The Economist has a good, short video on the problems of water usage, agriculture, and water in Spain. It talks about how farmers in Valencia and Andalucia have been tapping water supplies from the wetlands in Las Tablas de Daimiel National Park, south of Madrid. Last summer, the peatlands in this park began to self-combust, because it had become so dry.
Though there would seem to be little chance of civil conflict over these water supplies, it is important to note that there certainly is political conflcit between farmers and conservationists looking to preserve national parks. The video also briefly touches on regional ideas to transfer water from the Ebro river in the more lush north of Spain to the drier regions in the south and west. Though it doesn't discuss it, Spain has a history of regional disunity, and I should think that a large part of the reason that infrastructure to transfer water has never been built has been the mistrust that Catalonia and the Basque regionsit have for both the central government and the southern regions. If Spain was not a well-established Democracy in stable Europe, it is not hard to see how a similar situation -- further stressed by climate changes -- could lead to conflicts.