Analysis of groundwater-level response to rainfall and estimation of annual recharge in fractured hard rock aquifers, NW Ireland

Abstract

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.

Recharge Estimation of Hard Rock Aquifers under Sahelian Climate Conditions Using Water Table Fluctuation: Case Study of Tougou Catchment, Burkina Faso

“…These practices would have probably increased soil infiltration, resulting into deep drainage to the water table [34]. In general, groundwater recharge values in the Tougou catchment are within the range of recharge values obtained in several zones of West Africa [16] …”

“…The methods popularity comes from its straightforward use and the general availability of water table data for recharge estimation [7]. The WTF method is based on the hypothesis that any water table rise in unconfined aquifer is due to recharge [16]. The employed methodology is based on applying the WTF method in conjunction with the groundwater budget method developed by Marechal et al [8].…”

Statistical and Fractal Approaches on Long Time-Series to Surface-Water/Groundwater Relationship Assessment: A Central Italy Alluvial Plain Case Study

“…In general, a correlogram with a gentle slope can be an indicator of data series persistence, while, if it drops off rapidly, it describes the random nature of the values [45]; furthermore, the slower decline of ACF function for hydrological data describes an aquifer with low draining properties, low permeability or major groundwater storage, conversely a faster decline of the autocorrelation function indicates a more rapid flow of water through the aquifer and/or its limited storage capacity [1,2,5,11,18,52,53].…”

“…On the other hand, the behavior analysis of long piezometric level time series was almost neglected and limited to short periods that rarely exceeded a year (e.g., contaminated site studies). Recently, Cai and Ofterdinger [11] evaluated the statistical relationships between two-year rainfall and piezometric Table 1 for initials and abbreviations). …”

Assessment of the Exploitation Rate and Sustainability of an Alluvial Plain in Southwestern Burkina Faso

“…The method's popularity comes from its straightforward use and general availability of water table data for recharge estimation (Obuobie, 2012). WTF method is based on hypothesis that any water table rise in unconfined aquifer is due to recharge (Cai and Ofterdinger;2016). The employed methodology is based on applying the WTF method in conjunction with the groundwater budget method developed by Marechal et al (2006).…”