scholarly journals Contrasting lacustrine groundwater discharge and associated nutrient loads in different geological conditions

2021 ◽  
Author(s):  
Xiaoliang Sun ◽  
Yao Du ◽  
Yamin Deng ◽  
Hongchen Fan ◽  
Teng Ma
Keyword(s):  
Water Resource Management ◽  
Groundwater Discharge ◽  
Dongting Lake ◽  
Coarse Grained ◽  
Balance Model ◽  
Small Scale ◽  
The West ◽  
Geological Conditions ◽  
Spatial Differences ◽  
Hydraulic Gradients

Abstract. The spatial patterns of lacustrine groundwater discharge (LGD) and associated nutrients input is crucial for effective management and protection of lakes. Multiple factors have been found to influence the spatial differences in LGD rates and associated nutrients loads, but the influence of geological conditions on the differences have not been well understood. In this study, we quantified LGD rates and associated nutrients loads in two sides with contrasting geological conditions of East Dongting Lake (EDL) within central Yangtze catchment and discuss the influence of geology on the spatial differences, through 222Rn mass-balance model, water chemistry coupled with existing geological data. The results showed that LGD rates were 38.66 ± 21.07 mm d−1 in the east EDL which is characterized by hilly geomorphy, deep/fast/narrow flowing, coarse-grained lakebed and large hydraulic gradients (0.004–0.006). Surprisingly, LGD rates were higher (92.82 ± 51.98 mm d−1) in the west EDL which is characterized by alluvial-lacustrine plain geomorphology, shallow/sluggish flowing, clayey or silty lakebed and low hydraulic gradients (0.0002–0.0015). The remaining factor determining the higher LGD rates in the west EDL is the permeability of the porous aquifer connected with the lake, which could be enlarged by some preferential pathways including large-scale buried paleo-channel and small-scale plant roots. The groundwater around the east EDL existed in a less confined environment, and frequent flushing led to low concentrations of nutrients. On the contrast, rapid burial of sediments and deposition of paleo-lake sediments since Last Deglaciation formed an organic-rich and reducing environment, which facilitated the enrichment of geogenic nutrients. As a result, the loads of LGD-derived nutrients in the west generally exceeded that in the east by one order of magnitude. In practice, future water resource management and ecological protection of Dongting Lake should focus on groundwater discharge in west EDL. This study highlights an important role of geological conditions in determining contrasting LGD rates and associated nutrients loads in large freshwater lakes.

scholarly journals Geological and groundwater flow model of a submarine groundwater discharge site at Hanko (Finland), northern Baltic Sea

2021 ◽  
Author(s):  
Samrit Luoma ◽  
Juha Majaniemi ◽  
Arto Pullinen ◽  
Juha Mursu ◽  
Joonas J. Virtasalo
Keyword(s):  
Hydraulic Conductivity ◽  
Groundwater Flow ◽  
Baltic Sea ◽  
Submarine Groundwater Discharge ◽  
Flow Model ◽  
Groundwater Discharge ◽  
Coarse Grained ◽  
Local Geometry ◽  
Groundwater Flow Model ◽  
Submarine Groundwater

AbstractThree-dimensional geological and groundwater flow models of a submarine groundwater discharge (SGD) site at Hanko (Finland), in the northern Baltic Sea, have been developed to provide a geological framework and a tool for the estimation of SGD rates into the coastal sea. The dataset used consists of gravimetric, ground-penetrating radar and shallow seismic surveys, drill logs, groundwater level monitoring data, field observations, and a LiDAR digital elevation model. The geological model is constrained by the local geometry of late Pleistocene and Holocene deposits, including till, glacial coarse-grained and fine-grained sediments, post-glacial mud, and coarse-grained littoral and aeolian deposits. The coarse-grained aquifer sediments form a shallow shore platform that extends approximately 100–250 m offshore, where the unit slopes steeply seawards and becomes covered by glacial and post-glacial muds. Groundwater flow preferentially takes place in channel-fill outwash coarse-grained sediments and sand and gravel interbeds that provide conduits of higher hydraulic conductivity, and have led to the formation of pockmarks on the seafloor in areas of thin or absent mud cover. The groundwater flow model estimated the average SGD rate per square meter of the seafloor at 0.22 cm day−1 in autumn 2017. The average SGD rate increased to 0.28 cm day−1 as a response to an approximately 30% increase in recharge in spring 2020. Sensitivity analysis shows that recharge has a larger influence on SGD rate compared with aquifer hydraulic conductivity and the seafloor conductance. An increase in recharge in this region will cause more SGD into the Baltic Sea.

