A method for dividing a plain hydrological response unit

Abstract

The application provides a method for dividing a hydrological response unit in a plain area, which comprises the following steps: determining a river channel grid map composed of multiple river channels based on the lengths of the multiple river channels and the flow directions of the river channels; acquiring the angles of each corner in each sub-grid in the river channel grid map and determining the angle bisectors of each corner; and dividing a corresponding hydrological response unit for each river channel in each sub-grid according to the angle bisectors. According to the method, the hydrological response unit is divided for the river network in the plain area based on the principle that the distances from the point on the angle bisector to the two sides are equal, the problem that the DEM extraction method is not applicable to dividing the hydrological response unit for the plain area is solved, and the method has important significance for hydrological prediction and water resource planning in the plain area.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrology, and particularly relates to a method for dividing a hydrologic response unit in a plain area. BACKGROUND

[0002] A hydrologic response unit (HRU) is the smallest hydrologic unit with the same hydrologic characteristics according to vegetation, soil, slope and other factors in a basin, and is the basis for simulation of a distributed hydrologic model.

[0003] There are many methods for dividing a hydrologic response unit, in which a DEM (Digital Elevation Module) is the most widely used tool for extracting a river channel in a basin and analyzing topographic parameters. The concept was proposed by Miller in 1958, and with the development of geographic information technology, more and more researches on extraction of a river network based on a DEM are carried out at home and abroad, mostly in mountainous and hilly areas. The research contents are roughly pre-processing of a DEM, judgment of a flow direction, improvement of a model and an algorithm. Although the DEM extraction method has good application effect in mountainous and hilly areas, it often does not have good effect in plain areas. Wang Xue et al. selected a mountainous, hilly and plain topographic basin to discuss the influence of basin characteristic factors, and considered that the DEM extraction method is not suitable for plain areas. Zhao Hongxi compared the DEM application results in mountainous and plain areas, and considered that the extraction result error is large in a flat area or a serious human disturbance area. In view of the above problems, many scholars have done a lot of research work on improved application in plain areas. Turcotte et al. corrected the grid elevation information of a DEM, and used a digital river basin and lake network DRLN method to improve the processing of lakes and plains. Xie Shunping et al. constructed a river valley flat flow direction processing method, classified and merged the depressions and flats, and avoided generation of parallel river channels and pseudo river channels. Zhou Demin et al. used a program compiled by GIS combined with an improved uplift cracking algorithm to explore the hydrologic characteristics in a flood area of Sanjiang Plain, and there were problems of river channel deviation and distortion of a river network shape.

[0004] Although the DEM extraction method has good application effect in mountainous and hilly areas, it often does not have ideal effect in plain areas, especially in a plain river network area. Since there is no obvious height difference, the DEM water system extraction method will fail. Although many scholars have done corresponding improvement work based on a DEM, the obtained method is still not suitable for division of a hydrologic response unit in a plain river network area. SUMMARY

[0005] In order to solve the problem that the DEM is not conducive to division of a hydrologic response unit in a plain river network area, the application provides a method for dividing a hydrologic response unit in a plain area, which comprises the following steps.

[0006] determine a river grid map composed of a plurality of rivers based on lengths of the plurality of rivers and flow directions of the plurality of rivers;

[0007] obtain angles of each corner in each sub-grid in the river grid map, and determine an angle bisector of each of the corners;

[0008] divide each of the rivers in each of the sub-grids into a corresponding hydrological response unit according to the angle bisector.

[0009] Preferably, before the determining the river grid map composed of a plurality of rivers based on lengths of the plurality of rivers and flow directions of the plurality of rivers, the method further comprises:

[0010] obtain lengths of each of the rivers and determine flow directions of each of the rivers according to a river distribution of a river to be studied in a plain area.

[0011] Preferably, the rivers are straight-line rivers, and the obtaining lengths of each of the rivers and determining flow directions of each of the rivers comprises:

[0012] obtain lengths of each of the straight-line rivers and determine flow directions of each of the straight-line rivers.

