Modelling reef hydrodynamics and sediment mobility under sea level rise in atoll reef island systems

This is the author accepted manuscript. The final version is available on open access from Elsevier via the DOI in this record. Low-lying coral reef islands will be significantly impacted by future sea level rise (SLR). It is generally expected that SLR will destabilise reef islands because increasing reef submergence allows larger waves, and therefore greater energy transmission, across reef flats. However, the impact of SLR on altering both reef flat sediment transport and sediment delivery to island shorelines is poorly understood. Here, we use the currents of removal approach (coupling two-dimensional wave modelling with settling velocity data from 186 benthic sediment samples) to model shifts in both reef hydrodynamics and benthic sediment transport under scenarios of mean reef submergence (MRS = +0 m, +0.5 m, +1 m) at two atoll rim reef sites in the Maldives. Under contemporary conditions (MRS = +0 m), we found that benthic sediment transport is likely occurring, consistent with active reef-to-island sediment connectivity. Under conditions of increased MRS, shifts in wave velocities, and in turn sediment potential mobility, were both non-linear and non-uniform. Significant between-site differences were found in the magnitude of projected shifts in sediment mobility under scenarios of increased MRS, which implies that morphological responses to increases in MRS are likely to be diverse, even over local scales. Under increased MRS, the largest increases in sediment mobility were projected on the inner reef flat, whereas lagoonal zones remained as sinks for sediment deposition. We thus hypothesize that while reef islands will persist as sedimentary landforms under projected rates of MRS, lagoonward reef island migration is likely to occur. Findings have implications for predicting the future adaptive capacity of atoll nations. The challenge is to incorporate such potential increases in island mobility and intra-regional diversity in reef system geomorphic responses to sea level rise into national-scale vulnerability assessments.NER

Euro Area Enlargement and European Central Bank Reform

This contribution analyses the December 2002 reform of decision making in the European Central Bank’s (ECB) Governing Council in terms of national economy size reflected in the bargaining power of the ECB Governing Council members and member state macroeconomic interest. The National Central Bank (NCB) governors of the largest member states were concerned about the impact upon ECB monetary policy making of equal representation being extended to future member states. By eliminating equal voting rights, the reform distorts the meaning of equality, representativeness and ad personam participation as guiding principles of ECB decision making, moving from equal member state representation towards an emphasis placed upon Euro-zone economy representation. At the same time, two possible concerns watered down efforts to modify ‘representativeness’ and prevent enlargement contributing to inefficiency in Governing Council decision making. First, the current smaller member state NCB governors opposed a significant reduction of their ‘voice’ in ECB monetary policy making. Second, legitimacy concerns ensured persistent support for the maintenance of a large and ‘decentralised’ Governing Council