Regional Flow Model Research Articles

Modelling and analysis of the horizontal configuration of tidal fences in barrages

Tidal stream turbines are becoming an affordable option for harvesting sustainable energy in coastal areas. They can be retrofitted in barrages, providing an integral solution for flood protection and emission-free power generation, within environmental constraints. To optimize the turbine-barrage configuration with respect to these objectives, simulation tools are needed to predict the efficiency of the turbines as well as their impact on the adjacent tidal system. These tools should be based on an accurate representation of the underlying flow processes, which cover a wide range of spatial scales — from meters at the barrage and turbines to tenths of kilometers in the tidal basin. This article presents the development of such a tool by linking an analytical model for turbine fences in barrage gates to a regional flow model. The turbine model is validated with experimental data, and data from a thoroughly monitored tidal energy pilot project. Simulations reveal how clustering the turbines in small arrays can increase their efficiency, owing to array blockage effects, with only little effect on the tidal exchange. We also demonstrate the potential of using turbine fences to manipulate the tidal jet, issued from the barrage, with benefits for coastal — and wildlife protection in the basin. The presented research helps understanding how turbine fences in barrages can be configured with high energy yield and calculated impact to the environment.

Using geophysical data to assess groundwater levels and the accuracy of a regional numerical flow model

Using geophysical data to assess groundwater levels and the accuracy of a regional numerical flow model

Analyzing the Multiscale Impacts of Implementing Energy-Efficient HVAC Improvements Through Energy Audits and Economic Input–Output Analysis

Abstract Heating, ventilation, and air-conditioning (HVAC) systems are usually an industry’s highest consumer of energy, most of which goes toward space cooling in buildings. Industrial energy-efficiency audits not only benefit manufacturers but also generate significant economic and environmental benefits to localities, states, and the nation. This article analyzes the micro- and macro scale impacts of implementing energy-efficient HVAC systems by integrating the industrial building energy data with the macroeconomic regional economic flow model. Micro-scale data include 10 years of historical energy, cost, and carbon dioxide savings achieved from energy-efficient HVAC implementation offered to manufacturers through industrial energy audits. The data were integrated into the macroeconomic modeling framework to illuminate the cascading regional economic impacts of implementing energy-efficient HVAC recommendations in manufacturing facilities. Results show that if recommendations had been implemented throughout all manufacturers in the region, $656 M energy costs would have been directly saved, 7.8 million metric tons of carbon dioxide emissions would have been avoided, and 4387 jobs could have been created, resulting in a total annual economic impact of $899 M stemming from direct, indirect, and induced impacts. The results offer insight into how industrial energy systems can be designed and provide models for how communities can accomplish a net-zero society.

A numerical assessment on the managed aquifer recharge to achieve sustainable groundwater development in Chaobai River area, Beijing, China

Intensive groundwater exploitation has depleted groundwater storage and led to a series of geo-environmental problems in Beijing Plain, China. Managed Aquifer Recharge (MAR) has been endorsed to mitigate the groundwater storage depletion and achieve groundwater sustainability. A pilot MAR has been tested in the Chaobai River catchment since 2015. An innovative large-scale MAR consisting of 9 cascade terraced infiltration ponds was proposed and its effectiveness was assessed in this study using an integrated modelling approach. The integrated model coupled the regional and local transient flow and transport processes. The transient regional flow model simulated historical groundwater level declines and storage depletion in the Beijing Plain from 1995 to 2018. The coupled regional and local flow model was used to simulate the pilot MAR test in the Chaobai River from 2015 to 2018. A significant groundwater level increase was observed nearby the pilot MAR since 2015. The transport model results indicate that approximately 40% of the infiltrated water was captured by pumping wells in the No.8 well field. The models were further used to assess the long-term effects of the large-scale MAR from 2020 to 2050. The simulation results show that the groundwater system will reach a new equilibrium state under the implementation of the large-scale MAR scheme. Almost 91% of the abstracted water in the No. 8 well field will come from the MAR infiltration. The proposed large-scale MAR is very effective in restoring the depleted aquifer storage and maintaining the groundwater abstraction in the No.8 well field. However, with the increase of the groundwater level, the infiltration rate of several ponds will decrease. Therefore, it is important to maintain a dynamic balance between artificial recharge and groundwater abstraction in order to achieve a sustainable long-term MAR operation in the region.