[0013] Preferably, the rivers are arc-shaped rivers, and the obtaining lengths of each of the rivers and determining flow directions of each of the rivers comprises:

[0014] fit the arc-shaped rivers into at least one straight-line river;

[0015] obtain lengths of each of the straight-line rivers and determine flow directions of each of the straight-line rivers.

[0016] Preferably, the fitting the arc-shaped rivers into at least one straight-line river comprises:

[0017] determining a virtual center and an arc length of the arc-shaped river;

[0018] obtaining an arc angle of the arc-shaped river based on the virtual center;

[0019] fitting the arc-shaped river into at least one straight-line river by line fitting according to the arc angle and the arc length.

[0020] Preferably, the determining the river grid map composed of a plurality of rivers based on lengths of the plurality of rivers and flow directions of the plurality of rivers comprises:

[0021] determining a line segment where each of the rivers is located according to the length and the flow direction of each of the rivers;

[0022] If each two of the plurality of line segments intersect with each other, then the grid map composed of the plurality of line segments is determined as the river channel grid map composed of the plurality of river channels; or

[0023] If each two of the plurality of line segments do not intersect with each other, then the adjacent two line segments are extended until intersecting with each other, and the grid map composed of the unextended line segments and the extended line segments is determined as the river channel grid map composed of the plurality of river channels.

[0024] Preferably, the dividing, according to the angle bisector, a corresponding hydrological response unit for each of the river channels in each of the sub-grid, further comprises:

[0025] Based on the principle of proximity, the region adjacent to the river channel is divided into the hydrological response unit of the river channel according to the angle bisector.

[0026] Preferably, if the angle bisectors of the corners in the sub-grid intersect at a point in the sub-grid, the dividing, based on the principle of proximity, the region adjacent to the river channel into the hydrological response unit of the river channel according to the angle bisector, comprises:

[0027] Based on the angle bisectors of the corners in the sub-grid, the sub-grid is divided into a plurality of triangular regions;

[0028] Based on the principle of proximity, the triangular region adjacent to each river channel is divided into the hydrological response unit of the corresponding river channel according to the angle bisector.

[0029] Preferably, if the angle bisectors of the corners in the sub-grid do not intersect at a point in the sub-grid, the dividing, based on the principle of proximity, the region adjacent to the river channel into the hydrological response unit of the river channel according to the angle bisector, comprises:

[0030] The plurality of intersection points in the sub-grid intersected by the angle bisectors of the corners are connected two by two to obtain at least one intersection line segment;

[0031] Then, based on the angle bisectors of the corners and the intersection line segment, the sub-grid is divided into a plurality of regions;

[0032] Based on the principle of proximity, the region adjacent to each river channel is divided into the hydrological response unit of the corresponding river channel according to the angle bisector.

[0033] Preferably, the method further comprises:

[0034] According to the shape and the side length of the hydrological response unit, the area of the hydrological response unit is calculated.

[0035] The embodiment of the present application provides a method for dividing a hydrological response unit in a plain area, which comprises the following steps: determining a river channel grid map composed of a plurality of river channels based on the length of the plurality of river channels and the flow direction of the river channels; obtaining the angle of each corner in each sub-grid in the river channel grid map and determining the angle bisector of each corner; and dividing a corresponding hydrological response unit for each river channel in each sub-grid according to the angle bisector. The method of the present application divides the hydrological response unit for the river network in the plain area based on the principle that the distance from the point on the angle bisector to the two sides is equal, solves the problem that the DEM extraction method is not applicable to dividing the hydrological response unit for the plain area, and has important significance for the hydrological prediction and water resource planning of the plain area. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A principle diagram of the method for dividing the hydrological response unit in the plain area in the embodiment of the present application is shown;

[0037] Figure 2 A flow chart of the method for dividing the hydrological response unit in the plain area in the embodiment of the present application is shown;

[0038] Figure 3 A division schematic diagram of the river channel in the embodiment of the present application is shown;

[0039] Figure 4 A method schematic diagram of a method for determining a river channel grid map in the embodiment of the present application is shown;

[0040] Figure 5 A catchment schematic diagram of the river channel in the plain area as a triangular grid in the embodiment of the present application is shown;

[0041] Figure 6 A catchment schematic diagram of the river channel in the plain area as a quadrilateral grid in the embodiment of the present application is shown. DETAILED DESCRIPTION

[0042] In order to make the above-mentioned purpose, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in combination with the drawings and specific embodiments. The embodiments of the present application are described in detail below, and the present embodiment is implemented on the premise of the technical scheme of the present application, and a detailed implementation manner and specific operation process are given, but the protection scope of the present application is not limited to the following embodiments.

