Method, device and apparatus for determining sediment connectivity

Abstract

The application provides a method, device and equipment for determining sediment connectivity, which comprises the following steps: obtaining effective concentration areas of each grid unit affected by land use in a target basin; obtaining weight factors and slope gradients of each grid unit; obtaining runoff flow velocity factors of each grid unit, and the concentration path lengths of each grid unit to the nearest river or the nearest deposition area; and determining a sediment connectivity index of the target basin according to the effective concentration areas, the weight factors, the slope gradients, the runoff flow velocity factors and the concentration path lengths. The effective concentration areas are introduced in the uphill component, which can reflect the influence of the land use type, boundary, quantity and position of the uphill on the uphill concentration area. The runoff flow velocity factors are introduced in the downhill component, which enhances the description and response capability of the sediment transport process. Therefore, the present scheme has a clearer physical meaning than other existing algorithms, and can more comprehensively and sensitively represent the erosion and sediment production influence of the land use change of the basin.

Description

Technical Field

[0001] This application relates to the field of soil erosion technology, and in particular to a method, apparatus and equipment for determining sediment connectivity. Background Technology

[0002] Soil erosion is one of the major drivers of global land degradation. At the watershed scale, the processes of sediment transport, deposition, and redistribution caused by soil erosion influence the characteristics and mechanisms of sediment cascades, ultimately determining the flux and distribution of sediment yield from watershed erosion. Adjustments to land use types and structures, as well as their patch configurations, are important means of integrated watershed management, including soil and water conservation. Revealing the mechanisms by which watershed land use patterns influence sediment yield from erosion can provide a theoretical basis for more scientific and effective watershed management.

[0003] The Index of Connectivity (IC), a distributed connectivity index, has attracted considerable attention in recent years. It assesses the overall sediment connectivity of a watershed system by measuring the probability of sediment arriving at the river channel from different locations within the watershed, without relying on field observations. This has led to its widespread application in watershed sediment transport and generation processes. Furthermore, to meet the application needs and effects under different scenarios, a series of improved IC algorithms with added or replaced parameters have emerged to reflect more influencing factors or adjust the sensitivity and relative contribution of different influencing factors.

[0004] However, existing IC algorithms cannot accurately indicate the impact of land use change on sediment yield within the upslope confluence path of a watershed, and they lack a clear physical meaning overall. This limits their application scope and effectiveness, as they cannot provide an effective approach for watershed sediment connectivity research and erosion transport prediction. Summary of the Invention

[0005] This application provides a method, apparatus, and equipment for determining sediment connectivity, in order to address the problems that existing IC algorithms cannot accurately indicate the erosion and sediment yield impact of land use change within the upslope confluence path of a watershed, and lack a clear physical meaning overall, resulting in a relatively weak explanation of the physical processes of sediment transport in the watershed. Consequently, they cannot provide an effective approach for watershed sediment connectivity research and erosion and transport prediction, thus limiting their application scope and effectiveness.

[0006] In a first aspect, this application provides a method for determining sediment connectivity, comprising:

[0007] Obtain the effective runoff area of ​​each grid cell in the target watershed that is affected by land use;

[0008] Obtain the weight factor and slope of each grid cell, wherein the weight factor is used to indicate the magnitude of the influence of the sediment connectivity factor on the corresponding grid cell;

[0009] Obtain the runoff velocity factor of each grid cell, and the confluence path length of each grid cell to the nearest channel or the nearest sedimentation zone;

[0010] The sediment connectivity index of the target watershed is determined based on the effective catchment area, the weighting factor, the slope, the runoff velocity factor, and the catchment path length. The sediment connectivity index is used to indicate the sediment connectivity of the target watershed.

[0011] In one possible implementation, obtaining the effective runoff area of ​​each grid cell affected by land use in the target watershed includes:

[0012] The upslope confluence area of ​​each grid cell is determined based on the confluence direction;

[0013] Determine the catchment area contribution rate of each of the grid cells;

[0014] The effective confluence area of ​​each grid cell is determined based on the uphill confluence area contribution, the confluence area contribution rate, and the side length of each grid cell.

[0015] In one possible implementation, determining the catchment area contribution rate of each of the grid cells includes:

[0016] For any grid cell, a first runoff coefficient of the grid cell is determined based on the land use type of the grid cell;

[0017] Determine the second runoff coefficient corresponding to fallow land;

[0018] The flow contribution rate of the grid cell is determined based on the first flow generation coefficient and the second flow generation coefficient.

[0019] In one possible implementation, obtaining the weight factors for each of the grid cells includes:

[0020] For any given grid cell, obtain the average rainfall erosivity factor of the upslope runoff area of ​​that grid cell;

[0021] Obtain the average soil erodibility factor value of the uphill runoff area;

[0022] Obtain the average vegetation cover and management factor value and the average soil and water conservation measures factor value of the upslope confluence area;

[0023] The weighting factor of the grid cell is determined based on the average rainfall erosivity factor, the average soil erosibility factor, the average vegetation cover and management factor, and the average soil and water conservation measures factor.

[0024] In one possible implementation, the target watershed includes multiple observation points; obtaining the average rainfall erosivity factor of the upslope runoff area of ​​the grid cell includes:

[0025] Obtain the erosive rainfall at each observation point during a first preset time period;

[0026] The annual rainfall erosivity of each observation point is determined based on the erosive rainfall amount at each observation point during the first preset time period.

[0027] Based on the annual rainfall erosivity at each observation point, determine the annual rainfall erosivity of all grid cells within the target watershed;

[0028] The average rainfall erosivity factor is determined based on the annual rainfall erosivity of all grid cells within the target watershed.

[0029] In one possible implementation, obtaining the runoff velocity factor for each of the grid cells includes:

[0030] The hindrance coefficient of each grid cell is determined based on the Manning roughness corresponding to the land use type of each grid cell.

[0031] The runoff velocity factor of each grid cell is determined based on the slope and stagnation coefficient of each grid cell.

[0032] In one possible implementation, the method further includes:

[0033] Based on the sediment connectivity index, determine the change value of the first sediment connectivity index corresponding to each grid unit in each type of land use change patch within the second preset time period;

[0034] Based on the sediment connectivity index, determine the change value of the second sediment connectivity index corresponding to each grid unit outside each type of land use change patch within the second preset time period;

[0035] Based on the changes in the first and second sediment connectivity indices, the local and external contribution rates of sediment connectivity affecting the target watershed are determined.