Comparative Assessment of Methods for Coupling Regional and Local Groundwater Flow Models: A Case Study in the Beijing Plain, China

A coupled regional and local model is required when groundwater flow and solute transport are to be simulated in local areas of interest with a finer grid while regional aquifer boundary and major stresses should be retained with a coarser grid. The coupled model should also maintain interactions between the regional and local flow systems. In the Beijing Plain (China), assessment of managed aquifer recharge (MAR), groundwater pollution caused by rivers, capture zone of well fields, and land subsidence at the cone of depression requires a coupled regional and local model. This study evaluates three methods for coupling regional and local flow models for simulating MAR in the Chaobai River catchment in the Beijing Plain. These methods are the conventional grid refinement (CGR) method, the local grid refinement (LGR) method and the unstructured grid (USG) method. The assessment included the comparison of the complexity of the coupled model construction, the goodness of fit of the computed and observed groundwater heads, the consistency of regional and local groundwater budgets, and the capture zone of a well filed influenced by the MAR site. The results indicated that the CGR method based on MODFLOW-2005 is the easiest to implement the coupled model, capable of reproducing regional and local groundwater heads and budget, and already coupled with density and viscosity dependent model codes for transport simulation. However, the CGR method inherits shortcomings of finite difference grids to create multiple local models with inefficient computing efforts. The USG method based on MODFLOW-USG has the advantage of creating multi-scale models and is flexible to simulate rivers, wells, irregular boundaries, heterogeneities and the MAR site. However, it is more difficult to construct the coupled models with the unstructured grids, therefore, a good graphic user interface is necessary for efficient model construction. The LGR method based on MODFLOW-LGR can be used to create multiple local models in uniform aquifer systems. So far, little effort has been devoted to upgrade the LGR method for complex aquifer structures and develop the coupled transport models.

Assessment of alternative groundwater flow models for Beijing Plain, China

Three alternative groundwater flow models were evaluated for Beijing Plain, China. The first model (AM1) was constructed with the “thin layer approach” in which all 9 model layers, including five aquifers separated by four aquitards, are continuously present in the same model area. The second model (AM2) was constructed with the “quasi-3D approach” in which the hydrogeological formations were classified into five aquifer units consisting of mixed permeable and semi-permeable layers at different depth ranges. The third model (AM3) was constructed with the “true layer approach” in which aquifers and aquitards were defined according to hydrostratigraphic properties, and model layers are absent in the area where corresponding hydrogeological formations intersect bedrocks. All 3 models were calibrated with the parameter optimization method under the steady state flow condition with the same hydrological stresses and observation data. All three models fit to observations well with the similar calibration criteria values. Furthermore, AIC and BIC information criteria could not distinguish three alternative models. Only KIC could identify AM3 as the best model. Major differences of the three alternative models were identified from a hydrogeological perspective. The AM1 model depicted an illusion through contour maps that groundwater was present everywhere in the deep aquifers. The model computed larger vertical leakages because more abstraction rates were assigned improperly in deep aquifers. The AM2 model was able to compute regional groundwater balances and depicted spatial groundwater level variations. However, the AM2 model computed longer groundwater travel times around the wellfield and should not be used for the delineation of the well field protection zones and contaminant transport simulation. The AM3 model could not only compute the regional groundwater balances and describe spatial groundwater distribution in deep confined aquifers, but also delineate the capture zone of the wellfield. It can therefore be used for simulating contaminant transport. Furthermore, the AM3 model is suitable to construct a coupled regional and local flow model for simulating a managed aquifer recharge scheme.

Assessment of water quality status in the impact area of the “Piškornica” landfill

Disposal of household and industrial waste at the Piškornica site began in 1982 on what was then an unmanaged landfill cell, which allowed contamination to pass into underground layers. Landfill rehabilitation was conducted between 2005 and 2013 and conformed to the environmental protection conditions and measures that were prescribed by an EIA procedure, but rehabilitation still has not been fully completed. An environmental permit was issued for rehabilitation of the landfill. The decision and environmental permit prescribed groundwater quality monitoring. Prior to these documents, five piezometers were placed into operation in 1991. The objective of this paper is to determine the potential differences in ground and surface water quality that may have resulted from landfill operations, effectiveness of the rehabilitation efforts, and the potential risk of contamination of the Ivanščak water well. The results of the research were subjected to statistical analyses (e.g., T-test and ANOVA). Based on the regional flow model, a numerical groundwater flow model and contamination transport model were created, which provided scenarios for the potential spread of pollution from the Piškornica landfill while considering different water well operation regimes. It was concluded that a) even though rehabilitation has not been completed, the groundwater quality status improved and b) none of the analysed real flow scenarios generated redirection of streamline patterns towards the Ivanščak water well. Considering future development and likely increase of the Ivanščak well capacity, the expansion of monitoring was proposed for additional measuring locations

