| Records |
| Author |
Eliades, M.; Bruggeman, A.; Djuma, H.; Christofi, C.; Kuells, C. |
| Title |
Quantifying Evapotranspiration and Drainage Losses in a Semi-Arid Nectarine (Prunus persica var. nucipersica) Field with a Dynamic Crop Coefficient (Kc) Derived from Leaf Area Index Measurements |
Type |
Journal Article |
| Year |
2022 |
Publication |
Water |
Abbreviated Journal |
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| Volume |
14 |
Issue |
5 |
Pages |
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| Abstract |
Quantifying evapotranspiration and drainage losses is essential for improving irrigation efficiency. The FAO-56 is the most popular method for computing crop evapotranspiration. There is, however, a need for locally derived crop coefficients (Kc) with a high temporal resolution to reduce errors in the water balance. The aim of this paper is to introduce a dynamic Kc approach, based on Leaf Area Index (LAI) observations, for improving water balance computations. Soil moisture and meteorological data were collected in a terraced nectarine (Prunus persica var. nucipersica) orchard in Cyprus, from 22 March 2019 to 18 November 2021. The Kc was derived as a function of the canopy cover fraction (c), from biweekly in situ LAI measurements. The use of a dynamic Kc resulted in Kc estimates with a bias of 17 mm and a mean absolute error of 0.8 mm. Evapotranspiration (ET) ranged from 41% of the rainfall (P) and irrigation (I) in the wet year (2019) to 57% of P + I in the dry year (2021). Drainage losses from irrigation (DR_I) were 44% of the total irrigation. The irrigation efficiency in the nectarine field could be improved by reducing irrigation amounts and increasing the irrigation frequency. Future studies should focus on improving the dynamic Kc approach by linking LAI field observations with remote sensing observations and by adding ground cover observations. |
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2073-4441 |
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no |
Call Number  |
THL @ christoph.kuells @ w14050734 |
Serial |
85 |
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| Author |
Vushe, A.; Amutenya, M. |
| Title |
Investigating nitrate retention capacity, elementary and mineral composition of Kalahari sandy soils at Mashare farm in Namibia, Okavango river basin |
Type |
Journal Article |
| Year |
2019 |
Publication |
Scientific African |
Abbreviated Journal |
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| Volume |
6 |
Issue |
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Pages |
00193 |
| Keywords |
Irrigated field, Cultivated Kalahari sandy soil, Leaching, Nitrate retention capacity, Quartz mineral, Water saturated |
| Abstract |
Kalahari sands which cover a large part of Southern Africa and extend into Central Africa are infertile and marginal soils for intensive agriculture. Therefore, high nitrogen fertilisation rates may degrade ecosystems of rivers with catchments covered by the Kalahari sands. A study on Mashare Farm located in the Okavango River basin showed that irrigated Kalahari sandy soils had a nitrate retention capacity, which enabled the soil to resist nitrate leaching in water saturated conditions. The irrigated soils were modified by agricultural activities; hence this study investigated if uncultivated and cultivated Kalahari sand soils had similar nitrate retention properties. The elementary composition of the soils was investigated for obtaining an insight into chemical properties that may be causing the nitrate retention capacity. A permeameter was used to leach out nitrates from irrigated and uncultivated soil samples, and nitrate concentrations were measured on the leaching effluent from the permeameter. Elemental analysis was done on the cultivated and the uncultivated soil samples using a Scanning Electron Microscope, a portable X-Ray Fluorescence analyzer, and an X-Ray Diffraction machine, and the later was also used for crystalline structure analyses. Sieve analyses confirmed that the Mashare’s cultivated and uncultivated topsoils were similar, and both were similar to Botswana Kalahari topsoil. The irrigated and cultivated subsoil had a higher average nitrate retention capacity of 76% compared to 73% for the uncultivated subsoil. Both samples had the same elements, although the proportions were different. Both soil samples were dominated by a quartz mineral, but the field soil had traces of palygorskite. The presence of aluminum and transition metals outside the minerals structure, but as coatings on the quartz sand grains enhanced nitrate retention capacity properties of the Kalahari sand soils. |
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| ISSN |
2468-2276 |
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no |
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THL @ christoph.kuells @ VUSHE2019e00193 |
Serial |
277 |
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| Author |
Vogel, J.C.; Talma, A.S.; Heaton, T.H.E.; Kronfeld, J. |
| Title |
Evaluating the rate of migration of an uranium deposition front within the Uitenhage Aquifer |
Type |
Journal Article |
| Year |
1999 |
Publication |
Journal of Geochemical Exploration |
Abbreviated Journal |
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| Volume |
66 |
Issue |
1 |
Pages |
269-276 |
| Keywords |
redox changes in aquifer, sandstone-type uranium deposit, South Africa, uranium series |
