Vegetation-Hydrogeomorphology Interactions in a Low-Energy, Human-Impacted River

The work leading to this paper received funding from the European Union's FP7 programme under grant agreement no. 282656 (REFORM)

Physical ecosystem engineering by emergent aquatic vegetation: the importance of biomechanical traits

PhDThis thesis explores the potential of the emergent macrophyte Sparganium erectum to act as a physical ecosystem engineer and delivers an understanding of the vegetative processes that enable it to function in such a capacity. An ecosystem engineer is an organism that creates or modifies habitat; the habitats in question are rivers, particularly low energy sections, the modification relates to the capacity of the species to trigger geomorphological change via a process of flow velocity reduction, sediment accumulation, and reinforcement by underground biomass. The influence of S. erectum, and other aquatic species, on flow and sediment accumulation has been demonstrated before, but its changeable influence at different energy conditions and a detailed understanding of how its morphology influences physical processes has yet to be revealed. To address these gaps in understanding, the research conducted within this thesis is divided into three distinct results chapters; Chapter 4 investigates the influence of S. erectum on patterns of flow and sediment at three reaches of the River Blackwater, Surrey, UK; Chapter 5 explores the capacity of the species to resist mimicked hydraulic stress, and the biomechanical traits that underpin its influence on physical processes; Chapter 6 measures the changing belowground architecture and biomass of the species. The research demonstrates that growth of S. erectum significantly alters river habitats and physical processes, but the nature of its influence varies substantially at the three study reaches, which are indicative of different energy conditions. The species demonstrates a number of subtle biomechanical and morphological traits that cause it to function so efficiently as an ecosystem engineer; these include its long growth cycle, high resistance to uprooting, and tendency for underground mass to occupy surficial layers of sediment. The study concludes by assessing the management implications of the results, which include the potential of the species as a restoration tool, given its ability to create a diversity of river habitats

Diagnosing problems of fine sediment delivery and transfer in a lowland catchment

This paper is a product of research conducted within the REFORM collaborative project funded by the European Union Seventh Framework Programme under grant agreement 282656

Plants as river system engineers

I would like to acknowledge three research grants/contracts that are supporting my current research on this theme: Grant F/07 040/AP from the Leverhulme Trust; Grant NE/F014597/1 from the Natural Environment Research Council, UK, and the REFORM collaborative project funded by the European Union Seventh Framework Programme under grant agreement 282656

Modeling the interactions between river morphodynamics and riparian vegetation

The study of river-riparian vegetation interactions is an important and intriguing research field in geophysics. Vegetation is an active element of the ecological dynamics of a floodplain which interacts with the fluvial processes and affects the flow field, sediment transport, and the morphology of the river. In turn, the river provides water, sediments, nutrients, and seeds to the nearby riparian vegetation, depending on the hydrological, hydraulic, and geomorphological characteristic of the stream. In the past, the study of this complex theme was approached in two different ways. On the one hand, the subject was faced from a mainly qualitative point of view by ecologists and biogeographers. Riparian vegetation dynamics and its spatial patterns have been described and demonstrated in detail, and the key role of several fluvial processes has been shown, but no mathematical models have been proposed. On the other hand, the quantitative approach to fluvial processes, which is typical of engineers, has led to the development of several morphodynamic models. However, the biological aspect has usually been neglected, and vegetation has only been considered as a static element. In recent years, different scientific communities (ranging from ecologists to biogeographers and from geomorphologists to hydrologists and fluvial engineers) have begun to collaborate and have proposed both semiquantitative and quantitative models of river-vegetation interconnections. These models demonstrate the importance of linking fluvial morphodynamics and riparian vegetation dynamics to understand the key processes that regulate a riparian environment in order to foresee the impact of anthropogenic actions and to carefully manage and rehabilitate riparian areas. In the first part of this work, we review the main interactions between rivers and riparian vegetation, and their possible modeling. In the second part, we discuss the semiquantitative and quantitative models which have been proposed to date, considering both multi- and single-thread river

MISAME

Recording of David Liffen's Sweeping Statements. This piece is a set of contrast between pure and impure, minimal tonality (flute-like sounds), and maximum timbre (samples of brushing strokes). Only two sounds sources are used in the work and all melodic and mathematical patterns are interrelated and programmed