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Author |
Chase, B.M.; Meadows, M.E. |
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Title |
Late Quaternary dynamics of southern Africa’s winter rainfall zone |
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Journal Article |
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Year |
2007 |
Publication |
Earth-Science Reviews |
Abbreviated Journal |
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Volume |
84 |
Issue  |
3 |
Pages |
103-138 |
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Keywords |
Last Glacial Maximum, palaeoenvironment, Quaternary, southern Africa, westerlies, winter rainfall zone |
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Abstract |
Variations in the nature and extent of southern Africa’s winter rainfall zone (WRZ) have the potential to provide important information concerning the nature of long-term climate change at both regional and hemispheric scales. Positioned at the interface between tropical and temperate systems, southern Africa’s climate is influenced by shifts in the Intertropical Convergence Zone, the westerlies, and the development and position of continental and oceanic anticyclones. Over the last glacial–interglacial cycle substantial changes in the amount and seasonality of precipitation across the subcontinent have been linked to the relative dominance of these systems. Central to this discussion has been the extent to which the region’s glacial climates would have been affected by expansions of Antarctic sea-ice, equatorward migrations of the westerlies, more frequent/intense winter storms and an expanded WRZ. This paper reviews the developing body of evidence pertaining to shifts in the WRZ, and the evolution of ideas that have been presented to explain the patterns observed. Dividing the region into three separate axes, along the western and southern margins of the continent and across the interior into the Karoo and the Kalahari, a range of evidence from both terrestrial sites and marine cores is considered, and potential expansions of the WRZ expansions are explored. Despite the limitations of many of the region’s proxy records, a coherent pattern has begun to develop of a significantly expanded WRZ during phases of the last glacial period, with the best-documented being between 32–17 ka. While more detailed inferences will require the recovery and analysis of longer and better-dated records, this synthesis provides a new baseline for further research in this key region. |
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0012-8252 |
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THL @ christoph.kuells @ chase_late_2007 |
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102 |
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Author |
Chen, Y.; Hong, Y.; Huang, D.; Dai, X.; Zhang, M.; Liu, Y.; Xu, Z. |
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Title |
Risk assessment management and emergency plan for uranium tailings pond |
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Journal Article |
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Year |
2022 |
Publication |
Journal of Radiation Research and Applied Sciences |
Abbreviated Journal |
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Volume |
15 |
Issue |
3 |
Pages |
83-90 |
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Keywords |
Emergency management, Interpreted structural model (ISM), Resilience, Risk coupling, Uranium tailings pond |
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Abstract |
The safety of uranium tailings pond is closely related to social stability and economic development, so it is necessary to improve the emergency management of uranium tailings pond to ensure its safety by adjusting the emergency plan. The Interpretive Structural Model (ISM) is used to analyze the structural relationship between the main risk factors leading to the occurrence of emergencies. The results show that attention should be paid to the risk factors originating from humans and infrastructures, and effective management measures should be adopted in the process of emergency management, for example, people build tighter employee access system, clarify the responsibilities of employees at all levels, and improve monitoring and organizational means. According to the results of ISM analysis, a structural risk control system can be constructed, and a defensive barrier that can effectively block the risk coupling transmission can be designed to prevent the risk from being transformed into an event. For other risks, system resilience management should be strengthened to respond to risks. The process is set as emergency response and accident response. Different management objects use different management methods to make emergency management work efficiently. |
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1687-8507 |
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THL @ christoph.kuells @ chen_risk_2022 |
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128 |
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Orloff, K.G.; Mistry, K.; Charp, P.; Metcalf, S.; Marino, R.; Shelly, T.; Melaro, E.; Donohoe, A.M.; Jones, R.L. |
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Title |
Human exposure to uranium in groundwater |
Type |
Journal Article |
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Year |
2004 |
Publication |
Environmental Research |
Abbreviated Journal |
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Volume |
94 |
Issue |
3 |
Pages |
319-326 |
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Keywords |
Groundwater, Human exposure, Uranium, Urine |
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Abstract |
High concentrations of uranium (mean=620μg/L) were detected in water samples collected from private wells in a residential community. Based on isotopic analyses, the source of the uranium contamination appeared to be from naturally occurring geological deposits. In homes where well water concentrations of uranium exceeded the drinking water standard, the residents were advised to use an alternate water source for potable purposes. Several months after the residents had stopped drinking the water, urine samples were collected and tested for uranium. Elevated concentrations of uranium (mean=0.40μg/g creatinine) were detected in urine samples, and 85 percent of the urine uranium concentrations exceeded the 95th percentile concentration of a national reference population. Urine uranium concentrations were positively correlated with water uranium concentrations, but not with the participants’ ages or how long they had been drinking the water. Six months later, a second urine sample was collected and tested for uranium. Urine uranium concentrations decreased in most (63 percent) of the people. In those people with the highest initial urine uranium concentrations, the urine levels decreased an average of 78 percent. However, urine uranium concentrations remained elevated (mean=0.27μg/g), and 87 percent of the urine uranium concentrations exceeded the 95th percentile concentration of the reference population. The results of this investigation demonstrated that after long-term ingestion of uranium in drinking water, elevated concentrations of uranium in urine could be detected up to 10 months after exposure had stopped. |