| Abstract |
The solubility of uranium in groundwater is very sensitive to changes in redox conditions. Many secondary (sandstone-type) uranium deposits have been formed when soluble U has precipitated after encountering reducing conditions in the subsurface. In the groundwater of the Uitenhage Aquifer (Cape Province, South Africa), 238U-series isotopes were used to assist in studying the history of the reducing barrier. Uranium isotopes were used to determine the present position of the barrier. Radium and radon were used to evaluate the path of migration that the front of the oxygen depletion zone has taken over the past 105 years. During this time the reducing barrier has moved, leaving in its wake a trail of U in various stages of secular equilibrium with its daughter 230Th. The 226Ra daughter of 230Th is not very mobile. Its growth upon the aquifer wall is reflected in the Rn content of the water. This in turn, due to the relatively great age of the water, indicates the extent of the 230Th ingrowth (from precipitated U) that took place before the barrier migrated. |
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| ISSN |
0375-6742 |
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no |
| Call Number |
THL @ christoph.kuells @ vogel_evaluating_1999 |
Serial |
126 |
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| Author |
Vogel, J.C.; Talma, A.S.; Heaton, T.H.E. |
| Title |
Gaseous nitrogen as evidence for denitrification in groundwater |
Type |
Journal Article |
| Year |
1981 |
Publication |
Journal of Hydrology |
Abbreviated Journal |
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| Volume |
50 |
Issue |
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Pages |
191-200 |
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| Abstract |
By investigating the nitrate, oxygen, nitrogen and argon concentrations and 15N14N ratios in artesian groundwater with radiocarbon ages ranging up to 27,000 yr. a process of very slow denitrification in a confined aquifer is demonstrated. The calculated nitrogenisotope fractionation factor associated with this reaction is comparable to that reported for bacterial cultures in vitro and in vivo. |
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0022-1694 |
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no |
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THL @ christoph.kuells @ Vogel1981191 |
Serial |
280 |
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Veerasamy, N.; Kasar, S.; Murugan, R.; Inoue, K.; Natarajan, T.; Ramola, R.C.; Fukushi, M.; Sahoo, S.K. |
| Title |
234U/238U disequilibrium and 235U/238U ratios measured using MC-ICP-MS in natural high background radiation area soils to understand the fate of uranium |
Type |
Journal Article |
| Year |
2023 |
Publication |
Chemosphere |
Abbreviated Journal |
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| Volume |
323 |
Issue |
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Pages |
138217 |
| Keywords |
HBRA, MC-ICP-MS, Monazites, U/U, Uranium |
| Abstract |
The Chhatrapur-Gopalpur coastal area in Odisha, India is a well-known natural high background radiation (HBRA) area due to the abundance of monazite (a thorium bearing radioactive mineral) in beach sands and soils. Recent studies on Chhatrapur-Gopalpur HBRA groundwater have reported high concentrations of uranium and its decay products. Therefore, the soils of the Chhatrapur-Gopalpur HBRA are reasonably suspected as the sources of these high uranium concentrations in groundwater. In this report, first the uranium concentrations in soil samples were measured using inductively coupled plasma mass spectrometry (ICP-MS) and they were found to range from 0.61 ± 0.01 to 38.59 ± 0.16 mg kg−１. Next, the 234U/238U and 235U/238U isotope ratios were measured to establish a baseline for the first time in Chhatrapur-Gopalpur HBRA soil. Multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) was used for measurement of these isotope ratios. The 235U/238U ratio was observed to be the normal terrestrial value. The 234U/238U activity ratio, was calculated to understand the secular equilibrium between 234U and 238U in soil and it varied from 0.959 to 1.070. To understand the dynamics of uranium in HBRA soil, physico-chemical characteristics of soil were correlated with uranium isotope ratios and this correlation of 234U/238U activity ratio indicated the leaching of 234U from Odisha HBRA soil. |
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0045-6535 |
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THL @ christoph.kuells @ veerasamy_234u238u_2023 |
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149 |
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| Author |
Leeuwen, Z.R. van; Klaar, M.J.; Smith, M.W.; Brown, L.E. |
| Title |
Quantifying the natural flood management potential of leaky dams in upland catchments, Part II: Leaky dam impacts on flood peak magnitude |
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Journal Article |
| Year |
2024 |
Publication |
Journal of Hydrology |
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628 |
Issue |
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Pages |
130449 |
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Nature based solutions, Large wood, Empirical, Hydrograph analysis, Ecosystem services, Transfer function noise model |
| Abstract |
