scholarly journals Characterization of Karst Conduit Network Using Long-Distance Tracer Test in Lijiang, Southwestern China

Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 949 ◽  
Author(s):  
Jihong Qi ◽  
Mo Xu ◽  
Xinyu Cen ◽  
Lu Wang ◽  
Qiang Zhang
Keyword(s):  
Groundwater Level ◽  
Tracer Test ◽  
Breakthrough Curves ◽  
Southwestern China ◽  
Long Distance ◽  
Tracer Concentration ◽  
Injection Point ◽  
Ancient City ◽  
Karst Conduit ◽  
Conduit Network

The Ancient City in Lijiang of southwestern China was endowed as World Cultural Heritage by UNESCO, and the karst springs located in Black Dragon Pool are its main water source. However, the springs have dried up several times in recent years, which caused serious damages to the landscape as well as the city water supply. Triggered by the dried-up event in Black Dragon Pool, a long-distance artificial tracer test up to 17 km was employed to investigate the karst conduit network distributing in the study area. Based on the tracer concentration breakthrough curves (BTCs), the hydraulic connection from the same injection point (located in a giant depression named the Jiuzi Sea) to the springs on both sides of the topography watershed was proven, and the conduit structure was discussed. According to the characteristics of BTCs and considering the low tracer concentration and tracer recovery, a conceptual structure of leaky reservoir with threshold effect above a certain groundwater level was established to interpret why the springs in Black Dragon Pool dried up several times in history, but those in the Ancient City never did. Furthermore, a method of injecting surface water into the Jiuzi Sea to raise the groundwater level up to the height of Black Dragon Pool was proposed to restore the springs. Our study provides insights into the long-distance artificial tracer test, and opens a new avenue for groundwater resource recovery of this Ancient City.

scholarly journals Long distance seawater intrusion through a karst conduit network in the Woodville Karst Plain, Florida

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Zexuan Xu ◽  
Seth Willis Bassett ◽  
Bill Hu ◽  
Scott Barrett Dyer
Keyword(s):  
Seawater Intrusion ◽  
Long Distance ◽  
Karst Conduit ◽  
Conduit Network

scholarly journals Tracer Dispersion through Karst Conduit: Assessment of Small-Scale Heterogeneity by Multi-Point Tracer Test and CFD Modeling

Hydrology ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 168
Author(s):  
Romain Deleu ◽  
Sandra Soarez Frazao ◽  
Amaël Poulain ◽  
Gaëtan Rochez ◽  
Vincent Hallet
Keyword(s):  
Spatial Heterogeneity ◽  
Single Point ◽  
Tracer Tests ◽  
Tracer Test ◽  
Breakthrough Curves ◽  
Cfd Modeling ◽  
Small Scale ◽  
Tracer Concentration ◽  
Tracer Dispersion ◽  
The Impact

Tracer tests are widely used for characterizing hydrodynamics, from stream-scale to basin-wide scale. In karstic environments, the positioning of field fluorometers (or sampling) is mostly determined by the on-site configuration and setup difficulties. Most users are probably aware of the importance of this positioning for the relevance of data, and single-point tests are considered reliable. However, this importance is subjective to the user and the impact of positioning is not well quantified. This study aimed to quantify the spatial heterogeneity of tracer concentration through time in a karstic environment, and its impact on tracer test results and derived information on local hydrodynamics. Two approaches were considered: on-site tracing experiments in a karstic river, and Computational Fluid Dynamics (CFD) modeling of tracer dispersion through a discretized karst river channel. A comparison between on-site tracer breakthrough curves and CFD results was allowed by a thorough assessment of the river geometry. The results of on-site tracer tests showed significant heterogeneities of the breakthrough curve shape from fluorometers placed along a cross-section. CFD modeling of the tracer test through the associated discretized site geometry showed similar heterogeneity and was consistent with the positioning of on-site fluorometers, thus showing that geometry is a major contributor of the spatial heterogeneity of tracer concentration through time in karstic rivers.

scholarly journals Contaminant transfer and hydrodispersive parameters in basaltic lava flows: artificial tracer test and implications for long-term management