[0036] Secondly, this application provides an apparatus for determining the connectivity of sediment, comprising:

[0037] The first acquisition module is used to acquire the effective runoff area of ​​each grid cell affected by land use in the target watershed;

[0038] The second acquisition module is used to acquire the weight factor and slope of each grid cell, wherein the weight factor is used to indicate the magnitude of the influence of the sediment connectivity factor on the corresponding grid cell;

[0039] The third acquisition module is used to acquire the runoff velocity factor of each grid cell and the confluence path length of each grid cell to the nearest channel or the nearest sedimentation area.

[0040] The processing module is used to determine the sediment connectivity index of the target watershed based on the effective catchment area, the weighting factor, the slope, the runoff velocity factor, and the catchment path length. The sediment connectivity index is used to indicate the sediment connectivity of the target watershed.

[0041] In one possible implementation, the first acquisition module is specifically used for:

[0042] The upslope confluence area of ​​each grid cell is determined based on the confluence direction;

[0043] Determine the catchment area contribution rate of each of the grid cells;

[0044] The effective confluence area of ​​each grid cell is determined based on the uphill confluence area contribution, the confluence area contribution rate, and the side length of each grid cell.

[0045] In one possible implementation, the first acquisition module is specifically used for:

[0046] For any grid cell, a first runoff coefficient of the grid cell is determined based on the land use type of the grid cell;

[0047] Determine the second runoff coefficient corresponding to fallow land;

[0048] The flow contribution rate of the grid cell is determined based on the first flow generation coefficient and the second flow generation coefficient.

[0049] In one possible implementation, the second acquisition module is specifically used for:

[0050] For any given grid cell, obtain the average rainfall erosivity factor of the upslope runoff area of ​​that grid cell;

[0051] Obtain the average soil erodibility factor value of the uphill runoff area;

[0052] Obtain the average vegetation cover and management factor value and the average soil and water conservation measures factor value of the upslope confluence area;

[0053] The weighting factor of the grid cell is determined based on the average rainfall erosivity factor, the average soil erosibility factor, the average vegetation cover and management factor, and the average soil and water conservation measures factor.

[0054] In one possible implementation, the target watershed includes multiple observation points; the second acquisition module is specifically used for:

[0055] Obtain the erosive rainfall at each observation point during a first preset time period;

[0056] The annual rainfall erosivity of each observation point is determined based on the erosive rainfall amount at each observation point during the first preset time period.

[0057] Based on the annual rainfall erosivity at each observation point, determine the annual rainfall erosivity of all grid cells within the target watershed;

[0058] The average rainfall erosivity factor is determined based on the annual rainfall erosivity of all grid cells within the target watershed.

[0059] In one possible implementation, the third acquisition module is specifically used for:

[0060] The hindrance coefficient of each grid cell is determined based on the Manning roughness corresponding to the land use type of each grid cell.

[0061] The runoff velocity factor of each grid cell is determined based on the slope and stagnation coefficient of each grid cell.

[0062] In one possible implementation, the processing module is further configured to:

[0063] Based on the sediment connectivity index, determine the change value of the first sediment connectivity index corresponding to each grid unit in each type of land use change patch within the second preset time period;

[0064] Based on the sediment connectivity index, determine the change value of the second sediment connectivity index corresponding to each grid unit outside each type of land use change patch within the second preset time period;

[0065] Based on the changes in the first and second sediment connectivity indices, the local and external contribution rates of sediment connectivity affecting the target watershed are determined.

[0066] Thirdly, this application provides an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the method for determining sediment connectivity as described in any of the first aspects.

[0067] Fourthly, this application provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for determining sediment connectivity as described in any of the first aspects.

[0068] Fifthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the method for determining sediment connectivity as described in any of the first aspects.

[0069] The method, apparatus, and equipment provided in this application for determining sediment connectivity first obtain the effective runoff area of ​​each grid cell affected by land use in the target watershed, and then obtain the weighting factor and slope of each grid cell. The weighting factor is used to indicate the magnitude of the influence of sediment connectivity factors on the corresponding grid cell. Next, the runoff velocity factor of each grid cell and the runoff path length from each grid cell to the nearest channel or the nearest depositional area are obtained. Finally, based on the effective runoff area, weighting factor, slope, runoff velocity factor, and runoff path length, the sediment connectivity index of the target watershed is determined. The sediment connectivity index is used to indicate the sediment connectivity of the target watershed. This application's embodiments address the main common shortcomings of existing sediment connectivity algorithms by proposing a new improved algorithm and a method for separating and quantifying the local and exogenous contributions of watershed land use change to erosion and sediment production. The improved sediment connectivity index algorithm proposed in this application's embodiments introduces an original effective runoff area into the upslope component, which can reflect the influence of upslope land use type, boundary, quantity, and location on the upslope runoff area. Introducing a runoff velocity factor into the downslope component enhances the description and response capabilities to sediment transport processes. The resulting improved sediment connectivity index algorithm has a clearer physical meaning than other existing algorithms and can more comprehensively and sensitively characterize the erosion and sediment yield impacts of watershed land use change. Attached Figure Description

[0070] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0071] Figure 1 A flowchart illustrating the method for determining sediment connectivity provided in an embodiment of this application;

[0072] Figure 2 A schematic diagram of a typical small watershed provided in the embodiments of this application;

[0073] Figure 3 A schematic diagram showing the correlation between different sediment connectivity indices and runoff depth and sediment transport modulus in the Lüergou watershed, provided for embodiments of this application.

[0074] Figure 4A schematic diagram illustrating the local and off-site contribution rates of land use change on sediment connectivity index in the Lüergou watershed during a typical time period, as provided in this application embodiment.

[0075] Figure 5 A schematic diagram of the structure of the device for determining the connectivity of sediment provided in the embodiments of this application;

[0076] Figure 6 This is a schematic diagram of the physical structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0077] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0078] Soil erosion is one of the major drivers of global land degradation. At the watershed scale, the processes of sediment transport, deposition, and redistribution caused by soil erosion influence the characteristics and mechanisms of sediment cascades, ultimately determining the flux and distribution of sediment yield from watershed erosion. Adjustments to land use types and structures, as well as their patch configurations, are important means of integrated watershed management, including soil and water conservation. Revealing the mechanisms by which watershed land use patterns influence sediment yield from erosion can provide a theoretical basis for more scientific and effective watershed management.