[0043] Since the terrain in the plain area is gentle and there is no obvious height difference, the gravity effect of the surface runoff movement is not obvious compared with the mountain area, and therefore the DEM extraction method for dividing the hydrological response unit based on the height difference is not applicable to the plain river network area.

[0044] The inventor of the present application finds that the river channel in the plain area has a network feature, and the terrain in the plain area is relatively flat, and rainwater generally flows into the nearest river channel. Therefore, based on the nearest principle, the inventor proposes a division method of a hydrological response unit suitable for the terrain in the plain area, which assumes that the rainfall flows into the nearest river channel and uses the angle bisector method to divide the river channel into hydrological response units.

[0045] The main idea of the method is as follows: first, the elevation difference in the plain area is small, the rainfall flow direction is uncertain, and has the randomness of diffuse flow direction, so the nearest principle is proposed, and the rainfall at adjacent positions can be generalized as flowing in a unified direction; second, the plain area is approximately a plane figure, and the angle bisector principle is combined, that is, the distance from the point on the angle bisector to the two sides is equal, and then the rainfall on one side of the angle bisector flows into the nearest river channel.

[0046] Figure 1 The principle diagram of the division method of the hydrological response unit in the plain area in the embodiment of the present application is shown as shown in Figure 1 The principle of the division method in the embodiment of the present application is as follows:

[0047] Based on the assumption premise (that is, the rainfall flows into the nearest river channel) proposed by the present application, the angle bisector method is used to divide the hydrological response unit. The angle bisector theorem is used in this paper, that is, the distance from the point on the angle bisector to the two sides of the angle is equal. The principle of applying the angle bisector to divide the hydrological unit is shown as shown in Figure 1 AC and AB are the actual river channels on the plain area, the river channels in the plain area are regarded as the two sides of ∠A, AD is the angle bisector of ∠A, and the research area is divided by taking AD as the boundary line, the rainfall in the area on the upper side of AD flows into the AC river channel, and the rainfall in the area on the lower side of AD flows into the AB river channel.

[0048] Based on the above idea and principle, the embodiment of the present application provides a division method of a hydrological response unit in a plain area. Figure 2 The flow chart of the division method of the hydrological response unit in the plain area in the embodiment of the present application is shown. Referring to Figure 2 The division method of the hydrological response unit in the plain area provided by the embodiment of the present application includes the following steps:

[0049] S21, based on the length of the plurality of river channels and the flow direction of the river channels, a river channel grid map composed of the plurality of river channels is determined.

[0050] In practice, for a river, the river can be a curved river with multiple flow directions, or an approximately straight river with only one flow direction. Therefore, in the embodiment, the river channel refers to: according to the flow direction of the river, the river is divided into a plurality of river channels with different flow directions, and the different flow directions refer to the flow directions of adjacent two river channels. For example, as shown in Figure 3 ​Figure 3 As shown in the schematic diagram of the division of the river channel in the embodiment of the present application, for the river A, according to the flow direction of the river, according to the difference between the directions of the adjacent flow directions (the direction of the flow direction 1 is different from the direction of the adjacent flow direction 2, and the direction of the flow direction 2 is different from the direction of the adjacent flow direction 3), the river is divided into three river channels (the river channel CD, the river channel DE and the river channel EF). Therefore, one river may contain multiple river channels (such as the river a in Figure 3 ), or may contain only one river channel (such as the river channel GF of the river b in Figure 3 ).

