Surface Water Interactions Research Articles

Natural and Anthropogenic Geochemical Tracers to Investigate Residence Times and Groundwater–Surface-Water Interactions in an Urban Alluvial Aquifer

A multi-component geochemical dataset was collected from groundwater and surface-water bodies associated with the urban Fountain Creek alluvial aquifer, Colorado, USA, to facilitate analysis of recharge sources, geochemical interactions, and groundwater-residence times. Results indicate that groundwater can be separated into three distinct geochemical zones based on location within the flow system and proximity to surface water, and these zones can be used to infer sources of recharge and groundwater movement through the aquifer. Rare-earth-element concentrations and detections of wastewater-indicator compounds indicate the presence of effluent from wastewater-treatment plants in both groundwater and surface water. Effluent presence in groundwater indicates that streams in the area lose to groundwater in some seasons and are a source of focused groundwater recharge. Distributions of pharmaceuticals and wastewater-indicator compounds also inform an understanding of groundwater–surface-water interactions. Noble-gas isotopes corroborate rare-earth-element data in indicating geochemical evolution within the aquifer from recharge area to discharge area and qualitatively indicate variable groundwater-residence times and mixing with pre-modern groundwater. Quantitative groundwater-residence times calculated from 3H/3He, SF6, and lumped-parameter modeling generally are less than 20 years, but the presence of mixing with older groundwater of an unknown age is also indicated at selected locations. Future investigations would benefit by including groundwater-age tracers suited to quantification of mixing for both young (years to decades) and old (centuries and millennia) groundwater. This multi-faceted analysis facilitated development of a conceptual model for the investigated groundwater-flow system and illustrates the application of an encompassing suite of analytes in exploring hydrologic and geochemical interactions in complex systems.

Application of an environmental multimedia modeling system for health risk assessment: Key influencing factors and uncertainties research.

In this paper, an environmental multimedia modeling system (EMMS) that combines a risk assessment with a Monte Carlo method (MCM) was used to explore the interaction between groundwater and surface water with respect to chemical exposure and risk. The EMMS-MCM simulations incorporated several key influencing factors that are inherent in traditional predictions of subsurface and surface-water interactions, including soil permeability coefficients and parameters such as hydraulic conductivity, density, recharge, layers, and depth. These influencing factors are generally associated with the largest sources of uncertainty in modeling and pose significant challenges to water management and to the optimal allocation of water resources. A case study involving benzene at the Trail Road landfill site located in the Ottawa-Carlton area of Canada is presented to illustrate the use of the EMMS-MCM approach. The model results are verified by comparisons to the results of groundwater and surface-water investigations in the landfill. The EMMS-MCM results are evaluated using a risk quotient (RQ) risk assessment method to quantify environmental risk. The EMMS-MCM simulations can be used to support hazardous field work and contribute to environmental management by predicting the possible consequences of hazardous chemical contaminations in surface waters and groundwater. The integration of the EMMS-MCM and RQ approaches represents an appropriate tool for the accurate assessment of long-term pollutant risks and environmental management of surface- and groundwater resources. Integr Environ Assess Manag 2021;17:877-886. © 2021 SETAC.

Chemodiversity of water-extractable organic matter in sediment columns of a polluted urban river in South China.

Dissolved organic matter (DOM) in sediments of polluted rivers significantly contributes to oxygen consumption and river blackening and odorization. However, the chemodiversity of DOM at different depths or river reaches is poorly known. Here, we studied the storage and molecular-level signatures of water-extractable organic matter (WEOM) in the sediment column (0-100cm) of the upper, middle, and lower mainstream of Maozhou River (a polluted river in Shenzhen, China, with 40years of urbanization) using optical spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry. The sediment WEOM level increased from upstream to downstream. The relative abundances of sulfur-containing surfactants in all sediment WEOM were higher than those previously reported for surface water DOM. The WEOM in surface sediment had higher aromaticity, molecular size, and nominal oxidation state of carbon and greater signals from anthropogenic inputs than did deep sediment at the upper and middle mainstream sites. However, these characteristics varied little between surface and deep sediments at the lower mainstream site, probably due to intensive surface water and pore water interactions. The sediment WEOM at 0-40cm in the middle mainstream showed a greater anthropogenic signature (e.g., more surfactant and dissolved black carbon contributions) than any other sediment. We demonstrate strong anthropogenic impacts on the surface sediment over decades of urbanization.