[0079] As research has deepened, the methods for characterizing land use patterns have gradually shifted from traditional landscape indicators and source-sink theory indices to the concept of "connectivity." Among them, the earliest proposed concept of "sediment connectivity" is mainly used to characterize the sediment transport capacity of a watershed system and explain the sediment transport paths and processes between different landforms and landscape units in a watershed. It has been widely used in the study of the impact of watershed erosion and sediment yield on land use change. The calculation method of sediment connectivity can be found in the following formula (1):

[0080]

[0081] Wherein, IC is the sediment connectivity index of the watershed, and the value of IC ranges from [-∞, +∞]. The larger the value, the better the sediment connectivity and the stronger the sediment transport capacity; D up D represents the uphill component. dn Indicates the downhill component; w i The weighting factor for the i-th raster cell is assigned using the C factor of the Revised Universal Soil Loss Equation (RUSLE), primarily reflecting the impact of vegetation cover; si Let A be the slope (m / m) of the i-th grid cell; and let A be the upslope catchment area (m²) of the i-th grid cell. 2 );d i The confluence path length (m) from the i-th grid cell to the nearest channel or sedimentation zone; The average uphill weighting factor for the i-th grid cell; N represents the average uphill slope (m / m) of the i-th grid cell; p This represents the total number of all grid cells on the downhill confluence path of the i-th grid cell.

[0082] The sediment connectivity index, as a connectivity characterization index with distributed characteristics, has attracted much attention in recent years. It can assess the overall sediment connectivity of a watershed system by using the probability of sediment arriving at the river channel from different locations in the watershed without relying on field observations, and has been widely used in the study of sediment production and transport processes in watersheds.

[0083] Meanwhile, to address the application needs and effects in different scenarios, a series of improved IC algorithms with added or replaced parameters have emerged to reflect more influencing factors or adjust the sensitivity and relative contribution of different influencing factors. However, existing IC algorithms still have two common shortcomings:

[0084] Firstly, all different algorithms include the upslope runoff area parameter of the grid cell, which is used to characterize the surface runoff that may be formed on the upslope during rainfall and its potential impact on soil separation and transport of the grid cell.

[0085] In specific calculations, this parameter is based on the Digital Elevation Model (DEM) to determine the theoretical uphill runoff area, neglecting the runoff impact of factors such as land use change within the uphill runoff path, and the resulting changes in erosion and sediment transport within the grid cell. In reality, the land use / cover type, boundaries, quantity, and location of uphill cells all have a significant impact on the uphill runoff area. Soil and water conservation measures such as vegetation hedges and drainage ditches can also reduce or eliminate runoff in some land use patches. These factors will determine the final runoff conditions on the downhill slope, thereby altering downhill erosion and sediment yield and the sediment connectivity of the runoff path.

[0086] Secondly, all different algorithms retain the original structure of dividing the upslope and downslope components. The upslope component represents the potential for sediment separation and downward transport caused by the underlying surface conditions such as topography and land use in the upper runoff area of ​​the grid cell. The downslope component represents the sediment transport potential determined by the underlying surface conditions such as topography and land use in the runoff path from the grid cell down to the river channel or the nearest sedimentary area.

[0087] Although the parameters contained in the two components are constantly adjusted, the overall composition of each component still lacks a clear physical meaning and fails to establish an intuitive correspondence or effective relationship with other common important parameters. As a result, IC and its related improvement indexes remain weak in explaining the physical processes of watershed sediment transport, which limits their application scope and effectiveness in watershed erosion and sediment yield research.

[0088] In addition, land use change, as a crucial factor determining sediment yield (IC), plays both local and ex-situ roles in influencing the structural and functional connectivity of sediment transport and production within a watershed. The former refers to its impact on sediment erosion, transport, and deposition within its coverage area; the latter refers to its impact on sediment erosion, transport, and deposition in other areas within its confluence pathway. Clearly defining the local and ex-situ roles of land use change in erosion and sediment yield provides a scientific basis for more efficient and precise watershed management and guides the optimal allocation of soil and water conservation measures such as vegetation. For example, when increasing the same amount of vegetation to control watershed erosion and sediment yield, separating and comparing the local and ex-situ roles of different vegetation distribution patterns will help decision-makers determine the optimal implementation plan, thereby achieving more ideal results with the same or similar inputs in watershed management. However, existing studies on the impact of watershed land use change on erosion and sediment yield based on IC have not distinguished and quantitatively separated the contributions of land use change within and outside its coverage area to watershed erosion and sediment yield, limiting in-depth analysis of the mechanisms by which land use patterns, such as vegetation, influence watershed erosion and sediment yield.

[0089] To address the aforementioned technical problems, this application proposes a scheme for determining sediment connectivity. This scheme provides a more comprehensive and sensitive reflection of the impact of land use change, with a clearer physical meaning, and establishes a method for separating the local and exogenous sediment reduction contributions of land use change using a novel, improved IC algorithm. This provides an effective approach for watershed sediment connectivity research and erosion transport prediction, and offers a scientific basis for optimizing watershed land use patterns. The scheme of this application will be described below with reference to the accompanying drawings.

[0090] Figure 1 A flowchart illustrating the method for determining sediment connectivity provided in this application embodiment is shown below. Figure 1 As shown, the method may include:

[0091] S11, obtain the effective runoff area of ​​each grid cell in the target watershed that is affected by land use.

[0092] The target watershed is the watershed whose sediment connectivity needs to be determined, and each grid cell is a basic unit obtained by dividing the target watershed into parts of a specified size. By obtaining the effective runoff area of ​​each grid cell in the target watershed that is affected by land use, the upslope component is improved based on the effective runoff area that takes into account the impact of land use.

[0093] In the upslope component of IC, the effective runoff area (Ar) that takes into account the impact of land use is used instead of the theoretical runoff area based on the accumulation of DEM flow direction in the existing technology, so as to reflect the impact of upslope land use change runoff on downslope erosion and sediment yield.