[0051] In the implementation, first, according to the distribution of the river channels of the rivers studied in the plain area, the length of each river channel is obtained, and the flow direction of each river channel is determined. The distribution of the river channels of all the rivers refers to the distribution of all the river channels of all the rivers according to the flow directions and lengths of the river channels. Then, the length of each river channel is obtained by a measuring tool, and the flow direction of each river channel is determined based on the latitude and longitude.

[0052] Then, the obtained data (the length and the flow direction) of all the river channels are imported into a drawing software, and based on the lengths and the flow directions of the multiple river channels, a river channel grid graph composed of multiple river channels is drawn in the drawing software, such as the grid graph shown in Figure 3 .

[0053] In the implementation, when the river channel grid graph is drawn, the line segment where each river channel is located is determined according to the length and the flow direction of each river channel, and then the river channel grid graph composed of multiple river channels is determined according to the line segment where the river channel is located.

[0054] If two adjacent line segments of the multiple line segments intersect with each other, the grid graph composed of the multiple line segments is determined as the river channel grid graph composed of multiple river channels. For example, as shown in Figure 3 , for the river a and the river b, if the line segments CD, DE and EF all intersect with the line segment GF, the grid graph composed after the intersection is determined as the river channel grid graph composed of the river channel CD, the river channel DE, the river channel EF and the river channel GF.

[0055] If two adjacent line segments of the multiple line segments do not intersect with each other, the adjacent two line segments are extended until they intersect with each other, and the grid graph composed of the unextended line segments and the extended line segments is determined as the river channel grid graph composed of multiple river channels. For example, as shown in Figure 4 , the river channel b intersects with the river channel c and the river channel d respectively, but the river channel c does not intersect with the river channel d. When the river channel grid graph is drawn, the line segments where the river channel c and the river channel d are located are extended so as to intersect at the point C, and then the grid graph ABC composed of the unextended line segment AB and the extended line segments AC and BC is determined as the river channel grid graph composed of the river channel b, the river channel c and the river channel d.

[0056] S22, obtain the angle of each corner in each sub-grid in the river grid map, and determine the angle bisector of each corner.

[0057] In specific implementation, for the drawn river grid map, the angle of each corner in each sub-grid is obtained first, and then the angle bisector is drawn for each corner according to the obtained angle. As shown in FIG. 2, for the triangular sub-grid, the angle bisector CD of the angle ACB is drawn according to the size of the angle ACB; the angle bisector DB of the angle ABC is drawn according to the size of the angle ABC; and the angle bisector AD of the angle CAB is drawn according to the size of the angle CAB. Figure 5

[0058] S23, divide each river in each sub-grid into a corresponding hydrological response unit according to the angle bisectors.

[0059] In the embodiment of the present application, since the height difference in the plain area is not obvious, the inventor of the present application assumes that the rainwater flows into the nearest river. Therefore, based on the nearest principle, the area adjacent to the river is divided into the hydrological response unit of the river by taking the angle bisector as the boundary.

[0060] In specific implementation, if the angle bisectors of the corners in the sub-grid intersect at a point in the sub-grid, step S23 can be: dividing the sub-grid into a plurality of triangular areas based on the angle bisectors of the corners in the sub-grid; and dividing the triangular area adjacent to each river into the hydrological response unit of the corresponding river based on the nearest principle and taking the angle bisector as the boundary.

[0061] As shown in FIG. 2, the triangular grid is divided into three triangular areas (ACD, ADB and CBD) by taking the angle bisectors CD, BD and AD as the boundary, and then the triangular area adjacent to each river is divided into the hydrological response unit of the corresponding river based on the nearest principle and taking the angle bisector as the boundary, for example, the triangular area ACD is adjacent to the river b, so the triangular area ACD is divided into the hydrological response unit of the river b; the triangular area ABD is adjacent to the river c, so the triangular area ABD is divided into the hydrological response unit of the river c; and the triangular area BCD is adjacent to the river a, so the triangular area BCD is divided into the hydrological response unit of the river a. Figure 5