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0013-9351 |
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THL @ christoph.kuells @ orloff_human_2004 |
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136 |
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Author |
Min, M.; Xu, H.; Chen, J.; Fayek, M. |
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Title |
Evidence of uranium biomineralization in sandstone-hosted roll-front uranium deposits, northwestern China |
Type |
Journal Article |
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Year |
2005 |
Publication |
Ore Geology Reviews |
Abbreviated Journal |
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Volume |
26 |
Issue |
3 |
Pages |
198-206 |
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Keywords |
Biomineralization, China, Roll-front uranium deposit, Sandstone |
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Abstract |
We show evidence that the primary uranium minerals, uraninite and coffinite, from high-grade ore samples (U3O8\textgreater0.3%) in the Wuyiyi, Wuyier, and Wuyisan sandstone-hosted roll-front uranium deposits, Xinjiang, northwestern China were biogenically precipitated and psuedomorphically replace fungi and bacteria. Uranium (VI), which was the sole electron acceptor, was likely to have been enzymically reduced. Post-mortem accumulation of uranium may have also occurred through physio-chemical interaction between uranium and negatively-charged cellular sites, and inorganic adsorption or precipitation reactions. These results suggest that microorganisms may have played a key role in formation of the sandstone- or roll-type uranium deposits, which are among the most economically significant uranium deposits in the world. |
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ISSN |
0169-1368 |
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no |
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THL @ christoph.kuells @ min_evidence_2005 |
Serial |
186 |
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Author |
Hdeib, R.; Aouad, M. |
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Title |
Rainwater harvesting systems: An urban flood risk mitigation measure in arid areas |
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Journal Article |
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Year |
2023 |
Publication |
Water Science and Engineering |
Abbreviated Journal |
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Volume |
16 |
Issue |
3 |
Pages |
219-225 |
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Keywords |
Rainwater harvesting, Urban floods, Flood map, Hydrodynamic model, Built environment, Arid areas |
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Abstract |
Rainwater harvesting (RWH) systems have been developed to compensate for shortage in the water supply worldwide. Such systems are not very common in arid areas, particularly in the Gulf Region, due to the scarcity of rainfall and their reduced efficiency in covering water demand and reducing water consumption rates. In spite of this, RWH systems have the potential to reduce urban flood risks, particularly in densely populated areas. This study aimed to assess the potential use of RWH systems as urban flood mitigation measures in arid areas. Their utility in the retention of stormwater runoff and the reduction of water depth and extent were evaluated. The study was conducted in a residential area in Bahrain that experienced waterlogging after heavy rainfall events. The water demand patterns of housing units were analyzed, and the daily water balance for RWH tanks was evaluated. The effect of the implementation of RWH systems on the flood volume was evaluated with a two-dimensional hydrodynamic model. Flood simulations were conducted in several rainfall scenarios with different probabilities of occurrence. The results showed significant reductions in the flood depth and flood extent, but these effects were highly dependent on the rainfall intensity of the event. RWH systems are effective flood mitigation measures, particularly in urban arid regions short of proper stormwater control infrastructure, and they enhance the resilience of the built environment to urban floods. |
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1674-2370 |
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Call Number |
THL @ christoph.kuells @ Hdeib2023219 |
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242 |
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Author |
Robati, A.; Barani, G.A. |
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Title |
Modeling of water surface profile in subterranean channel by differential quadrature method (DQM) |
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Journal Article |
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Year |
2009 |
Publication |
Applied Mathematical Modelling |
Abbreviated Journal |
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Volume |
33 |
Issue |
3 |
Pages |
1295-1305 |
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Keywords |
Subterranean channel, Qanat, Differential quadrature method, Water surface profile, Porous media |
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Abstract |
This study, investigates the hydraulic of flow in a subterranean channel headspring. The continuity and momentum equations of flow in porous media considering real conditions were used and the basic equation of flow in a subterranean channel was resulted. This equation is very similar to the spatially varied flow with increasing discharge. An equation, defining the hydraulic parameters of a subterranean channel section was adopted. Then differential quadrature method (DQM), was applied to the equation of flow in subterranean channel, consequently the water surface profile was resulted. To illustrate the rightness of model, the hydraulic parameters of flow in the Gavgard branch of the Joopar Goharriz Qanat were measured and the water surface profile was determined. This water surface profile was compared to the water surface profile computed by the model, which are in good agreement. |
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0307-904x |
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THL @ christoph.kuells @ Robati20091295 |
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249 |
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Author |
