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Please cite this article as: Cai, Z., Ofterdinger, U., Analysis of groundwater-level response to rainfall and estimation of annual recharge in fractured hard rock aquifers, NW Ireland, Journal of Hydrology (2016), doi: http://dx.doi.org/ 10. 1016/j.jhydrol.2016.01.066 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Despite fractured hard rock aquifers underlying over 65% of Ireland, knowledge of key processes 7 controlling groundwater recharge in these bedrock systems is inadequately constrained. In this study, 8 we examined 19 groundwater-level hydrographs from two Irish hillslope sites underlain by hard rock 9 aquifers. Water-level time-series in clustered monitoring wells completed at the subsoil, soil/bedrock 10 interface, shallow and deep bedrocks were continuously monitored hourly over two hydrological 11 years. Correlation methods were applied to investigate groundwater-level response to rainfall, as well 12 as its seasonal variations. The results reveal that the direct groundwater recharge to the shallow and the relationship between the rainfall intensity and water-table rise reveal that the low rainfall intensity 22 group (≤ 1 mm/h) has greater impact on the groundwater recharge rate than other groups (> 1 mm/h). 23This study shows that the combination of the time-series analysis and the water-table fluctuation 24 method could be an useful approach to investigate groundwater recharge in fractured hard rock 25 aquifers in Ireland.

Fuel cells and solar energy are promising candidates for electricity generation. It is forecast that fuel cells and solar power systems will play an important role in reducing the greenhouse gas footprint and replacing fossil fuels. Therefore, the limitations of fuel cells and solar power systems, such as low efficiency, high cost, and low reliability, must be addressed appropriately to enable their full potentials. Metal foam is a new class of material that has gained immense attention due to its excellent properties suitable for a wide range of applications. Its unique characteristics distinguish it from typical solid metals. The properties of metal foam can be modified during the fabrication stage by manipulating its physical structure. The goal of this paper is to review the application of metal foam in fuel cells and solar power systems. Besides, the performance of metal foam in fuel cells and solar systems is also discussed. Metal foam has been applied to the electrodes, gas diffusion layer and flow field of fuel cells to enhance performance, especially in regard to current density and flow distribution. Furthermore, metal foam is a heat exchanger for the solar energy harvesting system to improve its efficiency. Superior performances in experimental testing allows the possibility of commercialization of metal foam products in the renewable energy field.

Natural gas extracted from hydraulically fractured shale formations potentially has a big impact on the global energy landscape. However, there are concerns of potential environmental impacts of hydraulic fracturing of the shale formations, particularly those related to water quality. To evaluate the potential impact of hydraulically fractured shale on overlying aquifers, we conduct realizations of numerical modeling simulations to assess fluid flow and chloride transport from a synthetic Bowland Shale over a period of 11,000 years. The synthetic fractured shale was represented by a three-dimensional discrete fracture model that was developed by using the data from a Bowland Shale gas exploration in Lancashire, UK. Chloride mass exchange between fractures and the rock matrix was fully accounted for in the model. The assessment was carried out to investigate fluid and chloride mass fluxes before, during, and after hydraulic fracturing of the Bowland Shale. Impacts of the upward fracture height and aperture, as well as hydraulic conductivity of the multilayered bedrock system, are also included this assessment. This modeling revealed that the hydraulically fractured Bowland Shale is unlikely to pose a risk to its overlying groundwater quality when the induced fracture aperture is 200 mm. With the fracture aperture 1000 mm, the upward chloride flux becomes very sensitive to the upward fracture height growth and hydraulic conductivity of the multilayered bedrock system. In the extremely unlikely event of the upward fracture growth directly connecting the shale formation to the overlying Sherwood Sandstone aquifer with the fracture aperture 1000 mm, the upward chloride mass flux could potentially pose risks to the overlying aquifer in 100 years. The model study also revealed that the upward mass flux is significantly intercepted by the horizontal mass flux within a high permeable layer between the Bowland Shale and its overlying aquifers, reducing further upward flux toward the overlying aquifers.

Mass discharge is one metric rapidly gaining acceptance for assessing the performance of in situ groundwater remediation systems. Multilevel sampling transects provide the data necessary to make such estimates, often using the Thiessen Polygon method. This method, however, does not provide a direct estimate of uncertainty. We introduce a geostatistical mass discharge estimation approach that involves a rigorous analysis of data spatial variability and selection of an appropriate variogram model. High-resolution interpolation was applied to create a map of measurements across a transect, and the magnitude and uncertainty of mass discharge were quantified by conditional simulation. An important benefit of the approach is quantified uncertainty of the mass discharge estimate. We tested the approach on data from two sites monitored using multilevel transects. We also used the approach to explore the effect of lower spatial monitoring resolution on the accuracy and uncertainty of mass discharge estimates. This process revealed two important findings: (1) appropriate monitoring resolution is that which yielded an estimate comparable with the full dataset value, and (2) high-resolution sampling yields a more representative spatial data structure descriptor, which can then be used via conditional simulation to make subsequent mass discharge estimates from lower resolution sampling of the same transect. The implication of the latter is that a high-resolution multilevel transect needs to be sampled only once to obtain the necessary spatial data descriptor for a contaminant plume exhibiting minor temporal variability, and thereafter less spatially intensely to reduce costs.

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