Classification of river morphology and hydrology to support management and restoration

Abstract

Vertical mixing in lakes is a key driver of transport of ecologically important dissolved constituents, such as oxygen and nutrients. In this study we focus our attention on biomixing, which refers to the contribution of living organisms towards the turbulence and mixing of oceans and lakes. While several studies of biomixing in the ocean have been conducted, no in situ studies exist that assess the turbulence induced by freshwater zooplanktonic organisms under real environmental conditions. Here, turbulence is sampled during three different sampling days during the sunset diel vertical migration of Daphnia spp. in a small man-made lake. This common genus may create hydrodynamic disturbances in the lake interior where the thermal stratification usually suppresses the vertical diffusion. Concurrent biological sampling assessed the zooplankton vertical concentration profile. An acoustic-Doppler current profiler was also used to track zooplankton concentration and migration via the backscatter strength. Our datasets do not show biologically-enhanced dissipation rates of temperature variance and turbulent kinetic energy in the lake interior, despite Daphnia concentrations as high as 60 org. L −1 . No large and significant turbulent patches were created within the migrating layer to generate irreversible mixing. This suggests that Daphnia do not affect the mixing in the lake at the organism concentrations observed here.

The contribution of citizen science volunteers to river monitoring and management: International and national perspectives and the example of the MoRPh survey

“…Following the citizen science methodology, a simple HydroMoRPh analysis of longer reaches containing each MultiMoRPh subreach used information extracted from images in Google Earth (Table ) coupled with estimates of bed material properties from the MultiMoRPh field surveys to establish the river type (Table , following Rinaldi, Gurnell, González del Tánago, Bussettini, & Hendriks, ). Each selected longer reach was determined by (a) absence of major tributaries, (b) broad consistency in river planform‐confinement, and (c) absence of major structures (e.g., dams).…”

Climate change and European rivers: An eco‐hydromorphological perspective

“…For instance, seasonal plant growth and abundance strongly affects water levels, sediment transport, and habitat availability, which, in turn, is influenced by temperature and flow regime. The structure and function of rive plant communities reflects the natural dynamism of rivers from their head waters to middle and lower reaches (Rinaldi et al, ; O'Briain et al, ), and any significant changes will be met with a corresponding adjustment by both river morphology and vegetation type.…”

Incorporating catchment to reach scale processes into hydromorphological assessment in the UK

“…The river typology is complemented by a floodplain typology, based on that proposed by Nanson and Croke () (see Rinaldi et al . for further details), since floodplain types and their geomorphic features reflect the river types that build them.…”