scholarly journals Mapping Groundwater Seepage in a Fen Using Thermal Imaging

Geosciences ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 29
Author(s):  
Ogochukwu Ozotta ◽  
Philip J. Gerla
Keyword(s):  
Hydraulic Conductivity ◽  
Thermal Imaging ◽  
Crucial Role ◽  
Groundwater Discharge ◽  
Late Summer ◽  
Groundwater Temperature ◽  
Groundwater Seepage ◽  
Heterogeneous Soil ◽  
Hydraulic Gradients ◽  
Warm Soil

The transport of dissolved minerals and groundwater flow plays a crucial role in the ecosystem of many wetlands. Nonetheless, installing equipment to monitor groundwater seepage is invasive, harms vegetation, and can impact biodiversity. By remotely mapping surface temperature in late summer, when there is the greatest difference between warm soil and cold groundwater, temperature patterns can expose areas with the greatest upward gradient and flow. The conventional method of using tensiometers to measure hydraulic gradient and estimate flux using Darcy’s law was applied and compared with thermal imaging to characterize groundwater seepage at two contrasting sites within a central North Dakota fen (groundwater discharge wetland). Both sites exhibited variable gradients between the shallow and deep tensiometers. The temperature trend determined from the thermal imaging showed a closer relationship to the measured hydraulic gradients at the herbaceous (Sedge) site than at the wooded (Willow) site. Saturated hydraulic conductivity K ranged from 6 × 10−5 to 2 × 10−4 m/s for the Willow site; and 6 × 10−6 to 1 × 10−4 m/s for Sedge site. The flux calculated for the Willow site ranged from 1.4 × 10−5 to 2.7 × 10−4 m/s and that of the Sedge site ranged from 2.2 × 10−6 to 6.3 × 10−5 m/s. The gradients are affected at shallow depth because of heterogeneous soil stratigraphy, which is likely the reason that seepage faces at the sites cannot be mapped solely by thermal imaging.

scholarly journals Correction: Spatial distribution of heavy metals in the West Dongting Lake floodplain, China

2020 ◽  
Vol 22 (5) ◽  
pp. 1306-1306
Author(s):  
Dong Peng ◽  
Ziyu Liu ◽  
Xinyue Su ◽  
Yaqian Xiao ◽  
Yuechen Wang ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Spatial Distribution ◽  
Dongting Lake ◽  
The West

Correction for ‘Spatial distribution of heavy metals in the West Dongting Lake floodplain, China’ by Dong Peng et al., Environ. Sci.: Processes Impacts, 2020, DOI: 10.1039/c9em00536f.

A Novel Turbulent Aggregation Device for Flue Gas

2014 ◽  
Vol 955-959 ◽  
pp. 2425-2429 ◽  
Author(s):  
Yun Fei Li ◽  
Jian Guo Yang ◽  
Yan Yan Wang ◽  
Xiao Guo Wang
Keyword(s):  
Size Distribution ◽  
Flue Gas ◽  
Large Scale ◽  
Balance Model ◽  
Small Scale ◽  
Multiphase Model ◽  
Specific Performance ◽  
Particles Size Distribution ◽  
Scale Turbulence ◽  
Eulerian Multiphase Model

The purpose of this study is to construct a turbulent aggregation device which has specific performance for fine particle aggregation in flue gas. The device consists of two cylindrical pipes and an array of vanes. The pipes extending fully and normal to the gas stream induce large scale turbulence in the form of vortices, while the vanes downstream a certain distance from the pipes induce small one. The process of turbulent aggregation was numerically simulated by coupling the Eulerian multiphase model and population balance model together with a proposed aggregation kernel function taking the size and inertia of particles into account, and based on data of particles’ size distribution measured from the flue of one power plant. The results show that the large scale turbulence generated by pipes favours the aggregation of smaller particles (smaller than 1μm) notably, while the small scale turbulence benefits the aggregation of bigger particles (larger than 1μm) notably and enhances the uniformity of particle size distribution among different particle groups.

