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11.
An Application of Hydraulic Tomography to a Large‐Scale Fractured Granite Site,Mizunami, Japan 
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下载免费PDF全文 Yuanyuan Zha Tian‐Chyi J. Yeh Walter A. Illman Tatsuya Tanaka Patrick Bruines Hironori Onoe Hiromitsu Saegusa Deqiang Mao Shinji Takeuchi Jet‐Chau Wen 《Ground water》2016,54(6):793-804
While hydraulic tomography (HT) is a mature aquifer characterization technology, its applications to characterize hydrogeology of kilometer‐scale fault and fracture zones are rare. This paper sequentially analyzes datasets from two new pumping tests as well as those from two previous pumping tests analyzed by Illman et al. (2009) at a fractured granite site in Mizunami, Japan. Results of this analysis show that datasets from two previous pumping tests at one side of a fault zone as used in the previous study led to inaccurate mapping of fracture and fault zones. Inclusion of the datasets from the two new pumping tests (one of which was conducted on the other side of the fault) yields locations of the fault zone consistent with those based on geological mapping. The new datasets also produce a detailed image of the irregular fault zone, which is not available from geological investigation alone and the previous study. As a result, we conclude that if prior knowledge about geological structures at a field site is considered during the design of HT surveys, valuable non‐redundant datasets about the fracture and fault zones can be collected. Only with these non‐redundant data sets, can HT then be a viable and robust tool for delineating fracture and fault distributions over kilometer scales, even when only a limited number of boreholes are available. In essence, this paper proves that HT is a new tool for geologists, geophysicists, and engineers for mapping large‐scale fracture and fault zone distributions. 相似文献
12.
D. E. Gillum M. Janghorbani M. D. Miller L. L. Chyi W. D. Ehmann 《Meteoritics & planetary science》1972,7(4):573-578
Abundances of 15 major, minor and trace elements have been determined in powders and interior chips derived from the Haverö ureilite. The values are in close agreement with mean values for other ureilites, as reported in the literature. The powdered samples exhibited slightly higher abundances of O and Si, than the interior chips. It is suggested that this may be due to alteration of the samples during the powdering process 相似文献
13.
Yonghong Hao Jing Wu Qingxia Sun Yuen Zhu Yan Liu Zhongtang Li Tian‐Chyi J. Yeh 《水文研究》2013,27(18):2605-2613
Based on the groundwater development process, and regional economic and social developing history, we divided the spring hydrological process of the Liulin Springs Basin into two periods: pre‐1973 and post‐1974. In the first period (i.e. 1957–1973), the spring discharge was affected by climate variation alone, and in the second period (i.e. 1974–2009), the spring discharge charge was influenced by both climate variation and human activities. A piecewise analysis strategy was used to differentiate the contribution of anthropogenic activities from climate variation on karst spring discharge depletion in the second period. Then, the ARIMAX model was applied to spring flow time series of the first period to develop a model for the effects of climate variation only. Using this model, we estimated the spring discharge in the second period solely under the influence of climate variation. Based on the water budget, we subtracted observed spring discharge from the estimated spring discharge and acquired the contribution of human activities on spring discharge depletion for the second period. The results of the analysis indicated that the contribution of climate variation to the spring discharge depletion is?0.20 m3/s from 1970s to 2000s. The contribution of anthropogenic activities to the spring flow depletion was ?2.56 m3/s in 2000s, which was about 13 times more than that of climate variation. Our analysis further indicates that groundwater exploitation only accounts for 29% of the spring flow depletion due to the effects of human activities. The remaining 71% of the depletion is likely to be caused by other human activities, including dam building, dewatering during coal mining, and deforestation. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
14.
Assessing the extent and sources of nitrate contamination in the aquifer system of southern Baldwin County,Alabama 总被引：1，自引：0，他引：1
A regional-scale groundwater study was conducted over a 2-year period to assess the extent of nitrate contamination and source
identification for southern Baldwin County, AL. Groundwater wells were sampled and analyzed for nitrate and a host of other
geochemical parameters which revealed that extensive areas within aquifer zone A2 exhibited nitrate concentrations exceeding
regulatory limits. Spatial iso-concentration maps of nitrate were constructed using ArcGIS software to determine the extent
and severity of contamination for the aquifers underlying southern Baldwin County with the primary interest focused on the
heavily utilized aquifer zone A2. Nitrate levels in the central and northeastern portion of the study area were most extensive
with maximum concentrations of 63 mg/L likely resulting from agricultural inputs. Several other small regions throughout the
study area exhibited elevated levels of nitrate and chloride as high as 112 and 51.1 mg/L, respectively, and sources likely
vary (i.e., residential septic systems, animal waste to agriculture). With the exception of a few groundwater samples, there
was no obvious correlative relationship between chloride and nitrate concentration for data collected during the 2-year period.
Collectively, a general inverse relationship between nitrate concentrations and well depth was observed for the aquifer system
under investigation. The study provides an initial current data set of areas impacted or most vulnerable to nitrate contamination
and initial assessment of likely sources of nitrate in the region. 相似文献
15.
