Evaluating the effects of tracer selection, source dominance and source number on the accuracy and sensitivity of source apportionment using sediment fingerprinting.

Sediment fingerprinting is a technique for determining the proportional contributions of sediment from erosion sources delivered to downstream locations. It involves selecting tracers that discriminate sediment sources and determining contributions from those sources using tracers.&#160; These tracers can include geochemical, fallout radionuclides, magnetic properties, and compound specific stable isotope (CSSI) values of plant-derived biotracers that label of soils and sediment. &#160;A range of tracer applications and developments in source un-mixing have been demonstrated in the literature and, while the basis for discriminating sediment sources is reasonably well understood, research has drawn increasing attention to limitations and uncertainties associated with source apportionment. Numerical mixtures provide a way to test model performance using idealized mixtures with known source proportions. Although this approach has been applied previously, it has not been used to test and compare model performance across a range of tracer types with varied source contribution dominance and number of sources.We used numerical mixtures to examine the ability of two different tracer sets (geochemical and CSSI), each with two tracer selections, to discriminate sources using a common source dataset. Sources were sampled according to erosion process and land cover in the Aroaro catchment (22 km2), New Zealand.&#160; Here we sampled top-soils and sub-soils from pasture (n = 12 sites), harvested pine (12), kanuka scrub (7) and native forest (4) locations. Composite soil samples were collected at 0-2 and 40-50 cm depth increments to represent surface and shallow landslide (subsoil) erosion sources. Stream sediment (11) samples were also collected for initial unmixing. &#160;Here, we focus on using numerical mixtures with geochemical and CSSI tracers for an increasing number of sources (3 to 6) where each individual and pairwise combination of sources were systematically set as the dominant source. &#160;Since mixing models for CSSI tracers produce source contributions based on isotopic proportions (Isotopic%) instead of soil contributions (Soil%), CSSI numerical mixtures were created for Isotopic% and Soil% to assess the impact this correction factor may have on model performance. &#160;In total, over 400 model scenarios were tested.Numerical mixture testing indicated that the dominant source can have a significant impact on model performance. &#160;If the dominant source is well discriminated, then the model performs well but accuracy declines significantly as discrimination of the dominant source reduces. This occurs more frequently with an increasing number of sources. The geochemical dataset performed well for erosion-based sources while both tracer sets produced larger apportionment errors for land cover sources. CSSI model performance was generally poorer for Soil% than Isotopic%, indicating high sensitivity to the percent soil organic carbon in each source, especially when there are large differences in organic matter between sources.&#160;

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Improving spatial representation of erosion sources using Sediment Fingerprinting with terrain data and sediment budget modelling

10.5194/egusphere-egu2020-11959 ◽

2020 ◽

Author(s):

Simon Vale ◽

Hugh Smith

Keyword(s):

Suspended Sediment ◽

Source Apportionment ◽

End Users ◽

Sediment Budget ◽

Storm Event ◽

Sediment Source ◽

Sediment Fingerprinting ◽

Sediment Sources ◽

Geochemical Tracers ◽

Source Contributions

Sediment fingerprinting quantifies proportional contributions of catchment sediment sources to downstream sediment mixtures and deposits. While the sediment fingerprinting technique is well established it is still challenged by the coarse spatial resolution of sediment source discrimination which hinders understanding of catchment sediment dynamics and limits its usefulness for land management where finer resolution spatial information is required.Here, two conventional sediment fingerprinting datasets from New Zealand are used to show how spatial modelling of source loads can improve 1) the usefulness of sediment fingerprinting approaches and 2) visualization of results for end-users by combining source apportionment with terrain information and sediment budget modelling. The two case studies involve unmixing sediment source contributions to 1) overbank deposits within the Oroua River catchment, where six sediment sources (Mountain Range, Mudstone, Hill Subsurface, Hill Surface, Unconsolidated Sandstone, and Channel Bank) across two size fractions (<63 &#181;m and 125&#8211;300 &#181;m) were characterized using bulk geochemical and radionuclide tracers and 2) suspended sediment in the Manawatu catchment, where a similar six sources were characterized using bulk geochemical tracers to determine changes in source contributions to hourly suspended sediment samples during a 53hr storm event.The proportional source contributions for each case study are applied to modelled sediment loads and spatially distributed using terrain information for rock type, slope and channel network extent to produce specific sediment yield maps for both catchments and spatial visualization of sediment generation during the Manawatu catchment storm event. Integrating sediment fingerprinting results with spatial datasets and modelling can enhance interpretation of source apportionment results and improve the utility of this information for end-users focused on the spatial targeting of erosion sources for mitigation to reduce downstream sediment impacts.&#160; &#160;

