Interpretation of environmental tracer data for conceptual understanding of groundwater flow: an application for fractured aquifer systems in the Kłodzko Basin, Sudetes, Poland

2017 ◽  
Vol 53 (5) ◽  
pp. 466-483 ◽  
Author(s):  
Mariusz Mądrala ◽  
Mirosław Wąsik ◽  
Piotr Małoszewski
Keyword(s):  
Groundwater Flow ◽  
Conceptual Understanding ◽  
Environmental Tracer ◽  
Fractured Aquifer ◽  
Aquifer Systems

scholarly journals Nonlinear effects of locally heterogeneous hydraulic conductivity fields on regional stream–aquifer exchanges

2015 ◽  
Vol 19 (11) ◽  
pp. 4531-4545 ◽  
Author(s):  
J. Zhu ◽  
C. L. Winter ◽  
Z. Wang
Keyword(s):  
Groundwater Flow ◽  
Effective Conductivity ◽  
Model Simulation ◽  
Three Dimensional ◽  
Small Scale ◽  
Heihe River ◽  
Effective Parameters ◽  
Aquifer Systems ◽  
Basin Scale ◽  
Local Grid

Abstract. Computational experiments are performed to evaluate the effects of locally heterogeneous conductivity fields on regional exchanges of water between stream and aquifer systems in the Middle Heihe River basin (MHRB) of northwestern China. The effects are found to be nonlinear in the sense that simulated discharges from aquifers to streams are systematically lower than discharges produced by a base model parameterized with relatively coarse effective conductivity. A similar, but weaker, effect is observed for stream leakage. The study is organized around three hypotheses: (H1) small-scale spatial variations of conductivity significantly affect regional exchanges of water between streams and aquifers in river basins, (H2) aggregating small-scale heterogeneities into regional effective parameters systematically biases estimates of stream–aquifer exchanges, and (H3) the biases result from slow paths in groundwater flow that emerge due to small-scale heterogeneities. The hypotheses are evaluated by comparing stream–aquifer fluxes produced by the base model to fluxes simulated using realizations of the MHRB characterized by local (grid-scale) heterogeneity. Levels of local heterogeneity are manipulated as control variables by adjusting coefficients of variation. All models are implemented using the MODFLOW (Modular Three-dimensional Finite-difference Groundwater Flow Model) simulation environment, and the PEST (parameter estimation) tool is used to calibrate effective conductivities defined over 16 zones within the MHRB. The effective parameters are also used as expected values to develop lognormally distributed conductivity (K) fields on local grid scales. Stream–aquifer exchanges are simulated with K fields at both scales and then compared. Results show that the effects of small-scale heterogeneities significantly influence exchanges with simulations based on local-scale heterogeneities always producing discharges that are less than those produced by the base model. Although aquifer heterogeneities are uncorrelated at local scales, they appear to induce coherent slow paths in groundwater fluxes that in turn reduce aquifer–stream exchanges. Since surface water–groundwater exchanges are critical hydrologic processes in basin-scale water budgets, these results also have implications for water resources management.

Developments in the conceptual understanding of groundwater flow in the chalk aquifer in London

2018 ◽  
Author(s):  
M.J. Streetly ◽  
P.J. Daily ◽  
E.R. Farren ◽  
N. Hoad ◽  
M.A. Jones
Keyword(s):  
Groundwater Flow ◽  
Conceptual Understanding ◽  
Chalk Aquifer

scholarly journals Using radon as an environmental tracer for estimating groundwater flow velocities in single-well tests

2011 ◽  
Vol 47 (3) ◽  
Author(s):  
Michael Schubert ◽  
Lutz Brueggemann ◽  
Kay Knoeller ◽  
Mario Schirmer
Keyword(s):  
Groundwater Flow ◽  
Environmental Tracer ◽  
Single Well ◽  
Well Tests ◽  
Flow Velocities

Comparison of 4He ages and 14C ages in simple aquifer systems: implications for groundwater flow and chronologies

2000 ◽  
Vol 15 (8) ◽  
pp. 1137-1167 ◽  
Author(s):  
Maria Clara Castro ◽  
Martin Stute ◽  
Peter Schlosser
Keyword(s):  
Groundwater Flow ◽  
Aquifer Systems

scholarly journals The use of Radon (Rn222) isotopes to detect groundwater discharge in streams draining Table Mountain Group (TMG) aquifers

Water SA ◽  
2021 ◽  
Vol 47 (2 April) ◽  
Author(s):  
T Strydom ◽  
JM Nel ◽  
M Nel ◽  
RM Petersen ◽  
CL Ramjukadh
Keyword(s):  
Surface Water ◽  
Water Discharge ◽  
Environmental Isotopes ◽  
Fractured Aquifer ◽  
Aquifer System ◽  
Water Interaction ◽  
Table Mountain ◽  
Interaction Studies ◽  
Aquifer Systems ◽  
Groundwater Surface Water Interaction

