Shoreline classification method based on erosion and deposition and form quantitative analysis

Abstract

The invention discloses a shoreline classification method based on erosion and deposition and form quantitative analysis, and the method comprises the steps: carrying out the longitudinal discretization of a shoreline, and determining the transverse topographic data of each discrete point on the shoreline; calculating erosion and deposition characteristic parameters and morphological characteristic parameters of each discrete point based on the transverse topographic data of each discrete point; drawing a shoreline erosion and deposition characteristic distribution diagram and a shoreline morphological characteristic distribution diagram based on the erosion and deposition characteristic parameters and the morphological characteristic parameters; and determining the type of each section on the shoreline according to the shoreline erosion and deposition characteristic distribution diagram, the shoreline morphological characteristic distribution diagram and the shoreline characteristic matrix. According to the shoreline classification method, the recent stable state of the shoreline can be visually expressed on the basis of erosion and deposition quantification and form quantification analysis and calculation of the river bank slope, and a good guiding effect is achieved on shoreline development and utilization behavior selection, flood control project safety evaluation, shoreline bearing capacity evaluation, shoreline protection improvement optimization and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of water conservancy engineering, and in particular relates to a shoreline classification method based on scouring and silting and morphological quantitative analysis. Background Art

[0002] The river (lake) coastline is an important transition zone between the land and water systems in nature. It is a non-renewable and precious natural resource. It has both natural ecological functions of regulating water flow, flood discharge and maintaining the ecological balance of rivers and lakes, and economic resource attributes with development and utilization value under certain circumstances. In the process of modern human social development, the development and utilization of river and lake coastlines have played a huge role in promoting industrial development, ecological environment construction, and improving the quality of life of residents in coastal cities. At present, the classification of coastlines is mostly based on their external attributes. For example, they are divided into living coastlines, production coastlines and ecological coastlines according to their use functions, and into protection areas, reserved areas, controlled utilization areas and development and utilization areas according to management and control requirements. There are few studies on the classification of coastlines according to internal attributes. The coastline is a strip area at the junction of water and land, and its internal attributes include material composition and dynamic changes. The material composition of the coastline is soil, sand, rock or silt, so it can be divided into soil coastline, sandy coastline, rocky coastline or silt coastline. The components of the coastline include the beach, the front slope of the beach and part of the river channel. Since the coastline is always in contact with the water flow, the water flow in the natural river channel is constantly moving, which will directly act on the front slope of the beach. The slope is a relatively loose accumulation, so the slope will also be in constant change, that is, the dynamic change of the coastline has become its inherent internal attribute. The dynamic change of the coastline will directly affect its use function and control requirements. Piers, parks, shipyards, etc. are built on the shore sections with severe scouring and poor stability. Once the coastline collapses, it will cause a devastating blow to the relevant economic facilities; the water intake is built on the silted coastline, which may cause an unfavorable situation where water cannot be obtained; the continuous collapse of the coastline in some locations may endanger the safety of flood control projects and cause the loss of people's lives and property. At present, there is no classification technology based on the dynamic changes of coastline scouring and silting. It is of great practical significance to explore the classification method based on the dynamic changes of the coastline and use it to guide the production practice and management and control of the coastline. Summary of the invention

[0003] The purpose of the present invention is to solve the deficiencies of the above-mentioned background technology and to provide a shoreline classification method based on scouring and silting and morphological quantitative analysis.

[0004] The technical solution adopted by the present invention is: a shoreline classification method based on scouring and silting and morphological quantitative analysis, comprising the following steps:

[0005] Discretize the coastline longitudinally and determine the lateral topographic data of each discrete point on the coastline;

[0006] Calculate the scouring and silting characteristic parameters and morphological characteristic parameters of each discrete point based on the lateral terrain data of each discrete point;

[0007] Draw the coastline scouring and silting characteristic distribution map and the coastline morphological characteristic distribution map based on the scouring and silting characteristic parameters and the morphological characteristic parameters;

[0008] The types of each section on the coastline are determined based on the coastline scouring and silting characteristics distribution map, coastline morphological characteristics distribution map and coastline characteristics matrix.

[0009] Furthermore, the process of longitudinally discretizing the coastline is as follows:

[0010] Set up several control points on the shoreline;

[0011] The shoreline is discretized according to the set interval to obtain a number of discrete points;

[0012] Determine the cumulative length of each control point and discrete point from the starting point of the shoreline;

[0013] For any discrete point, the cumulative length of the discrete point is compared with the cumulative length of any two adjacent control points to determine the two control points adjacent to the discrete point;

[0014] The coordinates of the corresponding discrete points are calculated based on the two control points adjacent to the discrete points to complete the longitudinal discretization of the coastline.

