Isbourne Catchment Community Report: Potential for Natural Flood Management in the Catchment

The School of Natural and Social Sciences (SNSS) and the Countryside and Communities Research Institute (CCRI) at the University of Gloucestershire were commissioned by the Isbourne Catchment Group (ICG) and the Environment Agency (EA) to undertake an initial assessment of the River Isbourne to determine the feasibility and potential benefits of applying natural flood management (NFM) techniques across the Isbourne catchment. Other engineering options had been considered in an analysis of the catchment in 2010 (Haycock 2010) and some minor changes have been made by the EA in the last few years. However, most significant engineering options were not considered to be cost effective whilst soft engineering options such as land use change and natural flood management were recommended for further investigation, which is the focus of this report – no assessment of hard engineering possibilities are made in this report as it is beyond the remit of the investigation. The report describes the catchment characteristics, gives an overview of potential NFM options and provides recommendations of which of these could be implemented in the catchments and ways forward

Isbourne Catchment Community Report: Potential for Natural Flood Management in the Catchment

The School of Natural and Social Sciences (SNSS) and the Countryside and Communities Research Institute (CCRI) at the University of Gloucestershire were commissioned by the Isbourne Catchment Group (ICG) and the Environment Agency (EA) to undertake an initial assessment of the River Isbourne to determine the feasibility and potential benefits of applying natural flood management (NFM) techniques across the Isbourne catchment. Other engineering options had been considered in an analysis of the catchment in 2010 (Haycock 2010) and some minor changes have been made by the EA in the last few years. However, most significant engineering options were not considered to be cost effective whilst soft engineering options such as land use change and natural flood management were recommended for further investigation, which is the focus of this report – no assessment of hard engineering possibilities are made in this report as it is beyond the remit of the investigation. The report describes the catchment characteristics, gives an overview of potential NFM options and provides recommendations of which of these could be implemented in the catchments and ways forward

Migration into the UK in the early twenty-first century: temporal trends and spatial patterns

Sam Scott and Lucy Clarke explore the data covering more recent migration to the United Kingdom, most especially from the EU. They discover that since 2000 migrant destinations have changed. No longer do migrants head exclusively to the big cities and industrial areas, but to rural areas, like Boston in Lincolnshire, where there is plenty of work to be had in the agricultural and food sectors of the economy

An evidence-based study mapping the decline in freshwater ponds in the Severn Vale catchment in the UK between 1900 and 2019

Freshwater ponds have long been an overlooked biodiversity store and changing types of land use and the land management practices has led to a steady decline in pond numbers. Establishing the regional extent of pond loss is the first step in identifying key areas for conservation action. This study calculated pond loss in the Severn Vale catchment UK since 1900. Identification of pond location and surrounding land use on historic and contemporary maps enabled a comparison of total number, density and distance between present day and historic ponds. 57.7% of ponds present in 1900 were lost and pond density declined from 7.3 to 4.5 ponds km−2 between 1900 and 2019. This resulted in a 24.6 m increase in the average distance between contemporary ponds. Land use was an important factor in determining pond loss. Although in 2019 the highest density of ponds are in rural areas, 62.3% of ponds lost were from agricultural settings (arable or pasture). Our results highlight the significant pond loss experienced in the Severn Vale since 1900 and provide a valuable baseline for pondscape restoration. The methods described are widely applicable to other regions either with a history of ponds or an environment that could sustain them

Monitoring the impact of leaky barriers used for natural flood management on three river reaches in the Stroud Frome and Twyver catchments, Gloucestershire, UK

• Three sites in the Stroud Frome and Twyver catchments in Gloucestershire, UK were monitored for hydrology, sediment and water quality variables in five different flow conditions; these included two featuring leaky barriers installed in different years and a natural control site. • The results indicated that that leaky barriers were effective at reducing channel velocity and storing water up to a 1 in 9-year flow event (no higher magnitude flow events were captured), but did not impact on low flow velocities. • The time a leaky barrier had been in place was important; there were improvements in water quality and a reduction in the suspended sediment content when leaky barriers were present and these were more pronounced the longer a leaky barrier had been present. However, associated with this there was an increase in silt content in the bedload sediment upstream of leaky barriers which was increased through time since installation

The effect of no-till farming on the soil functions of water purification and retention in north-western Europe: A literature review

This review provides a comprehensive evaluation of no-till (NT) based on recent studies (post-2000) in NW Europe and evaluates the separate effect of the NT and other associated practices (e.g. cover crops, crop residue and crop rotations) individually and collectively on the water purification and retention functions of the soil. It also assesses the applicability of NT compared to conventional tillage (CT) systems with reference to a number of soil physical characteristics and processes known to have an important influence on water purification and retention functions. The literature search was carried out by a systematic approach where NT practices were assessed against soil structure, erosion, nutrient leaching/loss, water retention, infiltration and hydraulic conductivity (combinations of criteria = 40). Articles were selected based on their relevance in relation to the topic and location within NW Europe (n = 174). Results show that NT has large potential as an erosion mitigation measure in NW Europe with significant reductions of soil losses from agricultural fields, providing potential beneficial effects regarding inputs of sediment and particulate phosphorous (P) to water bodies. However, NT increased losses of dissolved reactive phosphorus (DRP) and had little effect on nitrogen (N) leaching, limiting the overall positive effects on water purification. Soil structural properties were often found to be poorer under NT than CT soils, resulting in decreased water infiltration rates and lower hydraulic conductivity. This was an effect of increased topsoil compaction, reduced porosity and high bulk density under NT, caused by the absence of topsoil inversion that breaks up compacted topsoil pans and enhances porosity under CT. However, several studies showed that soil structure under NT could be improved considerably by introducing cover crops, but root and canopy characteristics of the cover crop are crucial to the achieve the desired effect (e.g. thick rooted cover crops beneficial to soil structural remediation can cause negative effects in soils sensitive to erosion) and should be considered carefully before implementation. The contribution of NT practices to achieve Water Framework Directive (WFD) objectives in NW Europe is still uncertain, in particular in regards to water retention and flood mitigation, and more research is required on the total upscaled effects of NT practices on catchment or farm scale

