow topology and drawdowns near the well illustrate that at small pumping rates a common concept of a purely radial 1-D flow can be superficially plausible but misleading.
Показать больше [+] Меньше [-]Application of multiple-isotope and groundwater-age data to identify factors affecting the extent of denitrification in a shallow aquifer near a river in South Korea | Application d’un traçage multi-isotopique et de lal datation des eaux souterraines pour identifier l’extension de la dénitrification dans un aquifère superficiel près d’une rivière, en Corée du Sud Aplicación de datos de isótopos múltiples y de edad del agua subterránea para identificar los factores que afectan el grado de desnitrificación en un acuífero poco profundo cerca de un río en Corea del Sur 利用多个同位素和地下水年龄数据确定影响南韩一条河流附近浅层含水层反硝化程度的因素 Aplicação de dados de multi-isótopicos e de datação de águas subterrâneas para identificar fatores que afetam a extensão da desnitrificação em um aquífero raso nas proximidades de um rio na Coréia do Sul Полный текст
2018
Kaown, Dugin | Koh, Eun-Hee | Mayer, Bernhard | Kim, Heejung | Pak, Tong-gyu | Park, Byeong-Hak | Lee, Kang-Kun
The extent of denitrification in a small agricultural area near a river in Yangpyeong, South Korea, was determined using multiple isotopes, groundwater age, and physicochemical data for groundwater. The shallow groundwater at one monitoring site had high concentrations of NO₃-N (74–83 mg L⁻¹). The δ¹⁵N-NO₃ values for groundwater in the study area ranged between +9.1 and +24.6‰ in June 2014 and +12.2 to +21.6‰ in October 2014. High δ¹⁵N-NO₃ values (+10.7 to +12.5‰) in both sampling periods indicated that the high concentrations of nitrate in the groundwater originated from application of organic fertilizers and manure. In the northern part of the study area, some groundwater samples showed elevated δ¹⁵N-NO₃ and δ¹⁸O-NO₃ values, which suggest that nitrate was removed from the groundwater via denitrification, with N isotope enrichment factors ranging between −4.8 and −7.9‰ and O isotope enrichment factors varying between −3.8 and −4.9‰. Similar δD and δ¹⁸O values of the surface water and groundwater in the south appear to indicate that groundwater in that area was affected by surface-water infiltration. The mean residence times (MRTs) of groundwater showed younger ages in the south (10–20 years) than in the north (20–30 years). Hence, it was concluded that denitrification processes under anaerobic conditions with longer groundwater MRT in the northern part of the study area removed considerable amounts of nitrate. This study demonstrates that multi-isotope data combined with physicochemical data and age-dating information can be effectively applied to characterize nitrate contaminant sources and attenuation processes.
Показать больше [+] Меньше [-]Evapotranspiration capture and stream depletion due to groundwater pumping under variable boreal climate conditions: Sudogda River Basin, Russia | Capture de l’évapotranspiration et diminution du débit des cours d’eau dus au pompage des eaux souterraines dans des conditions climatiques boréales variables: Bassin de la Rivière Sudogda, Russie Captura de la evapotranspiración y el agotamiento de una corriente debido al bombeo del agua subterránea en variables condiciones climáticas boreales: Cuenca del Río Sudogda, Rusia 在多变的北方气候条件下由于抽取地下水致使土壤水分蒸发蒸腾损失总量捕获及河流河水的消耗:俄罗斯Sudogda河流域 Captura de evapotranspiração e rebaixamento de riachos pelo bombeamento de águas subterrâneas sob condições climáticas boreais variáveis: Bacia do Rio Sudogda, Rússia Влияние эксплуатации подземных вод на эвапотранспирацию и речной сток при многолетней изменчивости гумидного климата на примере бассейна р. Судогда, Россия Полный текст
2018
Grinevskiy, Sergey | Filimonova, Elena | Sporyshev, Victor | Samartsev, Vsevolod | Pozdniakov, Sergey
Groundwater pumping and changes in climate-induced recharge lead to lower groundwater levels and significant changes in the water balance of a catchment. Water previously discharged as evapotranspiration can become a source of pumpage. Neglecting this effect leads to overestimated streamflow depletion. A small river basin (Sudogda River Basin, Russia) with a boreal climate and with long-term records of groundwater head and streamflow rate (showing that the measured stream depletion is less than the pumping rate) was investigated. The role of evapotranspiration in the water balance was analyzed by a hydrogeological model using MODFLOW-2005 with the STR package; the annual variation in recharge was obtained with the codes Surfbal and HYDRUS. The Sudogda River Basin was classified according to landscape and unsaturated-zone texture classes, and for each classified zone, the unsaturated-zone flow simulation was used to calculate the annual recharge dynamics for the observation period. Calibration of the regional flow model was conducted using flow and head observations jointly for two steady-state flow conditions—natural (before pumping started) and stressed (pumping). The simulations showed that pumped water originates from three sources: intercepted baseflow (75% of the annual total pumping rate), the capture of groundwater evapotranspiration discharge plus increased groundwater recharge (17%), and induced stream infiltration (8%). Additionally, multi-year precipitation records were analyzed to detect any long-term recharge and pumping water-budget changes. The results showed that increasing groundwater recharge by natural precipitation leads to (1) decreased intercepted baseflow and induced streamflow infiltration and (2) increased intercepted evapotranspiration discharge, thereby reducing stream depletion.
