Groundwater origin and flow dynamics in active rift systems – A multi-isotope approach in the Main Ethiopian Rift

Bretzler, Anja; Osenbrück, Karsten; Gloaguen, Richard; Ruprecht, Janina S.; Kebede, Seifu; Stadler, Susanne

doi:10.1016/j.jhydrol.2011.03.022

Cited by 77 publications

(50 citation statements)

References 38 publications

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“…Since Kaufman and Libby (1954) first proposed that tritium could be utilized for groundwater dating, it has been applied in many regions of the world (e.g. Edmunds 2009;Bretzler et al 2011). Tritium is a radioactive isotope of hydrogen with a half-life of 12.32 yr (Lucas and Unterweger 2000) produced naturally in the upper atmosphere by cosmic rays (Kaufman and Libby 1954;Clark and Fritz 1997).…”

Section: Introductionmentioning

confidence: 99%

Reconstruction and Optimization of Tritium Time Series in Precipitation of Beijing, China

et al. 2013

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ABSTRACT. Tritium time series for precipitation in Beijing have been reconstructed for the period 1953-2002 using various methods: Guanbingjun method; trend surface analysis method; double reference curve method; triangulation method; and correlation method. By comparing the reconstructed results with the measured data of Beijing as well as data of other regions available in the IAEA GNIP database, the corresponding tritium time series have been developed for Beijing for the period 1953-2002, and the optimal time series was selected. The reconstructed result can be used for groundwater dating and related studies in Beijing as well as the surrounding areas.

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Section: Introductionmentioning

confidence: 99%

Reconstruction and Optimization of Tritium Time Series in Precipitation of Beijing, China

et al. 2013

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“…While isotope studies may provide some clarity on such a complex hydrostratigraphic system (Bretzler et al 2011), no conclusive data could be retrieved. We conclude the limited data for now only support a coarse conceptual model.…”

Section: Conceptual Model On Historical Datamentioning

confidence: 99%

Modelling the Influence of Groundwater Abstractions on the Water Level of Lake Naivasha, Kenya Under Data-Scarce Conditions

Hogeboom

Oel

Krol

et al. 2015

Water Resour Manage

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This study presents the state-of-the-art understanding of the data-scarce and hydrogeologically complex groundwater system of Lake Naivasha, Kenya, with the particular aim of exploring the influence groundwater abstractions have on Lake Naivasha's water level. We developed multiple alternative but plausible parameterizations for a MODFLOW groundwater model, based on literature, existing models and available data, while trying not to overcomplicate the model. In doing so, we illustrate a possible strategy of going about data-scarce regions in modelling in general. Processes encountered in the calibrated parameterizations show groundwater flows laterally from the escarpments to the valley floor and axially from the lake along the Rift, with a larger portion flowing out southward than northward. Extraction of groundwater interrupts the flow from the northwestern highlands to the lake, leading to a lake stage reduction of 0.7-7.5 cm due to abstractions at our target farm (Flower Business Park) or an implied 7-75 cm due to total groundwater abstractions in the area. Although this study demonstrates our understanding of Naivasha's groundwater system remains fragile and the current model cannot be embedded in operational water management yet, it (i) reflects the contemporary understanding of the local groundwater system, (ii) illustrates how to go about modelling in data-scarce environments and (iii) provides a means to assess focal areas for future data collection and model improvements.

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“…Hydrogeochemical and isotope data provide strong evidence for a significant contribution of mountain block recharge in the central and northern part of the MER (Kebede et al, 2008(Kebede et al, , 2010Bretzler et al, 2011). Likewise, groundwater samples from Gidabo River Basin, located within the southern part of the MER (Figure 1a), display depleted values of δ 18 O and δD, indicating the contribution of water recharged in the highland (Degu et al, 2014;Mechal, 2015).…”

Section: Introductionmentioning

confidence: 99%

Characterizing regional groundwater flow in the Ethiopian Rift: A multimodel approach applied to Gidabo River Basin

Mechal¹,

Birk²,

Winkler³

et al. 2016

AJES

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Being located in the tectonically active Ethiopian Rift, the hydrogeology of the Gidabo River Basin is complex due to the disruption of lithologies by faults and the variability and lateral discontinuity of the aquifers. Hydrogeochemical and isotopic data suggest that the aquifers within the rift floor receive a relevant contribution of groundwater recharged in the highland. However, the incomplete knowledge about the aquifer properties, the hydraulic behavior of the faults, and the boundary conditions cause uncertainties in this conceptual hydrogeological model. To account for these uncertainties fourteen different numerical models with a stepwise increase from 7 to 40 adjustable parameters were developed, calibrated against the same hydraulic head observations, and ranked according to the Akaike information criteria (AIC and AICc) and Bayesian information criterion (BIC). Based on the information criteria five plausible models were identified, all of which were successfully verified against the river baseflow. The highest likelihood is attributed to a model with eleven adjustable parameters that does not explicitly account for the fault zones; other plausible models considering faults as semi-barriers achieve a slight improvement in model fit but have lower likelihood due to the increased number of calibration parameters. Thus, the effect of faults on groundwater flow needs further investigation, particularly at a local scale.On a regional scale, the hydraulic head distributions of the plausible models agree reasonably well with the equipotential map interpolated from well observations. The estimated transmissivity values range between 30 m 2 / day and 1350 m 2 / day and generally increase from the mountains towards the rift floor. The water budget shows that 75 % of the groundwater recharge supplies baseflow to the rivers. The remaining water infiltrates to the deeper aquifers where less than 1 % is abstracted by pumping wells and the rest flows towards Lake Abaya. Within the rift floor, the majority of inflow to the aquifers is from direct recharge; nevertheless, 35 % of the inflow is contributed by mountain block recharge (lateral groundwater flow from the escarpment and highland). The results of this study strongly advocate the idea to incorporate alternative plausible models instead of relying on single models in the practice of groundwater modeling especially in areas of complex hydrogeology and limited data availability.Die Hydrogeologie des im tektonisch aktiven Äthiopischen Graben gelegenen Gidabo-Flusseinzugsgebiets ist aufgrund der störungs bedingten Unterbrechungen der Lithologien sowie der Variabilität und lateralen Diskontinuität der Aquifere komplex. Hydro geochemische und Isotopen-Daten weisen darauf hin, dass in den Aquiferen der Grabensohle ein relevanter Beitrag von Grundwässern vorliegt, die im Hochland neugebildet werden. Die unvollständige Kenntnis der Aquifereigenschaften, der hydraulischen Wirkung der Störungen und der Randbedingungen führen jedoch zu Unsicherheiten in diesem ko...

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Groundwater origin and flow dynamics in active rift systems – A multi-isotope approach in the Main Ethiopian Rift

Cited by 77 publications

References 38 publications

Reconstruction and Optimization of Tritium Time Series in Precipitation of Beijing, China

Reconstruction and Optimization of Tritium Time Series in Precipitation of Beijing, China

Modelling the Influence of Groundwater Abstractions on the Water Level of Lake Naivasha, Kenya Under Data-Scarce Conditions

Characterizing regional groundwater flow in the Ethiopian Rift: A multimodel approach applied to Gidabo River Basin

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