[0015] Furthermore, the coordinates of discrete points are calculated by the following formula:

[0016]

[0017] Among them, x j For discrete points Q j The horizontal axis, y j For discrete points Q j The vertical coordinate, x i is the control point P i The horizontal axis, y i is the control point P i The vertical coordinate, x i－1 is the control point P i－1 The horizontal axis, y i－1 is the control point P i－1 The vertical coordinate of rj For discrete points Q j The corresponding cumulative length from the starting point of the coastline, d i is the control point P i The corresponding cumulative length from the starting point of the coastline, d i－1 is the control point P i－1 The corresponding cumulative length from the starting point of the coastline, discrete point Q j Located at control point Pi－1 With control point P i between.

[0018] Furthermore, the process of acquiring the lateral terrain data is as follows: taking the slope lines in the measured topographic map as a reference, assigning different elevations according to the actual elevation segments to form a number of contour lines; taking each discrete point as a starting point, drawing a ray to the center of the river channel with the direction perpendicular to the shoreline, the ray intersecting with the several contour lines, calculating the distance and elevation of each intersection point relative to the corresponding discrete point, obtaining the lateral terrain data of each discrete point, and drawing the lateral terrain curve of each discrete point.

[0019] Furthermore, the distance and elevation are calculated by the following formula:

[0020]

[0021] Z j，i1 =ELE i1

[0022] Among them, L j，i1 For discrete points Q j The corresponding intersection points and discrete points Q j The distance between j，i1 For discrete points Q j The horizontal coordinates of the corresponding intersection points, x j For discrete points Q j The horizontal axis, y j，i1 For discrete points Q j The ordinates of the corresponding intersection points, y j For discrete points Q j The vertical coordinate, Z j，i1 For discrete points Q j The elevations of the corresponding intersections, ELE i1 is the elevation of the contour line where the intersection is located, i1 takes values ​​of 1, 2, ..., n, where n is the number of intersection points.

[0023] Furthermore, the scouring and silting characteristic parameter is calculated by the following formula:

[0024]

[0025] Among them, E x，j For discrete points Q j The relative slope retreat rate, S1 is the scouring area caused by the slope retreat in the current year relative to the previous years, and D1 is the discrete point Q j The difference between the ordinates of the top inflection point and the bottom inflection point on the transverse topographic curve in previous years, B is the river width, E is the river width, Z，j For discrete points Q jThe relative slope downcutting rate, S2 is the scouring area caused by the slope downcutting in the current year relative to the previous years, and D2 is the discrete point Q j The difference between the maximum horizontal coordinate on the transverse topographic curve in previous years and the horizontal coordinate of the inflection point at the bottom of the slope, H is the average water depth of the river.

[0026] Furthermore, the morphological characteristic parameters are calculated by the following formula:

[0027] ΔH j =Z1u j -Z1d j

[0028] f j =(Z1u j -Z1d j ) / (L1d j -L1u j )

[0029] Where ΔH j For discrete points Q j The slope height, Z1u j For discrete points Q j The vertical coordinate of the inflection point of the uphill top of the transverse terrain curve, Z1d j For discrete points Q j The ordinate of the inflection point on the upslope of the transverse terrain curve, f j For discrete points Q j Slope ratio, L1u j For discrete points Q j The horizontal coordinate of the inflection point of the upslope top of the transverse terrain curve, L1d j For discrete points Q j The horizontal coordinate of the inflection point on the slope bottom of the transverse terrain curve.

[0030] Furthermore, a scouring and silting benchmark value is set, and the various sections of the coastline are classified according to the scouring and silting benchmark value based on the scouring and silting characteristic distribution map. The coastline sections with scouring and silting lower than the scouring and silting benchmark value are scouring sections, the coastline sections with scouring and silting higher than the scouring and silting benchmark value are silting sections, and the coastline sections with scouring and silting within the scouring and silting benchmark value range are neither scouring nor silting sections.

[0031] Furthermore, a slope height benchmark value and a slope ratio benchmark value are set, and the various sections of the coastline are morphologically classified based on the morphological benchmark value according to the coastline morphological characteristic distribution map. The coastline section with an average slope height higher than the slope height benchmark value and an average slope ratio lower than the slope ratio benchmark value is a section with a large height difference and a steep slope; the coastline section with an average slope height higher than the slope height benchmark value and an average slope ratio higher than the slope ratio benchmark value is a section with a large height difference and a gentle slope; the coastline section with an average slope height lower than the slope height benchmark value and an average slope ratio lower than the slope ratio benchmark value is a section with a small height difference and a steep slope; and the coastline section with an average slope height lower than the slope height benchmark value and an average slope ratio higher than the slope ratio benchmark value is a section with a small height difference and a gentle slope.