Показать больше [+] Меньше [-]Monitoring runoff coefficients and groundwater levels using data from GRACE, GLDAS, and hydrometeorological stations: analysis of a Colombian foreland basin | Suivi des coefficients de ruissellement et des niveaux piézométriques en utilisant les données de GRACE, GLDAS et des stations hydrométéorologiques: étude d’un bassin d’avant-pays colombien Monitoreo de coeficientes de escorrentía y niveles de agua subterránea utilizando datos de GRACE, GLDAS y estaciones hidrometeorológicas: análisis de una cuenca de antepaís colombiana 采用重力恢复和气候实验数据、全球大地数据同化系统数据以及水文气象站等数据监测径流系数:哥伦比亚沿海地区平原的分析 Monitoramento dos coeficientes de escoamento superficial e níveis das águas subterrâneas, utilizando dados do GRACE, GLDAS e estações hidrometeorológicas: análise de uma bacia de ante-país Colombiana Полный текст
2018
Ospina M., Diana L. | Vargas J., Carlos A.
The determination of space–time variation in groundwater accumulation in Colombia’s Eastern Llanos foreland basin from 2003 to 2014 was done using terrestrial water storage (TWS) anomalies identified in two versions of the Gravity Recovery and Climate Experiment (GRACE) data—from the Global Data Center for Space Research (CSR) at the University of Texas at Austin (USA) and from the Institute of Geodesy at the Graz University of Technology (ITSG, Austria)—and also soil moisture storage (SMS) data from the Global Land Data Assimilation System (GLDAS). These data were compared to changes in groundwater storage obtained using the water-budget equation, calculated based on recorded data from hydrometeorological stations. This study confirmed the viability of using satellite information to understand and monitor temporal variation in groundwater recharge in the study area. Temporal variations in TWS, SMS, and groundwater level were shown to correspond to regional rain and drought periods, which are sensitive to climate phenomena such as El Niño and La Niña. Comparing changes in TWS and groundwater level to changes in infiltration and recharge revealed correlation coefficients of 0.56 and 0.98 with CSR data and 0.71 and 0.86 with ITSG data, respectively.
Показать больше [+] Меньше [-]Seasonal variability of oxygen and hydrogen isotopes in a wetland system of the Yunnan-Guizhou Plateau, southwest China: a quantitative assessment of groundwater inflow fluxes | Variabilité saisonnière des isotopes de l’oxygène et de l’hydrogène dans un système de zones humides du Plateau de Guizhou au Yunnan, dans le sud-ouest de la Chine: une évaluation quantitative des flux des apports des eaux souterraines Variabilidad estacional de isótopos de oxígeno e hidrógeno en un sistema de humedales de la meseta de Yunnan Guizhou, suroeste de China: una evaluación cuantitativa de los flujos de entrada del agua subterránea 中国西南部云贵高原一个湿地系统氧氢同位素的季节性变化:地下水流入通量定量评价 Variação sazonal de isótopos de oxigênio e hidrogênio em um sistema de área úmida no planalto de Yunnan Guizhou, sudoeste da China: uma avaliação quantitativa do fluxo de recarga de águas subterrâneas Полный текст
2018
Cao, Xingxing | Wu, Pan | Zhou, Shaoqi | Han, Zhiwei | Tu, Han | Zhang, Shui
The Caohai Wetland serves as an important ecosystem on the Yunnan–Guizhou Plateau and as a nationally important nature reserve for migratory birds in China. In this study, surface water, groundwater and wetland water were collected for the measurement of environmental isotopes to reveal the seasonal variability of oxygen and hydrogen isotopes (δ¹⁸O, δD), sources of water, and groundwater inflow fluxes. Results showed that surface water and groundwater are of meteoric origin. The isotopes in samples of wetland water were well mixed vertically in seasons of both high-flow (September) and low-flow (April); however, marked seasonal and spatial variations were observed. During the high-flow season, the isotopic composition in surface wetland water varied from −97.13 to −41.73‰ for δD and from −13.17 to −4.70‰ for δ¹⁸O. The composition of stable isotopes in the eastern region of this wetland was lower than in the western region. These may have been influenced by uneven evaporation caused by the distribution of aquatic vegetation. During the low-flow season, δD and δ¹⁸O in the more open water with dead aquatic vegetation ranged from −37.11 to −11.77‰, and from −4.25 to −0.08‰, respectively. This may result from high evaporation rates in this season with the lowest atmospheric humidity. Groundwater fluxes were calculated by mass transfer and isotope mass balance approaches, suggesting that the water sources of the Caohai Wetland were mainly from groundwater in the high-flow season, while the groundwater has a smaller contribution to wetland water during the low-flow season.
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