The abundances of zirconium and hafnium have been determined in nine stony meteorites by a new, precise neutron-activation technique. The Zr/Hf abundance ratios for the chondrites vary in a rather narrow range, consistent with previously published observations from our group. Replicate analyses of new, carefully selected clean interior samples of the C1 chondrite Orgueil yield mean zirconium and hafnium abundances of 5.2 and 0.10 ppm, respectively. These abundances are lower than we reported earlier for two C1 chondrite samples which we now suspect may have suffered contamination. The new C1 zirconium and hafnium abundances are in closer agreement with predictions based on theories of nucleosynthesis than the earlier data. 相似文献
16.
Sea level rise (SLR) as a result of global warming has an impact on the increasing inundation on the coastal area. Nowadays,
Semarang coastal area in Indonesia is already subject to coastal hazard due to tidal inundation and land subsidence. The impact
of the inundation is predicted to be even more severe with the scenario of sea level rise. This paper concentrates on the
risk assessment to the population, land use, and monetary losses as a result of coastal inundation under enhanced sea level
rise. This paper uses the scenario of the depth of inundation to generate coastal inundation model using GIS-Technology. Anticipatory
issues including methodology development for hazard assessment would be necessary for Semarang coastal area, and therefore,
geo-information technology can be considered as a useful tool to rapidly assess the impact of the coastal hazard and evaluate
the economic losses. 相似文献
17.
In China, 9·5% of the landmass is karst terrain and of that 47,000 km2 is located in semiarid regions. In these regions the karst aquifers feed many large karst springs within basins of thousands of square kilometres. Spring discharges reflect the fluctuation of ground water level and variability of ground water storage in the basins. However, karst aquifers are highly heterogeneous and monitoring data are sparse in these regions. Therefore, for sustainable utilization and conservation of karst ground water it is necessary to simulate the spring flows to acquire better understanding of karst hydrological processes. The purpose of this study is to develop a parsimonious model that accurately simulates spring discharges using an artificial neural network (ANN) model. The karst spring aquifer was treated as a non‐linear input/output system to simulate the response of karst spring flow to precipitation and applied the model to the Niangziguan Springs, located in the east of Shanxi Province, China and a representative of karst springs in a semiarid area. Moreover, the ANN model was compared with a previous time‐lag linear model and it was found that the ANN model performed better. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
18.
Traditional aquifer vulnerability techniques primarily rely on spatial property data for a region and are limited by their ability to directly or indirectly assess flow and transport processes occurring from the surface to depth within an aquifer system. The main objective of this study was to investigate groundwater vulnerability in terms of aquifer interconnectivity and flow dynamics. A combination of stable isotopes, groundwater age‐dating (radiocarbon), and geomorphic/geogenic spatial analyses was applied to a regional, highly developed coastal aquifer to explain the presence of nitrate at depth. The average δ13C value (?17.3 ± 2‰ VPDB, n = 27) is characteristic of groundwater originating from locally infiltrated precipitation through extensively cultivated soils. The average δ18O and δD values (?4.0 ± 0.1‰ VSMOW, n = 27; δD: ?19.3 ± 1‰ VSMOW, n = 27, respectively) are similar to precipitation water derived from maritime sources feeding the region's surface water and groundwater. Stable and radioactive isotopes reveal significant mixing between shallow and deep aquifers due to high velocities, hydraulic connection, and input of local recharge water to depths. Groundwater overdevelopment enhances deeper and faster modern water downward flux, amplifying aquifer vulnerability. Therefore, aquifer vulnerability is a variable, dependent on the type and degree of stress conditions experienced by a groundwater system as well as the geospatial properties at the near surface. 相似文献
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Precipitation over southeastern Lake Baikal features a significant decreasing trend in July and August over 1979–2018 and is closely related to blocking occurrence over central Siberia(45°–70°N,75°–115°E).This study investigates the formation and maintenance of anticyclonic and cyclonic wave-breaking(AWB and CWB)blocking events and their climate impacts on precipitation in the southeastern Lake Baikal area.Both AWB and CWB blocking events are characterized by a cold trough deepening from the sub-Arctic region and a ridge amplifying toward its north over central Siberia,as well as an evident Rossby wave train over midlatitude Eurasia.For AWB blocking events,the ridge and trough pair tilts clockwise and the wave train exhibits a zonal distribution.In contrast,ridge and trough pair associated with CWB blocking events leans anticlockwise with larger-scale,meridional,and more anisotropic signatures.Moreover,the incoming Rossby wave energy associated with CWB blocking events is more evident than for AWB blocking events.Therefore,CWB blocking events are more persistent.AWB blocking events produce more extensive and persistent precipitation over the southeastern Lake Baikal area than CWB blocking events,in which moderate above-normal rainfall is seen in the decaying periods of blockings.A significant decreasing trend is found in terms of AWB blocking occurrence over central Siberia,which may contribute to the downward trend of precipitation over southeastern Lake Baikal. 相似文献