Louise J. Bracken

Applying flow resistance equations to overland flows

Resistance to flow determines routing velocities and must be adequately represented both within stream channels and over hillslopes when making predictions of streamflow and soil erosion. The limiting assumptions inherent in flow resistance equations can be relaxed if the spatial and temporal scale over which they are applied is restricted. This requires a substantial methodological advance in the study of overland flows over natural surfaces. It is suggested that terrestrial laser scanning will allow a greater understanding of overland flow hydraulics and present opportunities to investigate resistance to flow over complex morphologies. The Darcy-Weisbach, Chézy and Manning equations are the most widely used empirical equations for the calculation of flow velocity in runoff and erosion models. These equations rest on analyses originally developed for one-dimensional pipe flows and assume conditions which are not met by overland flows. The following assumptions are brought into question: flow can be described as uniform; flow is parallel to the surface; flow is of a constant width and the boundary to the flow is longitudinally uniform; grain roughness is homogeneous over the wetted perimeter and can be considered as random; form roughness and other sources of flow resistance can be ignored; resistance is independent of flow depth; and resistance can be modelled as a function of the Reynolds number. A greater appreciation of the processes contributing to resistance to overland flows must be developed. This paper also presents a brief history of the development of flow resistance equations.

Toward a dynamic representation of hydrological connectivity at the hillslope scale in semiarid areas

Smith, M. W., Bracken, L. J. (2010). Toward a dynamic representation of hydrological connectivity at the hillslope scale in semiarid areas. Water Resources Research, 46, Article Number: W12540.

Understanding sediment transfer and morphological change for managing upland gravel-bed rivers

Upland river systems constantly evolve in response to a wide range of complex and interlinked processes. These include internal factors such as the discharge, sediment supply and transfer, and the role of the channel boundary. All are influenced by external catchment-scale factors including climate and land use. Managing these systems to reduce flood risk, prevent bank erosion and preserve habitats is typically carried out without sufficient consideration of the complex interrelationships governing the fluvial system. This is partly due to a lack of broad-scale thinking and partly due to the intensive field-based data collection required to inform the processes. As such, decisions are often ill-informed, becoming unsuccessful or simply shifting the problems elsewhere in the system. Furthermore, the continually changing nature of rivers makes management more challenging as an implemented scheme is highly unlikely to remain effective in the long term. While upland catchment hydrology and the implications of climate and land-use change have received much attention in recent decades, in-channel interactions between sediment transfer and morphological change have been relatively neglected. These interactions are fundamental to flood risk, lateral channel adjustment, and habitat and ecology; thus, they require a more concentrated research effort. Central to this is a more holistic approach to catchment operations and a greater understanding of the links between the in-channel dynamics and broader catchment changes.

Transdisciplinary research: understanding the stakeholder perspective

It is accepted that the effective uptake of academic research into policy and practice requires the active involvement of stakeholders. However, understanding participation from the perspectives of stakeholders remains poorly understood. We show that non-academic participants bring multiple knowledges and expertises vital to research. We demonstrate that flexibility in terms of how research is framed, conducted and in the meaning of what constitutes “success” is crucial. We argue that research needs to move towards co-produced transdisciplinary research. In doing so, research can be more representative of stakeholder interests and knowledges, and also make important contributions to academic impact.

Flood risk management, an approach to managing cross-border hazards

River flooding is a serious hazard in the UK with interest driven by recent widespread events. This paper reviews different approaches to flood risk management and the borders (physical, conceptual and organisational) that are involved. The paper showcases a multi-method approach to negotiating flood risk management interventions. We address three fundamental issues around flood risk management: differences and similarities between a variety of approaches; how different approaches work across borders between professionals, lay people, organisations and between different planning regimes; and, whether the science evidence base is adequate to support different types of flood risk management. We explore these issues through a case study on the River Tweed using Q methodology, community mapping and focus groups, participatory GIS, and interviews, which enabled co-production of knowledge around possible interventions to manage flooding. Our research demonstrated that excellent networks of practice exist to make decisions about flood risk management in the Scottish–English borders. Physical and organisational borders were continually traversed in practice. There was an overwhelming desire from professional flood managers and local communities for an alternative to simply structural methods of flood management. People were keen to make use of the ability of catchments to store water, even if land needed to be sacrificed to do so. There was no difference in the desire to embrace natural flood management approaches between people with different roles in flood management, expertise, training or based in different locations. Thus conceptual borders were also crossed effectively in practice.

