Water and the environment : innovation issues in irrigation and drainage : selected papers of the 1st Inter-Regional Conference "Environment-Water: Innovative Issues in Irrigation and Drainage", held in Lisbon, Portugal, September 98 / edited by Luis S. Pereira and John W. Gowing ; Portuguese National Committee of the International Commission on Irrigation & Drainage. - Pereira, L. S.; Gowing, John W. (Spon, 1998)