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Purpose: Suspended sediment (SS) transport in rivers is highly variable, making it challenging to develop predictive models that are applicable across timescales and rivers. Previous studies have identified catchment and hydro-meteorological variables controlling SS concentrations. However, due to the lack of long-term, high-frequency SS monitoring, it remains difficult to link SS transport dynamics during high-flow events with annual or decadal trends in SS transport. This study investigated how processes driving SS transport during high-flow events impact SS transport dynamics and trends observed over longer timescales. Methods: Suspended sediment samples from the River Aire (UK) (1989–2017) were used to (i) statistically identify factors driving SS transport over multiple timescales (high-flow events, intra- and inter-annual) and (ii) conceptualize SS transport as a fractal system to help link and interpret the effect of short-term events on long-term SS transport dynamics. Results and discussion: Antecedent moisture conditions were a dominant factor controlling event-based SS transport, confirming results from previous studies. Findings also showed that extreme high-flow events (in SS concentration or discharge) mask factors controlling long-term trends. This cross-timescale effect was conceptualized as high fractal power, indicating that quantifying SS transport in the River Aire requires a multi-timescale approach. Conclusion: Characterizing the fractal power of a SS transport system presents a starting point in developing transferrable process-based approaches to quantify and predict SS transport, and develop management strategies. A classification system for SS transport dynamics in river systems in terms of fractal power could be developed which expresses the dominant processes underlying SS transport. [ABSTRACT FROM AUTHOR]

The study aims to assess the long‐term phosphorus (P) removal in a land treatment system (LTS) in the UK. Different sections of the site have been irrigated with wastewater effluent for different periods of time for up to 85 years. The amounts of P discharged and accumulated were calculated from historical data, estimations of water consumption, composition and soil measurement. The total P input during the study period was estimated to be 90 010 kg, the average P removal was 4% and there was no significant difference in the total P accumulated between plots irrigated for different periods, indicating that the sorption capacity of the soil might be saturated. Despite the low P retention rates in the LTS, there is no evidence that emissions from this system are affecting P concentrations in either the nearby river or the local chalk aquifer. Gaps remain, however, in performance optimisation and longevity forecasting. [ABSTRACT FROM AUTHOR]

Estimates of the magnitude and location of future irrigation demand are essential for strategic planning of water resources at national and regional levels. However, demand forecasting is fraught with difficulty, as water use for supplementary irrigation is highly sensitive to changes in agro-economic policy, climate and future water resources availability. Short-term forecasts are normally based on existing trends, modified by any expected variations. Following a long period of growth, the volume of water being abstracted for irrigation in England and Wales appears to be in decline. After allowing for annual weather variations, the underlying decline in dry year demand was -1.4% per annum from 1990 to 2010. Extrapolating these trends forward suggests a further reduction of around onequarter (-25%) by 2030. However longer-term forecasts (to the 2050s) need to consider alternative possible futures. The authors used a combination methodology to incorporate changes in population demographics, consumption and consumer preferences under a range of socioeconomic policies for four defined socioeconomic futures. The projected changes in 'unconstrained' demand in a dry year ranged from +40% to +167% by the 2050s; 'actual' water use will be constrained by water availability and allocation policy, which itself may lead to a relocation of demand. Combined with a probable decline in low-flow (summer) water availability, this indicates major future water resource issues. The figures need to be interpreted with caution as they are sensitive to model input values, and ignore impacts of stepchange genetic improvements and the effects of changing CO2 concentrations on crop growth. The differences between forecasts also highlight the sensitivity to assumptions and the potential impact of deeper-seated changes on current trends. Some policy options and potential adaptations are discussed. [ABSTRACT FROM AUTHOR]

Climate change is expected to modify rainfall, temperature and catchment hydrological responses across the world, and adapting to these water-related changes is a pressing challenge. This paper reviews the impact of anthropogenic climate change on water in the UK and looks at projections of future change. The natural variability of the UK climate makes change hard to detect; only historical increases in air temperature can be attributed to anthropogenic climate forcing, but over the last 50 years more winter rainfall has been falling in intense events. Future changes in rainfall and evapotranspiration could lead to changed flow regimes and impacts on water quality, aquatic ecosystems and water availability. Summer flows may decrease on average, but floods may become larger and more frequent. River and lake water quality may decline as a result of higher water temperatures, lower river flows and increased algal blooms in summer, and because of higher flows in the winter. In communicating this important work, researchers should pay particular attention to explaining confidence and uncertainty clearly. Much of the relevant research is either global or highly localized: decision-makers would benefit from more studies that address water and climate change at a spatial and temporal scale appropriate for the decisions they make. [ABSTRACT FROM AUTHOR]

Large quantities of water are required to produce the food for a nation, some of which is derived within the country and some associated with imported food commodities. In this study, we consider the spatially explicit potential impact of alternative healthier eating scenarios for the UK on global blue water scarcity using the concept of a water scarcity footprint. The water required to produce the food consumed by the UK was estimated at 52.6 Gm 3 /y of which 93% is from rainfall at the point where it falls and 7% is “blue” water withdrawn from surface and ground water resources. Five alternative healthier diets were considered and the impact on the blue water scarcity footprint was modest (ranging from −3% to +2% compared to baseline). However more significant impacts were projected on the geographical distribution of the blue water scarcity footprint. This study has shown that if current trade patterns continue, policies to promote healthier eating in the UK may contribute to increased blue water scarcity at home and in other parts of the world. The use of virtual water estimates and global datasets of water scarcity can help to understand the potential environmental impacts of alternative diets. [ABSTRACT FROM AUTHOR]

Water is a fundamental component in primary food production, whether it be rainfall, irrigation used to water crops, or for supplying drinking water for animals, while the amount of water in the soil determines it capacity to support machinery and animals. We identify that UK agriculture is exposed to five main water-related risks: agricultural drought, scarcity of water resources, restrictions on the right to abstract water, excess soil water, and inundation. Projected milder, wetter winters and hotter, drier summers by the end of the century will change the frequency, persistence, or severity of each of these risks. This paper critically reviews and synthesizes the scientific literature on the impact of these risks on primary food production and the technological and managerial strategies employed to build resilience to these changing risks. At the farm scale, the emphasis has been on strategies to build robustness to reduce the impact of a water-related risk. However, collaborative partnerships allow for a more optimal allocation of water during times of scarcity. Enhancing cross-scale interactions, learning opportunities, and catchment-scale autonomy will be key to ensuring the agricultural system can build adaptive and transformational capacity. [ABSTRACT FROM AUTHOR]

• 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]