An international scientific colloquium on Environmental Fluid Mechanics was held at the Karlsruhe Institute of Technology (KIT) in honour of Prof. Gerhard H. Jirka, who passed away unexpectedly on February 14, 2010. Prof. Jirka was widely known for his outstanding work in the area of Environmental Fluid Mechanics. At the colloquium 23 world-leading experts in his field presented invited keynote lectures in appreciation and recognition of his work. The lecturers provided high-quality state-of-the-art scientific information and covered several key areas of Environmental Fluid Mechanics, such as Fluvial Hydraulics, Shallow Flows, Buoyant/Stratified Flows, Gravity Currents, Mass Transfer and Small-Scale Phenomena! The book of abstracts can be downloaded as a PDF file. A Memorial Volume containing the full papers and also an overview of Prof. Jirka's main scientific achievements will be published in the IAHR Series by Taylor & Francis in spring 2012.