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
G. Bertrand ◽  
H. Celle-Jeanton ◽  
F. Huneau ◽  
A. Baillieux ◽  
G. Mauri ◽  
...  
Keyword(s):  
Point Source ◽  
Tracer Test ◽  
Breakthrough Curves ◽  
Lava Flows ◽  
Advective Transport ◽  
Mean Velocity ◽  
Volcanic System ◽  
Massif Central ◽  
Transit Times ◽  
Potential Contaminant

AbstractThe aim of this paper is to evaluate the vulnerability after point source contamination and characterize water circulations in volcanic flows located in the Argnat basin volcanic system (Chaîne des Puys, French Massif Central) using a tracer test performed by injecting a iodide solution. The analysis of breakthrough curves allowed the hydrodispersive characteristics of the massive lava flows to be determined. Large Peclet numbers indicated a dominant advective transport. The multimodal feature of breakthrough curves combined with high values of mean velocity and low longitudinal dispersion coefficients indicated thatwater flows in an environment analogous to a fissure system, and only slightly interacts with a low porosity matrix (ne < 1%). Combining this information with lava flow stratigraphy provided by several drillings allowed a conceptual scheme of potential contaminant behaviour to be designed. Although lava flows are vulnerable to point source pollution due to the rapid transfer of water within fractures, the saturated scoriaceous layers located between massive rocks should suffice to strongly buffer the transit of pollution through dilution and longer transit times. This was consistent with the low recovery rate of the presented tracer test.

scholarly journals Assessing lateral flows and solute transport during floods in a conduit-flow-dominated karst system using the inverse problem for the advection–diffusion equation

2017 ◽  
Vol 21 (7) ◽  
pp. 3635-3653 ◽  
Author(s):  
Cybèle Cholet ◽  
Jean-Baptiste Charlier ◽  
Roger Moussa ◽  
Marc Steinmann ◽  
Sophie Denimal
Keyword(s):  
Inverse Problem ◽  
Solute Transport ◽  
Unsaturated Zone ◽  
Flood Routing ◽  
Saturated Zone ◽  
Karst System ◽  
Advection Diffusion Equation ◽  
Advection Diffusion ◽  
Karst Conduit ◽  
Conduit Network

Abstract. The aim of this study is to present a framework that provides new ways to characterize the spatio-temporal variability of lateral exchanges for water flow and solute transport in a karst conduit network during flood events, treating both the diffusive wave equation and the advection–diffusion equation with the same mathematical approach, assuming uniform lateral flow and solute transport. A solution to the inverse problem for the advection–diffusion equations is then applied to data from two successive gauging stations to simulate flows and solute exchange dynamics after recharge. The study site is the karst conduit network of the Fourbanne aquifer in the French Jura Mountains, which includes two reaches characterizing the network from sinkhole to cave stream to the spring. The model is applied, after separation of the base from the flood components, on discharge and total dissolved solids (TDSs) in order to assess lateral flows and solute concentrations and compare them to help identify water origin. The results showed various lateral contributions in space – between the two reaches located in the unsaturated zone (R1), and in the zone that is both unsaturated and saturated (R2) – as well as in time, according to hydrological conditions. Globally, the two reaches show a distinct response to flood routing, with important lateral inflows on R1 and large outflows on R2. By combining these results with solute exchanges and the analysis of flood routing parameters distribution, we showed that lateral inflows on R1 are the addition of diffuse infiltration (observed whatever the hydrological conditions) and localized infiltration in the secondary conduit network (tributaries) in the unsaturated zone, except in extreme dry periods. On R2, despite inflows on the base component, lateral outflows are observed during floods. This pattern was attributed to the concept of reversal flows of conduit–matrix exchanges, inducing a complex water mixing effect in the saturated zone. From our results we build the functional scheme of the karst system. It demonstrates the impact of the saturated zone on matrix–conduit exchanges in this shallow phreatic aquifer and highlights the important role of the unsaturated zone on storage and transfer functions of the system.

