The relationship between landslides,land use,and sediment connectivity is not only a critical interdisciplinary topic,but also remains a challenging issue in assessing dynamic landslide susceptibility within reservoir...The relationship between landslides,land use,and sediment connectivity is not only a critical interdisciplinary topic,but also remains a challenging issue in assessing dynamic landslide susceptibility within reservoir areas.To explore the interactions among landslide,land use changes,and sediment dynamic,this study took Zigui Basin,the head area of the Three Gorges Reservoir,as the study area to examine this triadic relationship by single-factor detection and interactive detection.Here,we utilized Dynamic Attitude(DA)analysis to quantify land use changes and applied the Index of Connectivity(IC)to assess sediment connectivity evolution from 2018 to 2023.A multi-temporal analysis using the Landslide Susceptibility Index(LSI)was conducted to evaluate the degree of transformation in the three objects and the influence of these changes on the landslide susceptibility.According to the spatial analyst and statistics tools in ArcGIS,the results reveal that most of the landslides distributed in areas with high land use dynamic attitude,such as cultivated land transfers to forestland or garden plot,and the garden plot continuously increased across the study period with largest variation of 5%and an increment of 1.9%.Furthermore,linkage between land use and sediment transport can be effectively quantified by IC,and the resulting map indicated that garden plot increased,and catchment channel characteristics had a greater influence on the IC value than differences in vegetation cover.A comprehensive evaluation of the differences among the susceptibility maps reveals that the very high susceptibility classes are predominantly influenced by enhanced connectivity,whereas land use change has a greater effect on medium-low susceptibility region than that of sediment evolution.That is,both changes of land use and connectivity have positively correlated with landslide activity,but they exhibit differential influences on landslides susceptibility.展开更多
Severe soil and water loss have led to widespread land degradation on the Loess Plateau in China.Exploring the relationship between land use and sediment connectivity can be beneficial to control soil erosion.In this ...Severe soil and water loss have led to widespread land degradation on the Loess Plateau in China.Exploring the relationship between land use and sediment connectivity can be beneficial to control soil erosion.In this study,three catchments in the Yanhe River Basin on the Loess Plateau were selected to analyse the relationship between land use and sediment connectivity using grey correlation method.Index of connectivity(IC)was employed to quantify sediment connectivity,including two flow direction algorithms(D8 and D-infinity)and two final targets of sediment transport(outlet and main channel of catchment).Then,11 landscape metrics were used to evaluate the land use spatial patterns of catchments.By comparing the IC value ranges,histograms and classes,and their relationship with remote sensing images of the two flow direction algorithms,we find that the D8 algorithm is more suitable for this study area.The results showed that the three catchments are characterized by high sediment connectivity in the grassland and forest close to the channel.In addition,the roads and bare land close to the channel also have high or medium sediment connectivity.Grey correlation analysis showed that landscape division index(DIVISION),fractal dimension index(FRACMN),aggregation index(AI),total class area,patch cohesion index(COHESION),and largest patch index(LPI)indices were the main factors that affect sediment connectivity at the class scale.At the landscape scale,the landscape shape index(LSI),Shannon’s diversity index(SHDI),and gully density have an essential effect on sediment connectivity.This condition provides a way to control the sediment connectivity in the watershed by transforming land use type or changing its spatial pattern,but specific adjustment measures have to be further explored.展开更多
Torrential processes are among the main actors responsible for sediment production and mobility in mountain catchments.For this reason,the understanding of preferential pathways for sediment routing has become a prior...Torrential processes are among the main actors responsible for sediment production and mobility in mountain catchments.For this reason,the understanding of preferential pathways for sediment routing has become a priority in hazard assessment and mitigation.In this context,the sediment Connectivity Index(IC)enables to analyse the existing linkage between sediment sources and the selected target(channel network or catchment outlet).The IC is a grid-based index that allows fast computation of sediment connectivity based on landscape information derived from a single Digital Terrain Model(DTM).The index computation is based on the log-ratio between an upslope and a downslope component,including information about drainage area,slope,terrain roughness,and distance to the analysis target(e.g.outlet).The output is a map that highlights the degree of structural connectivity of sediment pathways over analysed catchments.Until now,these maps are however rarely used to help defining debris-flow hazard maps,notably due to a lack of guidelines to interpret the IC spatial distribution.This paper proposes an exploitation procedure along profiles to extract more information from the analysis of mapped IC values.The methodology relies on the analysis of the IC and its component variables along the main channel profile,integrated with information about sediment budgeting derived from Difference of DEMs(DoD).The study of connectivity was applied in the unmanaged sub-catchment(without torrent control works)of the Rio Soial(Autonomous Province of Trento–NE Italy)to understanding the geomorphic evolution of the area after five debris flows(in ten years)and the related changes of sediment connectivity.Using a recent DTM as validation,we demonstrated how an IC analysis over the older DTM can help predicting geomorphic changes and associated hazards.The results show an IC aptitude to capture geomorphic trajectories,anticipate debris flow deposits in a specific channel location,and depict preferential routing pathways.展开更多