Isbourne Catchment Project: Scoping Study (Final Report), Report to Isbourne Catchment Partnership & Environment Agency.

The School of Natural and Social Sciences (SNSS) and the Countryside and Communities Research Institute (CCRI) at the University of Gloucestershire were commissioned by the Environment Agency (EA) and the Isbourne Catchment Group (ICG) to undertake a Scoping Study of the River Isbourne to assess the feasibility and potential benefits of applying natural flood management (NFM) techniques across the Isbourne catchment. Other options had been considered in an analysis of the catchment in 2010 (Haycock 2010) and some minor changes have been made. However, most significant engineering options have been ruled out and not considered to be cost effective whilst soft engineering options such as land use change and natural flood management were recommended for further investigation. This report describes the catchment characteristics, outlines potential NFM methods before specifying which would be appropriate for the Isbourne catchment and making recommendations for future work

A numerical modelling and experimental study of flow width dynamics on alluvial fans

Alluvial fans are dynamic landforms, the evolution of which is controlled by both external environmental forcing (climate, tectonics and base level change) and internal process-form feedbacks. The latter include changes in flow configuration (between sheetflow and channelized flow states), driven by aggradation and degradation, which may in turn promote changes in sediment transport capacity. Recent numerical modelling indicates that such feedbacks may lead to dramatic and persistent fan entrenchment in the absence of external forcing. However, the parameterization of flow width within such models is untested to date and is subject to considerable uncertainty. This paper presents results from an experimental study of flow width dynamics on an aggrading fan in which spatial and temporal patterns of fan inundation are monitored continuously using analysis of digital vertical photography. Observed flow widths are compared with results from a simple theoretical model developed for non-equilibrium (aggradational) conditions. Results demonstrate that the theoretical model is capable of capturing the first-order characteristics of width adjustment over the course of the experiment, and indicate that flow width is a function of fan aggradation rate. This illustrates that models of alluvial flow width derived for equilibrium conditions may have limited utility in non-equilibrium situations, despite their widespread use to date

Can drones count gulls? Minimal disturbance and semiautomated image processing with an unmanned aerial vehicle for colony-nesting seabirds

Accurate counts of wild populations are essential to monitor change through time, but some techniques demand specialist surveyors and may result in unacceptable disturbance or inaccurate counts. Recent technological developments in unmanned aerial vehicles (UAVs) offer great potential for a range of survey and monitoring approaches. They literally offer a bird’s-eye view, but this increased power of observation presents the challenge of translating large amounts of imagery into accurate survey data. Seabirds, in particular, present the particular challenges of nesting in large, often inaccessible colonies that are difficult to view for ground observers, which are commonly susceptible to disturbance. We develop a protocol for carrying out UAV surveys of a breeding seabird colony (Lesser Black-backed Gulls, Larus fuscus) and subsequent image processing to provide a semiautomated classification for counting the number of birds. Behavioral analysis of the gull colonies demonstrated that minimal disturbance occurred during UAV survey flights at an altitude of 15 m above ground level, which provided high-resolution imagery for analysis. A protocol of best practice was developed using the expertise from both a UAV perspective and that of a dedicated observer. A GIS-based semiautomated classification process successfully counted the gulls, with a mean agreement of 98% and a correlation of 99% with manual counts of imagery. We also propose a method to differentiate between the different gull species captured by our survey. Our UAV survey and analysis approach provide accurate counts (when comparing manual vs. semi-automated counts taken from the UAV imagery) of a wild seabird population with minimal disturbance, with the potential to expand this to include species differentiation. The continued development of analytical and survey tools whilst minimizing the disturbance to wild populations is both key to unlocking the future of the rapid advances in UAV technology for ecological survey

The imprint of photoevaporation on edge-on discs

We have performed hydrodynamic and radiative transfer calculations of a photoevaporating disc around a Herbig Ae/Be star to determine the evolution and observational impact of dust entrained in the wind. We find that the wind selectively entrains grains of different sizes at different radii resulting in a dust population that varies spatially and increases with height above the disc at radii > 10 AU. This variable grain population results in a 'wingnut' morphology to the dust density distribution. We calculate images of this dust distribution at NIR wavelengths that also show a wingnut morphology at all wavelengths considered. We have also considered the contribution that crystalline dust grains will have in the wind and show that a photoevaporative wind can result in a significant crystallinity fraction at all radii, when the disc is edge-on. However, when the disc's photosphere is unobscured, a photoevaporative wind makes no contribution to the observable crystallinity fraction in the disc. Finally, we conclude that the analysis of extended emission around edge-on discs could provide a new and independent method of testing photoevaporation models.Comment: 8 pages, 6 figures, accepted for publication in MNRA