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Potential of environmental DNA for tracing land-use based sediment sources

10.5194/egusphere-egu2020-8358 ◽

2020 ◽

Author(s):

Anthony Foucher ◽

Olivier Evrard ◽

G. Francesco Ficetola ◽

Ludovic Gielly ◽

Julie Poulain ◽

...

Keyword(s):

Land Use ◽

Land Cover ◽

Genetic Material ◽

Complex Mixture ◽

Agricultural Practices ◽

Environmental Dna ◽

Sediment Sources ◽

Sediment Delivery ◽

Cultivated Species ◽

The Impact

Environmental DNA (eDNA) is a complex mixture of genetic material extracted from environmental samples like soil, water or sediment in order to obtain reliable information on the past and current biological communities. In recent years, the eDNA technique was successfully applied to sediment accumulated in lakes for providing information on past land use and land cover changes in their drainage areas. Recently, the potential of eDNA for providing detailed information on the plant species found in sediment sources was investigated. These research highlight the powerful potential of this method for improving our ability to detect the vegetal communities causing erosion and sediment delivery. Nevertheless, some fundamental questions remain like for example the DNA memory effect of soils. How long the plant signature can persist in soils? Are we recording the last species cultivated or a mixture of past plants in agricultural areas? These issues are of prime importance for examining the potential of eDNA as a new sediment tracer.To answer these questions, two contrasted sites located in intensively cultivated environments in France were studied. In the first site, soil samples were collected (n=30) in plots for which the crop rotation history was well documented since 1975. In particular, crops cultivated only once during the rotation were used as potential chronological markers. The impact of agricultural practices on eDNA preservation was also investigated comparing soil signatures under conventional and conservation farming. In the second site, samples were collected (n=40) to compare the abundance of currently observed taxa versus detected taxa in cropland, grassland, woodland and river channel banks.The results showed that the last cultivated crop was detected in 100% of the samples as the most abundant taxa under conventional farming and 75% under no-tillage. The last cultivated species was the most abundant in 80% of the studied plots. Interestingly, grapevine was detected in 46% of the cultivated plots of the second site, although this plant is no longer cultivated in this catchment. In addition, a large variety of weeds were detected in both sites in addition to the cultivated species. eDNA results provided by the current research illustrate the potential of this method for identifying the recent (<7 years) land cover history of soils which may allow to improve our understanding of sediment mobilization and transfer processes over short timescales.

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Assessing the contribution of natural and anthropogenic processes on sediment dynamics in the Rio Santa (Peru) through sediment fingerprinting

10.5194/egusphere-egu21-8487 ◽

2021 ◽

Author(s):

Jessica Kitch ◽

Caroline Clason ◽

Sally Rangecroft ◽

Sergio Morera ◽

Will Blake

Keyword(s):