Can a Species Be a Person?: A Trope and Its Entanglements in the Anthropocene Era

The notion that an animal species is comparable with a human person is unusual but significant in North Atlantic societies. We analyze this trope to make a case for rhetoric culture theory as a powerful form of anthropological analysis. The “species is person” trope has been woven with other tropes to make moral and cosmological arguments in the present geosocial era of environmental crisis. The trope stands against two others in North Atlantic societies, tropes that are themselves at odds: (1) other animal species are not persons but are means to our ends, and (2) each individual animal of a species is equivalent to an individual human person and so are ends in themselves. The “species is person” trope has been used to evoke the characteristically North Atlantic notion of sacred personhood to support action on behalf of human-distant species such as river-dwelling mollusks, species that unlike pandas or otters are not “charismatic.” The use of the trope both to alter understandings and to initiate commitments to action demonstrates its effectiveness as reasoning but also the importance of this style of analysis.

Equilibrium in the balance ? implications for landscape evolution from dryland environments.

Abstract Equilibrium is a central concept in geomorphology. Despite the widespread use of the term, there is a great deal of variability in the ways equilibrium is portrayed and informs practice. Thus, there is confusion concerning the precise meanings and usage of the concept. In this chapter we draw on examples from dryland environments to investigate the practical implications of applying and testing the concept of equilibrium. Issues that we cover include the importance of scale and spatial variability, time, the assumption of constant environmental feedbacks and nonlinearities. The evaluation demonstrates that there are a range of problems inherent with using ideas of geomorphological equilibrium explicitly or implicitly to structure research in drylands. Many of these problems also apply to other environments.

Competing paradigms of flood management in the Scottish/English borderlands

Purpose – The purpose of this paper is to explore how flood management practitioners rationalise the emergence of sustainable flood management. Key to this analysis are differences rooted in assumptions over what flood management is and should do. Design/methodology/approach – The popularity of natural flood management offers a case with which to explore how a dominant framing persists and how individuals at the government-public interface negotiate different visions of future flood management. The authors draw on the perceptions of flood experts, elucidating a deep hold amongst a professional community “grounded” in science and economics, but also their desire to innovate and become more open to innovative practices. Findings – The authors show how the idea of “sustainable” and “natural” flood management are understood by those doing flood management, which is with reference to pre-existing technical practices. Research limitations/implications – This paper explores the views of expert decision making, w...

Can a Species Be a Person

The notion that an animal species is comparable with a human person is unusual but significant in North Atlantic societies. We analyze this trope to make a case for rhetoric culture theory as a powerful form of anthropological analysis. The “species is person” trope has been woven with other tropes to make moral and cosmological arguments in the present geosocial era of environmental crisis. The trope stands against two others in North Atlantic societies, tropes that are themselves at odds: (1) other animal species are not persons but are means to our ends, and (2) each individual animal of a species is equivalent to an individual human person and so are ends in themselves. The “species is person” trope has been used to evoke the characteristically North Atlantic notion of sacred personhood to support action on behalf of human-distant species such as river-dwelling mollusks, species that unlike pandas or otters are not “charismatic.” The use of the trope both to alter understandings and to initiate commitments to action demonstrates its effectiveness as reasoning but also the importance of this style of analysis.

Connectivity and complex systems: learning from a multi-disciplinary perspective

In recent years, parallel developments in disparate disciplines have focused on what has come to be termed connectivity; a concept used in understanding and describing complex systems. Conceptualisations and operationalisations of connectivity have evolved largely within their disciplinary boundaries, yet similarities in this concept and its application among disciplines are evident. However, any implementation of the concept of connectivity carries with it both ontological and epistemological constraints, which leads us to ask if there is one type or set of approach(es) to connectivity that might be applied to all disciplines. In this review we explore four ontological and epistemological challenges in using connectivity to understand complex systems from the standpoint of widely different disciplines. These are: (i) defining the fundamental unit for the study of connectivity; (ii) separating structural connectivity from functional connectivity; (iii) understanding emergent behaviour; and (iv) measuring connectivity. We draw upon discipline-specific insights from Computational Neuroscience, Ecology, Geomorphology, Neuroscience, Social Network Science and Systems Biology to explore the use of connectivity among these disciplines. We evaluate how a connectivity-based approach has generated new understanding of structural-functional relationships that characterise complex systems and propose a ‘common toolbox’ underpinned by network-based approaches that can advance connectivity studies by overcoming existing constraints.