[0032] Furthermore, the type of each segment on the shoreline is any one of the following five types:

[0033] 1) Weakly stable coastline: coastline with large elevation difference, steep slope and erosion;

[0034] 2) Weakly stable coastline: including three situations, the first is a coastline with large height difference, gentle slope and erosion, the second is a coastline with small height difference, steep slope and erosion, and the third is a coastline with large height difference, steep slope and no erosion or siltation;

[0035] 3) Medium stable coastline: including four situations, the first is a coastline with small height difference, gentle slope and erosion, the second is a coastline with large height difference, gentle slope and no erosion or siltation, the third is a coastline with small height difference, steep slope and no erosion or siltation, and the fourth is a coastline with large height difference, steep slope and siltation;

[0036] 4) Strong and stable coastline: including three situations, the first is a coastline with small height difference, gentle slope and no erosion or siltation, the second is a coastline with large height difference, gentle slope and siltation, and the third is a coastline with small height difference, steep slope and siltation;

[0037] 5) Strong and stable coastline: a coastline with small elevation difference, gentle slope and siltation.

[0038] The beneficial effects of the present invention are:

[0039] The shoreline classification method of the present invention is based on the quantitative analysis and calculation of scouring and silting of river bank slopes and the quantitative morphological analysis, filling the gap in the shoreline classification system in this technical field; the method can intuitively express the recent stable state of the shoreline, and has a good guiding role in the selection of shoreline development and utilization behaviors, safety assessment of flood control projects, assessment of shoreline carrying capacity, and optimization of shoreline protection and regulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a flow chart of the present invention.

[0041] Figure 2 This is a schematic diagram of the right bank shoreline of a section of a river selected for the present invention.

[0042] Figure 3 The discrete points Q of the coastline determined by the present invention are j Schematic diagram of the transverse topographic curve of the coastline in the last two years.

[0043] Figure 4 This is a distribution map of shoreline scouring and silting characteristics determined by the present invention.

[0044] Figure 5 This is a distribution map of shoreline morphological characteristics determined by the present invention. DETAILED DESCRIPTION

[0045] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0046] The dynamic changes of the coastline include two aspects. The first is that the coastline undergoes changes such as scouring and siltation under the action of water flow, which can be directly reflected by the changes in the topography of the shore section. The second is that the front slopes of the coastline are all inclined surfaces. The slope surface composed of relatively loose soil will undergo landslides, bank collapses, and collapses under the action of certain factors. Since the composition and properties of the soil will not change in a short period of time, the stability of the slope surface is mainly determined by its shape. Therefore, in order to classify the coastline, we must first conduct a quantitative analysis and study of the changes in the above two aspects. The right bank of a section of a river channel is selected as an example to illustrate the specific implementation process of the present invention. The position of the coastline is as follows: Figure 2 As shown in the figure, the total length of this section of coastline is 25 km, which belongs to the coastline of the concave bank of the curved river. Figure 1 As shown, the present invention provides a shoreline classification method based on scouring and silting and morphological quantitative analysis, comprising the following steps:

[0047] (1) Longitudinal dispersion of the shoreline

[0048] Draw a control line segment along the coastline (you can also use the coastline as the benchmark directly), with a total length of 25km from the starting point (stake numbers are 0+000~25+000m), set a total of m control points on the line segment, the distance between adjacent control points is the same, and the coordinates of each control point are P i (x i ,y i )(i=1……m) is known. If the coastline is discretized at 200m intervals, the total number of discrete points is 126. Assuming that each discrete point Q j The coordinates of (x j ,y j )(j=1……126). To calculate the coordinates Q of the discrete points j (x j ,y j ), first we need to calculate the cumulative length of each control point on the coastline from the starting point:

[0049] d1=0

[0050]

[0051] For any discrete point Q j , the cumulative length r corresponding to the starting point j For r j=(j-1)×200m. Determine the discrete point Q j The position on this section of the coastline is determined as follows:

[0052] Starting from i=2, judge condition d i－1 <r j <d i Is it satisfied? If so, then the discrete point Q j Located at control point P i-1 and control P i If it is not satisfied, then i+1, and the cycle ends until i=m.

