Hydromorphological inventory and map of the Drava and Mura rivers (IAD pilot study)
The IAD pilot study "Hydromorphological Survey and Map of the Drava and Mura Rivers" reviews hydromorphological assessment methods across Europe focussing on large rivers, highlights the European CEN Guidance Standard (CEN 2004) which offers a methodological framework supporting WFD requirements and presents the survey method adaptations and mapping results. The Drava and Mura Rivers are characterized by modified upper and middle reaches by chains of hydropower plants and still free-flowing lower stretches. Based on the reviewed methods, in particularly those for large rivers and the. CEN standard from 2004 an adapted method was developed. In a next step morphological reference conditions were extracted based on fluvial-morphological parameters. During the summer 2005, over 350 river-km of the lower Mura and Drava were surveyed continuously by boat, and additionally stretches along the middle and upper courses by land survey. The results and evaluation show a high differentiation for the main parameter groups "channel", "banks/riparian zone" and "floodplain". The overall evaluation indicates that about 35% of the entire river stretches is classified as class two (good status) or better (mostly alonge the lower stretches), whereas the remaining 65% contributes to the classes 3-5, moderate±bad (over 25% are completely modified).