This book contains the selected extended abstracts presented at the First International Workshop on Environmental Hydraulics IWEH09, Theoretical, Experimental and Computational Solutions, held in Valencia from 29 to 30 October 2009. The aim of the workshop was to encourage scientists, engineers and researchers to present and facilitate communication on modeling environmental problems related to hydrodynamic aspects of fluid modeling, including fluid mechanics analysis, transport of pollutants, mathematical and system modeling, experimental and theoretical validation experiences, measurement techniques focused to environmental problems, etc. 80 papers have been selected for publication in the book, covering the following topics: Mathematical and numerical modeling of environmental fluid mechanics problems Turbulence modeling Dispersion and Transport Experimental experiences related to hydraulic models of environmental problems Models Validation Water and environmental engineering and hydroinformatics This book provides an up-to-date review of the results of research and practice in present and future environmental hydraulics developments, especially aspects related to modelling.