Hydrogeological Modeling in Tropical Regions via FeFlow

hydrological modeling is commonly crossed by the solution of inverse problems and the estimation for non-linear parameters techniques. Despite this common scenario, the use of these guidelines is limited to the proper sampling of in-field data. This sampling involves a variety of data that generally have little availability, especially in regions where geographical and climatic variability does not allow a constant measurement. In this article, we present the analysis of a regional underground flow model using two techniques: pilot points (PP) and constant zones (CZ). This methodologies allow identifying properly if there are any biased parameters and heterogeneity of hydraulic properties. For this purpose, we developed a numerical variable density model that is limited with reinterpreted data from real measurements. For the CZ technique, the initial parameters are assigned according to its layer, and every layer is considered constant for parameter values; in contrast for PP technique, the initial parameters are assigned according to interpolations using in-situ point measurements. The developed model was applied in an area under the influence of the ITCZ, located in the middle valley of Magdalena (MMV). This area is important on the development of the country due to its contribution to GDP and has been subject to significant changes in land use, as a result of intense economic activities, for example, agriculture, hydroelectric power, and production of oil and gas. The established model shows a scarce link with the observed state variable (hydraulic head -K), this proves the importance of spatial heterogeneity in K. The model is calibrated in order to establish K (as an anisotropic variable that varies spatially), the porosity (η) and the specific storage capacity (Ss) in the PP and CZ, reducing a “mean square” error of state variable dependable on the observation points. The results show that the PP system approach provides a better heterogeneity representation and shows that each parameter is sensitive, and does not depend on other parameters, giving to the parameter evaluation results factual independence and authenticity. This research compiles a methodology to assertively restrict a highly parameterized inverse model with field data to estimate aquifer parameters that vary spatially at a regional scale

Palaeorunoff from Lake Ladoga to the Baltic Sea during the Holocene

The article presents the results of the palaeohydrological analysis of the river system reorganization in the North-West of Russia, the Karelian Isthmus. This study aimed at the hydrological calculation of the runoff through the Heinjoki water connection of Lake Ladoga, the Gulf of Finland and PalaeoVuoksa during different periods of the Holocene. The methods of the equation of water balance, hydraulic-morphometric dependencies and the method of geographical analogy were used in this research. The main result of the carried work is the refinement of the existing regional flow model. In particular, the role of the Heinjoki Strait and the Neva River channel in different stages of the Holocene is considered. The authors came to the conclusion that Lake Ladoga always had a runoff to the Baltic Sea. It is shown that most probably in the period of 10,200-3,500 years ago the runoff was carried out through the Heinjoki waterway. The study underlines that the isostatic factor played a significant role in the forming of the water flow. The change in the runoff direction from the Heinjoki waterway to the Neva River is mainly related to the isostatic uplift of the Karelian Isthmus and the northern part of Lake Ladoga. Quantitative parameters of the Heinjoki palaeoflow (flow rate, annual runoff, runoff layer, runoff coefficient) seem to be roughly equivalent to the modern parameters of the flow of the Neva River. The article is dedicated to our colleague, a talented geographer and teacher, PhD Oleg Borisovich Averichkin (1979-2010) who first performed the calculations of the paleorunoff of Lake Ladoga

Traffic Flow Catastrophe Border Identification for Urban High-Density Area Based on Cusp Catastrophe Theory: A Case Study under Sudden Fire Disaster

For traffic management under sudden disasters in high-density areas, the first and foremost step is to prevent traffic congestion in the disaster-affected area by traffic flow management and control, so as to provide enough and flexible traffic capacity for emergency evacuation and emergency rescue. Catastrophe border identification is the foundation and the key to traffic congestion prediction under sudden disaster. This paper uses a mathematical model to study the regional traffic flow in the high-density area under sudden fire disaster based on the Cusp Catastrophe Theory (CCT). The catastrophe border is identified by fitting the CCT-based regional traffic flow model to explore the stable traffic flow changing to the instable state, as to provide a theoretical basis for traffic flow management and control in disaster-affected areas, and to prevent the traffic flow being caught into disorder and congestion. Based on VISSIM simulator data by building simulation scenarios with and without sudden fire disaster in a Sudoku traffic network, the catastrophe border is identified as 439 pcu/lane/h, 529 pcu/lane/h, 377 pcu/lane/h at 5 s, 10 s, 15 s data collection interval in a Sudoku traffic network respectively. The corresponding relative precision, which compares to the method of Capacity Assessment Approach (CAA), is 89.1%, 92.7% and 76.5% respectively. It means that 10 s data collection interval would be the suitable data collection interval in catastrophe border identification and regional traffic flow control in high-density area under sudden fire disaster.