[0094] For the effective runoff area (Ar) in the upslope component, it is obtained programmatically based on ASCII format data converted from land use and flow direction raster data. The specific calculation process is as follows: First, input the land use raster data, calculate the runoff area contribution rate of each raster cell according to the runoff generation coefficient corresponding to different land use types, and multiply it by the area of ​​the raster cell to obtain the runoff contribution area; then, for each raster cell, according to the runoff direction, accumulate the runoff contribution areas of all raster cells within its upslope runoff path to obtain the effective runoff area of ​​that raster cell; finally, convert the calculated effective runoff area data of each raster cell in ASCII format to Grid format data through ArcGIS for subsequent calculation and visualization processing.

[0095] For example, the uphill confluence contribution area of ​​each grid cell can be determined first based on the confluence direction. After determining the uphill confluence contribution area of ​​each grid cell, the confluence area contribution rate of each grid cell can be determined.

[0096] In one possible implementation, for any grid cell, the first runoff coefficient of the grid cell and the second runoff coefficient corresponding to fallow land can be determined based on the land use type of the grid cell. Then, the runoff area contribution rate of the grid cell can be determined based on the first and second runoff coefficients. The solution process for the runoff area contribution rate of any nth grid cell can be found in the following equation (2):

[0097] ω n =r l / r f (2)

[0098] Each grid cell has a corresponding flow path. For the i-th grid cell, n represents the grid cells into which the flow path enters the i-th grid cell, and r l r is the first runoff coefficient determined based on the land use type of grid cell n; f ω is the second runoff coefficient corresponding to fallow land. nLet n be the contribution rate of the flow area to the grid cell n. For any grid cell n into the i-th grid cell via the flow path, the contribution rate of grid cell n to the i-th grid cell can be obtained using the above formula (2). Then, based on the contribution rates of each grid cell n into the i-th grid cell via all flow paths, the contribution rate of the i-th grid cell can be obtained.

[0099] After determining the upslope runoff contribution area and the runoff contribution rate of each grid cell, the effective runoff area of ​​each grid cell can be determined based on the upslope runoff contribution area, the runoff contribution rate, and the side length of each grid cell. This process can be seen in the following equation (3):

[0100] A ri =∑(D 2 +A rn )ω n (3)

[0101] Among them, A ri The effective catchment area (m²) of the i-th grid cell considering the upslope land use / cover impact. 2 A is obtained by accumulating the effective confluence contribution surfaces of all grid cells flowing into the i-th grid cell; for grid cell n flowing into the i-th grid cell, A rn The uphill confluence area (m²) of grid cell n calculated based on the confluence direction. 2 D is the side length of the grid cell (m), ω n The solution can be found in equation (2) above, and will not be repeated here.

[0102] S12, obtain the weight factor and slope of each grid cell. The weight factor is used to indicate the magnitude of the influence of sediment connectivity factors on the corresponding grid cells.

[0103] After determining the effective catchment area of ​​each grid cell affected by land use in the target watershed, the weighting factor and slope of each grid cell can be obtained. The weighting factor is used to indicate the magnitude of the influence of sediment connectivity factors on the corresponding grid cell.

[0104] In one possible implementation, for any grid cell, the average rainfall erosivity factor of the upslope runoff area of ​​the grid cell is first obtained.

[0105] Specifically, the erosive rainfall at each observation point during the first preset time period is first obtained.

[0106] In calculating the average rainfall erosivity factor, daily rainfall data can be used to divide the year into 24 half-months for calculation, and the results are summed to obtain the annual rainfall erosivity factor. Taking dividing the year into 24 half-months as an example, the first preset period is these 24 half-months, and the erosive rainfall amount for these 24 half-months needs to be obtained. For any half-month, if there is no erosive rainfall in that half-month, the corresponding erosive rainfall amount P is... j,m If a value of 0 is assigned, and there is erosive rainfall (more than 10 mm) in that half-month, P can be adjusted based on the amount of erosive rainfall. j,m Assign a value.

[0107] Then, based on the erosive rainfall at each observation point during the first preset time period, the annual rainfall erosivity at each observation point is determined.

[0108] For any given observation point, let P be the amount of erosive rainfall at that observation point during the first preset time period. j,m Where j represents the corresponding first preset time period, and m represents the number of days with erosive rainfall within the first preset time period, the annual rainfall erosivity at the observation point can be determined according to the following formulas (4) and (5):

[0109]

[0110]

[0111] Where m represents the number of days with erosive rainfall within the first preset time period; P j,m R represents the erosive rainfall at the observation point during the first preset time period; α is a rainfall influence parameter, with a value of 0.3957 when the first preset time period falls between May and September, and a value of 0.3101 when the first preset time period falls between October and April of the following year; j The rainfall erosivity in the j-th half-month (MJ·mm·hm) -2 ·h -1 ·a -1 R represents the annual rainfall erosivity (MJ·mm·hm). -2 ·h -1 ·a -1 ).

[0112] Finally, based on the annual rainfall erosivity at each observation point, the annual rainfall erosivity of all grids within the target watershed is determined, and then the average rainfall erosivity factor is determined based on the annual rainfall erosivity of all grid cells.

[0113] Since there are multiple observation points in the target watershed, after determining the annual rainfall erosivity of each observation point according to equations (4) and (5) above, the maximum and minimum values ​​of the annual rainfall erosivity of each observation point can be determined, and the normalized rainfall erosivity factor can be obtained by performing natural logarithm standardization. This process can be seen in equation (6) below:

[0114]

[0115] Wherein, for any given observation point, R represents the annual rainfall erosivity at that observation point, R mim R is the minimum annual rainfall erosivity among all observation points. max R represents the maximum annual rainfall erosivity at each observation point. t This is the standardized rainfall erosivity factor for this observation point.

[0116] According to formula (6), the standardized rainfall erosivity factor calculation results of each observation point are input into ArcGIS, and the inverse distance weighted interpolation method is used to obtain the standardized rainfall erosivity factor of all raster cells in the target watershed. For the i-th raster cell, the average value of the standardized rainfall erosivity factor of all raster cells in the upslope runoff area of ​​the i-th raster cell is obtained by averaging the standardized rainfall erosivity factor of the upslope runoff area of ​​the i-th raster cell.

[0117] The above embodiments have described how to determine the average rainfall erosivity factor. The following will describe how to determine the average soil erosibility factor value in the upslope runoff area.

[0118] Let the soil erosibility factor be K. For any grid cell soil type, the soil erosibility factor K can be calculated using the erosion-productivity impact calculator (EPIC) model. The specific calculation method can be found in the following formula (7):

[0119]

[0120] Wherein, SAN represents the sand content (%) of a specific soil type; SIL represents the silt content (%) of the soil type; CLA represents the clay content (%) of the soil type; and SOC represents the organic matter content (%) of the soil type.