[0053] Based on discrete point Q j Located at control point P i-1 and control P i The corresponding coordinates are calculated according to the following formula:

[0054]

[0055] Among them, x j For discrete points Q j The horizontal axis, y j For discrete points Q j The vertical coordinate, x i is the control point P i The horizontal axis, y i is the control point P i The vertical coordinate, x i－1 is the control point P i－1 The horizontal axis, y i－1 is the control point P i－1 The vertical coordinate, r j For discrete points Q j The corresponding cumulative length from the starting point of the coastline, d i is the control point P i The corresponding cumulative length from the starting point of the coastline, d i－1 is the control point P i－1 The corresponding cumulative length from the starting point of the coastline, discrete point Q j Located at control point P i－1 With control point P i between.

[0056] The coordinates of each discrete point can be obtained by cyclic calculation according to the above judgment conditions, and the longitudinal discretization of the coastline is completed.

[0057] (2) Extraction of shoreline lateral terrain data

[0058] The stability of shoreline scouring and collapse can be reflected by topography. Therefore, after the shoreline is discretized, it is necessary to extract the lateral topographic data of the shoreline at each discrete point and draw the lateral topographic curve of each discrete point, so as to study the scouring and silting stability characteristics and morphological stability characteristics of the shoreline through topography. The measured topographic map of the river channel has complete topographic data information, so the lateral topographic data of the shoreline can be separated through the measured topographic map.

[0059] Usually, the measured topographic map of the river is in CAD format. A large number of contour lines are drawn in the topographic map. The contour lines contain rich topographic information. The plane coordinates of the contour line nodes represent the location information, and the elevation of the contour lines represents the elevation information. The layers corresponding to the contour lines are "counting curve", "first curve", "counting curve above water", "first curve above water", "underwater counting curve", "underwater first curve", etc. The counting curve is generally spaced at 5.0m, and the first curve is generally spaced at 1.0m. The density of the contour lines near the shoreline represents the steepness of the bank slope, and the changes in the contour lines between years represent the changes in the scouring and silting of the bank slope. Therefore, the characteristics of the bank slope can be analyzed through the contour lines.

[0060] In order to more accurately capture the shape of the front slope of the coastline, the process of extracting the lateral topographic data of the coastline at each discrete point is as follows: first, the slope line in the measured topographic map is used as the benchmark, and different elevations are assigned according to the actual elevation segmentation to form a number of contour lines. j (x j ,y j ) as the starting point, and draw a ray perpendicular to the shoreline to the center of the river. The ray automatically intersects with several contour lines, and calculates the relative position of each intersection point to the discrete point Q j The distance and elevation of each discrete point Q j Coastline lateral topographic data.

[0061] The information on the layers of "counting curve", "first curve", "counting curve above water", "first curve above water", "counting curve below water", and "first curve below water" in the measured topographic map of the river first determines the type of contour line, which can be a polyline, a two-dimensional polyline, or a straight line. Then, the function IntersectWith() provided by CAD is used to calculate the plane coordinates of the intersection points of the ray and several contour lines. Since the number of intersection points of each ray and the contour line is different, the number of intersection points of the ray and the contour line is counted as an array mm(j) (j=1...126). The intersection point is a function of both the number of discrete points 126 and the array mm(j), that is, the plane coordinates of all intersection points T j,i1 Should be a two-dimensional array (x j，i1 ,y j，i1 )(j=1……126,i1=1……mm(j)). Then each discrete point Q jThe calculation formula for the starting point distance of the corresponding shoreline transverse terrain data is:

[0062]

[0063] The calculation formula for elevation is:

[0064] Z j，i1 =ELE i1

[0065] Among them, L j，i1 For discrete points Q j The corresponding intersection points and discrete points Q j The distance between j，i1 For discrete points Q j The horizontal coordinates of the corresponding intersection points, x j For discrete points Q j The horizontal axis, y j，i1 For discrete points Q j The ordinates of the corresponding intersection points, y j For discrete points Q j The vertical coordinate, Z j，i1 For discrete points Q j The elevations of the corresponding intersections, ELE i1 is the elevation of the contour line where the intersection is located, i1 takes values ​​of 1, 2, ..., n, where n is the number of intersection points.

