Abstract
The primary aim of this study was to produce maps of various types of risk arising from the use of surface and ground water for irrigation (viz., soil degradation, plant nutritional disorders, clogging of irrigation systems and reservoir problems). The maps were obtained as the additive result of each hydrochemical variable (water properties and indices calculated from them) associated with each risk by using open-source GIS software. The study was conducted in the province of Jaen (southern Spain), which spans a total area of 13,489 km2, 5,860 of which is occupied by olive tree crops. Irrigated olive orchards in the province span more than 2,900 km2.
The potential risk of soil degradation and nutritional disorders at their highest rating by effect of the use of irrigation water spanned an area of 72 km2 with ground water and 874 km2 with surface water. Such a large difference was the result of the typically increased salinity and sodicity of surface water. Both types of water exhibited a very high risk of clogging irrigation systems; however, the risk at its highest rating with surface water spanned a larger area (11,781 km2) than that with ground water. Also, surface water posed more severe restrictions on water reservoirs by effect of its high contents in nutrients. Surface water invariably had a phosphate concentration falling in the medium risk region for reservoir problems.
The proposed information management model is useful for developing water quality maps with a view to assessing the potential risks associated with the use of irrigation water. Such information can be used to optimize irrigation practices in specific agricultural areas.