Resource Management ◽

Soil Erosion ◽

Water Resource Management ◽

Agricultural Land ◽

Sediment Dynamics ◽

Sediment Fingerprinting ◽

Sediment Sources ◽

Transport Pathway ◽

Distributed Approach ◽

The Impact

The combination of a changing climate and growing population poses a contemporary challenge for the water-food-energy security nexus in mountain regions, especially in glacier-fed catchments such as the Rio Santa in the Peruvian Andes. Soil erosion due to both natural processes and anthropogenic activities can exacerbate this challenge, with increased levels of sediment in river systems endangering crucial river functions, such as crop irrigation, drinking water, and hydroelectricity. Furthermore, sediment can act as a transport pathway for contaminants, in addition to being a source of contamination itself. Previous studies have suggested that soil erosion related to human activity vastly exceeds the rate of natural soil production in many Andean catchments, where research to date has primarily focused on larger eastern catchments. Smaller western catchments, however, are important for many major Andean cities reliant upon upstream water supplies. It is thus, important to identify sediment sources and better understand sediment dynamics to manage the threats to water supply.Sediment fingerprinting approaches are one technique that can contribute to improved understanding of sediment sources and dynamics and the impact of soil erosion in a catchment, and thus contribute to water resource management at the catchment level. Taking a distributed approach along the Rio Santa, this study aims to improve understanding of natural and anthropogenic contributions to sediment production in this Andean system. Key sediment sources explored are glacial sediment potentially enhanced by retreat, agricultural land, forestry operations, land under natural vegetation, and mining. The distributed approach permits quantification of their dynamics throughout the catchment. All source and mixture samples were analysed using Wavelength Dispersive X-ray Fluorescence (WD XRF) to develop geochemical fingerprints and the MixSIAR mixing model was used to apportion sediment sources. While sediment sampling presents a number of challenges when working in remote, mountainous regions such as the Rio Santa catchment, sediment fingerprinting has the potential to help reduce environmental degradation when used to guide local resource management decisions.

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Impact of the Wind Turbine on the Parameters of the Electricity Supply to an Agricultural Farm

Sustainability ◽

10.3390/su13137279 ◽

2021 ◽

Vol 13 (13) ◽

pp. 7279

Author(s):

Zbigniew Skibko ◽

Magdalena Tymińska ◽

Wacław Romaniuk ◽

Andrzej Borusiewicz

Keyword(s):

Power Plant ◽

Wind Turbine ◽

Wind Power ◽

Rural Areas ◽

Power Plants ◽

Reactive Power ◽

Supply Voltage ◽

Common Source ◽

Voltage Fluctuations ◽

The Impact

Wind power plants are an increasingly common source of electricity located in rural areas. As a result of the high variability of wind power, and thus the generated power, these sources should be classified as unstable sources. In this paper, the authors attempted to determine the impact of wind turbine operation on the parameters of electricity supplied to farms located near the source. As a result of the conducted field tests, variability courses of the basic parameters describing the supply voltage were obtained. The influence of power plant variability on the values of voltage, frequency, and voltage distortion factor was determined. To estimate the capacity of the transmission lines, the reactive power produced in the power plant and its effect on the value of the power factor were determined. The conducted research and analysis showed that the wind power plant significantly influences voltage fluctuations in its immediate vicinity (the maximum value registered was close to 2%, while the value required by law was 2.5%). Although all the recorded values are within limits specified by the current regulations (e.g., the THD value is four times lower than the required value), wind turbines may cause incorrect operation of loads connected nearby. This applies mainly to cases where consumers sensitive to voltage fluctuations are installed in the direct vicinity of the power plant.

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The Impact of Probability Density Functions Assessment on Model Performance for Slope Stability Analysis

Geosciences ◽

10.3390/geosciences11080322 ◽

2021 ◽

Vol 11 (8) ◽

pp. 322

Author(s):

Evelina Volpe ◽

Luca Ciabatta ◽

Diana Salciarini ◽

Stefania Camici ◽

Elisabetta Cattoni ◽

...

Keyword(s):

Probability Density ◽

Central Italy ◽

Model Performance ◽

Probability Density Functions ◽

Slope Instability ◽

Complex Nature ◽

Density Functions ◽

Umbria Region ◽

Input Variables ◽

The Impact

The development of forecasting models for the evaluation of potential slope instability after rainfall events represents an important issue for the scientific community. This topic has received considerable impetus due to the climate change effect on territories, as several studies demonstrate that an increase in global warming can significantly influence the landslide activity and stability conditions of natural and artificial slopes. A consolidated approach in evaluating rainfall-induced landslide hazard is based on the integration of rainfall forecasts and physically based (PB) predictive models through deterministic laws. However, considering the complex nature of the processes and the high variability of the random quantities involved, probabilistic approaches are recommended in order to obtain reliable predictions. A crucial aspect of the stochastic approach is represented by the definition of appropriate probability density functions (pdfs) to model the uncertainty of the input variables as this may have an important effect on the evaluation of the probability of failure (PoF). The role of the pdf definition on reliability analysis is discussed through a comparison of PoF maps generated using Monte Carlo (MC) simulations performed over a study area located in the Umbria region of central Italy. The study revealed that the use of uniform pdfs for the random input variables, often considered when a detailed geotechnical characterization for the soil is not available, could be inappropriate.