[0066] (3) Calculation of shoreline erosion and morphological characteristic parameters

[0067] Based on the calculated and extracted lateral topographic data of discrete point shorelines, the scouring and silting characteristic parameters and morphological characteristic parameters of discrete points can be further calculated. The scouring and silting characteristic parameters are dynamic indicators, which are calculated by comparing the topography of multiple years; the morphological characteristic parameters are static indicators, which are calculated by the topography of the most recent year. The scouring and silting characteristic parameters can be expressed by the scouring / silting rate E over a period of time. Since scouring / silting exists in both lateral and vertical directions, it can be decomposed into the retreat rate E x and cutting rate E z The morphological characteristic parameters determine the collapse stability of the bank slope, which can be expressed by the slope height △H and the slope ratio f. The slope height △H reflects the absolute height of the bank slope, and the slope ratio f reflects the steepness of the bank slope. The slope ratio f is defined as the ratio of the slope height △H to the horizontal projection length △L of the slope.

[0068] Figure 3 Q is the discrete point of the coastline jThe horizontal topographic drawing of the shoreline in the recent two years, the solid line is the topographic line of the most recent year (or the current year), and the dotted line is the topographic line of the previous years. From left to right, there are the high beach section, the bank slope section and the river channel section. The three sections can be distinguished by two inflection points, one is the inflection point of the top of the slope, and the other is the inflection point of the bottom of the slope. The inflection point is determined by the change of the positive and negative sign of the derivative function or the sudden change of the value. Set the coordinates of the inflection point of the top of the solid line to (L1u j , Z1u j ), the coordinates of the inflection point at the bottom of the slope are (L1d j , Z1d j ), the coordinates of the inflection point of the dotted line are (L2u j , Z2u j ), the coordinates of the inflection point at the bottom of the slope are (L2d j , Z2d j ).

[0069] Calculate discrete points Q with solid lines j Slope morphological characteristic parameters, including:

[0070] ΔH j =Z1u j -Z1d j

[0071] f j =(Z1u j -Z1d j ) / (L1d j -L1u j )

[0072] Where ΔH j For discrete points Q j The slope height, f j For discrete points Q j The slope ratio, Z1u j For discrete points Q j The vertical coordinate of the inflection point of the uphill top of the transverse terrain curve, Z1d j For discrete points Q j The vertical coordinate of the inflection point on the upslope of the transverse terrain curve, L1u j For discrete points Q j The horizontal coordinate of the inflection point of the upslope top of the transverse terrain curve, L1d j For discrete points Q j The horizontal coordinate of the inflection point on the slope bottom of the transverse terrain curve.

[0073] The characteristic parameters of bank slope erosion and deposition are calculated by the change from dotted line to solid line. First, the erosion and deposition area from dotted line to solid line is divided. Figure 3 middle is the scour area S1 formed by the retreat of the bank slope (i.e. the area surrounded by the four inflection points), The scour area S2 formed by the downcutting of the bank slope (i.e. the area enclosed by the two inflection points at the bottom of the slope and the two coordinate points on the rightmost side of the curve) is calculated by the strip accumulation method. S1 and S2 are calculated separately.

[0074] Absolute slope retreat rate

[0075] Absolute slope incision rate

[0076] Natural river channels are wide and shallow, with lateral dimensions generally much larger than vertical dimensions. The width of the main stream of the Yangtze River in the middle reaches can reach several kilometers, but the water depth is often only tens of meters. Corresponding to the channel shape, the lateral retreat of the river channel during scouring is generally much larger than the vertical downcut, which can reach hundreds of meters, while the maximum vertical downcut is only about ten meters. Therefore, the absolute scouring retreat rate of the bank slope is E x 1 and cutting rate E z 1 has no comparative value. Based on this, the absolute retreat rate E x 1 and cutting rate E z 1 to transform E x 1 and E z 1 is converted into the annual average change percentage relative to half river width (recession can occur in both directions of the left and right banks, so the half river width parameter B / 2 is used) and water depth (undercutting can only occur in the downward direction, so the average water depth parameter H is used).

[0077] Relative slope retreat rate

[0078] Relative slope incision rate

[0079] Among them, E x，j For discrete points Q j The relative slope retreat rate, S1 is the scouring area caused by the slope retreat in the current year relative to the previous years, and D1 is the discrete point Q j The difference between the ordinates of the top inflection point and the bottom inflection point on the transverse topographic curve in previous years, B is the river width, E is the river width, Z，j For discrete points Q j The relative slope downcutting rate, S2 is the scouring area caused by the slope downcutting in the current year relative to the previous years, and D2 is the discrete point Q j The difference between the maximum horizontal coordinate on the transverse topographic curve in previous years and the horizontal coordinate of the inflection point at the bottom of the slope, H is the average water depth of the river.

[0080] E x，j >0, indicating that the bank slope is silting up and moving forward; E x，j <0, indicating that the bank slope has retreated due to scouring; E z，j >0, indicating that the bank slope is silted up; E z，j<0, indicating that the bank slope is eroded and cut down.