Sediment delivery ratio can be used as a measure of sediment connectivity and it can be linked to the structural connectivity(morphological unit, slope length, slope steepness, travel time) of a basin and to the funct...Sediment delivery ratio can be used as a measure of sediment connectivity and it can be linked to the structural connectivity(morphological unit, slope length, slope steepness, travel time) of a basin and to the functional connectivity(rainfall-runoff processes at morphological unit scale). In this paper the sediment connectivity approach was applied at basin scale both using Sediment Delivery Distributed(SEDD) model, which takes into account the hillslope sediment transport, and sediment yield measurements carried out at SPA2 experimental basin(Sicily, Italy). The expression of the sediment delivery ratio SDRi of a morphological unit was modified for highlighting two components corresponding to the structural(SDR_(L,i)) and functional(SDR_(F,i)) sediment connectivity, respectively. For SPA2 basin the frequency distribution of the travel time of each morphological unit was used to estimate the coefficient βL of the structural component of the sediment delivery ratio of each morphological unit. Then, using the sediment yield measurements carried out at the outlet of the experimental SPA2 basin in the period April 2000-March 2015, the SEDD model was calibrated at event scale for estimating the coefficient βF of the functional component of the sediment delivery ratio. At event scale the developed analysis stated that the functional connectivity is dependent on the magnitude of erosion events. Intermediate and high events, which were characterized by the lowest values of the functional coefficient, determine a more high functional connectivity and are characterized by a more efficient sediment transport along the hillslopes. Finally, at annual scale, the model was calibrated for the period 2000-2015 and relationships for estimating the coefficient βF,a of the functional component of the sediment delivery ratio taking into account the intensity of erosion events occurring in each year were determined. At annual scale, the analysis demonstrated that the functional coefficient was always greater than the landscape coefficient and the sediment connectivity was always controlled by the low values of the functional component.展开更多
In this paper we introduce HOTSED,a novel,innovative GIS-based model designed for assessing potential hotspots of sediment dynamics at watershed scale.HOTSED integrates geomorphic spatial information with both structu...In this paper we introduce HOTSED,a novel,innovative GIS-based model designed for assessing potential hotspots of sediment dynamics at watershed scale.HOTSED integrates geomorphic spatial information with both structural and functional properties of connectivity.HOTSED provides a single and intuitive output that depicts the location of sediment source hotspots.Moreover,it enables the identification of“relative hazard”classes for sediment production and related effects.The general methodological framework is based on the initial elaboration of an Inventory Map(IM)of sediment-related landforms and processes,along with the implementation of a corresponding database.Subsequently,we used data stored in the IM to estimate the geomorphic Potential of Sediment Sources(PSS)through a relative scoring system.Furthermore,we computed Structural Sediment Connectivity(STC)and the Potential for Sediment Transport(PST)by combining terrain and hydrological parameters,vegetation roughness,and rainfall erosivity.Afterwards,PSS,STC,and PST components are integrated through a raster-based calculation method yielding the HOTSED model.We tested the HOTSED procedure in the upper Val d’Arda-Mignano watershed,which is a representative geomorphologically highly active Mediterranean area of the Northern Apennines(Italy).Through photointerpretation,terrain analysis,and fieldwork,we mapped sedimentrelated geomorphic features for a total of 4640 ha including:badlands and gullies(0.26%),rill-interrill erosion(15.03%),fluvial erosion(0.03%),landslides(70.06%),litho-structural erosional systems(0.87%),slope deposits(12.56%),and alluvial deposits(1.19%).HOTSED revealed hotspots with a very high hazard potential located near main channels or upstream of the reservoir.These areas are often linked with active landslides highly connected to the drainage system and frequently associated with other processes like bank erosion or surficial soil erosion.The model also highlighted linear hotspots corresponding to drainages flowing alongside or intersecting complex geomorphic systems such as landslides.Furthermore,HOTSED identified areas where sediments are stored in depositional landforms,exhibiting a low hazard potential,considering both low geomorphic potential and sediment connectivity.Our conceptual model is generally applicable but proves to be particularly effective in areas characterized by complex and polygenetic geomorphic systems,such as the Northern Apennines.HOTSED offers a valuable tool for watershed authorities to support sustainable watershed and reservoir management.展开更多
基金supported by the National Key R&D Program of China(Grant No.2024YFC3012702)National Natural Science Foundation of China(Grant No.42371014)+2 种基金Hubei Provincial Engineering Research Center of Slope Habitat Construction Technique Using Cement-based Materials Open Research Program(Grant No.2022SNJ11)National Natural Science Foundation of China(Grant No.42201094)Hubei Key Laboratory of Disaster Prevention and Mitigation(China Three Gorges University)Open Research Program(Grant No.2022KJZ12)。