Environmental isotopes have been used for decades as natural tracers in studies aimed at understanding complex hydrogeological processes such as groundwater and surface water interactions. Radon (Rn222) is a naturally occurring, radioactive isotope which is produced from radium (Ra226) during the radioactive decay series of uranium (U238). Since U238 is present in most geological substrates, Rn222 is produced in various lithological structures and subsequently transported with groundwater through fractures and pore spaces in an aquifer towards surface water discharge points in rivers and springs. This study aimed to determine (i) the concentration of Rn222 within both surface water and groundwater in Table Mountain Group (TMG) aquifer systems, and (ii) the feasibility of using Rn222 isotopes as a natural tracer in groundwater-surface water interaction studies. This study was conducted in a highly fractured TMG aquifer system near Rawsonville, South Africa. Surface water from two perennial rivers (i.e. Gevonden and Molenaars), together with groundwater from a nearby borehole, were sampled and their corresponding Rn222 concentrations measured. Our study found median Rn222 concentrations in the Gevonden River of 76.4 Bq∙L-1 and 67.2 Bq∙L-1 in the dry and wet seasons, respectively. Nearly 12% of surface water samples exceeded 100 Bq∙L-1.  These abnormally high Rn222 concentrations can only be attributed to the influx of groundwater with extremely high Rn222 concentrations. Under ambient (no pumping) conditions, Rn222 concentrations in groundwater range between 130–270 Bq∙L-1. However, when the borehole was pumped, and inflowing water from the surrounding aquifer was sampled, even higher Rn222 concentrations (391–593 Bq∙L-1) were measured. These extremely high Rn222 concentrations in groundwater are believed to be attributed to the underlying granitic geology and the prevalence of faults. The use of Rn222 isotopes as an environmental tracer in groundwater–surface water interaction studies is therefore regarded as a feasible option in similar highly fractured aquifer systems.

scholarly journals A high resolution global scale groundwater model

2014 ◽  
Vol 11 (5) ◽  
pp. 5217-5250 ◽  
Author(s):  
I. E. M. de Graaf ◽  
E. H. Sutanudjaja ◽  
L. P. H. van Beek ◽  
M. F. P. Bierkens
Keyword(s):  
Groundwater Flow ◽  
Land Surface ◽  
Regional Scale ◽  
Land Surface Model ◽  
Global Scale ◽  
Water Levels ◽  
Natural State ◽  
Surface Model ◽  
Groundwater Model ◽  
Aquifer Systems

Abstract. Groundwater is the world's largest accessible source of fresh water. It plays a vital role in satisfying needs for drinking water, agriculture and industrial activities. During times of drought groundwater sustains baseflow to rivers and wetlands, thereby supporting ecosystems. Most global scale hydrological models (GHMs) do not include a groundwater flow component, mainly due to lack of geohydrological data at the global scale. For the simulation of lateral flow and groundwater head dynamics a realistic physical representation of the groundwater system is needed, especially for GHMs that run at finer resolution. In this study we present a global scale groundwater model (run at 6' as dynamic steady state) using MODFLOW to construct an equilibrium water table at its natural state as the result of long-term climatic forcing. The aquifer schematization and properties were based on available global datasets of lithology and transmissivities combined with estimated aquifer thickness of an upper unconfined aquifer. The model is forced with outputs from the land-surface model PCR-GLOBWB, specifically with net recharge and surface water levels. A sensitivity analysis, in which the model was run with various parameter settings, showed variation in saturated conductivity causes most of the groundwater level variations. Simulated groundwater heads were validated against reported piezometer observations. The validation showed that groundwater depths are reasonably well simulated for many regions of the world, especially for sediment basins (R2 = 0.95). The simulated regional scale groundwater patterns and flowpaths confirm the relevance of taking lateral groundwater flow into account in GHMs. Flowpaths show inter-basin groundwater flow that can be a significant part of a basins water budget and helps to sustain river baseflow, explicitly during times of droughts. Also important aquifer systems are recharged by inter-basin groundwater flows that positively affect water availability.

scholarly journals Envisaging the Sustainability of an Aquifer by Developing Groundwater Flow Model for a Part of ChoutuppalMandal, Nalgonda District, Telangana, India

2020 ◽  
Vol 19 (1) ◽  
pp. 222-233
Author(s):  
P. K. Neupane ◽  
N. C. Mondal ◽  
A. Manglik
Keyword(s):  
Drinking Water ◽  
Groundwater Flow ◽  
Flow Equation ◽  
Visual Modflow ◽  
Fractured Aquifer ◽  
Pumping Rate ◽  
Groundwater Levels ◽  
The North ◽  
Weathered Layer ◽  
Nalgonda District

 Recurring droughts and increased exploitation of groundwater to meet the growing water needs have resulted in the decline of regional groundwater level and dry, weathered zone in a part of the Choutuppal Mandal, Nalgonda district, Telangana, India. A groundwater model has been developed using an inventory of 20 observation wells for future pumping schemes to evolve a classic interface (Build: 4.6.0.168) of available wells. The developed model has been reviewed using Visual MODFLOW, and a base map is prepared for the sub-surface structure. The area spreading about 0.43 km2is conceptualized as a two-layered model consisting of a weathered layer overlying a fractured aquifer. The model has been digitized into grids of 5m×5m in each layer. The integrated finite difference method has been utilized to discretize the groundwater flow equation and simulate groundwater flow with the help of calculated parameters along with the boundary conditions and acting stresses. Results show that the computed groundwater levels are in good agreement with the observed heads, and groundwater is flowing from the South to the North direction. The estimated velocities vary from 0.01 to 1.95 m/d. The optimum pumping schemes have also been simulated up to the year 2022. It has been observed that the maximum pumping rate should not go beyond 24m3/day. Since the drinking water demand(10-15m3/day) in the study site is below this limit, it can be inferred that the aquifer will sustain and provide enough drinking water.

Sign in / Sign up

Export Citation Format

Share Document