Rainfall–runoff trends in the south‐eastern USA: 1938–2005

An extensive dataset (230 precipitation gauges and 79 stream gauges) was used to analyse rainfall–runoff relationships in 10 subregions of a 482000 km² area in the south‐eastern USA (Maryland, Virginia, North Carolina, South Carolina and Georgia). The average annual rainfall and runoff for this study area between 1938 and 2005 were 1201 and 439 mm, respectively. Average runoff/rainfall ratios during this period varied between 0·24 in the southernmost Coastal Plain subregion to 0·64 in the Blue Ridge Province. Watershed elevation and relief are the principal determinants governing the conversion of rainfall to runoff. Temporal rainfall variation throughout the south‐eastern USA ranges from ～40% above and below normal while the variation for runoff is higher, from ? 75% to + 100%. In any given year there can exist a ± 25–50% error in predicted runoff deviation using the annual rainfall–runoff regression. Fast Fourier Transform and autoregressive spectral analysis revealed dominant cyclicities for rainfall and runoff between 14 and 17 years. Secondary periodicities were typically between 6–7 and 10–12 years. The inferred cyclicity may be related to ENSO and/or Central North Pacific atmospheric phenomena. Mann–Kendall analyses indicate that there were no consistent statistically significant temporal trends with respect to south‐eastern US rainfall and runoff during the study period. The results of U‐tests similarly indicated that rainfall between 1996 and 2005 was not statistically higher or lower than during earlier in the study period. Copyright © 2008 John Wiley & Sons, Ltd.     

A broad‐scale assessment of the effect of improved soil management on catchment baseflow index

Although the importance of sustainable soil management is recognized, there are many threats to soils including widespread soil structural degradation. This reduces infiltration through the soil surface and/or the percolation of water through the soil profile, with important consequences for crop yields, nutrient cycling and the hydrological response of catchments. This article describes a broad‐scale modelling approach to assess the potential effect that improved agricultural soil management, through reduced soil structural degradation, may have on the baseflow index (BFI) of catchments across England and Wales. A daily soil–water balance model was used to simulate the indicative BFI of 45 696 thirty‐year model runs for different combinations of soil type, soil/field condition, land cover class and climate which encapsulate the variability across England and Wales. The indicative BFI of catchments was then calculated by upscaling the results by spatial weighting. WaSim model outputs of indicative BFI were within the 95% confidence intervals of the national‐average BFI values given for the Hydrology of Soil Type (HOST ? ) classes for 26 of the 28 classes. At the catchment scale, the concordance correlation coefficient between the BFI from the WaSim model outputs and those derived from HOST was 0·83. Plausible improvements in agricultural soil/field condition produced modest simulated increases of up to 10% in the indicative BFI in most catchments across England and Wales, although for much of southern and northern England the increases were less than 5%. The results suggest that improved soil management might partially mitigate the expected adverse effects of climate change on baseflow to rivers. Healthy, well‐functioning soils produce many additional benefits such as better agricultural yields and reduced pollutant movement, so improved soil management should provide win‐win opportunities for society, agricultural systems and the environment and provide resilience to some of the expected environmental impacts of climate change. Copyright © 2011 John Wiley & Sons, Ltd.     

Superposition of gold mineralisation on pre‐existing carbonate alteration: Structural evidence from the Mulgarrie gold deposit,Yilgarn Craton

Carbonate alteration at the Mulgarrie gold mine in the Eastern Goldfields of Western Australia, is represented by porphyroblasts, veins and pervasive, texturally destructive, carbonatisation. Two foliations, S_1M and S_2M, were produced by two separate deformation events at the mine‐scale, D_1M and D_2M. D_1M and D_2M both occurred in response to regional D₂ tectonism. Carbonate alteration was the product of two separate episodes of fluid ingress: the earlier produced magnesite and the latter Fe‐dolomite. Both periods of carbonate alteration occurred pre‐ to early syn‐D_2M, when mafic to ultramafic komatiitic rocks reacted with fluids that moved along regional faults and pre‐date the alteration associated with regional peak metamorphism. Gold at Mulgarrie overprints pre‐ and late syn‐D₂ quartz veins in zones of massive carbonate alteration, suggesting it has a late‐ to post‐D₂ timing. This late timing agrees with the generally accepted syn‐D₃ (and younger) age for gold mineralisation in the Eastern Goldfields. We suggest that carbonate alteration at Mulgarrie is not a product of the hydrothermal event responsible for the gold mineralisation. Rather, the different relative timing of magnesite, Fe‐dolomite and gold indicates there were two carbonate‐producing fluid systems and a fluid transporting the gold overprinted these. Similarly, early carbonate alteration may play a role in localising auriferous vein deposits throughout the Yilgarn and other Archaean cratons.     