The Dynamic Equilibrium Mechanism of Regional Lithium Flow for Transportation Electrification.

To assess changes in the lithium supply chain resulting from the development of the electric vehicle industry and corresponding impacts, this study established a regional dynamic flow model of the entire anthropogenic life cycle of lithium in China from 2000 to 2050. Based on historical data, this model provides output data including production, consumption and international trade of lithium embodied in five types of commodities. Results indicate that the amount of lithium flow in 2050 will be 13-20 times greater than that in 2015. The lithium applied in electric vehicles will account for the largest proportion of in-use stocks of lithium starting in 2022. Lithium recovery will not play a big role in reducing supply pressure until 2030. Comparing all types of lithium-containing commodities, import dependence on minerals will remain the greatest within the temporal boundary. This factor reflects a nonnegligible risk to the supply demand balance considering the high concentration of mineral import structure in China currently. Several policy recommendations are offered for the optimization of China's flow structure. On the demand side, limited capacity expansion and cutting overcapacity of downstream commodities should be under consideration to distribute lithium import more reasonably. On the supply side, the potential oversupply issues caused by low-grade scrap require further development of recycling technology.

Density-Driven Mass Transfer in Repositories for Nuclear Waste

In geologic repositories for nuclear waste located in crystalline rocks, the waste is surrounded by a bentonite buffer that in practice is not permeable to water flow. The nuclides must escape by molecular diffusion to enter the seeping water in the fractures of the rock. At high water-seepage rates, the nuclides can be carried away rapidly. The seepage rate of the water can be driven by the regional hydraulic gradient as well as by buoyancy-driven flow. The latter is induced by thermal circulation of the water by the heat produced by radionuclide decay. The circulation may also be induced by salt exchange between buffer and water in the fractures. The main aim of this paper is to explore how salt exchange between the backfill and mobile water in fractures, by buoyancy effects, can increase the escape rate of radionuclides from a repository.A simple analytical model has been developed to describe the mass transfer rate induced by buoyancy. Numerical simulations support the simple solution. A comparison is made with the regional gradient-driven flow model. It is shown that buoyancy-driven flow can noticeably increase the release rate.

Salt dissolution and permeability in the Western Canada Sedimentary Basin

Extensive dissolution of evaporites has occurred in the Williston Basin, Canada, but it is unclear what effect this has had on bulk permeability. The bulk of this dissolution has occurred from the Prairie Evaporite Formation, which is predominantly halite and potash. However, minor evaporite beds and porosity infilling have also been removed from the overlying Dawson Bay and Souris River formations, which are predominantly carbonates. This study examines whether permeability values in the Dawson Bay and Souris River formations have been affected by dissolution, by analyzing 142 drillstem tests from those formations. For both the Dawson Bay and Souris River formations, the highest permeabilities were found in areas where halite dissolution had occurred. However, the mean permeabilities were not statistically different in areas of halite dissolution compared to those containing connate water. Subsequent precipitation of anhydrite is known to have clogged pore spaces and fractures in some instances. Geochemical relationships found here support this idea but there is no statistically significant relationship between anhydrite saturation and permeability. Geomechanical effects, notably closure of fractures due to collapse, could be a mitigating factor. The results indicate that coupling dissolution and precipitation to changes in permeability in regional flow models remains a significant challenge.

