Integrating geophysical data and upscaling techniques to support regional groundwater flow modelling: A practical example of the Lagan Valley, Northern Ireland

When studying heterogeneous aquifer systems, especially at regional scale, a degree of generalization is anticipated. This can be due to sparse sampling regimes, complex depositional environments or lack of accessibility to measure the subsurface. This can lead to an inaccurate conceptualization which can be detrimental when applied to groundwater flow models. It is important that numerical models are based on observed and accurate geological information and do not rely on the distribution of artificial aquifer properties. This can still be problematic as data will be modelled at a different scale to which it was collected. It is proposed here that integrating geophysics and upscaling techniques can assist in a more realistic and deterministic groundwater flow model. In this study, the sedimentary aquifer of the Lagan Valley in Northern Ireland is chosen due to intruding sub-vertical dolerite dykes. These dykes are of a lower permeability than the sandstone aquifer. The use of airborne magnetics allows the delineation of heterogeneities, confirmed by field analysis. Permeability measured at the field scale is then upscaled to different levels using a correlation with the geophysical data, creating equivalent parameters that can be directly imported into numerical groundwater flow models. These parameters include directional equivalent permeabilities and anisotropy. Several stages of upscaling are modelled in finite element. Initial modelling is providing promising results, especially at the intermediate scale, suggesting an accurate distribution of aquifer properties. This deterministic based methodology is being expanded to include stochastic methods of obtaining heterogeneity location based on airborne geophysical data. This is through the Direct Sample method of Multiple-Point Statistics (MPS). This method uses the magnetics as a training image to computationally determine a probabilistic occurrence of heterogeneity. There is also a need to apply the method to alternate geological contexts where the heterogeneity is of a higher permeability than the host rock.

An Enchanted Tool? Humanitarian Assistance and the ILC Draft Articles on the Protection of Persons in the Event of Disasters

Despite previous attempts at codification of international law regarding international responses to natural and human-made disasters, there is currently no binding international legal framework to regulate the provision of humanitarian assistance outside armed conflicts. Nevertheless, since the International Law Commission (ILC) included the protection of persons in the event of disasters on its programme of work in 2006, it has provisionally adopted eleven draft articles that have the potential to create binding obligations on states and humanitarian actors in disaster settings. Draft articles adopted include the definition of ‘a disaster’, the relationship of the draft articles to the international humanitarian law of armed conflict, recognition of the inherent dignity of the human person, and the duty of international cooperation. However, the final form of the draft articles has not been agreed. The Codification Division of the UN Office of Legal Affairs has proposed a framework convention format, which has seen support in the ILC and the UN General Assembly Sixth Committee. The overall aim of this article is to provide an analysis of the potential forms of international regulation open to the ILC and states in the context of humanitarian responses to disasters. However to avoid enchanting the ILC draft articles with unwarranted power, any examination of form requires an understanding of the substantive subject matter of the planned international regulation. The article therefore provides an overview of the international legal regulation of humanitarian assistance following natural and human-made disasters, and the ILC’s work to date on the topic. It then examines two key issues that remain to be addressed by the ILC and representatives of states in the UN General Assembly Sixth Committee. Drawing on the UN Guiding Principles on Internal Displacement, the development and implications of binding and non-binding international texts are examined, followed by an analysis of the suggested framework convention approach identified by the Special Rapporteur as a potential outcome of the ILC work.