Environment and Rural Affairs Monitoring & Modelling Programme - ERAMMP Report-57: Image Resolution Testing for Soil Erosion and Damage Features

Maintaining healthy soils in Wales is important in order to ensure the sustainable management of natural resources under the environment act. Monitoring of soils in Wales is conducted in order to assess the state and change of soils and forms part of the state of natural resources reporting cycle (SoNaRR), quantify the impact of Glastir on soil health and contribute to a range of other reporting requirements. Soil monitoring by ERAMMP is primarily based on structured sampling of topsoil but has also used aerial photography for peat condition and modelling. This report details work that examines the potential use of remote sensing for assessing the extent of soil erosion and damage (SED), and landsliding from space. The objective was to test different remote sensing imagery data sources, e.g. sentinel (~10m) and planet data (~3m) against high resolution APGB aerial imagery (~0.25m, by Bluesky International Limited), to determine if the resolution of the imagery is acceptable to replace aerial photographs for identifying features. The report summarises two tests of the data, one on the extent of soil erosion and damage and the other on coastal erosion and landslides

Environment and Rural Affairs Monitoring & Modelling Programme ERAMMP report-70: The use of remote sensing to assess soil erosion, poaching and disturbance features

Soil is a finite resource. Within the concepts of natural capital and ecosystem services, the erosion and compaction of soil are considered to be major threats to both ‘soil stock’ and ‘soil function’. Principal drivers of erosion include slope angle and length, precipitation quantity and intensity and vegetation coverage. Soil compaction (primarily caused by repeated movements by vehicles or poaching by animals leading to exposed soils) may reduce soil function in terms of water and gaseous movement and exacerbate N2O emission, as well as potentially creating pathways for erosion to occur. However, producing national scale assessments of soil erosion is expensive and difficult, whilst soil compaction, or disturbance remains largely unconsidered in assessments. Soil erosion is a compliance issue, however, the work outlined in this report is not aligned with any regulatory or compliance process such as outlined in Good Agriculture and Environmental Conditions 5 (Welsh Govt, 2022); it is purely a research project for the monitoring and assessment of soils. Many methods for measuring soil erosion exist and are used over a range of different spatial scales. These include plot experiments, field or catchment studies. However, widespread quantification of erosion rates are time consuming and still remain spatially restricted. Other approaches are more suited to national scale assessments. Modelling approaches, usually based on the ‘Universal Soil Loss Equation’ or its variants can provide an indication as to where long-term erosion is most likely to occur under certain land-use and climatic conditions and are useful for looking at potential change. Walk-over-surveys have the potential to measure area and sometimes volumes of soil erosion, but are also time consuming to undertake. However, they do provide the most repeatable basis for widespread or national scale monitoring. The use of earth observation presented here, combined with field survey, may be an effective and less time-consuming approach for the assessment of national scale soil erosion, but its benefits and limitations need to be explored. This study reports on (i) a desk-based soil erosion and disturbance survey undertaken using high resolution aerial images (0.25 m); and (ii) a subsequent ground survey of the aerial photo survey undertaken as part of the 2021 ERAMMP field survey

Multiple soil map comparison highlights challenges for predicting topsoil organic carbon concentration at national scale

Soil organic carbon (SOC) concentration is the fundamental indicator of soil health, underpinning food production and climate change mitigation. SOC storage is highly sensitive to several dynamic environmental drivers, with approximately one third of soils degraded and losing carbon worldwide. Digital soil mapping illuminates where hotspots of SOC storage occur and where losses to the atmosphere are most likely. Yet, attempts to map SOC often disagree. Here we compare national scale SOC concentration map products to reveal agreement of data in mineral soils, with progressively poorer agreement in organo-mineral and organic soils. Divergences in map predictions from each other and survey data widen in the high SOC content land types we stratified. Given the disparities are highest in carbon rich soils, efforts are required to reduce these uncertainties to increase confidence in mapping SOC storage and predicting where change may be important at national to global scales. Our map comparison results could be used to identify SOC risk where concentrations are high and should be conserved, and where uncertainty is high and further monitoring should be targeted. Reducing inter-map uncertainty will rely on addressing statistical limitations and including covariates that capture convergence of physical factors that produce high SOC contents

Environment and Rural Affairs Monitoring & Modelling Programme - ERAMMP Report-30: Analysis of National Monitoring Data in Wales for the State of Natural Resources Report 2020