[0062] In specific implementation, if the angle bisectors of the corners in the sub-grid do not intersect at a point in the sub-grid, step S23 can include:

[0063] connecting the intersection points intersected by the angle bisectors in the sub-grid two by two to obtain at least one intersection line segment; then dividing the sub-grid into a plurality of areas based on the angle bisectors of the corners and the intersection line segments; and dividing the area adjacent to each river into the hydrological response unit of the corresponding river based on the nearest principle and taking the angle bisector as the boundary. ​​

[0064] like Figure 6 As shown, if the angle bisectors AF, BF, CF, and DF of subgrid ABCD intersect at two points in the subgrid, then connect the intersection point F of angle bisectors AF and DF with the intersection point E of angle bisectors BF and CF to obtain an intersection line segment EF. Then, based on angle bisectors AF, BF, CF, DF, and the intersection line segment EF, subgrid ABCD is divided into four regions (triangular regions ADF and BCE, and quadrilateral regions AFEB and DFEC). Based on the principle of proximity, using the angle bisectors and the intersection line segment as boundaries, quadrilateral region AFEB adjacent to river channel a is designated as the hydrological response unit of river channel a, quadrilateral region DFEC adjacent to river channel c is designated as the hydrological response unit of river channel c, triangular region BCE adjacent to river channel b is designated as the hydrological response unit of river channel b, and triangular region ADF adjacent to river channel d is designated as the hydrological response unit of river channel d.

[0065] This invention provides a method for dividing hydrological response units in plain areas. The method includes: determining a river network map composed of multiple rivers based on their lengths and flow directions; obtaining the angles of each angle in each sub-grid of the river network map and determining the angle bisector of each angle; and dividing each river in each sub-grid into corresponding hydrological response units according to the angle bisectors. This method, based on the principle that points on the angle bisector are equidistant from both sides, divides river networks in plain areas into hydrological response units, solving the problem that the DEM extraction method is not suitable for dividing hydrological response units in plain areas. This method is of great significance for hydrological forecasting and water resource planning in plain areas.

[0066] In another embodiment of the present invention, before step S21 above, if the actual channel of a river can be directly regarded as a straight channel, the length of each channel is obtained and the flow direction of each channel is determined, including: directly measuring the length of the straight channel, obtaining the length of each straight channel, and determining the flow direction of each straight channel.

[0067] Before step S21 above, if the actual river channel of a certain river is characterized by a large curvature and multiple bends, i.e., the river channel is an arc-shaped or circular channel, then the length of each channel is obtained and the flow direction of each channel is determined, including: first, fitting the arc-shaped channel into at least one straight channel; then, obtaining the length of each fitted straight channel and determining the flow direction of each fitted straight channel.

[0068] The step of fitting the arc-shaped river channel into at least one straight river channel comprises: firstly determining a virtual center and an arc length of the arc-shaped river channel; obtaining an arc angle of the arc-shaped river channel based on the virtual center; and fitting the arc-shaped river channel into at least one straight river channel by means of polyline fitting according to the arc angle and the arc length.

[0069] In practice, the arc-shaped river channel can also be converted into at least one straight river channel in other ways, which are not limited in the present application.

[0070] In another embodiment of the present application, the present application further provides a method for calculating the area of the hydrological response unit, which comprises: calculating the area of the hydrological response unit according to the shape and side length of the hydrological response unit.

[0071] In practice, the shape of the obtained sub-grid is usually a triangular river network, a quadrilateral river network and a polygonal river network. In the present embodiment, the inventor describes the division method of the hydrological response unit and the calculation method of the area of the divided hydrological response unit for the three kinds of river networks. Specifically as follows:

[0072] 1) Sub-grid for triangular river network

[0073] The hydrological response unit is divided according to the angle bisector, and the catchment area of the hydrological response unit is obtained by the triangular formula and the sine theorem.