Leaky dams are an increasingly popular natural flood management measure, yet their impacts on flood peak magnitude have not yet been empirically quantified for a range of event types and magnitudes, even at the stream scale. In this study, the novel application of a transfer function noise modelling approach to empirical Before-After-Control-Impact stage data from an upland catchment allowed leaky dam effectiveness in reducing flood peak magnitude to be quantified. Flood peak stage and discharge magnitude changes were assessed from empirical data for 50 single and multi-peaked high flow events with return periods ranging from less than one year to six years. Overall, event peak magnitude was significantly reduced following the installation of eight leaky dams on the impact stream. Effectiveness was highly variable, but on average, flood peak magnitude was reduced by 10% for events with a return period up to one year. Some of the variability was explained by the size of the event and whether it was a single or multi-peaked event. This finding emphasises the need to manage expectations by considering both a range of event magnitudes and types when designing or assessing leaky dam natural flood management schemes. |
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0022-1694 |
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no |
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THL @ christoph.kuells @ Vanleeuwen2024130449 |
Serial |
228 |
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| Author |
Uugulu, S.; Wanke, H. |
| Title |
Estimation of groundwater recharge in savannah aquifers along a precipitation gradient using chloride mass balance method and environmental isotopes, Namibia |
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Journal Article |
| Year |
2020 |
Publication |
Physics and Chemistry of the Earth, Parts A/B/C |
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116 |
Issue |
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Pages |
102844 |
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Chloride mass balance, Groundwater recharge, Isotopic values, Precipitation gradient |
| Abstract |
The quantification of groundwater resources is essential especially in water scarce countries like Namibia. The chloride mass balance (CMB) method and isotopic composition were used in determining groundwater recharge along a precipitation gradient at three sites, namely: Tsumeb (600 mm/a precipitation); Waterberg (450 mm/a precipitation) and Kuzikus/Ebenhaezer (240 mm/a precipitation). Groundwater and rainwater were collected from year 2016–2017. Rainwater was collected monthly while groundwater was collected before, during and after rainy seasons. Rainwater isotopic values for δ18O and δ2H range from −10.70 to 6.10‰ and from −72.7 to 42.1‰ respectively. Groundwater isotopic values for δ18O range from −9.84 to −5.35‰ for Tsumeb; from −10.85 to −8.60‰ for Waterberg and from −8.24 to −1.56‰ for Kuzikus/Ebenhaezer, while that for δ2H range from −65.6 to −46.7‰ for Tsumeb; −69.4 to −61.2‰ for Waterberg and −54.2 to −22.7‰ for Kuzikus/Ebenhaezer. Rainwater scatters along the GMWL. Rainwater collected in January, February and March are more depleted in heavy isotopes than those in November, December, April and May. Waterberg groundwater plots on the GMWL which indicates absence of evaporation. Tsumeb groundwater plots on/close to the GMWL with an exception of groundwater from the karst Lake Otjikoto which is showing evaporation. Groundwater from Kuzikus/Ebenhaezer shows an evaporation effect, probably evaporation occurs during infiltration since it is observed in all sampling seasons. All groundwater from three sites plot in the same area with rainwater depleted in stable isotopic values, which could indicates that recharge only take place during January, February and March. CMB method revealed that Waterberg has the highest recharge rate ranging between 39.1 mm/a and 51.1 mm/a (8.7% – 11.4% of annual precipitation), Tsumeb with rates ranging from 21.1 mm/a to 48.5 mm/a (3.5% – 8.1% of annual precipitation), and lastly Kuzikus/Ebenhaezer from 3.2 mm/a to 17.5 mm/a (1.4% – 7.3% of annual precipitation). High recharge rates in Waterberg could be related to fast infiltration and absence of evaporation as indicated by the isotopic ratios. Differences in recharge rates cannot only be attributed to the precipitation gradient but also to the evaporation rates and the presence of preferential flow paths. Recharge rates estimated for these three sites can be used in managing the savannah aquifers especially at Kuzikus/Ebenhaezer where evaporation effect is observed that one can consider rain harvesting. |
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1474-7065 |
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no |
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THL @ christoph.kuells @ uugulu_estimation_2020 |
Serial |
99 |
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Uhrie, J.L.; Drever, J.I.; Colberg, P.J.S.; Nesbitt, C.C. |
| Title |
In situ immobilization of heavy metals associated with uranium leach mines by bacterial sulfate reduction |
Type |
Journal Article |
| Year |
1996 |
Publication |
Hydrometallurgy |
Abbreviated Journal |
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| Volume |
43 |
Issue |
1 |
Pages |
231-239 |
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| Abstract |