Spherically symmetric cosmological perturbations in the de Donder gauge

Cosmological perturbations on a F-R-W background are considered in a modified de Donder gauge. To guarantee the energy-momentum conservation for the perturbations in the de Donder gauge a compatibility condition is obtained. Finally we present the basic equations for the propagation of spherically symmetric perturbations. These equations are the basis for investigating the influence of cosmological epoches on the growing of density contrasts.     

Variable Grid Method: An Intuitive Approach for Simultaneously Quantifying and Visualizing Spatial Data and Uncertainty

Efforts to develop applications and methods that effectively quantify and communicate uncertainty associated with spatial data remains a focus within many scientific communities. However, the inherent complexity of uncertainty makes it difficult to define, characterize, and represent. Frequently, the products of spatial and spatio‐temporal data are presented without a clear explanation of the inherent uncertainty underlying the data. As uses and applications for spatial data and their products continues to increase, so does the importance for utilizing reliable approaches to effectively communicate spatial data along with their inherent uncertainties. To address this need, the Variable Grid Method (VGM) was developed as an intuitive approach that simultaneously communicates both spatial patterns and trends and the uncertainty associated with data or their analyses. This article details the VGM approach and demonstrates the utility of the VGM to provide critical information about the relationship between uncertainty and spatial data, necessary to support the increasing utilization of spatial information for a wide range of research and other needs.     

Improved methods for estimating equilibrium climate sensitivity from transient warming simulations

Climate Dynamics - Equilibrium climate sensitivity (ECS) refers to the total global warming caused by an instantaneous doubling of atmospheric CO2 from the pre-industrial level in a climate system....     

Globalization,Pacific Islands,and the paradox of resilience

On April 2nd, 2007 a 12 m tsunami struck Simbo, a relatively remote island in Western Province, Solomon Islands. Although Simbo's population continues to depend on their own food production and small-scale governance regimes regulate access to resources, the island's way of life over the last century has increasingly been affected by processes associated with globalization. In this context of a rapidly globalizing world, this article examines the island's resilience and vulnerability to the tsunami and the adaptive capacities that enabled the response and recovery. The tsunami completely destroyed two villages and damaged fringing coral reefs, but casualties were low and social–ecological rebound relatively brisk. By combining social science methods (household surveys, focus group and ethnographic interviews) and underwater reef surveys we identify a number of countervailing challenges and opportunities presented by globalization that both nurture and suppress the island's resilience to high amplitude, low-frequency disturbances like tsunamis. Analysis suggests that certain adaptive capacities that sustain general system resilience come at the cost of more vulnerability to low-probability hazards. We discuss how communities undergoing increasingly complex processes of change must negotiate these kinds of trade-offs as they manage resilience at multiple spatial and temporal scales. Understanding the shifting dynamics of resilience may be critical for Pacific Island communities who seek to leverage globalization in their favor as they adapt to current social–ecological change and prepare for future large-scale ecological disturbances.     

The Last Glacial Maximum in the North Sea Basin: micromorphological evidence of extensive glaciation

Despite a long history of investigation, critical issues regarding the last glacial cycle in northwest Europe remain unresolved. One of these refers to the extent, timing and dynamics of Late Devensian/Weichselian glaciation of the North Sea Basin, and whether the British and Scandinavian ice sheets were confluent at any time during this period. This has been the result of the lack of the detailed sedimentological data required to reconstruct processes and environment of sediments recovered through coring. This study presents the results of seismic, sedimentological and micromorphological evidence used to reconstruct the depositional processes of regionally extensive seismic units across the North Sea Basin. Thin section micromorphology is used here to provide an effective means of discriminating between subglacial and glacimarine sediments from cored samples and deriving process‐based interpretations from sediment cores. On the basis of micromorphology, critical formations from the basin have been reinterpreted, with consequent stratigraphic implications. Within the current stratigraphic understanding of the North Sea Basin, a complex reconstruction is suggested, with a minimum of three major glacial episodes inferred. On at least two occasions during the Weichselian/Devensian, the British and Scandinavian ice sheets were confluent in the central North Sea. Whilst micromorphology can provide much greater confidence in the interpretation of Late Quaternary offshore stratigraphic sequences, it is noted that a much better geochronology is required to resolve key stratigraphic issues between the onshore and offshore stratigraphic records. Copyright © 2006 John Wiley & Sons, Ltd.     

X-Ray Line Transfer in Plasmas with Large Velocity Gradients

An astrophysically relevant experiment is compared to the output of a multidimensional radiation transfer code in which populations and radiation are self-consistently treated. Experimental Al Ly α spectra obtained with a very high-resolution spectrometer are presented as quantitative evidence of dot plasma non-planar expansion. Analysis of these spectra using the code is performed, in particular examining the effects of velocity gradients in directions other than that of the primary expansion. These calculations are found to be in good agreement with the experimental results. Usage of the Ly α doublet as a planarity diagnostic is discussed.