[0121] By combining actual observed soil type distributions with calculations of soil erodibility factor values ​​for each soil type, the distribution of soil erodibility factor for each grid cell within the target watershed can be obtained. The average soil erodibility factor value for the upslope runoff area of ​​the i-th grid cell can then be calculated by averaging the soil erodibility factor values ​​of all grid cells within the i-th grid cell's upslope runoff area.

[0122] Then, the average vegetation cover and management factor values ​​of the uphill runoff area were obtained. and average soil and water conservation measures factor values Among them, the average vegetation cover and management factor value and average soil and water conservation measures factor values Values ​​can be assigned based on the land use type of the raster unit, which will not be elaborated here.

[0123] After obtaining the average rainfall erosivity factor, average soil erosibility factor, average vegetation cover and management factor, and average soil and water conservation measures factor, the weighting factor of the raster cell can be determined based on these factors. This process can be seen in the following formula (8):

[0124]

[0125] in, The weighting factor for the grid cells. The average rainfall erosivity factor, This represents the average soil erodibility factor value. The average vegetation cover and management factor value. This represents the average value of the soil and water conservation measures factor.

[0126] S13, obtain the runoff velocity factor of each grid cell, and the confluence path length of each grid cell to the nearest channel or the nearest sedimentation zone.

[0127] In this embodiment, the downhill component reflecting the physical process of sediment transport has been improved.

[0128] In the downslope component of IC, the internal runoff velocity factor (v) in the sediment delivery distributed model (SEDD) formula is selected to replace the weighting factor in the original algorithm. This makes the improved downslope component completely consistent with the sediment transport time (t) formula in the SDR calculation, attempting to reflect the ease or probability of transport by using the time cost of sediment transporting downward into the river channel or the nearest depositional area.

[0129] Specifically, firstly, based on the Manning roughness corresponding to the land use type of each grid cell, the retardation coefficient of each grid cell is determined. Then, based on the slope and retardation coefficient of each grid cell, the runoff velocity factor of each grid cell is determined. This process can be seen in the following equation (9):

[0130]

[0131] Among them, v i The runoff velocity factor for the grid cell; s i The slope (m / m) of the grid cell; k i The hindrance coefficient of the raster cell is determined based on the Manning roughness coefficient corresponding to the land use type.

[0132] Since the determination of sediment transport time (t) in the SDR formula takes into account factors such as land use, confluence length, and Manning roughness, its physical meaning of describing the downward transport time of sediment is clearer and conforms to the definition of sediment connectivity. Therefore, the improved sediment connectivity index will enhance the description and response capabilities of sediment transport processes and establish an organic relationship with other commonly used important indicators.

[0133] The confluence path length from a grid cell to the nearest channel or the nearest sedimentary area can be either the confluence path length from the grid cell to the nearest channel or the confluence path length from the grid cell to the nearest sedimentary area.

[0134] S14. Based on the effective catchment area, weighting factor, gradient, runoff velocity factor, and catchment path length, determine the sediment connectivity index of the target watershed. The sediment connectivity index is used to indicate the sediment connectivity of the target watershed.

[0135] Once the effective catchment area, weight factor, slope, runoff velocity factor, and catchment path length to the nearest river channel or sedimentation zone of each grid cell in the target watershed affected by land use are determined, the sediment connectivity index of the target watershed can be determined based on the effective catchment area, weight factor, slope, runoff velocity factor, and catchment path length.

[0136] The earliest proposed sediment connectivity index (IC) algorithm originally consisted of the ratio of upslope components to downslope components. The upslope component represents the potential for sediment separation and downward transport caused by underlying surface conditions such as topography and land use in the upper runoff area of ​​the grid cell, while the downslope component represents the sediment transport potential determined by underlying surface conditions such as topography and land use in the runoff path from the grid cell down to the nearest river channel or the nearest depositional area.

[0137] Later researchers incorporated four factors into the upslope component of RUSLE's calculation: rainfall erosivity (R), soil erodibility (K), vegetation cover and management (C), and soil and water conservation measures (P), proposing an improved IC algorithm (IC). LS ).

[0138] This application embodiment is in IC LS Based on the existing IC algorithm, and addressing two common problems, this paper proposes a new improved sediment connectivity index (IC) by introducing an original parameter, the effective catchment area (Ar), which considers land use influence, into the upslope component, and replacing the runoff velocity factor (v) of the SEDD model in the downslope component. ZQ For example, see formula (10):

[0139]

[0140] In the formula, IC ZQ The improved sediment connectivity index is defined as [-∞, +∞], with a larger value indicating better sediment connectivity and stronger sediment production and transport capacity; D up D dn Represent the uphill and downhill components respectively; s i For the slope (m / m), to avoid distortion of the calculation results, the values ​​need to be corrected to the range of 0.005-1; w i A represents the weighting factor for the i-th raster cell, reflecting the combined influence of factors such as rainfall, soil, vegetation, and soil and water conservation measures; ri The effective catchment area (m²) of the i-th grid cell considering the upslope land use / cover impact. 2 );d i v is the confluence path length (m) from the i-th grid cell to the nearest channel or sedimentation zone; i is the runoff velocity factor within the i-th grid cell.

[0141] Furthermore, the embodiments of this application also separate the local and ex-situ contributions of land use change to erosion and sediment yield in the target watershed.

[0142] Land use change affects erosion and sediment yield within cover patches, and also influences erosion and sediment yield outside cover patches by altering slope runoff and sediment transport capacity. With constant rainfall, the change in watershed sediment connectivity index (ΔIC) caused by land use change can be considered to include local effects (ΔIC). I ) and ex-situ effects (ΔIC) O The two parts are illustrated in the following formula (11):

[0143] ΔIC=ΔIC I +ΔIC O (11)

[0144] Specifically, firstly, based on the sediment connectivity index IC, the change value ΔIC of the first sediment connectivity index corresponding to each grid cell within each type of land use transformation patch during the second preset time period is determined. Is .

[0145] Then, based on the sediment connectivity index, the change value ΔIC of the second sediment connectivity index for each grid cell outside each type of land use change patch within the second preset time period is determined. Os .

[0146] Finally, based on the changes in the first and second sediment connectivity indices, the local and off-site contribution rates of sediment connectivity affecting the target watershed are determined.

