Modelling physical characteristics of river habitats

The physical characteristics of river habitats constitute the setting in which fluvial biota dwell and thrive. Determining the spatial and temporal patterns of physical habitat characteristics and the main factors that control them is extremely important to increase the efficiency of river management, conservation, and restoration. This study determined spatial patterns of physical habitat characteristics for Atlantic and Mediterranean rivers in northern Spain and developed a river classification based on hydromorphological characteristics. Data gathered from almost 600 sites following a modified version of the River Habitat Survey methodology were used. In addition to the usual River Habitat Survey variables, the sequence of hydromorphologic units (i.e., areas exhibiting similar hydraulic characteristics, in terms of water velocity and depth), water depths, and widths were recorded. Unmodified reaches were selected computing the Habitat Modification Score. Multiple Linear Regression models were employed to test relationships between Principal Component Analyses that summarized physical river habitat characteristics with ecological relevance and environmental variables (i.e., climate, topography, land cover, and geology) at different spatial scales and used to predict physical habitat attributes for all river reaches. The density of hydromorphologic units, flow turbulence, substrate size, and channel dimensions were able to discriminate river classes within the river network, with topography being the main environmental driver of habitat characteristics (although climate, geology, and land cover were also relevant). This classification scheme could constitute a useful tool to restore physical habitat conditions in modified river reaches.info:eu-repo/semantics/acceptedVersio

Beyond ‘just’ flood risk management: the potential for—and limits to—alleviating flood disadvantage

The threat of flooding poses a considerable challenge for justice. Not only are more citizens becoming exposed to risk, but they are expected to play increasingly active roles in flood risk management. However, until recently, few efforts have charted broader understandings of disadvantage relating to flood risk exposure. Drawing upon social science scholarship that has long been sensitive to concerns related to justice, we deploy and develop the notion of flood disadvantage as a means to assess the challenges to more ‘just’ flood risk management. We contend that the concept of flood disadvantage offers a useful lens to appreciate the constraints of technical approaches to flood risk management, in particular, its limited ability to incorporate complex social elements such as how individuals have differing vulnerabilities and sensitivities to flooding and uneven abilities to engage with risk agendas. The notion highlights the compounding interactions between flooding and other social disadvantages across multiple public policy areas and scales. We argue a fuller acknowledgement of the socio-spatial-temporal dimensions of intersecting disadvantages can help sensitise technical risk analyses that tend to see people and communities as homogeneous entities in a given spatiality. In doing so we can better reveal why some individuals or communities are more vulnerable to disasters or are slower to recover than others. Finally, we outline the challenges in turning more ‘just’ flood risk management from an abstract notion into one that could inform future practice

Are homeowners willing to adapt to and mitigate the effects of climate change?

The need to adapt to climate change impacts, whilst simultaneously limiting greenhouse gas emissions, requires that the government’s efforts are joined by public action. In England and Wales, housing contributes significantly to the emissions and many properties are at risk of flooding. This paper investigates the preparedness of homeowners in England and Wales to make changes to their homes in response to the predicted effects of climate change. A telephone survey of 961 homeowners investigated their interest in purchasing mitigation and adaptation improvements against their concern about climate change, awareness of flood risk and attribution of responsibility for action. Whilst the majority of homes had some energy-saving improvements, few were found to have property-level flood protection. The high levels of awareness about climate change and flooding were coupled with the perception of risks as low. Whilst some respondents accepted personal responsibility for action, most believed that the authorities were responsible for flood protection, and would not pay the costs required to make their home more energy-efficient and better prepared for the eventuality of floods. The results suggest that there is scope for further improvement of energy-saving measures, and that the levels of adoption of flood-protection measures are very low. Multi-faceted strategies, including more effective communication of risks and responsibilities, incentives, and material support for the poorest, will need to be developed to overcome the current reluctance by homeowners to invest in flood-protection measures and further energy conservation solutions in the futur

'The Muckle Spate of 1829': The physical and societal impact of a catastrophic flood on the River Findhorn, Scottish Highlands

On 3 August 1829, north-east Scotland recorded one of the most severe catastrophic floods in modern UK history. Sir Thomas Dick Lauder's An account of the great floods of August 1829 in the province of Moray and adjoining districts (1830) provides a detailed eyewitness account that can be used to reconstruct the flood. This paper reconstructs the hydrometeorology of the flood, assesses its geomorphological and societal impacts and provides a context for assessing present-day flood risk management. The flood was generated by a slow-moving depression in the Moray Firth, which produced an unstable northerly airflow over the NE Grampian Mountains and a minimum 24 hour rainfall of 95 mm. The River Findhorn, one of the most severely affected drainage basins, was subject to detailed analysis by Lauder, including the reporting of numerous flood levels on bridges and within bedrock gorges. Reconstruction of flood flows at five of these sites using Manning's equation and moving successively downstream yields peak flows of 711 m3/s (drainage area 322.2 km2), 1042 m3/s (515.4 km2), 1262 m3/s (568.1 km2) and 1484 m3/s (599.6 km2) on the main stem of the Findhorn, with 451 m3/s (171.9 km2) on a major tributary. Each peak flow based on a Manning's n of 0.04-0.08 represents the optimal value within limits which vary between -25% to +33% and all lie just within the upper boundary when plotted in relation to the envelope curve for catastrophic floods within the UK. Lauder also provides a detailed account of the geomorphic impacts of the flood in the Findhorn valley. Bedrock reaches and 'mixed' alluvial/ bedrock-controlled reaches proved to be robust and registered minimal change, but alluvial reaches reported widespread bank erosion and slope failures with extensive sheets of sand and gravel deposited downstream on valuable agricultural land. Meander cut-offs occurred and many new channels were excavated, especially in the coastal lowlands where the present-day channel broadly follows that excavated in 1829, attesting to the longevity of the flood's impacts. The immediate societal impact included eight fatalities, destitution for at least 289 families, large-scale destruction of roads and bridges, losses for estate owners approaching £2.83 million (2005 prices) and a major shock to a relatively prosperous rural economy. Human response and mitigation took the form of fatalistic acceptance, bearing the loss and dependence on local charitable relief. The reconstruction of the 1829 'Muckle Spate' has a significance far beyond its immediate setting in terms of hydrology (confirming the shape of the envelope curve for Britain's most extreme floods), geomorphology (reporting significant and long-lasting imprints on the riverscape, and confirming the primacy of water-based erosion early in the nineteenth century) and societal impact (contrasting individual bearing of loss mitigated by charitable relief with the present-day reliance on flood protection largely provided by the state). The reconstruction also demonstrates the value of reliable historical sources in placing recent catastrophic floods within their longer-term context. © 2007 The Author. Journal compilation © Royal Geographical Society (with The Institute of British Geographers) 2007