文摘The relationship between landslides,land use,and sediment connectivity is not only a critical interdisciplinary topic,but also remains a challenging issue in assessing dynamic landslide susceptibility within reservoir areas.To explore the interactions among landslide,land use changes,and sediment dynamic,this study took Zigui Basin,the head area of the Three Gorges Reservoir,as the study area to examine this triadic relationship by single-factor detection and interactive detection.Here,we utilized Dynamic Attitude(DA)analysis to quantify land use changes and applied the Index of Connectivity(IC)to assess sediment connectivity evolution from 2018 to 2023.A multi-temporal analysis using the Landslide Susceptibility Index(LSI)was conducted to evaluate the degree of transformation in the three objects and the influence of these changes on the landslide susceptibility.According to the spatial analyst and statistics tools in ArcGIS,the results reveal that most of the landslides distributed in areas with high land use dynamic attitude,such as cultivated land transfers to forestland or garden plot,and the garden plot continuously increased across the study period with largest variation of 5%and an increment of 1.9%.Furthermore,linkage between land use and sediment transport can be effectively quantified by IC,and the resulting map indicated that garden plot increased,and catchment channel characteristics had a greater influence on the IC value than differences in vegetation cover.A comprehensive evaluation of the differences among the susceptibility maps reveals that the very high susceptibility classes are predominantly influenced by enhanced connectivity,whereas land use change has a greater effect on medium-low susceptibility region than that of sediment evolution.That is,both changes of land use and connectivity have positively correlated with landslide activity,but they exhibit differential influences on landslides susceptibility.
基金supported by the National Natural Science Foundation of China(42077078,U2243213)。
文摘Severe soil and water loss have led to widespread land degradation on the Loess Plateau in China.Exploring the relationship between land use and sediment connectivity can be beneficial to control soil erosion.In this study,three catchments in the Yanhe River Basin on the Loess Plateau were selected to analyse the relationship between land use and sediment connectivity using grey correlation method.Index of connectivity(IC)was employed to quantify sediment connectivity,including two flow direction algorithms(D8 and D-infinity)and two final targets of sediment transport(outlet and main channel of catchment).Then,11 landscape metrics were used to evaluate the land use spatial patterns of catchments.By comparing the IC value ranges,histograms and classes,and their relationship with remote sensing images of the two flow direction algorithms,we find that the D8 algorithm is more suitable for this study area.The results showed that the three catchments are characterized by high sediment connectivity in the grassland and forest close to the channel.In addition,the roads and bare land close to the channel also have high or medium sediment connectivity.Grey correlation analysis showed that landscape division index(DIVISION),fractal dimension index(FRACMN),aggregation index(AI),total class area,patch cohesion index(COHESION),and largest patch index(LPI)indices were the main factors that affect sediment connectivity at the class scale.At the landscape scale,the landscape shape index(LSI),Shannon’s diversity index(SHDI),and gully density have an essential effect on sediment connectivity.This condition provides a way to control the sediment connectivity in the watershed by transforming land use type or changing its spatial pattern,but specific adjustment measures have to be further explored.
文摘Torrential processes are among the main actors responsible for sediment production and mobility in mountain catchments.For this reason,the understanding of preferential pathways for sediment routing has become a priority in hazard assessment and mitigation.In this context,the sediment Connectivity Index(IC)enables to analyse the existing linkage between sediment sources and the selected target(channel network or catchment outlet).The IC is a grid-based index that allows fast computation of sediment connectivity based on landscape information derived from a single Digital Terrain Model(DTM).The index computation is based on the log-ratio between an upslope and a downslope component,including information about drainage area,slope,terrain roughness,and distance to the analysis target(e.g.outlet).The output is a map that highlights the degree of structural connectivity of sediment pathways over analysed catchments.Until now,these maps are however rarely used to help defining debris-flow hazard maps,notably due to a lack of guidelines to interpret the IC spatial distribution.This paper proposes an exploitation procedure along profiles to extract more information from the analysis of mapped IC values.The methodology relies on the analysis of the IC and its component variables along the main channel profile,integrated with information about sediment budgeting derived from Difference of DEMs(DoD).The study of connectivity was applied in the unmanaged sub-catchment(without torrent control works)of the Rio Soial(Autonomous Province of Trento–NE Italy)to understanding the geomorphic evolution of the area after five debris flows(in ten years)and the related changes of sediment connectivity.Using a recent DTM as validation,we demonstrated how an IC analysis over the older DTM can help predicting geomorphic changes and associated hazards.The results show an IC aptitude to capture geomorphic trajectories,anticipate debris flow deposits in a specific channel location,and depict preferential routing pathways.
