scholarly journals Integrated MASW and ERT Imaging for Geological Definition of an Unconfined Alluvial Aquifer Sustaining a Coastal Groundwater-Dependent Ecosystem in Southwest Portugal

2020 ◽  
Vol 10 (17) ◽  
pp. 5905 ◽  
Author(s):  
Maria Paz ◽  
Francisco Alcalá ◽  
Ana Medeiros ◽  
Pedro Martínez-Pagán ◽  
Jaruselsky Pérez-Cuevas ◽  
...  

This paper integrates multichannel analysis of surface waves (MASW) and time-lapse electrical resistivity tomography (ERT) to define aquifer geometry and identify transient groundwater features of the Cascalheira Stream Basin Holocene alluvial aquifer (aquifer H), which contributes to the Santo André Lagoon, part of a coastal groundwater-dependent ecosystem (GDE), located in southwest Portugal. MASW measures shear-wave velocity (VS), allowing one to obtain steady geological models of the subsurface, and ERT measures subsurface electrical resistivity (ER), being subjected to ambient changes. MASW enables disambiguation of geological structures in low ER environments, such as coastal areas. This research covered one natural year and involved one MASW campaign, four ERT campaigns, and additional geological field surveys and groundwater monitoring to assist interpretation of results. In the area, the conjugate NW–SE and NE–SW strike-slip fault systems determine compartmentalization of geological structures and subsequent accommodation space for Holocene sedimentation. MASW and ERT surveys show how the NW–SE system deepens these structures toward the coast, whereas the NE–SW system generates small horsts and grabens, being one of these occupied by aquifer H. From upstream to downstream, aquifer H thickness and width increase from 10 m to 12 m and from 140 m to 240 m, respectively. Performance of VS and ER models was satisfactory, with a normalized error of the VR and ER models in the 0.01–0.09 range, meaning that a quantitative quota of uncertainty can be segregated from the overall uncertainty of groundwater models without substantially affecting its simulations accuracy. This methodology seeks to improve the design of shallow groundwater research in GDE preservation policies.

2017 ◽  
Vol 9 (2) ◽  
pp. 407-424
Author(s):  
Jamaluddin Jamaluddin

Indonesian reformation era begins with the fall of President Suharto. Political transition and democratic transition impact in the religious life. Therefore, understandably, when the politic transition is not yet fully reflects the idealized conditions. In addition to the old paradigm that is still attached to the brain of policy makers, various policies to mirror the complexity of stuttering ruler to answer the challenges of religious life. This challenge cannot be separated from the hegemonic legacy of the past, including the politicization of SARA. Hegemony that took place during the New Order period, adversely affected the subsequent transition period. It seems among other things, with airings various conflicts nuances SARA previously muted, forced repressive. SARA issues arise as a result of the narrowing of the accommodation space of the nation state during the New Order regime. The New Order regime has reduced the definition of nation-states is only part of a group of people loyal to the government to deny the diversity of socio-cultural reality in it. To handle the inheritance, every regime in the reform era responds with a pattern and a different approach. It must be realized, that the post-reform era, Indonesia has had four changes of government. The leaders of every regime in the reform era have a different background and thus also have a vision that is different in treating the problem of racial intolerance, particularly against religious aspect. This treatment causes the accomplishment difference each different regimes of dealing with the diversity of race, religion and class that has become the hallmark of Indonesian society.


2009 ◽  
Vol 7 (5-6) ◽  
pp. 475-486 ◽  
Author(s):  
G. Cassiani ◽  
A. Godio ◽  
S. Stocco ◽  
A. Villa ◽  
R. Deiana ◽  
...  

2012 ◽  
Vol 39 (24) ◽  
Author(s):  
Steven B. Meyerhoff ◽  
Marios Karaoulis ◽  
Florian Fiebig ◽  
Reed M. Maxwell ◽  
André Revil ◽  
...  

2019 ◽  
Author(s):  
Andrea Palacios ◽  
Juan José Ledo ◽  
Niklas Linde ◽  
Linda Luquot ◽  
Fabian Bellmunt ◽  
...  

Abstract. Surface electrical resistivity tomography (ERT) is a widely used tool to study seawater intrusion (SWI). It is noninvasive and offers a high spatial coverage at a low cost, but it is strongly affected by decreasing resolution with depth. We conjecture that the use of CHERT (cross-hole ERT) can partly overcome these resolution limitations since the electrodes are placed at depth, which implies that the model resolution does not decrease in the zone of interest. The objective of this study is to evaluate the CHERT for imaging the SWI and monitoring its dynamics at the Argentona site, a well-instrumented field site of a coastal alluvial aquifer located 40 km NE of Barcelona. To do so, we installed permanent electrodes around boreholes attached to the PVC pipes to perform time-lapse monitoring of the SWI on a transect perpendicular to the coastline. After two years of monitoring, we observe variability of SWI at different time scales: (1) natural seasonal variations and aquifer salinization that we attribute to long-term drought and (2) short-term fluctuations due to sea storms or flooding in the nearby stream during heavy rain events. The spatial imaging of bulk electrical conductivity allows us to explain non-trivial salinity profiles in open boreholes (step-wise profiles really reflect the presence of fresh water at depth). By comparing CHERT results with traditional in situ measurements such as electrical conductivity of water samples and bulk electrical conductivity from induction logs, we conclude that CHERT is a reliable and cost-effective imaging tool for monitoring SWI dynamics.


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