PEAK DEMANDS FROM SPRAY IRRIGATION

Although irrigation accounts for less than 2% of water use in the UK, direct abstraction for spray irrigation can be a significant user in c ertain catchments in dry summers. Peak demand is expected to grow nati onally by 1-2% per annum on average, but this growth varies locally. W ater resource planners need to know the peak demands and how they are likely to grow within each catchment or aquifer, and the likely local annual variation and timing of demand. This paper discusses how recent developments in irrigation modelling combined with the application of a 'geographic information system' can produce such forecasts, taking into account spatial variation in soils, climate, cropping and irrigat ion practice.