文摘Sediment delivery ratio can be used as a measure of sediment connectivity and it can be linked to the structural connectivity(morphological unit, slope length, slope steepness, travel time) of a basin and to the functional connectivity(rainfall-runoff processes at morphological unit scale). In this paper the sediment connectivity approach was applied at basin scale both using Sediment Delivery Distributed(SEDD) model, which takes into account the hillslope sediment transport, and sediment yield measurements carried out at SPA2 experimental basin(Sicily, Italy). The expression of the sediment delivery ratio SDRi of a morphological unit was modified for highlighting two components corresponding to the structural(SDR_(L,i)) and functional(SDR_(F,i)) sediment connectivity, respectively. For SPA2 basin the frequency distribution of the travel time of each morphological unit was used to estimate the coefficient βL of the structural component of the sediment delivery ratio of each morphological unit. Then, using the sediment yield measurements carried out at the outlet of the experimental SPA2 basin in the period April 2000-March 2015, the SEDD model was calibrated at event scale for estimating the coefficient βF of the functional component of the sediment delivery ratio. At event scale the developed analysis stated that the functional connectivity is dependent on the magnitude of erosion events. Intermediate and high events, which were characterized by the lowest values of the functional coefficient, determine a more high functional connectivity and are characterized by a more efficient sediment transport along the hillslopes. Finally, at annual scale, the model was calibrated for the period 2000-2015 and relationships for estimating the coefficient βF,a of the functional component of the sediment delivery ratio taking into account the intensity of erosion events occurring in each year were determined. At annual scale, the analysis demonstrated that the functional coefficient was always greater than the landscape coefficient and the sediment connectivity was always controlled by the low values of the functional component.
基金the financial support of the Earth and Environmental Sciences PhD-PON program(Research&Innovation,2014-2020,Education and research for recovery-REACT-EU,DOT1322534-4)of University of Pavia,Department of Earth and Environmental Sciencesthe financial support of the RTDA-PON program(Research&Innovation 2014-2020,Education and research for recovery-REACT-EU,C6-G-32370-3),University of Milano-Bicocca,Department of Earth and Environmental Sciencessupported by the Belmont ABRESO project(https://www.belmontforum.org).
文摘In this paper we introduce HOTSED,a novel,innovative GIS-based model designed for assessing potential hotspots of sediment dynamics at watershed scale.HOTSED integrates geomorphic spatial information with both structural and functional properties of connectivity.HOTSED provides a single and intuitive output that depicts the location of sediment source hotspots.Moreover,it enables the identification of“relative hazard”classes for sediment production and related effects.The general methodological framework is based on the initial elaboration of an Inventory Map(IM)of sediment-related landforms and processes,along with the implementation of a corresponding database.Subsequently,we used data stored in the IM to estimate the geomorphic Potential of Sediment Sources(PSS)through a relative scoring system.Furthermore,we computed Structural Sediment Connectivity(STC)and the Potential for Sediment Transport(PST)by combining terrain and hydrological parameters,vegetation roughness,and rainfall erosivity.Afterwards,PSS,STC,and PST components are integrated through a raster-based calculation method yielding the HOTSED model.We tested the HOTSED procedure in the upper Val d’Arda-Mignano watershed,which is a representative geomorphologically highly active Mediterranean area of the Northern Apennines(Italy).Through photointerpretation,terrain analysis,and fieldwork,we mapped sedimentrelated geomorphic features for a total of 4640 ha including:badlands and gullies(0.26%),rill-interrill erosion(15.03%),fluvial erosion(0.03%),landslides(70.06%),litho-structural erosional systems(0.87%),slope deposits(12.56%),and alluvial deposits(1.19%).HOTSED revealed hotspots with a very high hazard potential located near main channels or upstream of the reservoir.These areas are often linked with active landslides highly connected to the drainage system and frequently associated with other processes like bank erosion or surficial soil erosion.The model also highlighted linear hotspots corresponding to drainages flowing alongside or intersecting complex geomorphic systems such as landslides.Furthermore,HOTSED identified areas where sediments are stored in depositional landforms,exhibiting a low hazard potential,considering both low geomorphic potential and sediment connectivity.Our conceptual model is generally applicable but proves to be particularly effective in areas characterized by complex and polygenetic geomorphic systems,such as the Northern Apennines.HOTSED offers a valuable tool for watershed authorities to support sustainable watershed and reservoir management.