[0147] The local and ex-situ contributions of land use change to watershed sediment connectivity can be considered as the sum of the local effects generated by each land use change patch (grid cell) and its ex-situ effects on the surrounding area, as shown in the following formula (12):

[0148]

[0149] Among them, ΔIC Is Let ΔIC be the IC change value within the s-th type of land use change patch (raster cell). Os ΔIC represents the IC change value outside the s-th type of land use change patch (raster cell); s represents the land use change mode, s = 1, 2, 3, ..., m; SE This refers to the systematic error between split calculations and overall calculations.

[0150] The sediment connectivity index (IC) of the target watershed was calculated for each land use change pattern during typical time periods. ZQ Changes, and the sediment connectivity index IC of all grids for land use transformation. ZQ The sum of the changes represents a percentage of the basin-wide average sediment connectivity index (IC). ZQ The proportion of changes is considered as the local contribution rate of this type of land use change to the watershed's sediment connectivity, and the sediment connectivity index (IC) of all other graticles with no land use change. ZQ The sum of the changes represents a percentage of the basin-wide average sediment connectivity index (IC). ZQ The proportion of the change value is regarded as the contribution rate of the off-site effect. At the same time, the sum of the local contribution rates of all land use change patterns to the watershed sediment connectivity can be regarded as the local contribution rate of watershed land use to erosion and sediment production; the sum of the off-site contribution rates of all land use change patterns to the watershed sediment connectivity can be regarded as the off-site contribution rate of watershed land use to erosion and sediment production.

[0151] This application addresses the main shortcomings of existing sediment connectivity algorithms by proposing a novel improved algorithm and a method for separating and quantifying the local and ex-situ contributions of watershed land use change to erosion and sediment yield. Firstly, the proposed improved sediment connectivity index algorithm introduces an original effective catchment area (Ar) parameter into the upslope component, reflecting the influence of upslope land use type, boundaries, quantity, and location on the upslope catchment area. In the downslope component, it introduces the runoff velocity factor (v) from the SEDD model, aligning it with the sediment transport time (t) formula in the sediment transport ratio (SDR) calculation, thus more clearly describing the physical meaning of sediment downward transport time. The resulting improved sediment connectivity index algorithm has a clearer physical meaning than other existing algorithms and can more comprehensively and sensitively characterize the erosion and sediment yield impact of watershed land use change. Secondly, based on the improved sediment connectivity index algorithm, a method for separating and quantifying the local and ex-situ contributions of watershed land use change to erosion and sediment yield is proposed, providing support for a deeper understanding of the erosion and sediment yield impact mechanisms of watershed land use change. The above solution is simple to apply and has good overall results.

[0152] first, Figure 2 A schematic diagram of a typical small watershed provided in the embodiments of this application, such as Figure 2 As shown, in the arid and semi-arid region of the Loess Plateau, the Lüergou (12.01 km) area in Tianshui City, Gansu Province was selected. 2 For a typical small watershed, topographic, soil, and land use data, as well as all meteorological and hydrological data from the time meteorological, runoff, and sediment transport observations up to 2020, were collected. The improved IC algorithm proposed in this application and three commonly used IC algorithms (Table 1) were used to calculate watershed sediment connectivity. Quantitative relationships were established between the calculation results of different algorithms and watershed runoff depth and sediment transport modulus. Correlation analysis was used to compare the erosion and sediment transport prediction effects of different IC algorithms. Secondly, during two typical periods of land use change in the watershed (1985-1990 and 2015-2020), the local and exogenous contributions of land use change to erosion and sediment production, as proposed in this application, were separated using the improved IC algorithm. Under multi-year average rainfall conditions, the local and exogenous contribution rates of sediment connectivity changes caused by different land use transformation patterns were calculated and separated. Table 1 illustrates the parameter meanings of the three commonly used IC algorithms.

[0153] Table 1

[0154]

[0155] Table 2 shows the IC values ​​for the Lüergou small watershed. ZQ Statistical relationship table between runoff depth and sediment transport modulus, Figure 3This is a schematic diagram showing the correlation between different sediment connectivity indices and runoff depth and sediment transport modulus in the Lüergou watershed, provided in an embodiment of this application. Figure 4 This application provides a schematic diagram illustrating the local and ex-situ contribution rates of land use change on sediment connectivity index during a typical time period in the Lüergou watershed, as shown in the embodiments of this application. Figure 3 As shown, the improved sediment connectivity index (IC) algorithm proposed in this application has been tested and proven effective in the Lüergou small watershed of the Loess Plateau. ZQ There is a good linear relationship between sediment transport modulus and interannual runoff depth and sediment transport modulus (Table 2), and the correlation is better than that of the commonly used sediment connectivity index (IC). BC IC DS IC LS This can effectively characterize the runoff generation and sediment transport capacity of small watersheds under the influence of land use / cover and rainfall changes.

[0156] exist Figure 3 The example demonstrates runoff depth and sediment transport modulus calculated using several different IC algorithms. Figure 4 The text illustrates the contribution rates of local and ex-situ actions to the entire watershed, vegetation enhancement zones, and vegetation decline zones under drastic land-use change (1985-1990). It also illustrates the contribution rates of local and ex-situ actions to the entire watershed, vegetation enhancement zones, and vegetation decline zones under conditions of relatively weak land-use change (2015-2020). Specific figures can be found in [reference needed]. Figure 4 According to the calculation and analysis results, after eliminating the influence of rainfall, the dramatic land use change (1985-1990) mainly affected the watershed sediment connectivity through local effects, with a contribution rate of 61%. However, when land use change was weaker (2015-2020), the contribution rate of off-site effects increased to 52%.