The Development of Sweden's R&D-Intensive Electronics Industries: Exports, Outsourcing, and Territorial Distribution

1996 ◽  
Vol 28 (5) ◽  
pp. 783-817 ◽  
Author(s):  
L Suarez-Villa ◽  
C Karlsson
Keyword(s):  
Export Performance ◽  
Plant Size ◽  
Production Costs ◽  
Export Market ◽  
Small Scale ◽  
Performance Variables ◽  
Continuous Innovation ◽  
Spatial Differences ◽  
And Performance ◽  
Employment Characteristics

Sweden's research-intensive electronics industries have thrived by developing export-market niches that rely greatly on continuous innovation and substantial expenditures in R&D. Over the past two decades, three R&D-intensive sectors (telecommunications equipment, electronic instruments, and computing-equipment manufacturing) have experienced a progressive territorial distribution, that has made them less reliant on the metropolitan concentration of the capital for their outsourcing and research arrangements. In this article we explore the relationship between R&D intensity, territorial distribution, subcontracting, and establishment performance in the R&D-intensive electronics industries. The export performance of these industries is considered first, along with its relationship with employment characteristics and territorial location. An analysis of the territorial distribution, and its relationship with establishment downsizing and subcontracting, provides insights on the significance of lower costs and higher R&D intensity for small-scale operations. Statistical analyses of R&D intensity and performance variables that include labour skills, plant size, production costs, fixed capital assets, and profitability, with establishment-level survey data, provide important insights on the effects of subcontracting and any spatial differences resulting thereof.

scholarly journals Analysis of drought characteristics for improved understanding of a water resource system

2014 ◽  
Vol 364 ◽  
pp. 404-409 ◽  
Author(s):  
A. T. Lennard ◽  
N. Macdonald ◽  
J. Hooke
Keyword(s):  
Resource Management ◽  
Water Supply ◽  
Water Resource ◽  
Water Resource Management ◽  
Drought Indices ◽  
Drought Severity ◽  
Small Scale ◽  
Water Resource System ◽  
Drought Characteristics ◽  
Standardised Precipitation Index

Abstract. Droughts are a reoccurring feature of the UK climate; recent drought events (2004–2006 and 2010–2012) have highlighted the UK’s continued vulnerability to this hazard. There is a need for further understanding of extreme events, particularly from a water resource perspective. A number of drought indices are available, which can help to improve our understanding of drought characteristics such as frequency, severity and duration. However, at present little of this is applied to water resource management in the water supply sector. Improved understanding of drought characteristics using indices can inform water resource management plans and enhance future drought resilience. This study applies the standardised precipitation index (SPI) to a series of rainfall records (1962–2012) across the water supply region of a single utility provider. Key droughts within this period are analysed to develop an understanding of the meteorological characteristics that lead to, exist during and terminate drought events. The results of this analysis highlight how drought severity and duration can vary across a small-scale water supply region, indicating that the spatial coherence of drought events cannot be assumed.

Detecting Submarine Groundwater Plumes in the Salalah Area: a Radon Tracer and Numerical Integral Plume Model Approach

2019 ◽  
Author(s):  
◽  
Hajar Al Balushi
Keyword(s):  
Spatial Distribution ◽  
Submarine Groundwater Discharge ◽  
Arid Regions ◽  
Meteoric Water ◽  
Groundwater Discharge ◽  
Sultanate Of Oman ◽  
Exploration And Exploitation ◽  
Submarine Groundwater ◽  
Hydraulic Gradients ◽  
Model Approach

The inflow of fresh or brackish groundwater into the sea is referred to as Submarine Groundwater Discharge (SGD). The SGD is enforced by a terrestrial component whichmainly depends on freshwater extraction and recharge by meteoric water and on aquifer permeability. And a marine component that is mainly controlled by the spatial distribution of outflows and water depth (hydraulic gradients between land and sea). This study is motivated by the importance of freshwater in arid regions and, in particular, by the continuous challenges posed by the exploration and exploitation of fresh water sources inthe Sultanate of Oman. Moreover, there is a lack of studies on SGD phenomena alongthe 1000 km coastline in the South of Oman. The objective of this study is to develop a method to detect SGD spots in the offshore region, autonomously, and understanding thehydrodynamics of the discharge seepage for future backtracking, quantification and coastaland groundwater management. The study area Salalah, Dhofar Governorate, South of Oman is known to have a high natural groundwater recharge during the monsoon seasonand a karstic coastal seafloor, which results in a high potential of submarine groundwater discharge spots.

