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Research into weather circulation changes over the UK for future climate has mainly focused on changes in the Summer and Winter seasons, with less analysis on seasonality and the transition seasons. Using the 30 Met Office weather patterns we examine the influence of climate change on seasonality through atmospheric circulation using a number of climate models. Changes in seasonality are important as they can have large impacts on many sectors including agriculture, energy and tourism. This paper finds a noticeable increase in Autumn over the UK in the frequency of drier summer-type regimes and a decrease in stormy winter types that emerge as early as the 2020s. The change in circulation signal once isolated from the overall signal is responsible for a 4–12% decrease in Autumn mean rainfall on average for England by the end of this century (where the values in the range are dependent on the emissions scenario). This change is projected over English regions that are already experiencing water stress, and with predictions of drier summers over the UK in future, this could further increase drought risk. The change in circulation in Autumn also moderates the large increase in the number of large-scale extreme daily rainfall events over the same regions predicted due to climate change. While this future circulation change is replicated across all the climate models used, large differences remain in the strength of the signal between models. The climate models used replicate the frequency of the 30 weather patterns well for all seasons. [ABSTRACT FROM AUTHOR]

There are numerous anecdotal examples of drought terminations documented throughout the historical record on most continents. The end of a drought is the critical time during which water resource managers urgently require information on the replenishment of supplies. Yet this phase has been relatively neglected by the academic community, with much of the existing body of research on drought termination assessing the likelihood of droughts ending rather than its temporal profile. In particular, there has been little effort to characterise drought termination events themselves. This is partly explained by existing definitions of drought termination as a specific point in time when drought is considered to have finished, rather than a more holistic consideration based on approaches developed within biological sciences. There is also a lack of understanding about how drought termination propagates through the hydrological cycle. This paper specifically examines and reviews available research on drought termination, highlighting limitations associated with current definitions and offering suggestions for characterising the temporal stages of drought. An alternative definition of drought termination is proposed: a period between the maximum negative anomaly and a return to above-average conditions. Once this phase has been delineated, the duration, rate and seasonality of drought termination can be derived. The utility of these metrics is illustrated through a case study of the 2010-2012 drought in the UK, and the propagation of drought termination between river flows and groundwater levels. [ABSTRACT FROM AUTHOR]

There is a burgeoning international literature on hydro-climatic trend detection, motivated by the need to detect and interpret any emerging changes in river flows associated with anthropogenic climate change. The UK has a particularly strong evidence base in this area thanks to a well-developed monitoring programme and a wealth of studies published over the last 20 years. This paper reviews this research, with a view to assessing the evidence for climate change influences on UK river flow, including floods and droughts. This assessment is of international relevance given the scale of the research effort in the UK, a densely monitored and data-rich environment, but one with significant human disturbances to river flow regimes, as in many parts of the world. The review finds that changes can be detected in river flow regimes, some of which agree with future change projections, while others are in apparent contradiction. Observed changes generally cannot be attributed to climate change, largely due to the fact that river flow records are limited in length and the identification of short-term trends is confounded by natural variability. A UK ‘Benchmark’ network of near-natural catchments is an internationally significant example of an initiative to enable climate variability to be discerned from direct human disturbances (e.g. abstractions, dam construction). Generally, however, the problem of attribution has been tackled rather indirectly in the UK, as elsewhere, and more efforts are required to attribute change in a more rigorous manner. [ABSTRACT FROM AUTHOR]

Most countries experience periodic dry spells/droughts and climatologists predict these may become more severe and of longer duration in the future. Whilst ground movement associated with shrink/swell is well known, other implications of changes in the general climatic conditions are less often considered by the construction industry. Having discussed the effect of shrink/swell in open field and wooded areas, the pressures involved in re-hydration, the significance of desiccation cracks for slope stability and the influence of dry and moist periods on road construction, the paper highlights how a change in ground water level and/or temperature can induce the development of ground sulphates and cause irreversible heave in lime-stabilised ground. [ABSTRACT FROM AUTHOR]