The Glastir Monitoring and Evaluation Programme (GMEP, https://gmep.wales/) was at the forefront of the ecosystem approach to monitoring the impact of Pillar II schemes across the European Union - as recognised by the European Commission’s Monitoring and Evaluation Help Desk. GMEP also recruited a large sample of counterfactual “wider Wales” sites, thus enabling additional all Wales reporting. GMEP and other assimilated data represents a significant source of robust, timely and spatially relevant evidence which can contribute to SoNaRR. To facilitate use of GMEP data in SoNaRR, we present new analyses of national monitoring data which has been co-developed with SoNaRR technical leads at Natural Resources Wales (NRW)

Topsoil porosity prediction across habitats at large scales using environmental variables

Soil porosity and its reciprocal bulk density are important environmental state variables that enable modelers to represent hydraulic function and carbon storage. Biotic effects and their ‘dynamic’ influence on such state variables remain largely unknown for larger scales and may result in important, yet poorly quantified environmental feedbacks. Existing representation of hydraulic function is often invariant to environmental change and may be poor in some systems, particularly non-arable soils. Here we assess predictors of total porosity across two comprehensive national topsoil (0-15 cm) data sets, covering the full range of soil organic matter (SOM) and habitats (n = 1385 & n = 2570), using generalized additive mixed models and machine learning. Novel aspects of this work include the testing of metrics on aggregate size and livestock density alongside a range of different particle size distribution metrics. We demonstrate that porosity trends in Great Britain are dominated by biotic metrics, soil carbon and land use. Incorporating these variables into porosity prediction improves performance, paving the way for new dynamic calculation of porosity using surrogate measures with remote sensing, which may help improve prediction in data sparse regions of the world. Moreover, dynamic calculation of porosity could support representation of feedbacks in environmental and Earth System Models. Representing the hydrological feedbacks from changes in structural porosity also requires data and models at appropriate spatial scales to capture conditions leading to near-saturated soil conditions

The first ultracompact Roche lobe-filling hot subdwarf binary

We report the discovery of the first short period binary in which a hot subdwarf star (sdOB) fills its Roche lobe and started mass transfer to its companion. The object was discovered as part of a dedicated high-cadence survey of the Galactic Plane named the Zwicky Transient Facility and exhibits a period of Porb=39.3401(1) min, making it the most compact hot subdwarf binary currently known. Spectroscopic observations are consistent with an intermediate He-sdOB star with an effective temperature of Teff=42,400±300 K and a surface gravity of log(g)=5.77±0.05. A high-signal-to noise GTC+HiPERCAM light curve is dominated by the ellipsoidal deformation of the sdOB star and an eclipse of the sdOB by an accretion disk. We infer a low-mass hot subdwarf donor with a mass MsdOB=0.337±0.015 M⊙ and a white dwarf accretor with a mass MWD=0.545±0.020 M⊙. Theoretical binary modeling indicates the hot subdwarf formed during a common envelope phase when a 2.5−2.8 M⊙ star lost its envelope when crossing the Hertzsprung Gap. To match its current Porb, Teff, log(g), and masses, we estimate a post-common envelope period of Porb≈150 min, and find the sdOB star is currently undergoing hydrogen shell burning. We estimate that the hot subdwarf will become a white dwarf with a thick helium layer of ≈0.1 M⊙ and will merge with its carbon/oxygen white dwarf companion after ≈17 Myr and presumably explode as a thermonuclear supernova or form an R CrB star

Comparative empirical evaluations of internal migration models in subnational population projections

While population forecasters place considerable emphasis on the selection of appropriate migration assumptions, surprisingly little attention has been given to the effects on projection outcomes of the way internal migration is handled within population projection models. This paper compares population projections for Australia's states and territories prepared using ten different internal migration models but with identical assumptions for fertility, mortality and international migration and with the internal migration model parameters held constant. It is shown that the choice of migration model generates large differences in total population, geographical distribution and age--sex composition. It is argued that model choice should be guided by balancing model reality with practical utility and model performance is examined against these criteria. Of the ten models evaluated the authors argue that the migration pool, biregional, and biregional with net constraints models offer a good compromise between conceptual rigour and practicality. If the projected origin-destination flows are required then one of the versions of the standard multiregional model with reduced data inputs is preferred. The large variation in projection outputs points to the need for a better understanding of the spatio-temporal structure of migration in Australia