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Dwindling water supplies, increasing drought frequency and uncertainties associated with a changing climate mean Europe's irrigated agriculture sector needs to improve water efficiency and produce more 'crop per drop'. This paper summarizes the drivers for change, and the constraints and opportunities for improving agricultural water management through uptake of precision irrigation technologies. A multi-disciplinary and integrated approach involving irrigation engineers, soil scientists, agronomists and plant physiologists will be needed if the potential for precision irrigation within the field crop sector is to be realized., (© 2013 Society of Chemical Industry.)

A combination of a changing global climate coupled with rapid socio-economic development is putting unprecedented pressure on water, energy, and food resources. Addressing these issues within a nexus approach can help to identify appropriate management practices and strategic policies to ensure natural resources are used more sustainably thus avoiding exacerbating issues of water scarcity and food insecurity. In this study, we used an integrated water resource planning and irrigation model (WEAP) to assess emerging water-energy nexus issues on the Santa Elena peninsula in Ecuador. Simulated water demands showed that current water resources availability is insufficient to meet full irrigation requirements, especially during the dry season. Annual average energy demand for water conveyance in the SEP was significantly higher than for irrigation with 94.5 GWh and 13.5 GWh being used, respectively. Future challenges associated with changes in agricultural irrigation and urban demands within the SEP were evaluated using scenario analysis. This included considering various scenarios such as agricultural expansion, climate change, population growth, and a shift to export-oriented agriculture. The study underscores the significance of nexus thinking in guiding policy and decision-making in Santa Elena, although the limited data prevents its use in an operational framework. The benefits of adopting an integrated modelling approach to analyse water and energy nexus trade-offs are also discussed. [Display omitted] • An integrated reservoir simulation modelling approach for nexus analysis is used. • Water-energy nexus trade-offs during baseline and future scenarios are considered. • The system is unable to meet irrigation demand under baseline and all scenarios. • Energy demand for conveyance system is seven times higher than for irrigation. • Infrastructure expansion and more efficient agriculture needed if scenarios realise. [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]

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]