Summary: This paper develops tools to assess regional drought events based on limited periods of record and applies them to regional climate model output to examine potential future changes in drought due to increased greenhouse gases. The drought metric was defined as a monthly time series of standardized 12-month precipitation accumulations. Regional drought events were characterised by determining the severity, area, duration and frequency of dry periods. In order to improve statistical inference of drought events, a drought generator was adopted to synthesis a large number of events trained on the available data. In nearly all cases, the drought generator produces synthetic events with drought characteristics statistically indistinguishable from the training data. Severity–Area–Frequency (SAF) curves and Area–Probability (Area–P) curves could then be constructed from the synthetic data to determine the return period of a drought event of a given severity covering a given area. These techniques were applied to observations and to output from the Hadley Centre regional climate model (HadRM3). HadRM3, when driven by climate reanalysis data, has good correlation with the observed drought metric. HadRM3 also captures the timing of observed dry periods but not the relative seriousness of any particular period. Natural variability is large with regional drought characteristics highly dependent on the time period covered by the training data. Although the synthetic drought characteristics of HadRM3 generally overlap with the observed natural variability; the model slightly overestimates the area of observed drought; underestimate its frequency; and underestimate the severity at any given area. HadRM3 projections of changes in drought characteristics over the second half of the 21st century under increased atmospheric greenhouse gases hint at an increase in the severity of drought. However, any changes are not readily distinguishable from natural variability or projection uncertainty. Therefore it is not yet possible to robustly predict changes in UK meteorological droughts arising from increased greenhouse gasses. [Copyright &y& Elsevier]

Abstract: Water stress is becoming a permanent feature of life in Britain and other developed societies, and attempts to change ‘consumer behaviour’ are at the forefront of strategies for sustainability. This paper combines historical, geographical and sociological perspectives on the evolution of drought and water demand in modern England and Wales. Droughts have natural properties but their course, size and distribution is also the result of an interplay between governance, social norms and everyday practices. Focusing on seven significant droughts between 1893 and 2006, this article traces changing understandings of ‘normal’ water consumption and ‘rational’ demand and relates them to the evolving socio-technical management of water and identities of ‘the consumer’. We challenge the idea of a watershed between private supply (associated with passive ‘customers’) and public ownership (associated with active ‘citizens’). While private systems facilitated self-organised civic action more easily than public supply, the ideal of a citizen-contract blinded systems of public provision to the problem of expanding water use. An interdisciplinary analysis of droughts in the past offers lessons for the debate about sustainable consumption today. [Copyright &y& Elsevier]

• Maintaining 'headroom' in licensed allocations help minimise the risk of negative impacts from water shortages. • Increasing system redundancy confers robustness but conflicts with pressures to maximise efficiency. • Pursuit of robustness and efficiency locks systems into rigid production pathways. • Financial pressures force growers to focus on persistence of robust outputs at the cost of adaptability and transformability. Food production systems worldwide are increasingly exposed to water shortage shocks. Social-ecological resilience theory provides insights into the qualities which confer production systems with the capacity to absorb shocks and persist, undertake adaptations and ultimately achieve desirable transformations. Combining findings from the analysis of a set of 15 semi-structured interviews and 92 survey responses from growers in the UK, this paper uses resilience theory to explore the factors affecting exposure to the risk of water shortages, and management responses, within outdoor field vegetable production systems that depend on supplemental irrigation. The findings confirm that growers predominantly aim to build resilience by seeking to maintain a buffer or 'headroom' in their water resources to minimise the possibility that a shortage will disrupt their output of marketable produce and/ or lead to financial loss. This buffering strategy confers robustness by increasing system redundancy (availability of spare resources). But building-in redundancy conflicts with regulatory and supply chain pressures to maximise water and production efficiency respectively. Whilst stability of supply to consumers is, for the most-part, achieved, the discrepant pursuits of robustness and efficiency lock agricultural systems into increasingly rigid production and sales pathways, limiting capacities for adaptation and transformation - dimensions of resilience which permit successful system evolution in the context of more extreme shocks and stresses. [ABSTRACT FROM AUTHOR]