Water, Cacao, and The Early Maya of Chocóla

2018 ◽  
Author(s):  
Jonathan Kaplan ◽  
Federico Paredes Umaña
Keyword(s):  
Control Systems ◽  
New World ◽  
Intensive Agriculture ◽  
Water Control ◽  
Long Distance ◽  
Ancient Trade ◽  
Ancient City ◽  
The World ◽  
Maya People ◽  
Material Substances

Before the authors’ research, Chocolá was no more than an intriguing legend. Chocolá’s apparent political links to the greatest Preclassic southern Maya area polity, Kaminaljuyu, would make any discovery about Chocolá conceivably vital to a better understanding of Maya origins and New World archaeology, as both ancient cities are located in the Southern Maya Region. Two facts led researchers to search more specifically for the material bases for Chocolá’s rise to power: 1) Mesoamerica’s greatest rainfall, 2) cacao groves around the modern village lying atop the ancient city. Cacao was so important to the Maya that, mythologically, the cacao god was the maize god’s brother and uncle of the “Hero Twins,” conceived as the aboriginal creators of the Maya people. If water control systems have been documented archaeologically at virtually all great ancient cities around the world, cacao is uniquely a Maya “invention,” the Maya being the first people in the world to domesticate the plant and cultivate it through intensive agriculture. These two discoveries—impressive water management and cacao at Preclassic Chocolá—likely are not coincidental. A complex, hierarchical society would have been in place for arboriculture of water-thirsty cacao for long-distance ancient trade. Thus, two material substances, one necessary for human survival, the other highly valued throughout Mesoamerica as consumable and essential in Maya mythology, may explain, in part, how this and other Southern Maya “kingdoms of chocolate” may represent a “sweet beginning” for one of the greatest civilizations of the ancient world.

scholarly journals Tracer Test in Fractured Chalk

1993 ◽  
Vol 24 (4) ◽  
pp. 263-274 ◽  
Author(s):  
R. Jakobsen ◽  
K. Høgh Jensen ◽  
K. L. Brettmann
Keyword(s):  
Short Duration ◽  
Transport Mechanism ◽  
Arrival Time ◽  
Porous Matrix ◽  
Tracer Test ◽  
Breakthrough Curves ◽  
Advective Transport ◽  
Long Tail ◽  
Flow Through ◽  
Chalk Aquifer

A two-well tracer test was conducted in eastern Denmark, in which a short duration pulse of lithium chloride was injected into a recharge well and made to flow through a fractured chalk aquifer to a discharge well. The wells were 25 m apart, and the concentration of lithium arriving at the discharge well was monitored at five vertical intervals in the well for a 21-day period. The observed breakthrough curves show a sharp breakthrough front, with an arrival time that is consistent with advective transport through the fractures in the chalk. The breakthrough curves also exhibit a long tail in the falling limb, suggesting the influence of a secondary transport mechanism of diffusion into the porous matrix.

scholarly journals Tracer Test in Fractured Chalk

1993 ◽  
Vol 24 (4) ◽  
pp. 275-296 ◽  
Author(s):  
K.L. Brettmann ◽  
K. Høgh Jensen ◽  
R. Jakobsen
Keyword(s):  
Three Dimensional ◽  
Porous Matrix ◽  
Tracer Test ◽  
Breakthrough Curves ◽  
Dual Porosity ◽  
Local Concentration ◽  
Concentration Difference ◽  
Dual Porosity Model ◽  
Immobile Phase ◽  
Porosity Model

A two-well tracer test carried out in fractured chalk was analyzed using a three-dimensional finite-difference model for flow and transport which, was constructed on the basis of the geological and hydraulic information collected at the field site. The model was developed as a dual-porosity continuum model, in which advection was assumed to occur only in the fractures, and the water in the porous matrix was assumed to be static. The exchange of solute between the fractures (mobile phase) and the porous matrix (immobile phase) was assumed to occur as a diffusion process in response to the local concentration difference of solute between the two phases. Simulations from the dual-porosity model reproduced the shape of the observed breakthrough curves, although some portions of the tail were not accurately represented. The model was also applied as a single-porosity model for advection and dispersion in the fractures with no solute exchange with the porous matrix. The simulations from the single-porosity model greatly overestimated the observed lithium concentrations, and showed very little tailing effect in the falling limb. The study shows that, based on the given tracer test, solute transport in a fractured chalk cannot be represented by a single-porosity approach and hence when dealing with contaminant transport in such systems, both a fractured and a porous domain need to be considered.