Using Concentration–Discharge Relationships to Identify Influences on Surface and Subsurface Water Chemistry along a Watershed Urbanization Gradient

Urban development within watersheds impacts the hydrology and water quality of streams, but changes to groundwater–surface water interactions in this “urban stream syndrome” are not yet well understood. This study focused on three stream systems in a northern Virginia (USA) protected area with 14.2, 31.7, and 66.1% developed land in their watersheds. Surface water was sampled weekly for nutrients, dissolved metals, sulfate, ancillary water quality parameters, and discharge over two non-consecutive years with the hyporheic zone sampled during the second year. Concentration–discharge relationships revealed largely chemostatic behavior in surface water solutes in the least urbanized stream, while in the two more urbanized streams, these relationships tended to have significant positive and negative slopes, indicating diverse delivery pathways depending on the constituent. In the least urbanized stream, linear regressions between discharge and solute concentrations in hyporheic water had exclusively negative slopes, indicating source-limited delivery, while the other two urbanized streams maintained largely chemostatic behavior. Average specific conductance and nitrate + nitrite concentrations in stream surface water reflected an urbanization gradient, while sulfate, Ca, K and Sr concentrations suggested a threshold effect: the stream with a mostly forested watershed had the lowest concentrations, while the other two were higher and similar. Specific conductance indicated salinization of both surface and groundwater at the two more urban streams, possibly threatening aquatic organisms. Metal concentrations in surface and subsurface water were often positively correlated with specific conductance and negatively correlated with pH, suggesting that they may originate from road salt and/or be mobilized by acid precipitation. These results indicate the importance of monitoring both baseflow and stormflow as pathways for pollution.

Molecular Dynamics Simulation of Wetting Behavior: Contact Angle Dependency on Water Potential Models

The underlying principle of surface wettability has obtained great attentions for the development of novel functional surfaces. Molecular dynamics simulations has been widely utilized to obtain molecular-level details of surface wettability that is commonly quantified in term of contact angle of a liquid droplet on the surface. In this work, the sensitivity of contact angle calculation at various degrees of surface hydrophilicity to the adopted potential models of water: SPC/E, TIP4P, and TIP5P, is investigated. The simulation cell consists of a water droplet on a structureless surface whose hydrophilicity is modified by introducing a scaling factor to the water-surface interaction parameter. The simulation shows that the differences in contact angle described by the potential models are systematic and become more visible with the increase of the surface hydrophilicity. An alternative method to compute a contact angle based on the height of center-of-mass of the droplet is also evaluated, and the resulting contact angles are generally larger than those determined from the liquid-gas interfacial line.

A proposal of unit watershed for water management based on the interaction of surface water and groundwater

A proposal of unit watershed for water management based on the interaction of surface water and groundwater

Regional-scale interactions between groundwater and surface water under changing aridity: evidence from the River Awash Basin, Ethiopia

ABSTRACT Relationships between surface waters and groundwaters at basin scale are rarely investigated but have important implications for water resource development and management. Here, we integrate evidence from geochemical tracers and piezometry to advance the understanding of regional-scale, groundwater–surface water interactions in the River Awash Basin of Ethiopia. Hydrological characteristics are consistent with those observed in other semi-arid and arid basins where rivers are predominantly losing and act as a source of recharge rather than as a sink for groundwater discharge. Further, regional groundwater flow originating from the highlands exits the catchment rather than discharging to the riverine drainage. Consequently, groundwater abstraction from several regional-scale aquifers in the lowlands is not expected to impact river flow. However, salinity presents a major threat to irrigation and water supply. We identify critical areas for managing inflows, water use, wetlands and water quality that have significant implications for water security across the basin.

