[American Society of Agricultural and Biological Engineers 21st Century Watershed Technology: Improving Water Quality and Environment Conference Proceedings, 21-24 February 2010, Universidad EARTH, Costa Rica - ()] 21st Century Watershed Technology: Improving Water Quality and Environment Conference Proceedings, 21-24 February 2010, Universidad EARTH, Costa Rica - Equity and Transparency: General Principles of the Success of Collective River and Ground Water Management in Valencia, Southeast Spain