Evapotranspiration capture and stream depletion due to groundwater pumping under variable boreal climate conditions: Sudogda River Basin, Russia

Groundwater pumping and changes in climate-induced recharge lead to lower groundwater levels and significant changes in the water balance of a catchment. Water previously discharged as evapotranspiration can become a source of pumpage. Neglecting this effect leads to overestimated streamflow depletion. A small river basin (Sudogda River Basin, Russia) with a boreal climate and with long-term records of groundwater head and streamflow rate (showing that the measured stream depletion is less than the pumping rate) was investigated. The role of evapotranspiration in the water balance was analyzed by a hydrogeological model using MODFLOW-2005 with the STR package; the annual variation in recharge was obtained with the codes Surfbal and HYDRUS. The Sudogda River Basin was classified according to landscape and unsaturated-zone texture classes, and for each classified zone, the unsaturated-zone flow simulation was used to calculate the annual recharge dynamics for the observation period. Calibration of the regional flow model was conducted using flow and head observations jointly for two steady-state flow conditions—natural (before pumping started) and stressed (pumping). The simulations showed that pumped water originates from three sources: intercepted baseflow (75% of the annual total pumping rate), the capture of groundwater evapotranspiration discharge plus increased groundwater recharge (17%), and induced stream infiltration (8%). Additionally, multi-year precipitation records were analyzed to detect any long-term recharge and pumping water-budget changes. The results showed that increasing groundwater recharge by natural precipitation leads to (1) decreased intercepted baseflow and induced streamflow infiltration and (2) increased intercepted evapotranspiration discharge, thereby reducing stream depletion.

Seismic Anisotropy of the Upper Mantle Below the Western Rift, East Africa

AbstractAlthough the East African rift system formed in cratonic lithosphere above a large‐scale mantle upwelling, some sectors have voluminous magmatism, while others have isolated, small‐volume eruptive centers. We conduct teleseismic shear wave splitting analyses on data from 5 lake‐bottom seismometers and 67 land stations in the Tanganyika‐Rukwa‐Malawi rift zone, including the Rungwe Volcanic Province (RVP), and from 5 seismometers in the Kivu rift and Virunga Volcanic Province, to evaluate rift‐perpendicular strain, rift‐parallel melt intrusion, and regional flow models for seismic anisotropy patterns beneath the largely amagmatic Western rift. Observations from 684 SKS and 305 SKKS phases reveal consistent patterns. Within the Malawi rift south of the RVP, fast splitting directions are oriented northeast with average delays of ~1 s. Directions rotate to N‐S and NNW north of the volcanic province within the reactivated Mesozoic Rukwa and southern Tanganyika rifts. Delay times are largest (~1.25 s) within the Virunga Volcanic Province. Our work combined with earlier studies shows that SKS‐splitting is rift parallel within Western rift magmatic provinces, with a larger percentage of null measurements than in amagmatic areas. The spatial variations in direction and amount of splitting from our results and those of earlier Western rift studies suggest that mantle flow is deflected by the deeply rooted cratons. The resulting flow complexity, and likely stagnation beneath the Rungwe province, may explain the ca. 17 Myr of localized magmatism in the weakly stretched RVP, and it argues against interpretations of a uniform anisotropic layer caused by large‐scale asthenospheric flow or passive rifting.

Regional groundwater flow dynamics and residence times in Chaudière-Appalaches, Québec, Canada: Insights from numerical simulations

As part of the Quebec PACES III provincial groundwater resources assessment programme (Programme d’acquisition des connaissances en eaux souterraines), a regional-scale two-dimensional numerical groundwater model was developed in the Chaudière-Appalaches region, Québec, Canada. The model considers groundwater flow, transport of groundwater age and the influence of a fault on the flow system and its implications for groundwater quality. By including deep and shallow flow systems, the study helps fill a knowledge gap with respect to intermediate flow systems and the role they would play during potential energy resource development including shale gas exploitation from the Utica Shale. Physical and chemical hydrogeological data, including an analysis of 14C in dissolved inorganic carbon in sampled groundwater, supported a regional conceptual flow model forming the basis for numerical simulations. The numerical model is first calibrated to regional piezometry through a semi-automated workflow using the inverse model PEST. Although some evidence for deeper regional flow exists, the area appears to be dominated by local flow systems on maximum length scales of about 5 km, with significant flow through the top 40 to 60 m of the fractured sedimentary rock aquifer. This regional-scale flow model is also supported by the local hydrogeochemical signatures. Simulated mean groundwater ages show young shallow water of < 100 years with rapid increases in age with depth suggesting diffusion-controlled age evolution. Groundwater age is likely being perturbed in the vicinity of the Jacques Cartier River fault, which can act as both a barrier and a preferential pathway, provided permeability contrasts with the surrounding rock are at least two orders of magnitude.