The late Miocene eolian record at the eastern margin of the Puna Plateau, NW Argentina: Evidence of upper-tropospheric paleocirculation

2022 ◽  
Vol 92 (1) ◽  
pp. 32-49
Author(s):  
Jonathan Ledesma ◽  
Cecilia E. Del Papa ◽  
Patricio Payrola
Keyword(s):  
Atmospheric Circulation ◽  
Late Miocene ◽  
Amazon Basin ◽  
Coarse Grained ◽  
Small Scale ◽  
Provenance Analysis ◽  
Humid Climate ◽  
Upper Troposphere ◽  
Facies Associations ◽  
Puna Plateau

Abstract The Puna–Altiplano Plateau of the Central Andes is the second-highest plateau in the world (after Tibet), with a mean elevation of 4000 m.a.s.l. and an arid to hyperarid climate. Uplift of the Puna–Altiplano Plateau has affected lower-level atmospheric circulation, acting as a barrier to humid easterly winds from the Amazon basin and favoring an across-strike precipitation gradient resulting in a humid climate towards the east of the plateau and an arid to hyperarid climate in the orogen's interior. In the modern climate, the Bolivian High anticyclone regulates upper troposphere circulation, but little is known about the high-altitude tropospheric circulation of the past. This work focuses on the eolian record of the San Antonio de los Cobres basin along the eastern border of the Puna Plateau, NW Argentina, with the aim of analyzing its origin and thus elucidating the late Miocene winds. The eolian deposits are constrained by 7.8 Ma (K/Ar and U/Pb) and 6.4 Ma (U/Pb) ignimbrites at the nearly basal and upper contacts, respectively. Based on stratigraphic, sedimentological, and provenance analysis of the eolian units, we have identified three main facies associations (FAs): FA1) cross-stratified sandstones with large- to small-scale tabular, planar cross-bedding and with trough cross-stratification; FA2) sandstones with planar to low-angle stratification associated with thinly laminated ripple sandstone strata; FA3) medium- to coarse-grained massive sandstones associated with pebbly to bouldery, matrix-supported conglomerates and clast-supported conglomerates. The lateral and vertical facies assemblages indicate a dune field confined to topographic depressions dominated by transverse dunes with straight and sinuous crestlines that laterally grade into sandsheets associated with ephemeral streams. Paleoflows, lithotypes, and grain-size determinations indicate a persistent north-northwest provenance and wind velocities of 24–38 km/h (with maximum velocities of 55–75 km/h). The results of our analysis coupled with data from previous studies indicates that, for at least the last ca. 8 Myr, the winds have been blowing constantly from the north-northwest with an intensity similar to the present. This implies that the paleo-atmospheric circulation had a similar pattern to the present-day one. Therefore, we conclude that the upper-troposphere circulation in the Puna Plateau of NW Argentina was already regulated by the Bolivian High anticyclone during the Miocene, generating constant north-northwesterly winds.

scholarly journals Runoff Predicting and Variation Analysis in Upper Ganjiang Basin under Projected Climate Changes

2019 ◽  
Vol 11 (21) ◽  
pp. 5885 ◽  
Author(s):  
Chao Deng ◽  
Weiguang Wang
Keyword(s):  
Resource Management ◽  
Water Resource ◽  
Water Resource Management ◽  
Hydrological Modeling ◽  
Hydrologic Model ◽  
Global Climate Models ◽  
Balance Model ◽  
Model Parameters ◽  
The Mean ◽  
Parameter Approach

