Water pollution from point sources has been considerably reduced over the last few decades. Nevertheless, some water quality problems remain, which can be attributed to non-point pollution sources, and in particular to agriculture. In this paper the results of a study intended to assess the consequences, in terms of NO3 water pollution, of growing a crop, whose impact in terms of P pollution is already well known, are presented. The potential consequences, in terms of water pollution from nitrates of a BMP expressly applied to reduce P pollution are also discussed. The study site is the Lake Vico basin, Central Italy, which has suffered a shift in trophic state since the mid 1990s, caused by P compounds used for intensive cultivation of hazelnut trees. The results of the monitoring campaign described in this paper allow to assert that hazelnut tree cropping has probably caused a considerable increase in nitrate concentration in the groundwater, although not in the lake water, because of the specific hydrogeological characteristics of the basin. The main conclusion is that monitoring is essential to single out environmental characteristics peculiar of a specific area, which even the most sophisticated model would not have been able to highlight. This is why monitoring and model simulations should be integrated.

There is general agreement among scientists that global temperatures are rising and will continue to increase in the future. It is also agreed that human activities are the most important causes of these climatic variations, and that water resources are already suffering and will continue to be greatly impaired as a consequence of these changes. In particular, it is probable that areas with limited water resources will expand and that an increase of global water demand will occur, estimated to be around 35-60 % by 2025 as a consequence of population growth and the competing needs of water uses. This will cause a growing imbalance between water demand (including the needs of nature) and supply. This urgency demands that climate change impacts on water be evaluated in different sectors using a cross-cutting approach (Contestabile in Nat Clim Chang 3:11-12, 2013). These issues were examined by the EU FP7-funded Co-ordination and support action "ClimateWater" (bridging the gap between adaptation strategies of climate change impacts and European water policies). The project studied adaptation strategies to minimize the water-related consequences of climate change and assessed how these strategies should be taken into consideration by European policies. This article emphasizes that knowledge gaps still exist about the direct effects of climate change on water bodies and their indirect impacts on production areas that employ large amounts of water (e.g., agriculture). Some sectors, such as ecohydrology and alternative sewage treatment technologies, could represent a powerful tool to mitigate climate change impacts. Research needs in these still novel fields are summarized.

Modern intensive agriculture justified by the need to support the food requirement of an always growing population, because of the heavy use of agrochemicals, has revealed in many cases to be responsible for surface and groundwater pollution. In this paper, the problems of water and, in particular of groundwater pollution from agricultural nitrates are dealt, with reference to a sub-basin, located in southern Portugal, of river Guadiana, where olive groves and winter wheat are the most common crops. The study area suffers problems related to water availability from one year to another and, for this reason many reservoirs were recently built in the area. In the last few years the resulting greater water availability is causing a shift towards modern intensive agricultural production methods with a consequent, possible water quality deterioration. This is the reason why some BMP scenarios, aimed at reducing the impacts of agriculture on groundwater have been adjusted and their effect in terms of kg/ha of leached NO3 have been estimated using the simulation model GLEAMS. The irrigation water consumption referred to each scenario was also calculated. The load of leached nitrates and the water consumption from the whole area, with reference to each scenario were then merged within a unique synthetic index that summarizes in one number the suitability of that scenario at reducing both nitrate leaching and water consumption.Among the most interesting conclusions is the fact that, in the hypothesis of optimal agricultural management, modern intensive olive grove not always results to be responsible for a higher NO3 leaching in comparison to the traditional ones and could, for this reason, be considered in itself a way to perform a sustainable agriculture.