scholarly journals Determining the directions and characteristics of underground water flow in karst for the purpose of traffic routes construction: the case of the new Divača-Koper railway line (SW Slovenia)

2020 ◽  
Vol 49 (1) ◽  
Author(s):  
Metka Petrič ◽  
Nataša Ravbar ◽  
Luca Zini ◽  
Chiara Calligaris ◽  
Riccardo Corazzi ◽  
...  
Keyword(s):  
Water Flow ◽  
Fluorescent Dyes ◽  
Karst Aquifer ◽  
Underground Water ◽  
Tracer Test ◽  
Breakthrough Curves ◽  
Aquifer System ◽  
Railway Line ◽  
Hazard Control ◽  
Negative Impacts

The new railway line between Divača and Koper/Capodistria in south-western Slovenia is being built, a part of which crosses the southern outskirts of the Classical Karst plateaux. It will run through two tunnels, the northern tunnel T1 (6.7 km long) and the southern T2 (6 km long), which partially cross karst aquifer system. A multi-tracer test with injections of fluorescent dyes uranine and naphthionate, bypassing the karst vadose zone, was carried out to define the directions and dynamics of the underground water flow. The main goals were better understanding of the complex hydrogeological conditions in the area and assessment of possible environmental impacts on the nearby water sources. With tracing of uranine injected into a nearby cave stream, the direction of flow from the northern T1 tunnel mainly towards the Reka-Timavo aquifer system and further towards the Timava/Timavo springs was proved. The peak velocities, as determined from the peaks of the tracer breakthrough curves, range from 29 m/h to 36 m/h. Through the wider and well-connected conduits of the Reka-Timavo system, the peak velocities can reach up to 88 m/h. The recovery of uranine in an intermediate cave, i.e., Jama 1 v Kanjaducah, amounted to approximately 74 %. The northern section of the southern T2 tunnel is a part of a wider bifurcation zone between the Osapska Reka and the Boljunec/Bagnoli springs, where peak flow velocities between 10 and 13 m/h have been determined by tracing of naphthionate injected into a borehole located in the line of the planned tunnel. It has been estimated that about 25 % of the injected naphthionate flew out through the Osapska Reka spring and about 5 % through the Boljunec/ Bagnoli springs. Based on this research, proper monitoring of any potential negative impacts of the new railway line will be made possible. The study presents an approach to better planning of hazard control of traffic routes in complex and highly karstified rock settings.

scholarly journals On the late-time behavior of tracer test breakthrough curves

2000 ◽  
Vol 36 (12) ◽  
pp. 3467-3479 ◽  
Author(s):  
Roy Haggerty ◽  
Sean A. McKenna ◽  
Lucy C. Meigs
Keyword(s):  
Tracer Test ◽  
Breakthrough Curves ◽  
Late Time ◽  
Time Behavior

scholarly journals Trade, Merchants, and the Lost Cities of the Bronze Age*

2019 ◽  
Vol 134 (3) ◽  
pp. 1455-1503 ◽  
Author(s):  
Gojko Barjamovic ◽  
Thomas Chaney ◽  
Kerem Coşar ◽  
Ali Hortaçsu
Keyword(s):  
Nineteenth Century ◽  
Bronze Age ◽  
Gravity Model ◽  
Large Data ◽  
Long Distance ◽  
Data Set ◽  
Trade Data ◽  
Large Cities ◽  
Ancient City ◽  
The Bronze Age

AbstractWe analyze a large data set of commercial records produced by Assyrian merchants in the nineteenth century BCE. Using the information from these records, we estimate a structural gravity model of long-distance trade in the Bronze Age. We use our structural gravity model to locate lost ancient cities. In many cases, our estimates confirm the conjectures of historians who follow different methodologies. In some instances, our estimates confirm one conjecture against others. We also structurally estimate ancient city sizes and offer evidence in support of the hypothesis that large cities tend to emerge at the intersections of natural transport routes, as dictated by topography. Finally, we document persistent patterns in the distribution of city sizes across four millennia, find a distance elasticity of trade in the Bronze Age close to modern estimates, and show suggestive evidence that the distribution of ancient city sizes, inferred from trade data, is well approximated by Zipf’s law.

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