Variable Melt Production Rate of the Kerguelen HotSpot Due To Long‐Term Plume‐Ridge Interaction

AbstractFor at least 120 Myr, the Kerguelen plume has distributed enormous amounts of magmatic rocks over various igneous provinces between India, Australia, and Antarctica. Previous attempts to reconstruct the complex history of this plume have revealed several characteristics that are inconsistent with properties typically associated with plumes. To explore the geodynamic behavior of the Kerguelen hotspot, and in particular address these inconsistencies, we set up a regional viscous flow model with the mantle convection code ASPECT. Our model features complex time‐dependent boundary conditions in order to explicitly simulate the surrounding conditions of the Kerguelen plume. We show that a constant plume influx can result in a variable magma production rate if the plume interacts with nearby spreading ridges and that a dismembered plume, multiple plumes, or solitary waves in the plume conduit are not required to explain the fluctuating magma output and other unusual characteristics attributed to the Kerguelen hotspot.

Modeling saltwater intrusion scenarios for a coastal aquifer at the German North Sea

A 3d regional density-driven flow model of a heterogeneous aquifer system at the German North Sea Coast is set up within the joint project NAWAK (“Development of sustainable adaption strategies for the water supply and distribution infrastructure on condition of climatic and demographic change”). The development of the freshwater-saltwater interface is simulated for three climate and demographic scenarios. Groundwater flow simulations are performed with the finite volume code d3f++ (distributed density driven flow) that has been developed with a view to the modelling of large, complex, strongly density-influenced aquifer systems over long time periods.

Numerical modelling in support of a conceptual model for groundwater flow and geochemical evolution in the southern Outaouais Region, Quebec, Canada

A two-dimensional vertical-section numerical model for groundwater flow and transport using age, tritium and chloride was used to help validate a conceptual model of geochemical evolution within a representative regional-scale hydrogeological system in the Outaouais Region, Quebec, Canada. The flow system includes up to 30 m of Quaternary sediments and marine clays overlying fractured silicate rock of the Canadian Shield. Calibration of the regional flow model using observed piezometric levels and tritium concentrations showed that shallow groundwater flow is dominated by local flow systems limited to 30–40 m depth, 1–5 km long, and with groundwater residence times of 10–50 years. Intermediate systems, on the order of 5–15 km long, are less extensive than initially thought and are characterised by maximum depths of about 100 m and residence times of 200–6000 years. A model-calibrated hydraulic conductivity of 8 × 10−5 m.s−1 was required in the upper 50 m of the fractured bedrock. The active flow zone was inferred to extend to depths of about 100–150 m, with any deeper regional flow essentially negligible. Differences between tritium-based ages and simulated mean residence times were attributed to mixing of groundwater in open boreholes. Concentrations of 4He could be explained by diffusive transport from deeper and older groundwater, exacerbated by sampling. With new insight from the numerical modelling, the conceptual flow model has been updated to now include only a weak component of regional flow combined with significant local- and intermediate-scale flow systems connected to the upper fractured bedrock. The simulated flow system is also consistent with the geochemical evolution of the region, which is dominated by young Ca-HCO3-type waters in the unconfined aquifer and by older Cl− signatures from the remnant Champlain Sea seawater.

Use of numerical methods for identification of hydrodynamic field and hydrogeochemical processes in the Quaternary multi-aquifer system

Abstract The paper presents spatial analysis and numerical methods to describe the hydrodynamic and hydrochemical conditions in a groundwater system. The research was conducted in the northern part of the Białystok High Plane, eastern Poland, within a Quaternary multi-aquifer system. Spatial analysis was used for imaging the quasi-continuous structure of the system based on a discrete set of hydrogeological data. A high-resolution regional flow model was used to identify the groundwater discharge and discharge zones of the individual aquifers. Calculations have shown a marked asymmetry of the flow system. Deeply incised river valleys in the Niemen River basin more strongly affect the groundwater than the discharge zones in the valleys of the Vistula River basin. As a result, the underground watershed in deeper aquifers is clearly shifted westward in relation to the morphological watershed. The hydrodynamic conditions of the system determined by numerical methods were used to identify the points along the groundwater flow-path for the hydrochemical study. It was the basis for the identification of points located along the groundwater flow direction, which were used in the hydrochemical study. Computational schemes of water solution models were calculated for the quasi-equilibrium state of chemical reactions between the solution and the solid and gaseous phases. Presentation of the chemical reactions allowed determining the origin of changes in the concentrations of individual components dissolved in groundwater. It was found that kaolinitization, i.e. chemical weathering of feldspars and plagioclases is the basic process that most affects the groundwater chemistry.