Typology of Riverbed Structures and Habitats (TRiSHa) – A new method for a high resolution characterization of the spatial distribution and temporal dynamic of riverbed substrates and microhabitats

Abstract

The assessment of the ecological quality of surface water bodies has a long tradition and has become even more important over the last decade. Unfortunately the thorough sampling of the faunistic quality components is too seldom accompanied by an equally detailed analysis of the hydromorphological structures which form the basis of the aquatic ecosystems. This has led to sophisticated faunistic evaluations based on crude assumptions. The TRiSHa method (Typology of Riverbed Structures and Habitats) was specifically designed to correct this current lopsidedness. It is a hydromorphological mapping method that complements the state of the art hydrobiological methods like PERLODES and thus can provide the missing detailed information about the structural characteristics of riverbeds, which form the basis for the faunistic evaluations. TRiSHa provides a strong focus on the scale of the microhabitats, which are most relevant for the species of the macrozoobenthos, an often used ecological quality indicator. The method is easy to apply, scales well for (wadeable) river stretches of different sizes and is, due to its inductive habitat classification system, fully expandable. It is well suited for a wide range of scientific and water management topics like the high resolution analysis of riverbed structures, their heterogeneity and diversity as well as the spatial and temporal dynamic of individual parameters or whole river stretches. This paper presents the TRiSHa method in detail and exemplifies potential scientific applications through two showcase examples.