Assessing the impacts of irrigated agriculture on hydrological regimes in an oasis-desert system

Irrigated agriculture greatly affects the hydrological systems and thereby eco-environment and food security in arid and semi-arid regions. However, a comprehensive assessment of the hydrological system dynamics in response to irrigated agriculture is still scarce, especially in oasis-desert systems of arid inland regions. Thus, we investigated the impact of irrigated agriculture on hydrological regimes in an oasis-desert system of northwest China. Temporal variations in water balance and lateral groundwater flow in oasis and desert experimental fields (i.e. oasis plot and desert plot) were quantified using the water balance analysis method. Soil water variations, groundwater dynamics and surface water and groundwater interactions in the oasis-desert system were determined by combining line transect survey methods and stable isotope (18O, 2H) techniques using the USGS MODFLOW software. The results showed that water exchange fluxes and groundwater dynamics were altered by the application of water-saving irrigation techniques and the increase in total precipitation. In particular, the downward total exchanging flux above groundwater table and the outward total lateral groundwater flow reduced significantly in the oasis plot. Spatial heterogeneity and profile variability of soil moisture along the soil water content (SWC) transect significantly reduced. Simultaneously, the depth dependence of SWC in oasis cropland and the deep soil moisture at the edge of desert were improved under water-saving irrigation scenario. Temporal variations in groundwater table depths (GTDs) exhibited three different patterns (i.e. stable, metastable and fluctuating) and maintained a continuously downward trend except for the oasis-desert ecotone along the GTD transect, and an abrupt change was found to have occurred during 2006–2012, prompting changes in the seasonality of groundwater resource availability. Groundwater recharge and discharge processes changed dramatically due to large-scale land reclamation and groundwater pumping. Groundwater depletion is approaching hydrological limits although the process is largely compensated by precipitation and streamflow variability. Water-saving irrigation in conjunction with restriction of land reclamation and adaptation of water management practices is, at least for the present, the most effective way to maintain the coexistence of oasis and desert ecosystems in arid inland regions.

Conversion relationship between groundwater and surface water in the Taizi River Basin in China based on geochemical and isotopic characteristics.

Stable isotopes (δDVSMOW and δ18OVSMOW) and hydrochemical characteristics were analyzed to determine the groundwater and surface water characteristics of the Taizi River Basin in Northeast China. Total dissolved solids and major ion concentrations gradually increase along the Taizi River, and only parts of the middle and lower reaches were slightly reduced by replenishment from the Hun River and the tributaries of the eastern mountainous areas. The hydrochemical evolution of the surface water and groundwater may be due to a combination of mineral dissolution, mixing processes, cation exchange, and evaporation along the groundwater flow path. The geochemical and isotopic characteristics of the waters suggest that the surface water from the piedmont recharges the groundwater through faults and that precipitation near the mountain reservoirs contributes immensely to both water types. Lateral groundwater movement from the piedmont may be an effective source for replenishing river water in the middle and lower reaches. The geochemical and isotopic characteristics of the groundwater and surface water interaction in the Taizi River Basin contribute toward their comprehensive management.

Role of river stage in characterization of phreatic line

PurposeThe purpose of this study is to understand the basics of interactions of groundwater and surface water, which is needed for effective management of water resources.Design/methodology/approachThe experimental setup was framed using curved flume and the straight flume, which simulates the model of river and groundwater storage, respectively. The model set up further consists, downstream, central and upstream sections where 14 observation wells, which are arranged at a measured distance from the canal side.FindingsExit gradient is higher at downstream when the average head differences between canal and river are 31.9 cm and 35.7 cm. Free seepage height is more in the downstream wells than upstream and central wells. At the downstream section, there is a greater chance of instability of the riverbank.Research limitations/implicationsResults will be used for better planning of hydraulic structural design.Practical implicationsResults will help in storing the large water and better irrigation planning for the water acute states and locations.Originality/valueThe originality is own developed physical model and its own first type to understand the basic of interaction and effects.

Effect of temperature on D.O and T.D.S: A measure of Ground and Surface Water Interaction

ABSTRACT To statistically quantify ground and surface water interaction using temperature as a tracer and its effect on chemical properties of rivers, a total number of 30 sample points were selected at regular intervals along the profile of the two rivers. Ten points on the upper Ona River, and ten on the Alaro River, the remaining ten on the lower section of the river. Also, a corresponding number of nearby groundwater samples were obtained from a parallel source, for each of the surface water sample points so as to aid comparison. The coordinates of the sample points along the river profile were obtained using a global positioning system (GPS) device. The result of the investigation showed that two of the properties (Total Dissolved Solid and Dissolved Oxygen) of surface water vary significantly while the third (Temperature) does not vary significantly across the river profile extending from the upstream section to the downstream section. It was further observed that the underlying geology in terms of rock types have a significant influence on the properties of the surface water body, this was corroborated through comparison of the groundwater properties against that of the surface water. No significant correlation was observed between temperature and total dissolved solids and dissolved oxygen, thus inferring no form of noteworthy influence from temperature on the considered parameters in this study. The analysis of temperature gradients along a river profile and its effect on water properties provided an insight to the quantitative estimates of rates of interaction through the use of statistics and a possible inferred direction.

