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Külls, C., Leibundgut, C., Schwarz, U., & Schick, A. P. (1995). Channel infiltration study using dye tracers. IAHS Publications-Series of Proceedings and Reports-Intern Assoc Hydrological Sciences, 232, 429–436.
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Külls, C., Adar, E. M., & Udluft, P. (2000). Tracer Studies and Modelling of Regional Groundwater Systems-Resolving patterns of groundwater flow by inverse hydrochemical modelling in a semiarid Kalahari basin. IAHS Publications-Series of Proceedings and Reports-Intern Assoc Hydrological Sciences, 262, 447–452.
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Klock, H., Külls, C., & Udluft, P. (2001). Quantification of Groundwater Recharge-Estimating recharge values using hydrochemical and geological data: A case study from the semiarid Kalahari catchment of northern Namibia. IAHS Publications-Series of Proceedings and Reports-Intern Assoc Hydrological Sciences, 269, 25–32.
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Klock, H., Külls, C., & Udluft, P. (2001). Estimating recharge values using hydrochemical and geological data: a case study from the. In Impact of Human Activity on Groundwater Dynamics: Proceedings of an International Symposium (Symposium S3) Held During the Sixth Scientific Assembly of the International Association of Hydrological Sciences (IAHS) at Maastricht, The Netherlands, from 18 t (25).
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Külls, C., & Bittner, A. (2013). Passive barriers for long-term containment of Uranium and Vanadium.
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Külls, C., Bittner, A., & Marx, V. (2013). Strategic Assessment of Water Resources for the Erongo Uranium Province.
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Gunkel, A. K., C. (2006). Towards agent-based modelling of stakeholder behaviour – a pilot study on drought vulnerability of decentral water supply in NE Brazil. International Congress on Environmental Modelling and Sofware, .
Abstract: 3rd International Congress on Environmental Modelling and Sofware – Burlington, Vermont
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Hofmann, H., Pearce, J. K., Hayes, P., Golding, S. D., Hall, N., Baublys, K. A., et al. (2023). Multi-tracer approach to constrain groundwater flow and geochemical baseline assessments for CO2 sequestration in deep sedimentary basins. International Journal of Coal Geology, , 104438.
Abstract: Geological storage of gases will be necessary in the push to net zero and the energy transition to reduce carbon emissions to atmosphere. These include CO2 geological storage in suitable sandstone reservoirs. Understanding groundwater flow, connectivity and hydrogeochemical processes in aquifer and storage systems is vital to prevent risk and protect important water resources, such as the Great Artesian Basin. Here, we provide a ‘tool-box’ of geochemical assessment methods to provide information on flow patterns through the basin’s aquifers (changes in chemistry along flow path), stagnant versus flowing conditions (cosmogenic isotopes and noble gases), inter-aquifer connectivity and seal properties (major ions, Sr and stable isotopes), water quality (major ions and metals) and general assessments on residence times of groundwater (cosmogenic isotopes and noble gases). This information can be used with reservoir and groundwater models to inform on possible changes in the above-mentioned processes and serve as input parameters for CO2 injection impact modelling. We demonstrate the use and interpretation on an example of a potential CO2 storage geological sequestration site in the Surat Basin, part of the Great Artesian Basin, and the aquifers that overly the reservoir. The stable water isotopes are depleted compared to average rainfall and most likely indicate greater contributions from monsoonal rain events from the northern monsoonal troughs, where amount and rainout effects lead to the depletion rather than colder recharge climates. This is supported by the modern recharge temperatures from noble gases. Inter-aquifer mixing between the Precipice Sandstone reservoir and the Hutton Sandstone aquifer seems unlikely as the Sr isotope ratios are distinctly different suggesting that the Evergreen Formation is a seal in the locations sampled. Mixing, however, occurs on the edges of the basin, especially in the south-east and east where the Surat Basin transitions into the Clarence-Moreton Basin. Groundwater flow appears to be to the south in the Precipice Sandstone, with a component of flow east to the Clarence-Morton Basin. The cosmogenic isotopes and noble gases strongly indicate very long residence times of groundwater in the central south Precipice Sandstone around a proposed storage site. 14C values below analytical uncertainty, R36Cl ratios at secular equilibrium as well as high He concentrations and high 40Ar/36Ar ratios support the argument that groundwater flow in this area is extremely slow or groundwater is stagnant. The results of this study reflect the geological and hydrogeological complexities of sedimentary basins and that baseline studies, such as this one, are paramount for management strategies.
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de Jong, I. J. H., Arif, S. S., Gollapalli, P. K. R., Neelam, P., Nofal, E. R., Reddy, K. Y., et al. (2021). Improving agricultural water productivity with a focus on rural transformation*. Irrigation and Drainage, 70(3), 458–469.
Abstract: ABSTRACT As a result of population growth, economic development and climate change, feeding the world and providing water security will require important changes in the technologies, institutions, policies and incentives that drive present-day water management, as captured in Goal 6.4 of the Millennium Development Goals. Irrigation is the largest and most inefficient water user, and there is an expectation that even small improvements in agricultural water productivity will improve water security. This paper argues that improvements in irrigation water productivity involves a complex and comprehensive rural transformation that goes beyond mere promotion of water saving technologies. Many of the measures to improve water productivity require significant changes in the production systems of farmers and in the support provided to them. Looking forward, water use and competition over water are expected to further increase. By 2025, about 1.8 billion people will be living in regions or countries with absolute water scarcity. Demand for water will rise exponentially, while supply becomes more erratic and uncertain, prompting the need for significant shifts of inter-sectoral water allocation to support continued economic growth. Advances in the use of remote sensing technologies will make it increasingly possible to cost-effectively and accurately estimate crop evapotranspiration from farmers’ fields.
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Severi, A., Masoudian, M., Kordi, E., & Roettcher, K. (2015). Discharge coefficient of combined-free over-under flow on a cylindrical weir-gate. ISH Journal of Hydraulic Engineering, 21(1), 42–52.
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