[0081] For 126 discrete points on the coastline, the slope scouring and deposition characteristic parameters and morphological characteristic parameters of each discrete point can be obtained by performing a cyclic calculation according to the above formula.

[0082] (4) Draw a coastline erosion and deposition map, morphological distribution map, and preliminary coastline classification

[0083] After calculating the characteristic parameters of the bank slope at each discrete point, the relative retreat rate E of the bank slope characteristic parameters is calculated with the length of the bank as the horizontal coordinate. x and the relative cutting rate E z As the vertical coordinate, the changes of shoreline erosion and siltation along the way can be plotted, such as Figure 4 shown.

[0084] Then set the scouring and silting reference value, which can be the reference value of the relative retreat rate of the bank slope, or the reference value of the relative downcut rate of the bank slope, or a combination of the two. Generally, the value is 0%. For more accurate classification, it can be set to a range value, i.e. [-A%, +A%], where A is determined according to actual needs. According to the scouring and silting characteristic distribution map, each section of the coastline is classified according to the scouring and silting reference value. The coastline sections with scouring and silting below the lower limit of the scouring and silting reference value are scouring sections, the coastline sections with scouring and silting above the upper limit of the scouring and silting reference value are silting sections, and the coastline sections with scouring and silting within the scouring and silting reference value range are non-scouring and non-silting sections. The annual average relative retreat rate of this embodiment fluctuates slightly, so the reference value of the relative downcut rate is used as the basis, and the reference value of the relative downcut rate is used as the basis. Figure 4 For example, the coastline is initially divided into: 0-4000m coastline is the scouring section, 4000-10000m coastline is the silting section, 10000-17500m coastline is the scouring section, and 17500-25000m coastline is the non-scouring and non-silting section. After the classification based on the scouring and silting characteristics, the length of each section of the corresponding coastline is determined, and the classification is carried out based on the length of each section determined at this time.

[0085] After calculating the characteristic parameters of the bank slope morphology at each discrete point, the changes in the bank slope morphology along the way can be plotted with the length of the bank as the horizontal coordinate and the bank slope height △H and slope ratio f as the vertical coordinate, as shown in the figure below: Figure 5 As shown, the larger △H is, the greater the slope height is; the smaller f is, the steeper the slope is.

[0086] The slope height benchmark value and the slope ratio benchmark value are set. The two benchmark values ​​are calibrated according to actual needs. According to the coastline morphological characteristics distribution map, each section of the coastline (i.e. each section after the above scouring and silting classification) is morphologically classified based on the morphological benchmark value. The average slope height and average slope ratio of each section of the coastline are calculated. The coastline section with an average slope height higher than the slope height benchmark value and an average slope ratio lower than the slope ratio benchmark value is a section with a large height difference and a steep slope. The coastline section with an average slope height higher than the slope height benchmark value and an average slope ratio higher than the slope ratio benchmark value is a section with a large height difference and a gentle slope. The coastline section with an average slope height lower than the slope height benchmark value and an average slope ratio lower than the slope ratio benchmark value is a section with a small height difference and a steep slope. The coastline section with an average slope height lower than the slope height benchmark value and an average slope ratio higher than the slope ratio benchmark value is a section with a small height difference and a gentle slope. Figure 5 Taking the example of the Yangtze River Delta as an example, the preliminary division is as follows: the coastline section of 0-4000m is the section with large height difference and steep slope, the coastline section of 4000-10000m is the section with small height difference and steep slope, the coastline section of 10000-17500m is the section with large height difference and steep slope, and the coastline section of 17500-25000m is the section with small height difference and gentle slope.

[0087] (5) Constructing shoreline characteristic matrix and classifying shoreline types

[0088] According to the characteristics of scouring and silting, the coastline is divided into three categories: scouring, no scouring and no silting, and silting. According to the morphological characteristics, the coastline is classified into four categories, namely, large height difference-steep slope, large height difference-gentle slope, small height difference-steep slope, and small height difference-gentle slope. The risk of collapse of the coastline with large height difference and steep slope is extremely high, the risk of collapse of the coastline with large height difference and gentle slope and small height difference and steep slope is moderate, and the risk of collapse of the coastline with small height difference and gentle slope is almost non-existent, so it can be further divided into three categories.

[0089] Combining the scouring and silting characteristics and morphological characteristics, a 3×3 shoreline characteristic matrix can be constructed and divided into 9 grids, as shown in Table 1.