Perspectives of the development of complex interdisciplinary hydrological and geocryological research in the North-East of Russia

Climate warming and anthropogenic impact causes transformation of geocryological conditions in the river basins of the North-East of Russia. Changes in the thickness of the active layer, configuration of taliks, types of landscapes and other factors lead to transformation of water exchange processes between surface and groundwater runoff. This is manifested in the seasonal redistribution of the components of the water balance, accelerated melting of aufeis, change in the ratio of waters of different genesis in the structure of river runoff. As a result, natural and anthropogenic risks that affect the safe and efficient development of infrastructure and socio-economic processes are increasing. At the same time the system of observations developed in the Soviet period has been practically destroyed in the region. This paper offers a vision of organizing complex multidisciplinary research to assess and project the changes in the conditions of underground and surface water interaction in natural and disturbed river basins of the cryolithozone of the North-East of Russia, including for solving applied problems, based on permafrost, hydrology, hydrogeology, landscape science and geophysics with applications of remote sensing and field research integrated through mathematical modeling methods. To achieve the goal, the identification of natural and disturbed landscapes using remote sensing data, and key areas for detailed research will be selected. Geophysical and drilling works will be carried out within the sites to establish permafrost-hydrogeological conditions, monitoring stations will be equipped to determine hydrogeological, hydrometeorological and geocryological characteristics, including sampling for isotopic and hydrogeochemical studies. As the main key sites, it is proposed to use the area of ​​the Kolyma water-balance station and the site on Anmangynda aufeis, for which there are long-term observation series in the 20th century. Field data will become the basis for improving the mathematical model of runoff formation, considering the relationship between groundwater and river runoff in the conditions of permafrost. Mathematical modeling will make it possible to quantitatively analyze the water balance of rivers considering various factors and project water availability both for specific industrial facilities and for the region as a whole.

ОЦІНКА ВПЛИВУ ФАКТОРІВ УРБАНІЗАЦІЇ НА НЕБЕЗПЕКУ АКТИВІЗАЦІЇ КАР-СТОВИХ ПРОЦЕСІВ У РЕГІОНАХ УКРАЇНИ

The article presents the analysis of the exogenous geological process activation hazards, namely karst, in the conditions of urbanization processes. The scale of geoecological problems is shown to be directly or indirectly determined by the scale of urbanization. The relevance of the research is associated with the study of the nature of changes in the expansion of karst rocks in regions with different levels of urbanization in the period 2001 – 2020. The main aim is to analyze the hazards of karst development in relation with the factors of urbanization processes in the regions of Ukraine based on the indicator method. The particular characteristics of the impact of urbanized territories on the initiation of natural disasters and geological hazards have been determined. The urbogenic load of the regions was assessed using determined and calculated earlier indicators of ecological and ecological-demographic urbanization. The assessment of the dependence between the hazard indicator of the spread of karst rocks and the indicator of ecological urbanization in the regional context has been carried out. It is shown that in the third part of the regions, the growing hazard levels of karst processes practically coincide with the growth of the ecological urbanization index. A nearly doubling of the area of karst terrains was noted during 2001 – 2020 in all administrative regions. The coefficient of expansion of karst territories for the specified period has been calculated. Four groups of regions were identified according to the increase in karst areas in comparison with the hazards of karst processes and the index of ecological-demographic urbanization. Expansion of open karst areas in the Transcarpathian, Odessa, Rivne, Kherson, Chernivtsi regions was noted. For this group of regions, a tendency to increase the areas of surface karst in accordance with an increase in the values of urbanization indicators has been established. This is due to the exploitation of natural territorial resources, changes in the nature of land use, depletion of vegetation cover, anthropogenic loads on the ground, and imbalances in the interaction of surface and underground waters in urbanized areas. Thus, the Ukraine’s regions with different urbogenic load are differentiated depending on the territorial indicator of the danger of karst terrains, as well as the dynamics of changes in the areas of karst rocks.