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The impact of data quality filtering of opportunistic citizen science data on species distribution model performance

Ecological Modelling ◽

10.1016/j.ecolmodel.2021.109453 ◽

2021 ◽

Vol 444 ◽

pp. 109453

Author(s):

Camille Van Eupen ◽

Dirk Maes ◽

Marc Herremans ◽

Kristijn R.R. Swinnen ◽

Ben Somers ◽

...

Keyword(s):

Data Quality ◽

Citizen Science ◽

Species Distribution ◽

Species Distribution Model ◽

Model Performance ◽

Distribution Model ◽

Science Data ◽

Quality Filtering ◽

The Impact

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Monitoring the Spatial Variation of Aerosol Optical Depth and Its Correlation with Land Use/Land Cover in Wuhan, China: A Perspective of Urban Planning

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18031132 ◽

2021 ◽

Vol 18 (3) ◽

pp. 1132

Author(s):

Qijiao Xie ◽

Qi Sun

Keyword(s):

Land Use ◽

Air Quality ◽

Urban Planning ◽

Land Cover ◽

Aerosol Optical Depth ◽

Optical Depth ◽

Water Bodies ◽

Landsat 8 ◽

Land Use Land Cover ◽

The Impact

Aerosols significantly affect environmental conditions, air quality, and public health locally, regionally, and globally. Examining the impact of land use/land cover (LULC) on aerosol optical depth (AOD) helps to understand how human activities influence air quality and develop suitable solutions. The Landsat 8 image and Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol products in summer in 2018 were used in LULC classification and AOD retrieval in this study. Spatial statistics and correlation analysis about the relationship between LULC and AOD were performed to examine the impact of LULC on AOD in summer in Wuhan, China. Results indicate that the AOD distribution expressed an obvious “basin effect” in urban development areas: higher AOD values concentrated in water bodies with lower terrain, which were surrounded by the high buildings or mountains with lower AOD values. The AOD values were negatively correlated with the vegetated areas while positively correlated to water bodies and construction lands. The impact of LULC on AOD varied with different contexts in all cases, showing a “context effect”. The regression correlations among the normalized difference vegetation index (NDVI), normalized difference built-up index (NDBI), normalized difference water index (NDWI), and AOD in given landscape contexts were much stronger than those throughout the whole study area. These findings provide sound evidence for urban planning, land use management and air quality improvement.

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How far from the road should land cover be assessed? A case study on mesopredator mortality on roads

European Journal of Wildlife Research ◽

10.1007/s10344-021-01461-x ◽

2021 ◽

Vol 67 (2) ◽

Author(s):

Angelika Nieszała ◽

Daniel Klich

Keyword(s):

Land Cover ◽

Red Fox ◽

Home Range Size ◽

Buffer Size ◽

Local Conditions ◽

Explanatory Variables ◽

The Road ◽

Spatially Correlated ◽

European Badger ◽

The Impact

AbstractThe methods used to assess the significance of land cover in the vicinity of a road for the mortality of mesopredators are diverse. In assessing the effect of land cover along the road on road causalities, scientists use various buffer sizes, or even no buffer along the road. The aim of this study was to verify how results of land cover effects on the mortality of mesopredators on roads may differ when analyzing various buffer sizes from the road. We assessed road causalities in the Warmian-Masurian voivodeship (Poland) from 3 consecutive years: 2015, 2016, and 2017. The roads were divided into equal sections of 2000 m each with buffer size of radius: 10, 250, 500, and 1000 m. We analyzed the number of road kills of red fox and European badger separately in a generalized linear model, whereas explanatory variables we used land cover types (based on the Corine Land Cover inventory) and traffic volume. Mean annual mortality from road collisions amounts to 2.36% of the red fox population and 3.82% of the European badger population. We found that the buffer size determines the results of the impact of land cover on mesocarnivore mortality on roads. The red fox differed from the European badger in response to land cover depending on the buffer size. The differences we have shown relate in particular to built-up areas. Our results indicate a 500-m buffer as best reflecting the land cover effects in road kills of both species. This was confirmed by model evaluation and a tendency to use or avoid the vicinity of human settlements of the analyzed species. We concluded that buffer size will probably affect mostly the significance of cover types that are spatially correlated with roads, positively or negatively. We suggest that the home range size of given species in local conditions should be assessed before determining the size of the buffer for analysis.

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