[0090] Table 1 Shoreline characteristic matrix

[0091]

[0092] The coastline is divided into five types based on the combination of scouring and silting characteristics and morphological characteristics:

[0093] 1) Weakly stable coastline: a coastline with large elevation difference, steep slope and continuous erosion in the recent period.

[0094] 2) Weakly stable coastline: There are three situations. The first is the coastline with large height difference, gentle slope and continuous erosion in the recent period. The second is the coastline with small height difference, steep slope and continuous erosion in the recent period. The third is the coastline with large height difference, steep slope and no erosion or siltation in the recent period.

[0095] 3) Moderately stable coastline: It includes four situations. The first is the coastline with small height difference, gentle slope and continuous erosion in the recent period. The second is the coastline with large height difference, gentle slope and no erosion or siltation in the recent period. The third is the coastline with small height difference, steep slope and no erosion or siltation in the recent period. The fourth is the coastline with large height difference, steep slope and continuous siltation in the recent period.

[0096] 4) Relatively strong and stable coastline: including three situations, the first is the coastline with small height difference, gentle slope and no recent erosion or siltation, the second is the coastline with large height difference, gentle slope and recent continuous siltation, and the third is the coastline with small height difference, steep slope and recent continuous siltation.

[0097] 5) Strong and stable coastline: a coastline with small elevation difference, gentle slope and continuous siltation in the recent period.

[0098] According to the above characteristic matrix, the typical coastline classification results of this embodiment are as follows: the coastline section of 0-4000m is a weakly stable coastline, the coastline section of 4000-10000m is a relatively strong stable coastline, the coastline section of 10000-17500m is a weakly stable coastline, and the coastline section of 17500-25000m is a relatively strong stable coastline.

[0099] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in the field.

Claims

1. A shoreline classification method based on scouring and silting and morphological quantitative analysis, characterized by: Discretize the coastline longitudinally and determine the lateral topographic data of each discrete point on the coastline; Calculate the scouring and silting characteristic parameters and morphological characteristic parameters of each discrete point based on the lateral terrain data of each discrete point; Draw the coastline scouring and silting characteristic distribution map and the coastline morphological characteristic distribution map based on the scouring and silting characteristic parameters and the morphological characteristic parameters; The types of each section on the coastline are determined based on the coastline scouring and silting characteristics distribution map, coastline morphological characteristics distribution map and coastline characteristics matrix.

2. The shoreline classification method based on scouring and silting and morphological quantitative analysis according to claim 1 is characterized in that: The process of longitudinal discretization of the coastline is as follows: Set up several control points on the shoreline; The shoreline is discretized according to the set interval to obtain a number of discrete points; Determine the cumulative length of each control point and discrete point from the starting point of the shoreline; For any discrete point, the cumulative length of the discrete point is compared with the cumulative length of any two adjacent control points to determine the two control points adjacent to the discrete point; The coordinates of the corresponding discrete points are calculated based on the two control points adjacent to the discrete points to complete the longitudinal discretization of the coastline.

3. The shoreline classification method based on scouring and silting and morphological quantitative analysis according to claim 2 is characterized in that: The coordinates of discrete points are calculated using the following formula: Among them, x j For discrete points Q j The horizontal axis, y j For discrete points Q j The vertical coordinate, x i is the control point P i The horizontal axis, y i is the control point P i The vertical coordinate, x i－1 is the control point P i－1 The horizontal axis, y i－1 is the control point P i－1 The vertical coordinate, r j For discrete points Q j The corresponding cumulative length from the starting point of the coastline, d i is the control point P i The corresponding cumulative length from the starting point of the coastline, d i－1 is the control point P i－1 The corresponding cumulative length from the starting point of the coastline, discrete point Q j Located at control point P i－1 With control point P i between.

4. The shoreline classification method based on scouring and silting and morphological quantitative analysis according to claim 1 is characterized in that: The process of acquiring the transverse terrain data is as follows: taking the slope lines in the measured topographic map as the reference, assigning different elevations according to the actual elevation segments to form a number of contour lines; taking each discrete point as the starting point, drawing a ray to the center of the river channel with the direction perpendicular to the shoreline, the ray intersecting with the several contour lines, calculating the distance and elevation of each intersection point relative to the corresponding discrete point, obtaining the transverse terrain data of each discrete point, and drawing the transverse terrain curve of each discrete point.