Force fields for water-surface interaction: is reproduction of the experimental water contact angle enough?

A new protocol based on quantum chemical calculations and molecular dynamics simulations is proposed to revisit water-MoS2 interfacial force fields (FFs). The accurate reproduction of experimental water contact angles is suggested to be insufficient to ensure reliable FFs for recovering structural properties of the interfacial solvent. As an example, this protocol is used to develop a new set of FF parameters to both capture interfacial structural phenomena at the interface between water and MoS2 and recover experimental water contact angle data. This approach can be applied to any interface where contact angle data are available.

Revealing the influence of hyporheic water exchange on the composition and abundance of bottom-dwelling macroinvertebrates in a temperate lowland river

We studied distributions and abundances of macroinvertebrates in relation to hyporheic water exchange (HWE) patterns of the upper Biebrza − a small, lowland, low dynamic European river located in Northeast Poland. On a 6-km stretch of the river; we determined the variability of water exchange in the hyporheic zone by using direct field measurements of the pressure gradient to determine groundwater–surface water interactions. We identified locations with upwelling and downwelling fluxes of HWE as well as ambiguous hydraulic contact between groundwater and surface water along the river. In these locations, we sampled bottom-dwelling macroinvertebrates. In total, 627 individuals of benthic macroinvertebrates of 34 taxa were identified. We revealed that bottom-dwelling macroinvertebrate fauna is more abundant and diverse in river stretches where water from the river infiltrates the hyporheic zone. Results also show higher taxonomic richness and abundances of benthic macroinvertebrates in stretches with diagnosed infiltrating conditions (downwelling flux in a hyporheic zone) compared to in stretches where the river drained groundwater (upwelling flux in a hyporheic zone), but the recorded differences were not statistically significant.

Structure and sum-frequency generation spectra of water on neutral hydroxylated silica surfaces.

Structural organization and vibrational sum-frequency generation (VSFG) spectra of water on crystalline and amorphous neutral silica surfaces were investigated by classical molecular dynamics simulations. The liquid phase represented with neat water and 1 M NaCl solution was analysed in terms of bonded interfacial layer (BIL), diffuse layer (DL) and bulk region. The simulations show that the structure of BIL depends on the surface morphology and density of surface OH groups. The water-silanol H-bond network and BIL structure are mainly insensitive to the presence of ions in the liquid phase. Molecules in DL of SiO2/neat water interfaces preferentially orient their OH bonds towards the surfaces. This effect is directly related to an effective negative charge of formally neutral surfaces. Ions of the electrolyte solution affect the intermolecular structure in DL by screening the surface electric field and by the chaotropic effect. Calculated phase-sensitive VSFG (Im[χ(2)]) spectrum of BIL features low-frequency negative and high-frequency positive bands. Characteristics of the positive band reflect the strength of water-surface interactions and surface crystallinity, while the position and shape of the negative band are common to all interfaces. The Im[χ(2)] spectrum of DL is dominated by a contribution from the third-order χ(3) susceptibility with the sign of the contribution directly related to the sign of electrostatic potential in the interfacial region. The DL spectrum is strongly affected by the presence of solvated ions. The computed intensity and Im[χ(2)] spectra of the amorphous silica/NaCl solution interface are in a good agreement with the conventional and phase-sensitive experimental VSFG spectra of fused SiO2/water system at low pH, in contrast to the spectra of the amorphous silica/neat water interface. Origins of the discrepancy are discussed.

Nitrogen and oxygen isotopomeric constraints on the sources of nitrous oxide and the role of submarine groundwater discharge in a temperate eutrophic salt‐wedge estuary