Rubin, R. |
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Title |
Water conservation methods in Israel’s Negev desert in late antiquity |
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Journal Article |
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Year |
1988 |
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Journal of Historical Geography |
Abbreviated Journal |
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14 |
Issue |
3 |
Pages |
229-244 |
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Abstract |
Settlement in Israel’s Negev desert historically has been dependent on water conservation techniques. Fieldwork carried out on settlement sites constructed during the Byzantine period, when agriculture and trade flourished, revealed a variety of water installations some of which are in use today. Perennial springs in the Negev are generally small and difficult of access. Cisterns were the most common conservation devices and came in both large, enclosed and single, open forms. Cisterns were common particularly in the towns, where they were usually built as part of house foundations. Dams were discovered at several sites but proved to be inefficient and easily abandoned because of evaporation and siltation problems. Public reservoirs were part of the structure of the largest towns and were open and among the larges structures uncovered at settlement sites. Wells were distributed widely throughout the desert and were part of the only conservation system that did not depend directly on surface rainfall. A qanat system was located in the eastern Negev dating from the late settlement period before the area was abandoned at the turn of the eighth century. These various water systems raise questions about their builders and their origins, and suggests that builders originating in more humid Mediterranean environments tended to produce less adaptable installations than builders derived from the south or the east. |
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0305-7488 |
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THL @ christoph.kuells @ Rubin1988229 |
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262 |
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Author |
Zhang, Y.; Liu, X.; Yuan, S.; Song, J.; Chen, W.; Dias, D. |
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Title |
A two-dimensional experimental study of active progressive failure of deeply buried Qanat tunnels in sandy ground |
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Journal Article |
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Year |
2023 |
Publication |
Soils and Foundations |
Abbreviated Journal |
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Volume |
63 |
Issue |
3 |
Pages |
101323 |
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Qanat tunnel, Sand, Failure effect, Soil arching, Model test |
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Abstract |
As an ancient underground hydraulic engineering facility, the Qanat system has been used to draw groundwater from arid regions. A qanat is a horizontal tunnel with a slight incline that draws groundwater from a higher location and delivers it to lower agricultural land. During long-term water delivery, the qanat tunnel has experienced different degrees of aging and collapse, which may result in the significant ground settlement and even disasters. This paper developed a two-dimensional laboratory system to investigate the influence of progressive failure on the stability of deeply buried qanat tunnels. The developed system is fully instrumented with a particle image velocimetry (PIV) system and earth pressure and displacement monitoring. A special cylindrical membrane tube is designed and connected to an advanced pressure–volume controller to simulate the step-wise failure process of the tunnel. Three model tests were conducted on a dry sand considering the buried qanat tunnels at three different depths. Experimental results clearly show the progressive evolution of soil arching effect in the dry sand associated with the progressive failure of the tunnels. The failure of the Qanat ground starts from the vault and develops upwards, which is closely related to the evolution of stress contour at three consecutive stages. Ground surface settlement and volume loss corresponding to three burial depths were compared. A deeply buried qanat tunnel has a small effect on surface settlement. Earth pressure evolution on the 2D plane shows the load redistribution when the qanat collapses. The maximum arch and the initial point of the limit state correspond to a volume loss of 12.5 % and 50 %, respectively. For the collapse of the deep buried qanat tunnel, ground earth pressure evolution can be divided into a stress-increasing region, stress-decreasing region, and no redistribution region. Furthermore, a multi trap-door model considering soil expansion is proposed to describe the progressive failure behavior and its effects. |
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0038-0806 |
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THL @ christoph.kuells @ Zhang2023101323 |
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274 |
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Author |
Klaus, J.; Külls, C.; Dahan, O. |
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Evaluating the recharge mechanism of the Lower Kuiseb Dune area using mixing cell modeling and residence time data |
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Journal Article |
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2008 |
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Journal of Hydrology |
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358 |
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3-4 |
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304-316 |
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Elsevier |
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THL @ christoph.kuells @ Klaus2008evaluating |
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28 |
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Klock, H.; Külls, C.; Udluft, P. |
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Estimation of relative recharge values for the northern Kalahari catchment, Namibia |
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Journal Article |
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2000 |
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Journal of African Earth Sciences |
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30 |
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4 |
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47-48 |
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THL @ christoph.kuells @ Klock2000estimation |
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33 |
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