Laboratory experiments with mixed populations of sulfate-reducing bactreria were shown to mediate the removal of milligrams/liter concentrations of uranium, selenium, arsenic and vanadium from aqueous solution via reduction, precipitation and adsorption. Results of laboratory experiments with active sulfidogenic biomass suggest that injection of sulfate and a source of carbon could enhance anaerobic microbial activity in and around uranium leach mines leading to in situ immobilization contaminating metals. |
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0304-386x |
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no |
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THL @ christoph.kuells @ uhrie_situ_1996 |
Serial |
197 |
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Uddin, M.G.; Diganta, M.T.M.; Sajib, A.M.; Hasan, M.A.; Moniruzzaman, M.; Rahman, A.; Olbert, A.I. |
| Title |
Assessment of hydrogeochemistry in groundwater using water quality index model and indices approaches |
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Journal Article |
| Year |
2023 |
Publication |
Heliyon |
Abbreviated Journal |
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| Volume |
9 |
Issue |
9 |
Pages |
19668 |
| Keywords |
CCME index, Groundwater quality, Hydrogeochemistry, Irrigation indices, Nuclear power plant, Water quality index |
| Abstract |
Groundwater resources around the world required periodic monitoring in order to ensure the safe and sustainable utilization for humans by keeping the good status of water quality. However, this could be a daunting task for developing countries due to the insufficient data in spatiotemporal resolution. Therefore, this research work aimed to assess groundwater quality in terms of drinking and irrigation purposes at the adjacent part of the Rooppur Nuclear Power Plant (RNPP) in Bangladesh. For the purposes of achieving the aim of this study, nine groundwater samples were collected seasonally (dry and wet season) and seventeen hydro-geochemical indicators were analyzed, including Temperature (Temp.), pH, electrical conductivity (EC), total dissolved solids (TDS), total alkalinity (TA), total hardness (TH), total organic carbon (TOC), bicarbonate (HCO3−), chloride (Cl−), phosphate (PO43−), sulfate (SO42−), nitrite (NO2−), nitrate (NO3−), sodium (Na+), potassium (K+), calcium (Ca2+) and magnesium (Mg2+). The present study utilized the Canadian Council of Ministers of the Environment water quality index (CCME-WQI) model to assess water quality for drinking purposes. In addition, nine indices including EC, TDS, TH, sodium adsorption ratio (SAR), percent sodium (Na%), permeability index (PI), Kelley’s ratio (KR), magnesium hazard ratio (MHR), soluble sodium percentage (SSP), and Residual sodium carbonate (RSC) were used in this research for assessing the water quality for irrigation purposes. The computed mean CCME-WQI score found higher during the dry season (ranges 48 to 74) than the wet season (ranges 40 to 65). Moreover, CCME-WQI model ranked groundwater quality between the “poor” and “marginal” categories during the wet season implying unsuitable water for human consumption. Like CCME-WQI model, majority of the irrigation index also demonstrated suitable water for crop cultivation during dry season. The findings of this research indicate that it requires additional care to improve the monitoring programme for protecting groundwater quality in the RNPP area. Insightful information from this study might be useful as baseline for national strategic planners in order to protect groundwater resources during the any emergencies associated with RNPP. |
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2405-8440 |
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no |
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THL @ christoph.kuells @ uddin_assessment_2023 |
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167 |
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| Author |
Ubierna, J.A.J. |
| Title |
Tunnel heritage in Spain: Roots of the underground |
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Journal Article |
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1998 |
Publication |
Tunnelling and Underground Space Technology |
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13 |
Issue |
2 |
Pages |
131-141 |
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Spain has deep roots in the underground. The territory of myth and legend, of cave and tunnel, has existed in Spain since that ancient time overwhelmed with shreds of fog, where all was myth around heros like Túbal Hércules, Gárgoris and Abidis. The underground evokes strong links with life and death, light and darkness, and has served as a source of inspiration for art through the centuries. The history of tunnels in Spain reflects the mosaic of cultures that have inhabited Iberia from prehistoric times till today. This contribution on the subterranean History of Spain traces the country’s heritage in the form of natural caves, troglodyte dwellings, mining, crypts, galleries in fortresses and castles, aqueducts, qanats, cellars, and other landmarks. |
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0886-7798 |
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no |
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THL @ christoph.kuells @ Ubierna1998131 |
Serial |
260 |
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