Hydromorphological assessment within the EU-Water Framework Directive—trans-boundary cooperation and application to different water basins

Abstract

Many water authorities face the challenge to comply with WFD criteria. Overview survey methods are faster and more economic compared to more intensive field surveys. This work tests the quality of both approaches, with a focus on the hydromorphological status assessment. First, WFD criteria and descriptions for hydromorphological quality components and monitoring demands are summarized. A practical assessment of hydromorphological features follows, performed in German and Czech sub-catchments of the Elbe River. Three different methods of stream habitat survey were applied, two German field and overview survey standards by LAWA (Weisseritz basin), and a new Czech field survey method EcoRivHab (Rolava basin). Comparability of results and suitability to fulfil the WFD and CEN standard requirements were tested. Results show that the field and overview survey methods are non-interchangeable and irreplaceable. The overview method provides good results when conditions of large areas need to be evaluated but results seem to overestimate the true quality of the aquatic ecosystem. The field survey methods provide more accurate information. Both field survey methods (LAWA and EcoRivHab) offer good results on hydromorphological river characteristics, evaluated by a point system. Both methods are powerful in evaluating riparian belts and floodplain hydromorphology. The relative added effort of field mapping is overcompensated by the quality of the outputs, which are fully compatible with the aims of the WFD.