[0074] As shown in FIG. 1, a, b and c are three river channels; ∠A, ∠B and ∠C are the included angles between the river channels; D is the intersection point of the angle bisectors; AD, BD and CD are the angle bisectors of the respective angles, and the distances from the points on the angle bisectors to the respective sides are equal; a cluster of arrows is the flow direction of the simulated water flow, and the water flow flows towards the nearest side. The actual lengths of the river channels a, b and c are measured, and the lengths of the sides a, b and c in the triangle are adjusted based on a predetermined reduction ratio; and the angles ∠A, ∠B and ∠C in the triangle are tested. Figure 5 Figure 5 Then, the area of each hydrological response unit corresponding to each river channel is calculated based on the triangular formula and the sine theorem. For example, the area of the hydrological response unit BCD is calculated, which is specifically:

[0075] The hydrological response unit on the side of the river channel a is BCD, and the area formula thereof can be obtained by combining the sine theorem, as shown in formula (1). The area calculation formula of the hydrological response unit is:

[0076]

[0077] (1)

[0078] In formula (1), , ​​​, , , , .

[0079] Similarly, if the other side of the river channel a is also divided into a hydrological response unit f, based on the same method as above, the area of the other side of the hydrological response unit is calculated, and then for the river channel a, the hydrological response unit f and the hydrological response unit BCD all belong to the hydrological response unit of the river channel a, so the area of the hydrological response unit of the river channel a can be the total area obtained by area superposition of the hydrological response unit f and the hydrological response unit BCD. In the scenario of rainwater confluence, the confluence area of the river channel a can be the area obtained by area superposition of all hydrological response units of the river channel a.

[0080] Wherein, the river channel a can be an edge of a subgrid or an edge of multiple subgrids, and correspondingly, each subgrid of the river channel a will become a hydrological response unit of the river channel a. For example, the river channel a is a common edge of the subgrid No. 1 and the subgrid No. 2, so the subgrid No. 1 will divide a hydrological response unit No. 1 for the river channel a, and the subgrid No. 2 will also divide a hydrological response unit No. 2 for the river channel a, and when confluence, the water flow of the hydrological response unit No. 1 and No. 2 will all flow to the river channel a. Therefore, if the confluence area of the river channel a is calculated, the areas of all the multiple hydrological response units of the river channel a need to be superimposed.

[0081] 2) For the subgrids of quadrilateral river network

[0082] The hydrological response unit is divided according to the angle bisector, and the catchment area of the hydrological response unit is obtained by the triangular formula and the sine theorem.

[0083] As shown in FIG. 1, Figure 6 , Figure 6 , wherein a, b, c, d are four river channels; ∠A, ∠B, ∠C, ∠D are the included angles between the river channels; E, F are the intersection points of the angle bisectors; AF, BE, CE, DF, EF are the angle bisectors, and the distances from the points on the angle bisectors to the two sides are equal; G, H are the intersection points of E, F and the perpendicular lines of AB; a cluster of arrows is the flow direction of the simulated water flow, and all flow into the direction of the nearest river channel. The actual lengths of the river channels a, b, c, d are measured, and based on the preset reduction ratio, they are adjusted to Figure 6 , the lengths of the sides a, b, c, d; and the angles of ∠A, ∠B, ∠C, ∠D in the quadrilateral are tested.

[0084] It should be noted that for the sub-grid of quadrilateral river network, the angle bisectors of its four corners may intersect at a point in the sub-grid, or may not intersect at a point in the sub-grid. The area calculation methods for the two cases are described below.

[0085] A. If the angle bisectors intersect at a point:

[0086] At this time, the angle bisectors intersect at a point, i.e. Figure 6 E and F points coincide in the middle, and the area to be solved is the area of a triangle. The solving process is equivalent to the area solving of a triangle in the plain area, and the method is described in the above 1) part.

[0087] B. If the angle bisectors do not intersect at a point:

[0088] At this time, the intersection point of the angle bisectors is E and F points, and the area to be solved can be divided into two triangles and one quadrilateral. For example Figure 6 In the middle, the hydrological response unit corresponding to the river bank on one side of the river a is quadrilateral ABEF, which is divided into two triangles and one quadrilateral as shown in formula (2). The lengths of edges a, b, c, d and the angles of ∠A, ∠B, ∠C, ∠D are known. The area formula can be obtained by combining the sine theorem as shown in formula (3)-(5).

