This rendered the water unsuitable for artificial recharge of groundwater, and the plant had to be closed. Thus, opposite meteorological extremes had the same practical impact, highlighting the potential implications of climate change for the control and management of artificial groundwater recharge with river water. Rising temperatures may result in the northward extension of cultivation of a whole range of crops. Hotter and drier summers are likely to increase the demand for seasonal supplementary irrigation, both within and beyond existing irrigated lands. Modelling studies in the Guadalquivir River Basin suggested an increase in seasonal irrigation requirements of 15% to 20% by the 2050s, and even in the United Kingdom irrigation demand is likely to increase,20 These substantial demands may be difficult to predict and plan for. Policy choices to mitigate impacts are important, and some promising efforts are already being made in several of the major transboundary basins - the Rhine, Meuse and Danube.