[0157] Table 2

[0158]

[0159] In summary, the method for determining sediment connectivity provided in this application first obtains the effective runoff area of ​​each grid cell affected by land use in the target watershed, and obtains the weighting factor and slope of each grid cell. The weighting factor is used to indicate the magnitude of the influence of sediment connectivity factors on the corresponding grid cell. Then, the runoff velocity factor of each grid cell and the runoff path length from each grid cell to the nearest channel or the nearest depositional area are obtained. Finally, based on the effective runoff area, weighting factor, slope, runoff velocity factor, and runoff path length, the sediment connectivity index of the target watershed is determined. The sediment connectivity index is used to indicate the sediment connectivity of the target watershed. This application addresses the main common shortcomings of existing sediment connectivity algorithms by proposing a new improved algorithm and a method for separating and quantifying the local and exogenous contributions of watershed land use change to erosion and sediment production. The improved sediment connectivity index algorithm proposed in this application introduces an original effective runoff area into the upslope component, which can reflect the influence of upslope land use type, boundary, quantity, and location on the upslope runoff area. Introducing a runoff velocity factor into the downslope component enhances the description and response capabilities to sediment transport processes. The resulting improved sediment connectivity index algorithm has a clearer physical meaning than other existing algorithms and can more comprehensively and sensitively characterize the erosion and sediment yield impacts of watershed land use change. Furthermore, based on the improved sediment connectivity index algorithm, a method for separating and quantifying the local and exogenous contributions of watershed land use change to erosion and sediment yield is proposed, providing support for a deeper understanding of the erosion and sediment yield impact mechanisms of watershed land use change. The above scheme is generally simple to apply and yields good results.

[0160] The apparatus for determining sediment connectivity provided in this application is described below. The apparatus for determining sediment connectivity described below can be referred to in correspondence with the method for determining sediment connectivity described above.

[0161] Figure 5 A schematic diagram of the structure of the device for determining sediment connectivity provided in the embodiments of this application is shown below. Figure 5 As shown, the device includes:

[0162] The first acquisition module 51 is used to acquire the effective runoff area of ​​each grid cell affected by land use in the target watershed;

[0163] The second acquisition module 52 is used to acquire the weight factor and slope of each grid cell, wherein the weight factor is used to indicate the magnitude of the influence of the sediment connectivity factor on the corresponding grid cell.

[0164] The third acquisition module 53 is used to acquire the runoff velocity factor of each grid cell and the confluence path length of each grid cell to the nearest channel or the nearest sedimentation area.

[0165] Processing module 54 is used to determine the sediment connectivity index of the target watershed based on the effective catchment area, the weighting factor, the slope, the runoff velocity factor and the catchment path length. The sediment connectivity index is used to indicate the sediment connectivity of the target watershed.

[0166] In one possible implementation, the first acquisition module 51 is specifically used for:

[0167] The upslope confluence area of ​​each grid cell is determined based on the confluence direction;

[0168] Determine the catchment area contribution rate of each of the grid cells;

[0169] The effective confluence area of ​​each grid cell is determined based on the uphill confluence area contribution, the confluence area contribution rate, and the side length of each grid cell.

[0170] In one possible implementation, the first acquisition module 51 is specifically used for:

[0171] For any grid cell, a first runoff coefficient of the grid cell is determined based on the land use type of the grid cell;

[0172] Determine the second runoff coefficient corresponding to fallow land;

[0173] The flow contribution rate of the grid cell is determined based on the first flow generation coefficient and the second flow generation coefficient.

[0174] In one possible implementation, the second acquisition module 52 is specifically used for:

[0175] For any given grid cell, obtain the average rainfall erosivity factor of the upslope runoff area of ​​that grid cell;

[0176] Obtain the average soil erodibility factor value of the uphill runoff area;

[0177] Obtain the average vegetation cover and management factor value and the average soil and water conservation measures factor value of the upslope confluence area;

[0178] The weighting factor of the grid cell is determined based on the average rainfall erosivity factor, the average soil erosibility factor, the average vegetation cover and management factor, and the average soil and water conservation measures factor.

[0179] In one possible implementation, the target watershed includes multiple observation points; the second acquisition module 52 is specifically used for:

[0180] Obtain the erosive rainfall at each observation point during a first preset time period;

[0181] The annual rainfall erosivity of each observation point is determined based on the erosive rainfall amount at each observation point during the first preset time period.

[0182] Based on the annual rainfall erosivity at each observation point, determine the annual rainfall erosivity of all grid cells within the target watershed;

[0183] The average rainfall erosivity factor is determined based on the annual rainfall erosivity of all grid cells within the target watershed.

[0184] In one possible implementation, the third acquisition module 53 is specifically used for:

[0185] The hindrance coefficient of each grid cell is determined based on the Manning roughness corresponding to the land use type of each grid cell.

[0186] The runoff velocity factor of each grid cell is determined based on the slope and stagnation coefficient of each grid cell.

[0187] In one possible implementation, the processing module 54 is further configured to:

[0188] Based on the sediment connectivity index, determine the change value of the first sediment connectivity index corresponding to each grid unit in each type of land use change patch within the second preset time period;

[0189] Based on the sediment connectivity index, determine the change value of the second sediment connectivity index corresponding to each grid unit outside each type of land use change patch within the second preset time period;

[0190] Based on the changes in the first and second sediment connectivity indices, the local and external contribution rates of sediment connectivity affecting the target watershed are determined.

[0191] Figure 6 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 6As shown, the electronic device may include a processor 610, a communications interface 620, a memory 630, and a communication bus 640, wherein the processor 610, communications interface 620, and memory 630 communicate with each other via the communication bus 640. The processor 610 can call logical instructions in the memory 630 to execute a method for determining sediment connectivity. This method includes: obtaining the effective runoff area of ​​each grid cell affected by land use in the target watershed; obtaining the weighting factor and slope of each grid cell, wherein the weighting factor indicates the magnitude of the influence of sediment connectivity factors on the corresponding grid cell; obtaining the runoff velocity factor of each grid cell and the runoff path length from each grid cell to the nearest channel or the nearest depositional area; and determining the sediment connectivity index of the target watershed based on the effective runoff area, the weighting factor, the slope, the runoff velocity factor, and the runoff path length, wherein the sediment connectivity index indicates the sediment connectivity of the target watershed.

[0192] Furthermore, the logical instructions in the aforementioned memory 630 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0193] On the other hand, this application also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the method for determining sediment connectivity provided in the above embodiments. The method includes: obtaining the effective runoff area of ​​each grid cell affected by land use in a target watershed; obtaining the weighting factor and slope of each grid cell, wherein the weighting factor is used to indicate the magnitude of the influence of sediment connectivity influencing factors on the corresponding grid cell; obtaining the runoff velocity factor of each grid cell and the runoff path length from each grid cell to the nearest channel or the nearest depositional area; and determining the sediment connectivity index of the target watershed based on the effective runoff area, the weighting factor, the slope, the runoff velocity factor, and the runoff path length, wherein the sediment connectivity index is used to indicate the sediment connectivity of the target watershed.