[0089] (2)

[0090] (3)

[0091] (4)

[0092] (5)

[0093] In formula (3), , , ; similarly in formula (4), , , ; in formula (5), At this time, the quadrilateral EFHG is a trapezoid, , , .

[0094] 3) For the sub-grid of polygon river network

[0095] For the case of a large bending arc of the river channel and multiple bending, that is, arc or circle, a broken line fitting is adopted, and the river channel is approximated as a plurality of straight lines, a polygon is formed, and then an angle bisector is divided for the polygon sub-grid, and it is judged whether the angle bisector intersects in the sub-grid. If it intersects, the method described in the first part above is used to calculate the area of the hydrological response unit of the river channel; if it does not intersect, the method described in the second part above is used to calculate the area of the hydrological response unit of the river channel.

[0096] Finally, when calculating the catchment area of the river channel, the areas of all the hydrological response units of the river channel are superimposed, and the sum of the superposition is the catchment area of the river channel.

[0097] In the embodiment of the present application, the above describes the calculation method of the catchment area for a river channel, and for the entire river containing the river channel, the catchment area of the river is the superimposed sum of the catchment areas of all the river channels. For example, as shown in the figure, Figure 3 for the river a, the catchment area of the river is the superimposed sum of the catchment areas of the river channel a1, the river channel a2 and the river channel a3. Among them, the hydrological response unit of the river channel a2 can be understood as: the superimposed sum of the hydrological response unit of the triangle HDJ based on the nearest principle and divided by the angle bisector for the river channel a2, and the hydrological response unit of the triangle JEF based on the nearest principle and divided by the angle bisector for the river channel a2.

[0098] In another embodiment of the present application, a method for dividing a hydrological response unit in a plain area is provided, which can include the following steps:

[0099] Step 1, determining a grid according to the actual distribution of the river channel.

[0100] In specific implementation, the grid is divided according to the actual distribution of the river channel, and one or more grids are obtained. The form of the grid includes triangle, quadrilateral, polygon, etc., and the edges of the grid represent the river channel. If two river channels do not intersect, the line where the river channel is located is extended based on the flow direction of the river channel, so that the two non-intersecting river channels intersect.

[0101] Step 2, obtaining the length of each edge and the angle of each corner of each grid.

[0102] In specific implementation, each grid is measured separately to measure the length of each edge and the angle of each corner of each grid.

[0103] Step 3, drawing a river channel grid map based on the length of the edge and the angle of the grid.

[0104] In practice, the river channel grid is drawn in the drawing software based on the side lengths and angles of each grid obtained in step 2. For arc-shaped rivers, a polyline fitting method is used to fit the arc-shaped river into at least one straight river before drawing the river channel grid.

[0105] Step 4: Divide the river channel into hydrological response units based on the river grid map.

[0106] In practice, firstly, for each subgrid in the river grid map, the angle bisectors of each angle in the subgrid are created; then, using the angle bisectors as boundaries, the area on the same side as a certain river is taken as the control range of that river, and this control range is the hydrological response unit of that river on that subgrid.

[0107] Step 5: Calculate the area of ​​the hydrological response unit based on its shape and size.

[0108] In practice, for a specific river channel, the area of ​​the hydrological response unit is calculated based on the shape and size of the hydrological response unit.

[0109] Step 6: Determine the catchment area.

[0110] In practice, if a river channel is used as an edge of multiple grids, then the river channel has corresponding hydrological response units on each grid. In this case, steps 2-5 must be repeated to superimpose the areas of the hydrological response units on all grids. The superimposed area is the total area of ​​the hydrological response units of the river channel.

[0111] For example, such as Figure 3 As shown, for river a, the catchment area of ​​the river is the sum of the catchment areas of the three channels a1, a2, and a3. The hydrological response unit of channel a2 is the sum of the hydrological response units assigned to channel a2 in triangle HDJ based on proximity and the angle bisector, and the hydrological response units assigned to channel a2 in triangle JEF based on proximity and the angle bisector.

