GroundwaterPub Date : 2026-01-13DOI: 10.1111/gwat.70045
M. J. Hinton, S. Alpay, H. L. Crow
{"title":"Groundwater Transport in a Glaciomarine Aquitard: Paleosalinity and Landslide Implications","authors":"M. J. Hinton, S. Alpay, H. L. Crow","doi":"10.1111/gwat.70045","DOIUrl":"10.1111/gwat.70045","url":null,"abstract":"<p>Leaching of marine salinity in the porewater of glaciomarine muds is one precursor to landslide hazard. In this study, groundwater modeling is used to quantify vertical groundwater flow, constrain paleosalinity, and characterize past and future progression of leaching with depth in Champlain Sea sediments. The Breckenridge Creek site, ~15 km northwest of Ottawa, Canada, was cored within a thick sequence (up to 98 m) of Champlain Sea muds that form a regional aquitard in the St. Lawrence Lowlands and Ottawa Valley. Porewater chloride concentrations ([Cl]), up to 12,250 mg/kg, and δ<sup>18</sup>O as high as −7.18‰, indicate remnant seawater. One-dimensional groundwater transport modeling simulates porewater [Cl] and δ<sup>18</sup>O with depth simultaneously and constrains specific discharge, q, from 2.40 to 2.51 mm/a. Groundwater transport modeling and three-component mixing of seawater, glacial meltwater and meteoric water constrain the range of initial [Cl] between 14,000 and 15,700 mg/kg (72–80% seawater) and initial δ<sup>18</sup>O between −5.99 and −5.61‰. The glacial meltwater component of Champlain Sea bottom waters at the Breckenridge site has a maximum δ<sup>18</sup>O value of −22.4‰. Downward leaching to the salinity threshold of <2 g/L for geotechnical sensitivity development reached a depth of 20.6 m. Modeling indicates the leaching front currently progresses at a rate of 2.5 m/1000 years, slower than advection of freshwater infiltration because of upward diffusion and dispersion of marine solutes. Notably for landslide hazard, the highest measurements of geotechnical sensitivity coincide with the leached zone.</p>","PeriodicalId":12866,"journal":{"name":"Groundwater","volume":"64 1","pages":"49-63"},"PeriodicalIF":2.0,"publicationDate":"2026-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12857530/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145961045","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Simulation Method for Variable Permeability of Delay Interbed Based on Stress Variation Principle","authors":"Shangqi Han, Chuiyu Lu, Wen Lu, Qingyan Sun, Chu Wu","doi":"10.1111/gwat.70039","DOIUrl":"10.1111/gwat.70039","url":null,"abstract":"<p>The compaction simulation of compressible delay interbed is an important part of land subsidence simulation. Currently, the most widely used MODFLOW software has two modules, SUB and CSUB, both of which can simulate compressible delay interbed. The difference lies in that the head diffusion equation of the SUB module is based on the principle of head change, while CSUB can use either head change or geological stress variation principles. When based on the principle of geostress variation, the CSUB method is more physically reasonable. However, its limitation lies in the fact that, when solving the diffusion equation for compressible delay interbeds, it does not account for the effects of variations in the discrete nodal cell thickness and hydraulic conductivity of the interbed. This study improves the solution method for the head diffusion equation of compressible delay interbeds based on the principle of geostress variation. The Kozeny–Carman equation was introduced to establish a relationship between the hydraulic conductivity and porosity of the interbeds, while variations in the thickness of discrete nodal cells were also incorporated into the solution process. Collectively, these improvements lead to a more rigorous approach. To verify the effectiveness of the proposed simulation method, three representative test cases were developed and comprehensively compared with the CSUB results. The results indicate that notable discrepancies emerge between the two approaches when the interbed undergoes substantial compression, whereas the method proposed in this study effectively prevents the occurrence of “overcompaction” within the interbed.</p>","PeriodicalId":12866,"journal":{"name":"Groundwater","volume":"64 1","pages":"90-102"},"PeriodicalIF":2.0,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145901950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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