Catchment runoff is significantly affected by climate condition changes. Predicting the runoff and analyzing its variations under future climates play a vital role in water security, water resource management, and the sustainable development of the catchment. In traditional hydrological modeling, fixed model parameters are usually used to transfer the global climate models (GCMs) to runoff, while the hydrologic model parameters may be time-varying. It is more appropriate to use the time-variant parameter for runoff modeling. This is achieved by incorporating the time-variant parameter approach into a two-parameter water balance model (TWBM) through the construction of time-variant parameter functions based on the identified catchment climate indicators. Using the Ganjiang Basin with an outlet of the Dongbei Hydrological Station as the study area, we developed time-variant parameter scenarios of the TWBM model and selected the best-performed parameter functions to predict future runoff and analyze its variations under the climate model projection of the BCC-CSM1.1(m). To synthetically assess the model performance improvements using the time-variant parameter approach, an index Δ was developed by combining the Nash–Sutcliffe efficiency, the volume error, the Box–Cox transformed root-mean-square error, and the Kling–Gupta efficiency with equivalent weight. The results show that the TWBM model with time-variant C (evapotranspiration parameter) and SC (water storage capacity of catchment), where growing and non-growing seasons are considered for C, outperformed the model with constant parameters with a Δ value of approximately 5% and 10% for the calibration and validation periods, respectively. The mean annual values of runoff predictions under the four representative concentration pathways (RCPs) exhibited a decreasing trend over the future three decades (2021–2050) when compared to the runoff simulations in the baseline period (1982–2011), where the values were about −9.9%, −19.5%, −16.6%, and −11.4% for the RCP2.6, RCP4.5, RCP6.0, and RCP8.5, respectively. The decreasing trend of future precipitation exerts impacts on runoff decline. Generally, the mean monthly changes of runoff predictions showed a decreasing trend from January to August for almost all of the RCPs, while an increasing trend existed from September to November, along with fluctuations among different RCPs. This study can provide beneficial references to comprehensively understand the impacts of climate change on runoff prediction and thus improve the regional strategy for future water resource management.

scholarly journals Investigating patterns and controls of groundwater up-welling in a lowland river by combining Fibre-optic Distributed Temperature Sensing with observations of vertical hydraulic gradients

2012 ◽  
Vol 16 (6) ◽  
pp. 1775-1792 ◽  
Author(s):  
S. Krause ◽  
T. Blume ◽  
N. J. Cassidy
Keyword(s):  
Surface Water ◽  
Water Exchange ◽  
Structural Heterogeneity ◽  
Temperature Sensing ◽  
Small Scale ◽  
Lowland River ◽  
Fibre Optic ◽  
Distributed Temperature Sensing ◽  
Hydraulic Gradients ◽  
Cold Spots

Abstract. This paper investigates the patterns and controls of aquifer–river exchange in a fast-flowing lowland river by the conjunctive use of streambed temperature anomalies identified with Fibre-optic Distributed Temperature Sensing (FO-DTS) and observations of vertical hydraulic gradients (VHG). FO-DTS temperature traces along this lowland river reach reveal discrete patterns with "cold spots" indicating groundwater up-welling. In contrast to previous studies using FO-DTS for investigation of groundwater–surface water exchange, the fibre-optic cable in this study was buried in the streambed sediments, ensuring clear signals despite fast flow and high discharges. During the observed summer baseflow period, streambed temperatures in groundwater up-welling locations were found to be up to 1.5 °C lower than ambient streambed temperatures. Due to the high river flows, the cold spots were sharp and distinctly localized without measurable impact on down-stream surface water temperature. VHG patterns along the stream reach were highly variable in space, revealing strong differences even at small scales. VHG patterns alone are indicators of both, structural heterogeneity of the stream bed as well as of the spatial heterogeneity of the groundwater–surface water exchange fluxes and are thus not conclusive in their interpretation. However, in combination with the high spatial resolution FO-DTS data we were able to separate these two influences and clearly identify locations of enhanced exchange, while also obtaining information on the complex small-scale streambed transmissivity patterns responsible for the very discrete exchange patterns. The validation of the combined VHG and FO-DTS approach provides an effective strategy for analysing drivers and controls of groundwater–surface water exchange, with implications for the quantification of biogeochemical cycling and contaminant transport at aquifer–river interfaces.

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