5. The shoreline classification method based on scouring, deposition and morphological quantitative analysis according to claim 4 is characterized in that: The distance and elevation are calculated using the following formula: WITH j，i1 =ELE i1 Among them, L j,i1 For discrete points Q j The corresponding intersection points and discrete points Q j The distance between j，i1 For discrete points Q j The horizontal coordinates of the corresponding intersection points, x j For discrete points Q j The horizontal axis, y j,i1 For discrete points Q j The ordinates of the corresponding intersection points, y j For discrete points Q j The vertical coordinate, z j,i1 For discrete points Q j The elevations of the corresponding intersections, ELE i1 is the elevation of the contour line where the intersection is located, i1 takes values ​​of 1, 2, ..., n, where n is the number of intersection points.

6. The shoreline classification method based on scouring and silting and morphological quantitative analysis according to claim 1 is characterized in that: The scouring and silting characteristic parameters are calculated by the following formula: Among them, E x，j For discrete points Q j The relative slope retreat rate, s1 is the scouring area caused by the slope retreat in the current year relative to the previous years, and D1 is the discrete point Q j The difference between the ordinates of the top inflection point and the bottom inflection point on the transverse topographic curve in previous years, B is the river width, E is the z，j For discrete points Q j The relative slope downcutting rate, s2 is the scouring area caused by the slope downcutting in the current year relative to the previous years, and D2 is the discrete point Q j The difference between the maximum horizontal coordinate on the transverse topographic curve in previous years and the horizontal coordinate of the inflection point at the bottom of the slope, H is the average water depth of the river.

7. The shoreline classification method based on scouring, deposition and morphological quantitative analysis according to claim 1 is characterized in that: The morphological characteristic parameters are calculated by the following formula: ΔH j =Z1u j -Z1d j f j =(Z1u j -Z1d j ) / (L1d j -L1u j ) Where ΔH j For discrete points Q j The slope height, Z1u j For discrete points Q j The vertical coordinate of the inflection point of the upslope top of the transverse terrain curve, Z1d j For discrete points Q j The ordinate of the inflection point on the upslope of the transverse terrain curve, f j For discrete points Q j Slope ratio, L1u j For discrete points Q j The horizontal coordinate of the inflection point of the upslope top of the transverse terrain curve, L1d j For discrete points Q j The horizontal coordinate of the inflection point on the slope bottom of the transverse terrain curve.

8. The shoreline classification method based on scouring, silting and morphological quantitative analysis according to claim 1 is characterized by: Set a scouring and silting benchmark value, and classify the coastline sections according to the scouring and silting benchmark value based on the scouring and silting characteristic distribution map. Coastline sections with scouring and silting below the scouring and silting benchmark value are scouring sections, coastline sections with scouring and silting above the scouring and silting benchmark value are silting sections, and coastline sections with scouring and silting within the scouring and silting benchmark value range are neither scouring nor silting sections.

9. The shoreline classification method based on scouring, silting and morphological quantitative analysis according to claim 1 is characterized by: The slope height benchmark value and the slope ratio benchmark value are set, and the coastline sections are morphologically classified according to the coastline morphological characteristic distribution map and the morphological benchmark value. The coastline section with the average slope height higher than the slope height benchmark value and the average slope ratio lower than the slope ratio benchmark value is the section with large height difference and steep slope; the coastline section with the average slope height higher than the slope height benchmark value and the average slope ratio higher than the slope ratio benchmark value is the section with large height difference and gentle slope; the coastline section with the average slope height lower than the slope height benchmark value and the average slope ratio lower than the slope ratio benchmark value is the section with small height difference and steep slope; the coastline section with the average slope height lower than the slope height benchmark value and the average slope ratio higher than the slope ratio benchmark value is the section with small height difference and gentle slope.

10. The shoreline classification method based on scouring, deposition and morphological quantitative analysis according to claim 1 is characterized in that: The type of each segment on the shoreline is any one of the following five types: 1) Weakly stable coastline: coastline with large elevation difference, steep slope and erosion; 2) Weakly stable coastline: including three situations, the first is a coastline with large height difference, gentle slope and erosion, the second is a coastline with small height difference, steep slope and erosion, and the third is a coastline with large height difference, steep slope and no erosion or siltation; 3) Medium stable coastline: including four situations, the first is a coastline with small height difference, gentle slope and erosion, the second is a coastline with large height difference, gentle slope and no erosion or siltation, the third is a coastline with small height difference, steep slope and no erosion or siltation, and the fourth is a coastline with large height difference, steep slope and siltation; 4) Strong and stable coastline: including three situations, the first is a coastline with small height difference, gentle slope and no erosion or siltation, the second is a coastline with large height difference, gentle slope and siltation, and the third is a coastline with small height difference, steep slope and siltation; 5) Strong and stable coastline: a coastline with small elevation difference, gentle slope and siltation.

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