1. CETaqua, Centro Tecnológico del Agua, Carretera d'Esplugues 75, 08940 Cornellà de Llobregat, Spain
2. Department of Economic Policy, Faculty of Economics and Business, Tinent Coronel Valenzuela, 1-11, 08034 Barcelona, Spain
3. Department of Mathematics for Economics, University of Valencia, Avda. Tarongers S/N, 46022 Valencia, Spain
4. Department of Applied Economics II, University of Valencia, Avda. Tarongers S/N, 46022 Valencia, Spain