[0194] In another aspect, this application also provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the method for determining sediment connectivity provided in the above embodiments. The method includes: obtaining the effective runoff area of ​​each grid cell in a target watershed affected by land use; obtaining a weighting factor and slope of each grid cell, the weighting factor indicating the magnitude of the influence of sediment connectivity factors on the corresponding grid cell; obtaining the runoff velocity factor of each grid cell and the runoff path length from each grid cell to the nearest channel or the nearest depositional area; and determining a sediment connectivity index of the target watershed based on the effective runoff area, the weighting factor, the slope, the runoff velocity factor, and the runoff path length, the sediment connectivity index indicating the sediment connectivity of the target watershed.

[0195] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0196] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0197] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for determining the connectivity of sediment, characterized in that, include: Obtain the effective runoff area of ​​each grid cell in the target watershed that is affected by land use; Obtain the weight factor and slope of each grid cell, wherein the weight factor is used to indicate the magnitude of the influence of the sediment connectivity factor on the corresponding grid cell; Obtain the runoff velocity factor of each grid cell, and the confluence path length of each grid cell to the nearest channel or the nearest sedimentation zone; The sediment connectivity index of the target watershed is determined based on the effective catchment area, the weighting factor, the slope, the runoff velocity factor, and the catchment path length. The sediment connectivity index is used to indicate the sediment connectivity of the target watershed. The sediment connectivity index of the target watershed is determined based on the effective catchment area, the weighting factor, the slope, the runoff velocity factor, and the catchment path length, including: according to Determine the sediment connectivity index of the target watershed; Among them, IC ZQ The sediment connectivity index is a numerical value that indicates better sediment connectivity and stronger sediment production and transport capacity. , These represent the uphill and downhill components, respectively; For slope descent; , which is the weight factor of the i-th grid cell, reflecting the combined influence of rainfall, soil, vegetation and soil and water conservation measures; The effective catchment area for the i-th grid cell considering the upslope land use / cover impact; The length of the confluence path from the i-th grid cell to the nearest channel or sedimentation zone; is the runoff velocity factor within the i-th grid cell.

2. The method according to claim 1, characterized in that, The acquisition of the effective runoff area of ​​each grid cell affected by land use in the target watershed includes: The upslope confluence area of ​​each grid cell is determined based on the confluence direction; Determine the catchment area contribution rate of each of the grid cells; The effective confluence area of ​​each grid cell is determined based on the uphill confluence area contribution, the confluence area contribution rate, and the side length of each grid cell.

3. The method according to claim 2, characterized in that, Determining the catchment area contribution rate of each of the grid cells includes: For any grid cell, a first runoff coefficient of the grid cell is determined based on the land use type of the grid cell; Determine the second runoff coefficient corresponding to fallow land; The flow contribution rate of the grid cell is determined based on the first flow generation coefficient and the second flow generation coefficient.

4. The method according to claim 1, characterized in that, The step of obtaining the weight factor for each of the grid cells includes: For any given grid cell, obtain the average rainfall erosivity factor of the upslope runoff area of ​​that grid cell; Obtain the average soil erodibility factor value of the uphill runoff area; Obtain the average vegetation cover and management factor value and the average soil and water conservation measures factor value of the upslope confluence area; The weighting factor of the grid cell is determined based on the average rainfall erosivity factor, the average soil erosibility factor, the average vegetation cover and management factor, and the average soil and water conservation measures factor.

5. The method according to claim 4, characterized in that, The target watershed includes multiple observation points; obtaining the average rainfall erosivity factor of the upslope runoff area of ​​the grid cell includes: Obtain the erosive rainfall at each observation point during a first preset time period; The annual rainfall erosivity of each observation point is determined based on the erosive rainfall amount at each observation point during the first preset time period. Based on the annual rainfall erosivity at each observation point, determine the annual rainfall erosivity of all grid cells within the target watershed; The average rainfall erosivity factor is determined based on the annual rainfall erosivity of all grid cells within the target watershed.

6. The method according to claim 1, characterized in that, The step of obtaining the runoff velocity factor for each of the grid cells includes: The hindrance coefficient of each grid cell is determined based on the Manning roughness corresponding to the land use type of each grid cell. The runoff velocity factor of each grid cell is determined based on the slope and stagnation coefficient of each grid cell.

7. The method according to any one of claims 1-6, characterized in that, The method further includes: Based on the sediment connectivity index, determine the change value of the first sediment connectivity index corresponding to each grid unit in each type of land use change patch within the second preset time period; Based on the sediment connectivity index, determine the change value of the second sediment connectivity index corresponding to each grid unit outside each type of land use change patch within the second preset time period; Based on the changes in the first and second sediment connectivity indices, the local and external contribution rates of sediment connectivity affecting the target watershed are determined.

8. A device for determining the connectivity of sediment, characterized in that, include: The first acquisition module is used to acquire the effective runoff area of ​​each grid cell affected by land use in the target watershed; The second acquisition module is used to acquire the weight factor and slope of each grid cell, wherein the weight factor is used to indicate the magnitude of the influence of the sediment connectivity factor on the corresponding grid cell; The third acquisition module is used to acquire the runoff velocity factor of each grid cell and the confluence path length of each grid cell to the nearest channel or the nearest sedimentation area. The processing module is used to determine the sediment connectivity index of the target watershed based on the effective catchment area, the weighting factor, the slope, the runoff velocity factor, and the catchment path length. The sediment connectivity index is used to indicate the sediment connectivity of the target watershed. The processing module is configured to determine the sediment connectivity index of the target watershed based on the effective catchment area, the weighting factor, the slope, the runoff velocity factor, and the catchment path length, including: according to Determine the sediment connectivity index of the target watershed; Among them, IC ZQ The sediment connectivity index is a numerical value that indicates better sediment connectivity and stronger sediment production and transport capacity. , These represent the uphill and downhill components, respectively; For slope descent; , which is the weight factor of the i-th grid cell, reflecting the combined influence of rainfall, soil, vegetation and soil and water conservation measures; The effective catchment area for the i-th grid cell considering the upslope land use / cover impact; The length of the confluence path from the i-th grid cell to the nearest channel or sedimentation zone; is the runoff velocity factor within the i-th grid cell.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the method for determining sediment connectivity as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method for determining sediment connectivity as described in any one of claims 1 to 7.

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