AbstractEstuaries have been identified as sources of nitrous oxide (N2O) emissions to the atmosphere but questions remain as to which production pathway(s) govern the oversaturation of N2O observed in most estuaries worldwide. Here, we use a suite of nitrate and N2O isotopes, as well as the 15N site preference signatures of N2O to assess (1) the relative importance of different N2O production pathways in a eutrophic groundwater‐impacted salt‐wedge estuary and the aquifers underlying the estuary and (2) the influence of groundwater input on the overall N2O saturation in the estuary. This is one of the few studies to examine the effect of groundwater–surface water interaction on N2O cycling using N2O isotopes. The site preference values of N2O in the deep aquifer below the estuary were distinctive (83‰ ± 25‰) and were much higher than in either surface water (21‰ ± 6‰) or shallow groundwater (44‰ ± 8‰), suggesting the influence of multiple biotic and/or abiotic processes which proceed through multiple cycles, and/or the occurrence of a yet unidentified N2O production pathway. Isotope endmember considerations revealed that nitrifier‐denitrification was the major N2O production pathway within the shallow aquifer whereas within the estuarine water column, N2O saturation was governed by chemodenitrification and discharge of N2O‐laden submarine groundwater. Our study not only emphasizes the substantial, yet often underappreciated role of submarine groundwater discharge in estuarine N2O budgets, but also highlights the need to reevaluate the importance of the noncanonical denitrification pathways (i.e., chemodenitrification and nitrifier‐denitrification) in controlling the overall N2O production from estuarine and groundwater environments.

Determination of the Boundaries of Flooded Zones Based on Hydrodynamic Modeling

The paper discusses the problem of determining the boundaries of flooding zones, flooding of territories. The paper describes technique for constructing cadastral maps of flooded zones for various values of the estimated availability of water levels, which is based on hydrodynamic and geoinformation modeling. For creating digital elevation models (DEM) of the conformation, we use spatial data obtained from a large number of sources. We applied the described technique to construct cadastral maps for a number of settlements in the Volgograd region of the Russian Federation. As a result, we get a set of xml-files prepared for registration with the Federal Agency for State Registration, Cadastre and Cartography. For the Republic of Belarus, the problem of flooding the territories is also urgent. The floodplain areas of the Pripyat River are most prone to flooding. We built a DEM for the area in the vicinity of Petrikov city and carried out hydrodynamic modeling. As a result, the inundation maps were obtained. The method proposed in this work is based on a mathematical model of shallow water in a single-layer approximation. This model is successfully applied in simulation of flooding for territories by flood waters. Solving the problem of determining the boundaries of flooding zones requires a transition to a two-layer shallow water model that takes into account the interaction of surface and ground waters.

Water Layer at Hydrophobic Surface: Electrically Dead but Dynamically Alive?

The origin of the anomalous low value of the static dielectric constant (SDC) of confined water has been addressed and unearthed. While the low value is partly due to the different dielectric boundaries, a significant role is played by the "electrically dead layer" (EDL). As the observed dielectric constant is the harmonic mean of the grid-wise SDCs, the first layer, having the smallest SDC, makes a disproportionately large contribution. This enhanced contribution, in turn, arises from the orientationally ordered surface water molecules. They exhibit reduced fluctuations in collective dipole moment, as the molecules remain partly caged due to water-surface interactions. This phenomenon is found to be universal. We study the structure and dynamics of the water molecules which characterize the EDL. We demonstrate that while the EDL remains alive at a molecular level, with a finite residence time, it displays time scales not substantially different compared to the distant water layers.

Understanding Contaminant Migration Within a Dynamic River Corridor Through Field Experiments and Reactive Transport Modeling

The behavior of a persistent uranium plume within an extended river corridor at the DOE Hanford site is dominantly controlled by river stage fluctuations in the adjacent Columbia River. The plume behavior is further complicated by substantial heterogeneity in physical and geochemical properties of the host aquifer sediments. Multi-scale field and laboratory experiments and reactive transport modeling were integrated to understand the complex plume behavior influenced by highly variable hydrologic and geochemical conditions in time and space. In this paper, we (1) describe multiple data sets from field-scale uranium adsorption and desorption experiments performed at our experimental well-field, (2) develop a reactive transport model that incorporates hydrologic and geochemical heterogeneities characterized from multi-scale and multi-type datasets and a surface complexation reaction network based on laboratory studies, and (3) compare the modeling and observation results to provide insights on how to refine the conceptual model and reduce prediction uncertainties. The experimental results revealed significant spatial variability in uranium adsorption/desorption behavior, while modeling demonstrated that ambient hydrologic and geochemical conditions and heterogeneities in sediment physical and chemical properties both contributed to complex plume behavior and its persistence. This research underscores the great challenges in adequately characterizing this type of site to model the reactive transport processes over scales of 10 m or more. Our analysis provides important insights into the characterization, understanding, modeling, and remediation of groundwater contaminant plumes influenced by dynamic surface water and groundwater interactions.