[0112] In its implementation, this invention solves the problem of dividing hydrological response units in plain areas, which is of great significance for hydrological forecasting and water resources planning.

[0113] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0114] The above describes in detail the method for dividing the hydrological response unit in the plain area provided by the present application, and the principle and implementation mode of the present application are described by using specific examples. The above description of the examples is only used to help understand the method of the present application and its core idea. Meanwhile, for the general technical personnel in the field, the specific implementation mode and application range will be changed according to the idea of the present application. In summary, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A method for dividing hydrological response units in a plain area, characterized in that, The partitioning method includes: Based on the distribution of river channels in the plain area, the length of each river channel is obtained, and the flow direction of each river channel is determined; based on the length and flow direction of multiple river channels, a river channel grid map composed of multiple river channels is determined. Obtain the angles of each corner in each subgrid of the river channel grid map, and determine the angle bisector of each corner; Based on the angle bisector, each river channel in each subgrid is divided into corresponding hydrological response units; Wherein, the river channel is an arc-shaped river channel, and the step of obtaining the length of each of the river channels and determining the flow direction of each of the river channels includes: The arc-shaped river channel is fitted into at least one straight river channel by polyline fitting; Obtain the length of each of the straight river channels and determine the flow direction of each of the straight river channels.

2. The method according to claim 1, characterized in that, The river channel is a straight channel. Obtaining the length of each river channel and determining the flow direction of each river channel includes: Obtain the length of each of the straight channels and determine the flow direction of each of the straight channels.

3. The method according to claim 1, characterized in that, The step of fitting the arc-shaped river channel into at least one straight river channel by polyline fitting includes: Determine the virtual center and arc length of the arc-shaped river channel; Based on the virtual center, obtain the arc angle of the arc-shaped river channel; Based on the arc angle and arc length, the arc-shaped river channel is fitted into at least one straight river channel using a polyline fitting method.

4. The method according to claim 1, characterized in that, The process of determining a river network map composed of multiple river channels based on their lengths and flow directions includes: Based on the length and direction of each river channel, determine the line segment containing each river channel; If multiple line segments intersect each other, the grid diagram formed by the multiple line segments will be determined as a river grid diagram formed by the multiple river channels; or If there are two adjacent line segments that do not intersect among the multiple line segments, then extend the two adjacent line segments until they intersect. The grid diagram composed of the unextended line segments and the extended line segments is determined as a river grid diagram composed of the multiple river channels.

5. The method according to claim 1, characterized in that, Based on the angle bisector, each of the waterways in each of the sub-grids is divided into corresponding hydrological response units, and the method further includes: Based on the principle of proximity, the area adjacent to the river channel is divided into hydrological response units of the river channel, with the angle bisector as the boundary.

6. The method according to claim 5, characterized in that, If the angle bisectors of all angles in the subgrid intersect at a single point in the subgrid, the area adjacent to the river channel, based on the principle of proximity and using the angle bisectors as boundaries, is divided into hydrological response units for the river channel, including: Based on the angle bisectors of each angle in the sub-grid, the sub-grid is divided into multiple triangular regions; Based on the principle of proximity, the triangular region adjacent to each river channel is divided into hydrological response units corresponding to the river channel, with the angle bisector as the boundary.

7. The method according to claim 5, characterized in that, If the angle bisectors of all angles in the subgrid do not intersect at a single point in the subgrid, the area adjacent to the river channel, based on the principle of proximity and using the angle bisectors as boundaries, is divided into hydrological response units for the river channel, including: Connect each pair of intersection points of the angle bisectors in the subgrid to obtain at least one intersection line segment; Based on the angle bisectors of each angle and the intersection line segments, the subgrid is divided into multiple regions; Based on the principle of proximity, the area adjacent to each river channel is divided into hydrological response units corresponding to the river channel, with the angle bisector as the boundary.

8. The method according to any one of claims 1-7, characterized in that, The method further includes: The area of ​​the hydrological response unit is calculated based on its shape and side length.

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